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Mad Cow Disease - Bovine Spongiform Encephalopathy
- Information, Guides, and References

 
Bovine spongiform encephalopathy (more commonly BSE or mad cow disease) is a fatal neurodegenerative disease of cattle, part of the transmissible spongiform encephalopathy family of diseases. BSE is believed to be caused by prions and to have evolved from the sheep prion disease scrapie through the use of sheep protein in animal feed for cattle. One type of human prion disease, Creutzfeldt-Jakob disease, is thought to be transmitted to humans through the ingestion of beef contaminated with BSE. Another related prion based disease found in deer and elk is Chronic Wasting Disease (CWD). .... Eating meat from cattle with BSE is thought to have caused the new variant of Creutzfeldt-Jakob disease (nvCJD) in about 131 cases (2003 June data) in the United Kingdom and some few in France. Rodents injected with brain tissue obtained from cows with BSE develop a fatal neurological disorder in one or two years. (continued ... see reference in continuation) Latest books on: mad cow disease
The Pathological Protein: Mad Cow, Chronic Wasting, and Other Deadly Prion Diseases by Philip Yam
How the Cows Turned Mad by Maxime Schwartz
The Trembling Mountain: A Personal Account of Kuru, Cannibals, and Mad Cow Disease by Robert Klitzman
The Mad Cow Crisis: Health and the Public Good by Scott C. Ratzan
Mad Cow Disease (Bovine Spongiform Encephalopathy B.S.E: Index of New Information and Guide-Book for Reference and Research by Research
Mad Cow Disease in America: Something Special and Other Plays by Lance Tait
Mad Cows and Cannibals: A Guide to the Transmissible Spongiform Encephalopathies by Charlotte A. Spencer
Mad Cow U.S.A.: Could the Nightmare Happen Here? by Sheldon Rampton
The Trembling Mountain: A Personal Account of Kuru, Cannibals, and Mad Cow Disease by Robert Klitzman
Where's the Beef? : The Mad Cow Disease Conspiracy by David L Cole
Mad Cows & Milk Gate by Virgil M. Hulse
Mad Cow Disease: Bovine Spongiform Encephalopathy by Tom Ridgway
The Mad Cow Crisis: Health and the Public Good by Scott C. Ratzan
Prions and Mad Cow Disease by Brian K. Nunnally
How the Cows Turned Mad by University of California Press


Latest books on: Bovine Spongiform Encephalopathy
Mad Cow Disease (Bovine Spongiform Encephalopathy B.S.E: Index of New Information and Guide-Book for Reference and Research by Research
Mad Cows and Cannibals: A Guide to the Transmissible Spongiform Encephalopathies by Charlotte A. Spencer
Mad Cow Disease: Bovine Spongiform Encephalopathy by Tom Ridgway
Sub-Acute Spongiform Encephalopathies: Proceedings of a Seminar in the Cec Agricultural Research Programme, Held in Brussels, 12-14 November, 1990 by Ray Bradley
Potential transmission of spongiform encephalopathies to humans : the Food and Drug Administration's (FDA) ruminant to ruminant feed ban and the safety of other products : hearing before the Committee on Government by U.S. G.P.O.
Mad Cow Disease Bovine Spongiform Encephalopathy B.S.E: Index of New Information and Guide-Book for Reference and Research by Research
Bovine Spongiform Encephalopathy: the Bse Dilemma by Clarence J. Gibbs
The Bovine Spongiform Encephalopathy Compensation (Amendment) Order 1997 (Statutory Instruments: 1997) by The Stationery Office Books (Agencies)
The Bovine Spongiform Encephalopathy (No. 2) (Amendment) Order 1999: ??????????????? (Statutory Instruments: 1999: 921) by The Stationery Office Books (Agencies)
The Bovine Spongiform Encephalopathy Order 1991: Animals (Statutory Instruments: 1991: 2246) by The Stationery Office Books
Die BSE-Krise : Agrarpolitik im Spannungsfeld zwischen Handelsfreiheit und Konsumentenschutz by Christian Wolters
Food safety : controls can be strengthened to reduce the risk of disease linked to unsafe animal feed : report to the Honorable Richard J. Durbin, United States Senate (SuDoc GA 1.13:RCED-00-255) by U.S. General Accounting Office
An Act to Establish a Federal Interagency Task Force for the Purpose of Coordinating Actions to Prevent the Outbreak of Bovine Sp by U.S. National Archives and Records Administration
Bovine Spongiform Encephalopathy (BSE) and Creutzfeldt-Jacob Disease (CJD): Recent Developments: Minutes of Evidence: Recent Developments: [HC]: [1995-96]: House of Commons Papers: [1995-96] (House of Commons Paper) by Jerry Wiggin
The Bovine Spongiform Encephalopathy (No. 2) Order 1996 (Statutory Instruments: 1996) by The Stationery Office Books (Agencies)
It is possible to detect the abnormal prion protein in some, but not all, of these animals' brain tissues. Although there is substantial evidence for transmission of the disease by prions, and various theories have developed about the absorption of prion proteins by intestinal cells, there is still no definite proof reliably showing that eating infected beef is really the cause of the new variant Creutzfeldt-Jakob disease. There is also some concern about those who work with (and therefore inhale) cattle meat and bone meal, such as horticulturalists who use it as fertilizer. The first BSE epidemic was recognized in the United Kingdom in 1986. BSE is thought to have spread by the practice of feeding cattle a diet which included meat and bone meal, a high-protein substance obtained from the remnants of butchered animals. This practice allowed the accumulation of prions over many generations. The use of meat and bone meal as a protein supplement in cattle feed was widespread in Europe prior to about 1987. Soybean meal is the primary plant-based protein supplement fed to cattle, and soybeans do not grow well in Europe. This means high costs, and cattlemen throughout Europe turned to the less expensive animal byproduct feeds as an alternative. Soybean meal is cheap and plentiful in the United States. As a result, the use of animal byproduct feeds was never as common as it was in Europe. U.S. federal regulations have partially prohibited the use of animal byproducts in feed for ruminants since June 1997. Ruminant animals, such as cattle, sheep and goats, are not allowed to be fed back to other ruminants. Pigs, chickens, pets, deer, and other animals, however, still can eat ruminant slaughterhouse waste as well as the animal byproducts of their own species. Ruminants also can still be fed non-ruminant waste under the rules. [1] In February 2001, the United States General Accounting Office released a report that said the United States Food and Drug Administration, which is in charge of regulating animal feed, has not adequately policed the feeding ban. [2] The USDA now estimates that, should BSE occur in a U.S. cattle herd, it would die out of its own accord rather than spreading, due to these restrictions. At least three cases of BSE have occurred in North America, with one occuring in the United States on December 23, 2003. No case of new-variant Creutzfeldt-Jakob disease has occurred in North America so far, except among those who have travelled to Europe. A case of BSE was reported in Canada on May 20, 2003. It occurred in a single older cow that may have contracted the disease from contaminated feed in earlier years. The animal had been destroyed and declared unfit for consumption prior to being diagnosed. The United States issued a temporary ban on all Canadian beef. The last North American case of BSE was in 1993, involving an animal born in Britain. On September 26, 2003, it was reported that an experimental treatment given to a Northern Irish teenager halted the progress of brain damage caused by variant Creutzfeldt-Jakob Disease (vCJD). The drug, called pentosan polysulphate and commonly used to treat cystitis, was injected into the patient's brain. The patient's weight and heart rate returned to normal levels after receiving the treatment. Still, there is no cure for vCJD, a fatal disease. [3] On December 23, 2003, the first case of BSE in the United States was found in a single Holstein cow in Washington State. Agriculture Secretary Ann Veneman said a sample taken on December 9 was tested twice and came back as a "presumptive positive." Ms. Veneman said that 20,526 cows had been tested in 2003, and that this discovery was "a clear indication that our surveillance and detection program is working." Shortly after the discovery of BSE in the United States, Japan and South Korea instituted temporary bans on US beef imports, until more information about the US BSE outbreak becomes available. Japan and South Korea are the number 1 and number 3 importers of US beef in the world. The economic impact of their bans on beef imports from the US will be critical for all involved, and it is hoped that the beef crisis can be resolved quickly so trading can begin again. [4] From Wikipedia, the free encyclopedia.

 

 

 

PUBMED based records for the year 2003 presented for scholars to expedite research

:(2003). "International Animal Health, disease surveillance and trade in 2002." Vet Rec 152(17): 520-4.
 
(2003). "Eight questions consumers should ask on the threat of mad cow disease." Wkly Epidemiol Rec 78(6): 36-8.
 
Adjou, K. T., S. Simoneau, et al. (2003). "A novel generation of heparan sulfate mimetics for the treatment of prion diseases." J Gen Virol 84(Pt 9): 2595-603.
 The accumulation of PrP(res), the protease-resistant abnormal form of the host-encoded cellular prion protein, PrP(C), plays a central role in transmissible spongiform encephalopathies. Human contamination by bovine spongiform encephalopathy (BSE) has propelled many scientific teams on a highway for anti-prion drug development. This study reports that heparan sulfate mimetics (HMs), developed originally for their effect on tissue regeneration, abolish prion propagation in scrapie-infected GT1 cells. PrP(res) does not reappear for up to 50 days post-treatment. When tested in vivo, one of these compounds, HM2602, hampered PrP(res) accumulation in scrapie- and BSE-infected mice and prolonged significantly the survival time of 263K scrapie-infected hamsters. Interestingly, HM2602 is an apparently less toxic and more potent inhibitor of PrP(res) accumulation than dextran sulfate 500, a molecule known to exhibit anti-prion properties in vivo. Kinetics of PrP(res) disappearance in vitro and unaffected PrP(C) levels during treatment suggest that HMs are able to block the conversion of PrP(C) into PrP(res). It is speculated that HMs act as competitors of endogenous heparan sulfates known to act as co-receptors for the prion protein. Since these molecules are particularly amenable to drug design, their anti-prion potential could be developed further and optimized for the treatment of prion diseases.

Agrimi, U., M. Conte, et al. (2003). "Animal transmissible spongiform encephalopathies and genetics." Vet Res Commun 27 Suppl 1: 31-8.
 The genotype of the host plays a crucial role in the pathogenesis of transmissible spongiform encephalopathies (TSEs). In this respect, the most important factor is represented by the gene of the prion protein (PrP). The present work summarizes the currently available knowledge on the genetic basis of TSEs focusing, in particular, on sheep scrapie. Interest in this disease has grown markedly following the discovery of bovine spongiform encephalopathy, both for scientific and health reasons. In Italy, specific research grants from the Ministry of Health and the National Research Council (CNR), together with cooperation between the Istituto Superiore di Sanita and the Istituti Zooprofilattici Sperimentali, have allowed us to study the PrP genotype and to investigate the genetic susceptibility to scrapie in the most important Italian sheep breeds, with special reference to Sarda, Comisana and Massese. The PrP genotype in relation to scrapie susceptibility was also studied in goats of Ionica breed.

Arnold, M. and J. Wilesmith (2003). "Modelling studies on bovine spongiform encephalopathy occurrence to assist in the review of the over 30 months rule in Great Britain." Proc R Soc Lond B Biol Sci 270(1529): 2141-5.
 The objective of this study was to contribute to a risk assessment to review the over 30 months (OTM) scheme in cattle, whereby all cattle aged over 30 months slaughtered in the UK are removed from the human food chain. We use back-calculation methods to estimate the impact of changes to the OTM rule, by using passive and active surveillance data collected between 1 July 2001 and 30 June 2002. There are two types of change considered: increasing the age limit and allowing animals born after a certain date into the food chain. Results indicate that under the OTM rule less than 1 animal in the last 12 months of the incubation period would enter the food chain in 2003. The birth date changes considered and small changes to the upper age limit would increase this number by a relatively small amount.

Badiola, J. J., A. Rabano, et al. (2003). "Emboli in bulls killed in Spanish traditional bullfighting." J Comp Pathol 128(2-3): 207-9.
 The finding of brain tissue fragments in blood and lungs of cattle stunned in slaughterhouses has raised concerns about food safety in the context of the bovine spongiform encephalopathy epidemic. In the present study, the possible occurrence of brain tissue emboli in animals killed in traditional Spanish bullfighting was investigated. Thorough histological analysis of multiple possible target organs was carried out in 434 bulls. No evidence of brain tissue embolism was obtained, but emboli from diverse sources were detected in pulmonary and hepatic tissue of a significant number of animals. These emboli seem to have been caused by the use of a long sword, which extensively disrupts intra-thoracic and intra-abdominal organs and vascular structures.

Barret, A., F. Tagliavini, et al. (2003). "Evaluation of quinacrine treatment for prion diseases." J Virol 77(15): 8462-9.
 Based on in vitro observations in scrapie-infected neuroblastoma cells, quinacrine has recently been proposed as a treatment for Creutzfeldt-Jakob disease (CJD), including a new variant CJD which is linked to contamination of food by the bovine spongiform encephalopathy (BSE) agent. The present study investigated possible mechanisms of action of quinacrine on prions. The ability of quinacrine to interact with and to reduce the protease resistance of PrP peptide aggregates and PrPres of human and animal origin were analyzed, together with its ability to inhibit the in vitro conversion of the normal prion protein (PrPc) to the abnormal form (PrPres). Furthermore, the efficiencies of quinacrine and chlorpromazine, another tricyclic compound, were examined in different in vitro models and in an experimental murine model of BSE. Quinacrine efficiently hampered de novo generation of fibrillogenic prion protein and PrPres accumulation in ScN2a cells. However, it was unable to affect the protease resistance of preexisting PrP fibrils and PrPres from brain homogenates, and a "curing" effect was obtained in ScGT1 cells only after lengthy treatment. In vivo, no detectable effect was observed in the animal model used, consistent with other recent studies and preliminary observations in humans. Despite its ability to cross the blood-brain barrier, the use of quinacrine for the treatment of CJD is questionable, at least as a monotherapy. The multistep experimental approach employed here could be used to test new therapeutic regimes before their use in human trials.

Belay, E. D., R. A. Maddox, et al. (2003). "Monitoring the occurrence of emerging forms of Creutzfeldt-Jakob disease in the United States." Neurology 60(2): 176-81.
 
Belkin, N. L. (2003). "Creutzfeldt-Jakob disease--identifying prions and carriers." Aorn J 78(2): 204-8, 210.
 Two major obstacles to be overcome in minimizing the possibility of transmitting Creutzfeldt-Jakob disease or variant Creutzfeldt-Jakob disease are associated with identifying the prion on disinfected surgical instruments and identifying carriers of the protease-resistant form of the prion. New developments indicate that the means for doing both soon may be available.

Bellagamba, F., F. Valfre, et al. (2003). "Polymerase chain reaction-based analysis to detect terrestrial animal protein in fish meal." J Food Prot 66(4): 682-5.
 The recent European bovine spongiform encephalopathy crisis has focused attention on the importance of adopting stringent control measures to avoid the risk of the diffusion of mad cow disease through meat meal-based animal feedstuffs. Potential adulteration of such feedstuffs with bone particles from terrestrial animals is determined by microscopic examination by law before the release of these feedstuffs for free circulation in the European Community. This study describes a DNA monitoring method to examine fish meal for contamination with mammalian and poultry products. A polymerase chain reaction (PCR) method based on the nucleotide sequence variation in the 12S ribosomal RNA gene of mitochondrial DNA was developed and evaluated. Three species-specific primer pairs were designed for the identification of ruminant, pig, and poultry DNA. The specificity of the primers used in the PCR was tested by comparison with DNA samples for several vertebrate species and confirmed. The PCR specifically detected mammalian and poultry adulteration in fish meals containing 0.125% beef, 0.125% sheep, 0.125% pig, 0.125% chicken, and 0.5% goat. A multiplex PCR assay for ruminant and pig adulteration was optimized and had a detection limit of 0.25%.

Beringue, V., G. Mallinson, et al. (2003). "Regional heterogeneity of cellular prion protein isoforms in the mouse brain." Brain 126(Pt 9): 2065-73.
 Prion diseases are a group of invariably fatal neurodegenerative disorders that include Creutzfeldt-Jakob disease in humans, scrapie in sheep and goats, and bovine spongiform encephalopathy in cattle. The infectious agent or prion is largely composed of an abnormal isoform (PrPSc) of a host encoded normal cellular protein (PrPc). The conversion of PrPc to PrPSc is a dynamic process and, for reasons that are not clear, the distribution of spongiform change and PrPSc deposition varies among prion strains. An obvious explanation for this would be that the transformation efficiency in any given brain region depends on favourable interactions between conformations of PrPc and the prion strain being propagated within it. However, identification of specific PrPc conformations has until now been hampered by a lack of suitable panels of antibodies that discriminate PrPc subspecies under native conditions. In this study, we show that monoclonal antibodies raised against recombinant human prion protein folded into alpha or beta conformations exhibit striking heterogeneity in their specificity for truncations and glycoforms of mouse brain PrPc. We then show that some of these PrPc isoforms are expressed differentially in certain mouse brain regions. This suggests that variation in the expression of PrPc conformations in different brain regions may dictate the pattern of PrPSc deposition and vacuolation, characteristic for different prion strains.

Bhakdi, S. and J. Bohl (2003). "Prions, mad cow disease, and preventive measures: a critical appraisal." Med Microbiol Immunol (Berl) 192(3): 117-22.
 
Billette de Villemeur, T. (2003). "[Prion diseases]." Arch Pediatr 10(1): 54-7.
 Prion is an ubiquitous membrane protein in mammals, which is mainly synthesized in central nervous system. Prion diseases are the result of an accumulation of prions having acquired a resistance to the physiological degradation and an infectious capacity. Human prion diseases are very rare diseases including sporadic Creutzfeldt-Jakob disease (the most frequent form manifesting as a presenile dementia), familial transmissible spongiform encephalopathies and two juvenile transmissible forms: iatrogenic Creutzfeldt-Jakob secondary to treatment with human extractive growth hormone and variant Creutzfeldt-Jakob disease resulting from bovine spongiform encephalopathy food transmission. Knowledge of the underlying prion biology has led to preventive measures which offer today a reasonable guarantee against the juvenile forms.

Bird, S. M. (2003). "European Union's rapid TSE testing in adult cattle and sheep: implementation and results in 2001 and 2002." Stat Methods Med Res 12(3): 261-78.
 After the discovery of variant Creutzfeldt-Jakob disease (vCJD), scientific advances quickly led to post-mortem tests to identify late-stage bovine spongiform encephalopathy (BSE) disease. These were first used in Switzerland in 1999 for active BSE surveillance of a) fallen and emergency-slaughter bovines (risk stock) and b) 5% sample of routinely slaughtered cattle over 30 months of age. In 1999 and 2000, Switzerland's estimated 103 BSE positives per 1000000 adult cattle put it in the same BSE risk classification as UK and Portugal. In July 2000, the European Union's Scientific Steering Committee published its methodology (and first vetted results) for geographical BSE risk (GBR) assessment in cattle. Member states with no BSE cases found themselves, on rational assessment, classified as GBR III (BSE likely but not confirmed, or confirmed at a lower level). Because of Europe's thus highly assessed BSE risks, active BSE surveillance of adult cattle in all member states began in January 2001 using one of three validated post-mortem tests. Implementation was variable across member states in January to March 2001 but, where operational, active surveillance was typically achieved for around 13300 routinely slaughtered and 1000 risk stock per month per 1000000 adult cattle; BSE positive rates were 60 and 600 per 1000000 routinely slaughtered and risk cattle, respectively. By the second half of 2001, active BSE surveillance was operating reasonably in most member states, although anomalies persisted. Performance and results for July to December 2001 and for January to June 2002 are considered in detail. The BSE positive rate decreased substantially in UK, Portugal and Ireland between semesters, whereas Spain's rates increased for both routinely slaughtered and risk bovines. Based on 1450000 routinely slaughtered and 135000 risk stock as standard, France could have expected 153 BSE positives in July to December 2001 (109 in January to June 2002); Italy 154 (67); and Germany only 39 (48). When sample-based surveillance data were scaled up and combined with clinical BSE cases, Great Britain's BSE positives were estimated at around 400 per 1000000 adult cattle in 2002 compared with over 1000 per 1000000 adult cattle in 2000. Age distributions for cattle subject to active BSE surveillance have been underexploited. The major transmissible spongiform encephalopathy (TSE) which affects sheep and goats is scrapie. Passive surveillance of scrapie is associated with substantial under-reporting. Susceptibility to scrapie depends strongly on sheep genotype; but resistance to scrapie does not necessarily confer resistance of sheep to BSE. Because of uncertainty about the true prevalence of scrapie-infected adult sheep and concern that BSE in sheep may be missed, the European Union pre-empted its planned evaluation of rapid post-mortem TSE tests in sheep by requiring the rapid TSE testing of small ruminants from April 2002 with one of the three cattle-validated tests. Basic requirements for active TSE surveillance in sheep were: random sample of 6000 fallen sheep and of 60000 routinely slaughtered adult native sheep to be tested per member state by end March 2003. Lower surveillance targets were set for countries with under 1000000 adult sheep. Adequately to map scrapie-susceptible genotypes and identify resistant genotypes, a random sample of 500 routinely slaughtered native adult sheep was to be genotyped, together with each TSE rapid test positive adult sheep and two sets of three suitably sampled controls. By the end of August 2002, when 41% of the initial surveillance time had elapsed, only 20% of the European joint target for routinely slaughtered adult sheep had been completed, but that for fallen sheep was exceeded. Except in Ireland, the upper 95% confidence bound on TSE prevalence exceeded 500 per 1000000 routinely slaughtered adult sheep in reporting-compliant countries with more than 1000000 adult sheep. The UK, Greece, Italy and France were likely to approach the goal of 100 TSE rapid test positives on completion of their assigned first-year surveillance target for sheep. Results from the recommended genotyping of TSE positive adult sheep and controls for use in inferring differential TSE-positive susceptibility by genotype are awaited. Only by genotyping 5000-50000 TSE-positive adult sheep, a massive undertaking even on the European scale, will it become clear whether scrapie resistance is relative rather than absolute. This paper details Europe's quantitative evolution in TSE surveillance.

Bonacina, C. (2003). "The BSE emergency in Lombardy." Vet Res Commun 27 Suppl 1: 63-7.
 
Bottero, M. T., I. A. Dalmasso, et al. (2003). "Development of a PCR assay for the detection of animal tissues in ruminant feeds." J Food Prot 66(12): 2307-12.
 The European Community ban on use of meat and bone meal in ruminant feed, as a consequence of the spread of bovine spongiform encephalopathy in Europe, has prompted a number of investigations about the possibility of detecting animal tissues in feedstuff. In this paper, a study on vertebrate primers, designed in the 16S rRNA gene of mitochondrial DNA, is described. These primers were able to amplify fragments that contained between 234 and 265 bp. The fragments were specific for bovine, porcine, goat, sheep, horse, rabbit, chicken, trout, and European pilchard and were confirmed by sequence analysis amplicons. The primers were used in a PCR assay applied to five samples of meat and blood meals of different species and subjected to severe rendering treatments (134.4 to 141.9 degrees C and 3.03 to 4.03 bar for 24 min). The presence of vertebrate tissues was detected in all samples. The assay proved to be rapid and sensitive (detection limit 0.0625%). It can be used as a routine method to detect animal-derived ingredients in animal feedstuff.

Bottero, M. T., T. Civera, et al. (2003). "Design of universal primers for the detection of animal tissues in feedstuff." Vet Res Commun 27 Suppl 1: 667-9.
 
Bozzetta, E., M. Caramelli, et al. (2003). "BSE surveillance in Italy: neuropathological findings in cattle in the frame of the passive surveillance programme." J Vet Med A Physiol Pathol Clin Med 50(1): 48-9.
 
Bradley, R. (2003). "BSE risks for humans consuming beef and beef products: how any risks are managed." Vet Res Commun 27 Suppl 1: 15-23.
 
Brown, D. A., M. E. Bruce, et al. (2003). "Comparison of the neuropathological characteristics of bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (vCJD) in mice." Neuropathol Appl Neurobiol 29(3): 262-72.
 Bovine spongiform encephalopathy (BSE) and variant Creutzfeldt-Jakob disease (vCJD) belong to a group of diseases called the transmissible spongiform encephalopathies (TSEs). Transmission studies in inbred mice (strain typing) provided overwhelming evidence that vCJD arose from BSE. In this study, we compare the patterns of neuropathology in a panel of three inbred mouse strains (RIII, C57BL and VM) and one cross (C57BL x VM) infected with either vCJD or BSE. For each mouse strain, patterns of abnormal prion protein (PrPres) deposition, astrocytosis and vacuolation were similar in the vCJD- and BSE-challenged mice. Prion protein (PrP)-positive plaques were prominent in the VM and C57BL x VM mice in addition to diffuse PrPres accumulation, whereas only diffuse PrPres labelling was observed in the RIII and C57BL mice. The hippocampus was targeted in all mouse strains, as was the cochlear nucleus in the medulla, both showing consistent severe vacuolation and heavy PrPres deposition. Although the targeting of PrPres was similar in the BSE- and vCJD-infected brains, the amount and intensity of PrPres observed in the brains treated with formic acid during fixation was reduced considerably. The distribution of astrocytosis was similar to the targeting of PrPres deposition in the brain, although some differences were observed in the hippocampi of mice challenged with vCJD. We conclude that there are no significant differences in the targeting of neuropathological changes observed in the BSE- and vCJD-infected mice, consistent with the previous evidence of a link between BSE and vCJD.

Brown, P., R. Meyer, et al. (2003). "Ultra-high-pressure inactivation of prion infectivity in processed meat: a practical method to prevent human infection." Proc Natl Acad Sci U S A 100(10): 6093-7.
 Bovine spongiform encephalopathy contamination of the human food chain most likely resulted from nervous system tissue in mechanically recovered meat used in the manufacture of processed meats. We spiked hot dogs with 263K hamster-adapted scrapie brain (10% wtwt) to produce an infectivity level of approximately 9 log(10) mean lethal doses (LD(50)) per g of paste homogenate. Aliquots were subjected to short pressure pulses of 690, 1,000, and 1,200 MPa at running temperatures of 121-137 degrees C. Western blots of PrPres were found to be useful indicators of infectivity levels, which at all tested pressures were significantly reduced as compared with untreated controls: from approximately 10(3) LD(50) per g at 690 MPa to approximately 10(6) LD(50) per g at 1,200 MPa. The application of commercially practical conditions of temperature and pressure could ensure the safety of processed meats from bovine spongiform encephalopathy contamination, and could also be used to study phase transitions of the prion protein from its normal to misfolded state.

Bruce, M. E. (2003). "TSE strain variation." Br Med Bull 66: 99-108.
 Studies in mice have revealed considerable strain variation in the agents causing transmissible spongiform encephalopathies (TSEs). TSE strains interact with genetic factors in the host (in particular PrP genotype) to influence characteristics of the disease such as incubation period and neuropathology. TSE strains can retain their identity after propagation in different host species or PrP genotypes, showing that these agents carry their own strain-specific information. It is not known whether this information resides in specific self-perpetuating modifications of PrP, or whether a separate informational molecule is required. Strain typing in mice can be used to explore links between TSEs occurring naturally in different species. Such studies have demonstrated that the strain causing BSE in cattle has also infected domestic cats and exotic ungulates. Most importantly, the BSE strain has also been isolated from patients with variant CJD. In contrast, different TSE strains are associated with sporadic CJD and sheep scrapie.

Cao, J., X. A. Lu, et al. (2003). "[Method on PCR detection of bovine materials in animal feedstuffs]." Wei Sheng Yan Jiu 32(1): 30-1.
 The reliable, simple and easy to operate methods were established to extract DNA from animal feedstuffs. A set of PCR primers were designed for bovine specific mitochondrial DNA sequence. With this method, PCR can be successfully utilized to evaluate the presence of bovine materials in animal feedstuffs. A set of commonly used primers of 18Sr-RNA were designed as endogenuous reference gene, and check on the quality of template extraction from animal feedstuffs, and avoid the result of false negative. PCR amplification condition was one cycle of 96 degrees C for 2 min, then 35 cycle of (94 degrees C for 40s, 60 degrees C for 50s, 72 degrees C for 60s), and finally one cycle of 72 degrees C for 5 min. PCR amplified specific gene sequence 271 bp for bovine materials from animal feedstuffs.

Capucchio, M. T., F. Carnino, et al. (2003). "Critical observations on BSE control in Italy." Vet Res Commun 27 Suppl 1: 53-5.
 
Caramelli, M., P. Acutis, et al. (2003). "The role of CEA (Center of Animal Encephalopathies) in the BSE surveillance: BSE in Italy." Vet Res Commun 27 Suppl 1: 29-30.
 
Castilla, J., A. Gutierrez Adan, et al. (2003). "Early detection of PrPres in BSE-infected bovine PrP transgenic mice." Arch Virol 148(4): 677-91.
 Transgenic mouse lines expressing different levels of the bovine prion protein gene (boPrP(C)) were generated. Upon infection with BSE prions, all transgenic lines tested exhibited characteristics of the bovine disease. Typical CNS spongiform degeneration was observed by histopathology and presence of PrP(res) could be detected both by Western blot and immunohistochemistry (IHC) assays, confirming for this model the absence of an interspecies barrier to BSE infection. Differences in incubation times post-inoculation depend upon the expression level of boPrP(C) and the amount of prions in the inoculum. In the absence of clinical signs, pathognomonic markers of disease could be detected as early as 150 or 196 days post-inoculation by IHC and Western blot analysis, respectively. This result indicates that prion infectivity in experimental mouse bioassays can be measured earlier by assessing immunologically the presence of PrP(res) in brains from inoculated animals. Although these transgenic mice were also susceptible to sheep scrapie prion infection, the extent of incubation times was considerably longer and PrP(res) was detected in only 70 % of inoculated mice. Interestingly, transgenic mice-propagated sheep scrapie prions displayed distinct biochemical properties when compared to both the original sheep scrapie and transgenic mouse-propagated BSE inoculum.

Caughey, B. (2003). "Prion protein conversions: insight into mechanisms, TSE transmission barriers and strains." Br Med Bull 66: 109-20.
 Conversion of PrP(C) to aberrant forms such as PrP(Sc) appears to be critical in the transmission and pathogenesis of transmissible spongiform encephalopathies (TSEs) or prion diseases. In vitro studies have shown that TSE-associated, protease-resistant forms of PrP can cause PrP(C) to convert to forms that are similarly protease-resistant under a wide variety of conditions. These observations have provided evidence that pathological forms of PrP have at least limited capacity to propagate themselves, which is necessary for them to be infectious. PrP conversion reactions have proven to be highly specific and appear to account, at least in part, for TSE species barriers and the propagation of strains. Such in vitro conversion systems have yielded insights into the molecular mechanisms of TSE disease and are being exploited as screens for anti-TSE drugs and as bases for diagnostic tests.

Cervenakova, L., P. Brown, et al. (2003). "Failure of immunocompetitive capillary electrophoresis assay to detect disease-specific prion protein in buffy coat from humans and chimpanzees with Creutzfeldt-Jakob disease." Electrophoresis 24(5): 853-9.
 The emergence of a new environmentally caused variant of Creutzfeldt-Jakob disease (vCJD), the result of food-born infection by the causative agent of bovine spongiform encephalopathy (BSE), has stimulated research on a practical diagnostic screening test. The immunocompetitive capillary electrophoresis (ICCE) assay has been reported to detect disease-specific, proteinase-resistant prion protein (PrPres) in the blood of scrapie-infected sheep. We have applied this method to blood from CJD-infected chimpanzees and humans. The threshold of detection achieved with our ICCE was 0.6 nM of synthetic peptide corresponding to the prion protein (PrP) C-terminus, and 2 nM of recombinant human PrP at the optimized conditions. However, the test was unable to distinguish between extracts of leucocytes from healthy and CJD-infected chimpanzees, and from healthy human donors and patients affected with various forms of CJD. Thus, the ICCE assay as presently performed is not suitable for use as a screening test in human transmissible spongiform encephalopathies (TSEs).

Chaala, A. and C. Roy (2003). "Recycling of meat and bone meal animal feed by vacuum pyrolysis." Environ Sci Technol 37(19): 4517-22.
 Due to the recent bovine spongiform encephalopathy (BSE) crisis in the European beef industry, the use of animal-derived products to feed cattle is now severely restricted. Large quantities of waste animal meat and bone meal (MBM), also known as animal flour, have to be safely disposed of or transformed. One disposal option is pyrolysis. Vacuum pyrolysis of an animal flour sample has been performed in a laboratory reactor. The results obtained revealed that vacuum pyrolysis can be an attractive alternative to incineration and cement kilns. The process generated a combustible gas (15.1 wt %), a high calorific value oil (35.1 wt %), a solid residue rich in minerals (39.1 wt %), and an aqueous phase rich in organics (10.7 wt %). The gas and the aqueous phase can be used to provide heat to the vacuum pyrolysis reactor and the MBM drying unit. The oil can be used alone or mixed with petroleum products as a fuel in boilers or gas turbines. Conversion of animal waste by pyrolysis into fuels can contribute to the reduction of greenhouse gases. It is suggested to use the solid residue for agricultural soil enrichment in minerals and as a soil moisturizer.

Chadeau-Hyam, M., A. Tard, et al. (2003). "Estimation of the exposure of the French population to the BSE agent: comparison of the 1980-95 consumption of beef products containing mechanically recovered meat in France and the UK, by birth cohort and gender." Stat Methods Med Res 12(3): 247-60.
 Assuming that human exposure to BSE was through beef mechanically recovered meat (MRM) consumed as burgers and other meat products, we estimated the French consumption of different food items containing beef MRM, and compared these consumptions for French and British populations. To estimate consumption of meat products containing bovine MRM, we used dietary data from national individual and household food surveys conducted between 1980 and 1995. After reconciliation of consumption data between the available surveys and calendar year adjustments, we simulated consumption of one-thousandth of the French population. Consumption was estimated by birth cohort and gender, and for the periods 1980-89 and 1990-95 separately. Data showed that burgers (including manufactured minced meat) represented around 75-80% of the individual consumption of meat products containing MRM, and that consumption of burgers increased by 40% over the 1980-95 period. In all age groups, consumption was higher in males than in females. In both genders, the 1940-69 birth cohort had the highest mean consumption of burgers and other beef products containing MRM. Similar findings have been reported for the UK population. Estimated consumption of bovine MRM per calendar year increased markedly over the study period, concomitantly with an increase of bovine carcasses imported from the UK. Comparison of the 1980-1995 pattern of bovine MRM consumption in the UK and France indicated thatthis consumption peaked later in France than in the UK. This difference might result in different temporal pattern of vCJD incidence.

Chesebro, B. (2003). "Introduction to the transmissible spongiform encephalopathies or prion diseases." Br Med Bull 66: 1-20.
 Sheep scrapie has been known for at least 200 years and was described as a transmissible disease over 100 years ago. Since then, three groups of transmissible spongiform encephalopathies or TSE diseases have been identified in humans including familial, infectious and sporadic types. The discovery of the prion protein (PrP) in the 1980s greatly accelerated knowledge of the biology and pathogenesis of TSE diseases as this protein was found to play a critical role in disease susceptibility and the TSE species-barrier and may also be a component of the infectious agent itself. Nevertheless, the nature of the TSE agents remains an enigma. Proof of the protein-only hypothesis may require generation of biologically active transmissible agent in a cell-free environment where a virus cannot replicate. Conversely, proof of a viral aetiology will require identification and isolation of a candidate virus. Further understanding of the structure of the disease-associated protease-resistant PrP should help elucidate the mechanism of PrP conversion from the normal to the abnormal form. Such information should open up new approaches to both diagnosis and therapy.

Clery, D. (2003). "Public engagement. Bringing science to the cafes." Science 300(5628): 2026.
 
Collie, D. A., D. M. Summers, et al. (2003). "Diagnosing variant Creutzfeldt-Jakob disease with the pulvinar sign: MR imaging findings in 86 neuropathologically confirmed cases." AJNR Am J Neuroradiol 24(8): 1560-9.
 BACKGROUND AND PURPOSE: Variant Creutzfeldt-Jakob disease (vCJD) is a rare but important cause of dementia and death in young patients and is causally linked to bovine spongiform encephalopathy. Symmetrical hyperintensity in the pulvinar (posterior) nuclei of the thalamus (pulvinar sign) on brain MR images was described as a specific, noninvasive, diagnostic sign of vCJD in a previous small series. This purpose of this larger study was to evaluate this sign prospectively and further define the MR imaging characteristics of vCJD. METHODS: As part of the ongoing surveillance program in the United Kingdom, MR images of suspected cases of vCJD were collected during a 6-year period. All available images were assessed prospectively by one observer for the presence of the pulvinar sign. Images of neuropathologically confirmed cases were then assessed independently by two neuroradiologists for the degree of hyperintensity of the pulvinar on images of different MR sequences, and for the presence of abnormal hyperintensity in other areas of the brain. Discrepancies were reviewed jointly and a consensus opinion formed. RESULTS: Prospective analysis identified the pulvinar sign in 74 of 82 cases of vCJD. In the retrospective study, the pulvinar sign, as defined by hyperintensity of the pulvinar relative to the anterior putamen, was present on seven (9%) of 75 T1-weighted, 77 (71%) of 108 T2-weighted, 47 (81%) of 58 proton density-weighted, and 30 (100%) of 30 fluid-attenuated inversion-recovery (FLAIR) images. Diffusion-weighted images were available in two cases and were positive for the pulvinar sign in one. Other features were hyperintensity of the dorsomedial thalamic nuclei (93%), caudate head (40%), and periaqueductal gray matter (83%) on FLAIR images. CONCLUSION: In the appropriate clinical context, demonstration of the pulvinar sign on MR images is a highly accurate diagnostic sign for vCJD. FLAIR sequence is more sensitive than other sequences. Positive MR images may obviate more invasive diagnostic tests in most cases.

Comer, P. J. and P. J. Huntly (2003). "TSE risk assessments: a decision support tool." Stat Methods Med Res 12(3): 279-91.
 The paper presents a practical approach to assessing the risks of exposure to the infective agents from transmissible spongiform encephalopathies. Current data on the infectivity of bovine tissues have been reviewed and values for use in risk assessment studies proposed for the infectivity of central nervous system and other tissues, the development of infectivity through the incubation period and the cattle-human species barrier. A study to assess the risk of exposure to BSE infectivity in cattle disposed of during the 2001 foot and mouth epidemic in the UK by burning in pyres or burial is used to illustrate the application of TSE risk assessment and the way in which it can be used as an input to decision making.

Concepcion, G. P. and E. A. Padlan (2003). "Are humans getting 'mad-cow disease' from eating beef, or something else?" Med Hypotheses 60(5): 699-701.
 Bovine spongiform encephalopathy (BSE) or 'mad-cow disease' is believed to have been caused by the consumption of scrapie-infected sheep matter that had been added to cattle feed. BSE is then believed to have been transmitted to humans by the consumption of infected beef. We have compared the sequences of human and various animal prion proteins with regards to the fragments that could result from gastric digestion. We noted the close similarity of the sequences of human and rodent prion proteins in a peptic fragment that corresponds very closely to one that had been shown by others to be protease resistant and infective. Since rats and mice are known to be susceptible to prion disease, we propose that ingestion of infected rodent parts, possibly droppings, may be a possible mode of transmission of scrapie or BSE to humans.

Cooper, J. D. and S. M. Bird (2003). "Predicting incidence of variant Creutzfeldt-Jakob disease from UK dietary exposure to bovine spongiform encephalopathy for the 1940 to 1969 and post-1969 birth cohorts." Int J Epidemiol 32(5): 784-91.
 BACKGROUND: To investigate variant Creutzfeldt-Jakob disease (vCJD) incubation period, transmission barrier, and short-term vCJD predictions for methionine homozygotes in 1940-1969 and post-1969 birth cohorts by use of gender- and age-specific exposure intensities to bovine spongiform encephalopathy (BSE), based on consumption of beef mechanically recovered meat (MRM) and head meat. METHODS: Simulation (from vCJD infections generated randomly from gender and age-specific dietary exposure intensities to BSE), constrained to equal the 47 and 64 vCJD onsets before 2001 in 1940-1969 and post-1969 birth cohorts, was used to estimate lognormal (and other) incubation mean and standard deviation which fitted the calendar year distribution of observed vCJD onsets; and to explore exponential decay in susceptibility to infection with age above 15 years. RESULTS: For the post-1969 birth cohort, the best-fitting lognormal incubation period mean of 11 years (SD 1.5 years and 195 infections) was associated with 194 vCJD onsets (64 before 2001, 105 in 2001-2005, and 25 in 2006-2010). About one-fifth of simulated vCJD onsets before 2001 arose from infections in 1990-1996; age and gender of simulated and observed vCJD patients agreed closely. For the 1940-1969 birth cohort, well-fitting lognormal means ranged widely, the marginally best fitting being 26 years (SD 16.5 years and 382 infections; 47 vCJD onsets before 2001, 58 in 2001-2005, and 63 in 2006-2010). An age-dependent susceptibility function was required to match the age distribution of vCJD patients in the 1940-1969 birth cohort. CONCLUSIONS: About three-fifths of predicted vCJD onsets are expected to be in males, and nearly two-thirds of vCJD onsets in 2001-2005 are expected to be in post-1969 birth cohort according to best-fitting predictions.

Coulthart, M. B., R. Mogk, et al. (2003). "Prion protein gene sequence of Canada's first non-imported case of bovine spongiform encephalopathy (BSE)." Genome 46(6): 1005-1009.
 In May 2003, Canada became the 22nd country outside of the United Kingdom to report a case of bovine spongiform encephalopathy (BSE) in an animal not known to be imported from a country with cattle previously affected by this fatal, transmissible prion disease. Despite extensive testing of thousands of other animals that may have been exposed to contaminated feed at the same time as the affected animal, no evidence has been found for other infections. This finding leaves room for conjectures that the single confirmed case arose spontaneously, perhaps (by analogy with human Creutzfeldt–Jakob disease) as a result of a somatic protein misfolding event or a novel germline mutation. Here we present DNA sequence data from the affected animal's prion protein coding sequence that argue definitively against the latter hypothesis.

Cousens, S., D. Everington, et al. (2003). "The geographical distribution of variant Creutzfeldt-Jakob disease cases in the UK: what can we learn from it?" Stat Methods Med Res 12(3): 235-46.
 The causative agents of variant Creutzfeldt-Jakob disease (vCJD) and of bovine spongiform encephalopathy (BSE) are currently indistinguishable. However, the route(s) by which humans became infected remain unknown. The path by which humans were infected with the BSE agent might impact on the geographical distribution of cases and we therefore sought evidence of regional variation and local clustering of vCJD cases. With the notable exception of a group of five cases in Leicestershire, the absence of local clustering of vCJD cases is compatible with most human exposure to the vCJD agent arising through routes that result in the risk of infection being similar over wide geographical areas, rather than through small-scale local events. Infection through the consumption of mechanically recovered meat (MRM) contaminated with the BSE agent was a potential route for such widespread exposure. An ecological analysis relating the regional incidence of vCJD to historical dietary data does not provide a dear evidence that humans became infected through consumption of MRM.

Croes, E. A. and C. M. van Duijn (2003). "Variant Creutzfeldt-Jakob disease." Eur J Epidemiol 18(6): 473-7.
 A variant form of Creutzfeldt-Jakob disease (vCJD) has had major impact in Europe during the last decade. In this article, we review the aetiology of vCJD and its relation with bovine spongiform encephalopathy. Further, treatment of the disease, the strategies focusing on prevention of transmission, future prospects, and the limitations encountered in epidemiological research of vCJD are discussed.

Cuenot, M., D. Calavas, et al. (2003). "Temporal and spatial patterns of the clinical surveillance of BSE in France, analysed from January 1991 to May 2002 through a vigilance index." Vet Res 34(3): 261-72.
 Between 1991 and mid 2000, the surveillance of Bovine Spongiform Encephalopathy (BSE) in France was based solely on clinical surveillance through a Mandatory Reporting System. Since 2000, the implementation of active surveillance programmes using rapid tests, as a complementary tool targeted at dead and slaughtered cattle has shown that part of the BSE cases were not detected with the clinical surveillance. In order to obtain a better knowledge of the strength of the clinical surveillance, we analysed a vigilance index defined as the ratio of negative clinical suspicions to the cattle population in the region and period of interest. The temporal analysis of the vigilance index showed that it did not vary much between 1991 and 1999, increased sharply since 2000, and then decreased partly in 2001. The geographical analysis of the variations of the vigilance index was performed at the department level by comparing the observed number of negative clinical suspicions per department to the expected number, computed on the basis of the national average index and standardised on the production type of the cattle - dairy versus beef suckling cattle. As assumed, the data followed a Poisson distribution. We observed a high geographical variation of the vigilance index: ten departments out of 91 presented a significantly higher vigilance index than the national one, and four a significantly lower vigilance index. The vigilance index showed that the clinical surveillance was heterogeneous during the past twelve years, both in time and geographic location, in a range of one to ten. So the apparent trend in the BSE epidemic during this period as well as the differences in the spatial incidence of BSE have to be analysed with caution.

Dahlanuddin, T. Dam Van, et al. (2003). "An exploration of risk factors for bovine spongiform encephalopathy in ruminant production systems in the tropics." Rev Sci Tech 22(1): 271-81.
 The epidemic of bovine spongiform encephalopathy (BSE) in Europe in the late Twentieth Century required the interplay of two sets of factors, which now provide reference points for assessment of the BSE risk throughout the world. One set of factors consisted of the presence of infective agent in cattle or some other ruminant. The second set consisted of transmission and amplification of the disease, made possible through a particular feeding system that allowed persistent and habitual feeding of meat-and-bone meal (MBM) derived from cattle. The authors explore the ruminant production systems of three representative countries in South-East Asia against the background of factors required for the manifestation of BSE. The results can be extended to other countries in sub-tropical and tropical regions where similar, non-industrial ruminant production systems operate. In short, the lack of a nutritionally or economically rational niche for MBM as a source of dietary protein or nitrogen in many ruminant production systems removes the hazard of BSE.

Dahms, S. (2003). "[Epidemiological model development using BSE as an example--observations from a statistical viewpoint]." Berl Munch Tierarztl Wochenschr 116(1-2): 22-30.
 Since first BSE cases in cattle born in Germany were recognized, questions have been raised concerning the future development of the disease and the epidemiological dynamics of BSE, and, consequently, modelling approaches that might answer these questions. The database for such modelling efforts is formed by BSE incidence numbers or incidence rates, broken down by age at onset of clinical disease, and by time of onset or time of birth, respectively, from available information gathered for suspect and confirmed BSE cases. To describe such data, statistical age-period-cohort-models and two epidemiologically/biologically oriented modelling approaches are discussed: the so-called three-factor-model used by the Central Veterinary Laboratory of the British Ministry for Agriculture, Fisheries and Food (MAFF) (now Department of the Environment and Rural Affairs (DEFRA)), and a back-calculation-model developed by a working group at the University of Oxford. Resulting model calculations are supposed to serve several purposes, including a prediction of future BSE incidence numbers, and, especially based on the "Oxford"-model, a back-calculation of the epidemic of BSE infections from the epidemic of clinically diseased BSE cases. Analysis of these approaches reveals some problems even to identify unique age, period, or birth cohort effects. An additional estimation of epidemiological components of BSE, for example the frequency distribution of incubation times, has to rely on further assumptions that cannot be validated by the model fit as such. Therefore, modelling results should be interpreted with caution. However, the limitations demonstrated by this discussion emphasize the need for specific studies to investigate certain aspects of the BSE epidemic, for example the distribution of times from infection to disease onset, and for the centralised collection of valid and detailed population data for cattle.

Debeer, S., T. Baron, et al. (2003). "Neuropathological characterisation of French bovine spongiform encephalopathy cases." Histochem Cell Biol 120(6): 513-21.
 Bovine spongiform encephalopathy (BSE) in cattle is a neurodegenerative disease belonging to the transmissible spongiform encephalopathies, a group of diseases including sheep scrapie and human Creutzfeldt-Jakob disease. The pathological characteristics of BSE are vacuolation, mild gliosis, little neuronal degeneration without inflammatory process and abnormal prion protein (PrPsc) accumulation. The aim of this study was to define precisely the neuropathology of BSE in French cases by assessing the distributions of vacuolar lesions and PrPsc within cattle brains. We showed that vacuolation and PrPsc accumulation varied from one structure to the other, and most often coexisted. These distributions were in accordance with British and Portuguese data previously published. Seven types of PrPsc immunolabelling were described based on morphology and localisation. Besides mild gliosis mainly associated with vacuolation, we observed a very slight neuronal apoptosis. In addition, we saw a moderate vimentin labelling colocalised with vacuolation, a discrete ubiquitin staining and no Tau protein staining. This study provides precise histopathological data that will be completed with a quantitative study on more than 100 obex samples of French BSE cases.

Deslys, J. P. (2003). "[Prions and risks for blood transfusion: the situation in 2003]." Transfus Clin Biol 10(3): 113-25.
 In 2003, Prions still constitute a biological enigma and a public health concern. The risks of transmission of the so called "mad cow disease" are now under control but concerns still persist about potential secondary transmissions, notably via blood transfusion. Information obtained from diseases previously observed in animals (scrapie of sheep and goat) and in man (Kuru, Creutzfeldt-Jakob disease) demonstrate the complexity of the relations between these transmissible agents and their host. The difficulty in decontamination, the very long silent incubation period during which diagnosis is not possible and the lack of treatment are alarming elements which explain the increased perception of risk for these diseases. The development of rapid screening tests used on bovine at slaughterhouse has represented an important improvement in the development of a targeted protection against these agents. Today, technical evolutions in diagnosis let us imagine the possibility of blood detection for prions: on one hand new garanties for security may arise but on the other hand it points out the potential infectivity of blood with these agents responsible for constant fatal diseases. Precautionary security measures have to ensure an optimal ratio benefit/risk for the patient and thus, in this field, to balance the risk linked to prions with those clearly identified elsewhere.

Doerr, H. W., J. Cinatl, et al. (2003). "Prions and orthopedic surgery." Infection 31(3): 163-71.
 Prions are a novel class of infectious agents that cause subacute encephalopathy in man and animals as human Creutzfeldt-Jakob disease (CJD), sheep scrapie and bovine spongiform encephalopathy (BSE). Previously, prions were shown to be transmitted by neuro- and ophthalmosurgical measures and by application of brain-derived therapeutic hormones. Recently, prions have been detected in blood specimens of experimentally infected monkeys indicating a principal threat to transfusion medicine, furthermore in human or bovine materials used in reconstructive surgery. In this article the risk of prion transmission from the surgeon to the patient or vice versa during (orthopedic) surgery is reevaluated including the issues of blood transfusion. This is accomplished based on recent epidemiologic findings and biometric calculations on the spread of prions in animals and humans as well as in terms of experimental data on artificially contaminated medical materials and devices. The overall risk of prion transmission in orthopedic surgery is considered very low if adequately prepared and sterilized materials and devices are used.

Donnelly, C. A., N. M. Ferguson, et al. (2003). "Extending backcalculation to analyse BSE data." Stat Methods Med Res 12(3): 177-90.
 We review the origins of backcalculation (or back projection) methods developed for the analysis of AIDS (acquired immunodeficiency syndrome) incidence data. These techniques have been used extensively for >15 years to deconvolute clinical case incidence, given knowledge of the incubation period distribution, to obtain estimates of past HIV (human immunodeficiency virus) infection incidence and short-term predictions of future AIDS incidence. Adaptations required for the analysis of bovine spongiform encephalopathy (BSE) incidence included: stratification of BSE incidence by age as well as birth cohort; allowance for incomplete survival between infection and the onset of clinical signs of disease; and decomposition of the age- and time-related infection incidence into a time-dependent feed risk component and an age-dependent exposure/susceptibility function. The most recent methodological developments focus on the incorporation of data from clinically unaffected cattle screened using recently developed tests for preclinical BSE infection. Backcalculation-based predictions of future BSE incidence obtained since 1996 are examined. Finally, future directions of epidemiological analysis of BSE epidemics are discussed taking into account ongoing developments in the science of BSE and possible changes in BSE-related policies.

Ducrot, C., P. Roy, et al. (2003). "How the surveillance system may bias the results of analytical epidemiological studies on BSE: prevalence among dairy versus beef suckler cattle breeds in France." Vet Res 34(2): 185-92.
 Until recently, epidemiological studies on Bovine Spongiform Encephalopathy (BSE) were based on Mandatory Reporting Systems (MRS) of clinically suspect bovines only, but rapid diagnostic tests were validated in 1999 and are used for targeted surveillance in Switzerland, France and other countries, as a complementary and secondary tool. Data on 30491 cattle issued from a French pilot program targeted at cattle having died on the farm, subjected to euthanasia or sent for emergency slaughter, did not show any significant difference in BSE risk between dairy and beef suckler breeds. The data also revealed that part of the clinical cases of BSE escaped the MRS, which permitted to detect more dairy than beef suckler affected cattle compared to the targeted surveillance in the same period (from August to December 2000) and region (Bretagne, Pays de la Loire and Basse Normandie regions). Analyzing together the data of the targeted surveillance and mandatory reporting system programs with a non-conditional logistic regression, we found that the odds of a dead cow being a BSE case among all dead cattle was 3.2 times higher for dairy breeds compared to beef suckler breeds. This confirmed British findings but points out to the fact that considering either MRS or targeted surveillance data alone may possibly create biases in epidemiological studies on BSE.

Ersdal, C., M. J. Ulvund, et al. (2003). "Accumulation of pathogenic prion protein (PrPSc) in nervous and lymphoid tissues of sheep with subclinical scrapie." Vet Pathol 40(2): 164-74.
 All sheep older than 1 year of age from a flock of the Rygja breed in which clinical scrapie was detected for the first time in two animals (4%) were examined for accumulation of pathogenic prion protein (PrPSc) by immunohistochemistry in the obex, the cerebellum, and the medial retrophayngeal lymph node. In addition, six lambs, 2-3 months old, all offspring of PrPSc-positive dams, were examined for PrPSc in the ileal Peyers' patch (IPP), the distal jejunal lymph node, the spleen, and the medial retropharyngeal lymph node (RPLN). In this flock, 35% (17/48) of the adult sheep showed accumulation of PrPSc, an eightfold increase compared with clinical disease. All positives carried susceptible PrP genotypes. Three sheep had deposits of PrPSc in the RPLN and not in the brain, suggesting that this organ, easily accessible at slaughter, is suitable for screening purposes. Two 7-year-old clinically healthy homozygous V136Q171 ewes showed sparse immunostaining in the central nervous system and may have been infected as adults. Further, two littermates, 86-days-old, showed PrPSc in the IPP. Interestingly, one of these lambs had the intermediate susceptible PrP genotype, VA136QR171. In addition to early immunolabeling in the dorsal motor nucleus of the vagal nerve, a few of the sheep had early involvement of the cerebellum. In fact, a 2-year-old sheep had sparse deposits of PrPSc in the cerebellum only. Because experimental bovine spongiform encephalopathy (BSE) in sheep seems to behave in a similar manner as natural scrapie, these results, particularly regarding spread of infectivity, may have implications for the handling of BSE should it be diagnosed in sheep.

Ferguson, N. M. and C. A. Donnelly (2003). "Assessment of the risk posed by bovine spongiform encephalopathy in cattle in Great Britain and the impact of potential changes to current control measures." Proc R Soc Lond B Biol Sci 270(1524): 1579-84.
 We extended an existing back-calculation model to analyse data on reported clinical cases of bovine spongiform encephalopathy (BSE), data from random testing of healthy animals slaughtered in abattoirs and testing data from animals reported as sick or dying on the farm. Extensive analysis of demographic data was also undertaken. We estimated past and current BSE infection prevalences in the cattle population and the degree of case under-ascertainment resulting from excess mortality in cattle near to disease onset. Ongoing levels of human exposure to BSE infectivity were also estimated, together with the effect on these of a range of possible exposure-reduction strategies that might replace the current rule banning tissue from cattle over 30 months (OTM) of age from the human food supply. While any policy change that allows a wider age range of animals into the human food supply will increase levels of human exposure to infectivity, the risk posed by such increases is small by comparison with historical exposure levels. Making the pessimistic assumption that there will be 5000 deaths during the variant Creutzfeldt-Jakob disease (vCJD) epidemic in total, our analysis indicates that replacement of the OTM rule with testing would result in 0.04 additional vCJD deaths over the next 60 years. However, there is substantial (more than 40-fold) uncertainty surrounding this estimate, the sources of which are discussed.

Ferreira, A. S., M. A. da Silva, et al. (2003). "Stochastic modeling approach to the incubation time of prionic diseases." Phys Rev Lett 90(19): 198101.
 Transmissible spongiform encephalopathies are neurodegenerative diseases for which prions are the attributed pathogenic agents. A widely accepted theory assumes that prion replication is due to a direct interaction between the pathologic (PrP(Sc)) form and the host-encoded (PrP(C)) conformation, in a kind of autocatalytic process. Here we show that the overall features of the incubation time of prion diseases are readily obtained if the prion reaction is described by a simple mean-field model. An analytical expression for the incubation time distribution then follows by associating the rate constant to a stochastic variable log normally distributed. The incubation time distribution is then also shown to be log normal and fits the observed BSE (bovine spongiform encephalopathy) data very well. Computer simulation results also yield the correct BSE incubation time distribution at low PrP(C) densities.

Frezza, D., M. Favaro, et al. (2003). "A competitive polymerase chain reaction-based approach for the identification and semiquantification of mitochondrial DNA in differently heat-treated bovine meat and bone meal." J Food Prot 66(1): 103-9.
 The risk of bovine spongiform encephalopathy propagation was drastically reduced after the European Union (EU) Health Authorities adopted restrictions involving a ban on animal-derived proteins in the diet of farm animals. Currently, the EU's officially recommended method for controlling meat and bone meal (MBM) in animal feed is the microscopic method, which involves the identification of bone fragments on the basis of their morphological characteristics. Recently, we demonstrated that a polymerase chain reaction (PCR)-based assay can be used for the detection of taxon-specific DNA in MBM and animal feeds. To ensure the safe rendering of animal by-products, the EU Council requires that this material be treated at 133 degrees C at 300 kPa for 20 min. Here we investigate the relationship between DNA degradation, PCR amplification, and MBM heat treatment. With a competitive PCR-based approach, we compare the amplification efficiency of bovine mitochondrial DNA target sequences of different lengths in several heat-treated MBM samples. For our method, a synthetic competitive DNA is used as an internal control for both DNA extraction and PCR reaction. A correlation between an increase in treatment temperature and a reduction in the size of the target sequences suitable for amplification was observed, suggesting progressive DNA fragmentation due to the temperature. We show that short amplicons (147 bp) can be used to detect the presence of bovine mtDNA in MBM samples treated according to the current European regulations. The use of such a competitive approach to compare amplification efficiency levels of targets of different lengths might represent a useful tool for the determination of both the amount of MBM in animal feeds and its proper heat treatment.

Fries, R., T. Eggers, et al. (2003). "Autonomous nervous system with respect to dressing of cattle carcasses and its probable role in transfer of PrP(res) molecules." J Food Prot 66(5): 890-5.
 Pathogen prions are widely recognized as the causative agent in bovine spongiform encephalopathy (BSE) and other transmissible spongiform encephalopathies. However, more research on the possible transmission mutes of this agent once it has reached the host is needed. There is evidence based on the anatomy and physiology of the autonomous nervous system (ANS), as well as observations for different animal species, that the ANS might be involved in the axonal drainage of pathogen prions toward the central nervous system. In this context, more attention should be paid to the cranial cervical ganglion, the stellate ganglion, the chain of paravertebral ganglia next to the first six thoracic vertebrae, the chain of the paravertebral ganglia next to loin vertebrae 1 through 6, the vagus nerve in the neck region and in the mediastine, and the esophagus (because of its close connection to the vagus nerve). For a more detailed risk analysis with respect to these tissues, the ANSs of animals having shown clinical signs of BSE might be examined to corroborate the evidence presented here. In the meantime, as a precautionary measure, the tissue addressed should be taken out of the human food chain, taken out of animal feed, and handled as if it were specified risk material. It is technically possible to remove these parts during cutting and dressing.

Geldermann, H., S. Preuss, et al. (2003). "Analysis of polymorphic microsatellites within the bovine and ovine prion protein (PRNP) genes." Anim Genet 34(4): 283-9.
 Twenty-four microsatellite sites with at least three repeats were found in the bovine prion protein gene (PRNP) and 23 in the ovine PRNP gene. Eight microsatellite sites were polymorphic in cattle and six in sheep with up to 10 alleles per site. In many cases allelic DNA fragments had variants in microsatellite sites and in flanking regions. Distances between microsatellite sites in eight genes from cattle and sheep occurred on average every 0.9 kb. The numerous polymorphic microsatellite sites will improve analysis of phylogenetic origin of different PRNP alleles and trait association studies for bovine spongiform encephalopathy (BSE) and scrapie.

Ghani, A. C. (2003). "Commentary: Predicting the unpredictable: the future incidence of variant Creutzfeldt-Jakob disease." Int J Epidemiol 32(5): 792-3.
 
Ghani, A. C., N. M. Ferguson, et al. (2003). "Short-term projections for variant Creutzfeldt-Jakob disease onsets." Stat Methods Med Res 12(3): 191-201.
 Projections of both the short- and long-term course of the variant Creutzfeldt-Jakob disease (vCJD) epidemic in Great Britain have demonstrated great uncertainty due to the lack of knowledge of key aspects of the biology and epidemiology of this new disease. Such projections are sensitive to assumptions made regarding the pattern of exposure to BSE-infected animals, the effectiveness of control measures introduced in 1989 and 1996 in reducing this exposure, the functional form of the incubation period distribution and patterns of age-dependent susceptibility/exposure. This paper provides short-term projections for vCJD onsets using the time- and age-distributed onset data to the end of 2000, with results that are directly comparable to the other papers in this issue. These results demonstrate the continued uncertainty in the future scale of this disease.

Ghani, A. C., N. M. Ferguson, et al. (2003). "Factors determining the pattern of the variant Creutzfeldt-Jakob disease (vCJD) epidemic in the UK." Proc R Soc Lond B Biol Sci 270(1516): 689-98.
 Following the emergence of a new variant of Creutzfeldt-Jakob disease (vCJD) 6 years ago, and the gradual rise in clinical cases, there has been increased speculation regarding the overall magnitude of this epidemic in Great Britain. In this paper, we explore the epidemiological factors and uncertainties determining the scale of this epidemic in light of the most recent data on reported vCJD mortality. Our results demonstrate that, while the magnitude of the uncertainty has decreased dramatically since 1996, it is still not possible to predict with any degree of accuracy the final magnitude of this epidemic, with the 95% confidence interval for future cases being from 10 to 7000 deaths. However, short-term projections show that it is unlikely that a dramatic increase in case numbers will be observed in the next 2-5 years (95% confidence interval for 2 years: 10-80 cases, for 5 years: 10-200 cases). The results confirm significant age-dependent susceptibility/exposure to infection, with the likelihood profile demonstrating that those aged between 10 and 20 years are at highest risk of infection. We also demonstrate how projections based on onset data may be substantially biased, and explore the sensitivity of results to assumptions concerning the exposure to bovine spongiform encephalopathy (BSE) and the incubation-period distribution.

Gizzi, G., L. W. van Raamsdonk, et al. (2003). "An overview of tests for animal tissues in feeds applied in response to public health concerns regarding bovine spongiform encephalopathy." Rev Sci Tech 22(1): 311-31.
 Enforcing the ban on meat-and-bone meal in feed for farmed animals, and especially ruminants, is considered an important measure to prevent the spread of bovine spongiform encephalopathy. The authors describe current analytical methods for the detection and identification of animal tissues in feed. In addition, recently approved requirements, such as the ban of intra-species recycling (practice of feeding an animal species with proteins derived from the bodies, or parts of bodies, of the same species) are described. In principle, four different approaches are currently applied, i.e. microscopic analysis, polymerase chain reaction, immunoassay analysis and near infrared spectroscopy or microscopy. The principal performance characteristics of these methods are presented and compared, and their specific advantages and disadvantages described. Special emphasis is also placed on the impact of rendering conditions, particularly high temperatures and on the use of molecular biology techniques.

Glatzel, M., P. M. Ott, et al. (2003). "Human prion diseases: epidemiology and integrated risk assessment." Lancet Neurol 2(12): 757-63.
 Human prion diseases are devastating and incurable, but are very rare. Fears that the bovine spongiform encephalopathy epizootic would lead to a large epidemic of its presumed human counterpart, variant Creutzfeldt-Jakob disease (vCJD), have not been realised. Yet a feeling of uncertainty prevails in the general public and in the biomedical world. The lack of data on the prevalence of asymptomatic carriers of vCJD compounds this uncertainty. In addition to this problem, Switzerland is currently faced with another issue of major public concern: a recent rise in the incidence of CJD. Here we examine the plausibility of several scenarios that may account for the increase in CJD incidence, including ascertainment bias due to improved reporting of CJD, iatrogenic transmission, and transmission of a prion zoonosis. In addition, we present the design and current status of a Swiss population-wide study of subclinical vCJD prevalence.

Gonzalez, L., S. Martin, et al. (2003). "Distinct profiles of PrP(d) immunoreactivity in the brain of scrapie- and BSE-infected sheep: implications for differential cell targeting and PrP processing." J Gen Virol 84(Pt 5): 1339-50.
 Previous studies have shown that the patterns of disease-specific prion protein (PrP(d)) accumulation in the brain (the 'PrP(d) profile') of scrapie-affected sheep are mainly influenced by the source of scrapie agent. We have now extended those studies to investigate the effect of different PrP antibodies on the PrP(d) profile of scrapie- and bovine spongiform encephalopathy (BSE)-affected sheep. Immunohistochemical examination of brains of 20 sheep was performed with four different PrP antibodies (P4, 521.7, 505.2 and R486), and the animals were allocated to four groups of five sheep each depending on the transmissible spongiform encephalopathy (TSE) agent source (two natural scrapie sources, SSBP/1 and BSE). Although the PrP(d) profiles depended on the antibody used, the four TSE sources could always be differentiated. Natural Suffolk scrapie showed the highest levels of glia-associated PrP(d), natural Welsh Mountain scrapie uniquely had consistent vascular PrP(d) plaques, SSBP/1 produced the highest intracellular accumulations of PrP(d) and BSE led to moderate accumulation of all PrP(d) patterns except for vascular plaques. The variations in PrP(d) profile between TSE sources appeared to be the result of variations in cell tropism and in PrP processing. These processing differences are possibly associated with changes in PrP(d) conformation, and are manifest as differences in intracellular truncation and in release to the extracellular space of the abnormal protein. Moreover, variations in PrP(d) conformation would appear to be also influenced by the cell type supporting infection, arguing that it is modulated by the interaction between the infectious agent and the host.

Gould, D. H., J. L. Voss, et al. (2003). "Survey of cattle in northeast Colorado for evidence of chronic wasting disease: geographical and high-risk targeted sample." J Vet Diagn Invest 15(3): 274-7.
 A geographically targeted survey of potentially high-risk, adult cattle in chronic wasting disease (CWD)-endemic areas in Colorado was initiated to assess the possibility of the spread of CWD from deer to cattle under natural conditions. Surveyed cattle were sympatric with free-roaming deer in geographically defined areas where CWD occurs and where CWD prevalence has been estimated. To qualify for inclusion in the survey, cattle had to be at least 4 years old and had to have spent a minimum of 4 years in surveyed areas. Brains from culled cattle were examined microscopically and immunohistochemically for tissue alterations indicative of a transmissible spongiform encephalopathy (TSE). Two hundred sixty-two brains were suitable for evaluation and were found to lack changes indicative of a TSE infection. Prion deposition was not demonstrable using a method involving formic acid and proteinase-K treatment before application of monoclonal antibody to bovine prion protein (F99/97.6.1). Some incidental neuropathologic changes unrelated to those of TSEs were detected. Findings from this study suggest that large-scale spread of CWD from deer to cattle under natural range conditions in CWD-endemic areas of northeast Colorado is unlikely.

Grassi, J. (2003). "Pre-clinical diagnosis of transmissible spongiform encephalopathies using rapid tests." Transfus Clin Biol 10(1): 19-22.
 During the past few years, important progress has been made in the post-mortem diagnosis of transmissible spongiform encephalopathies (TSEs) (scrapie and BSE) due to the development of the so-called "rapid test" based on the immunological detection of the abnormal form of the prion protein (PrPres) in the central nervous system. These methods now allow routine and high throughput testing, opening the door to large-scale epidemiological studies and systematic testing at slaughterhouses, thus preventing the entry of contaminated carcasses into the human food chain. It has been shown that some of these rapid tests allow pre-clinical diagnosis, anticipating by few months the appearance of clinical signs. In sheep and goat, PrPres can also be detected in peripheral lymphoid tissues a long time before the onset of clinical symptoms. As a consequence, the same rapid tests are suitable for pre-clinical diagnosis of scrapie in these species. It is very likely that the same kind of early diagnosis could be obtained for vCJD. The real challenge in the field of TSE diagnosis is the establishment of a vCJD test, conducted either on blood or urine, since these are the only biological fluids easily accessible from infected people. This is a very important issue to avoid iatrogenic transmission of vCJD within the human population. This is also very difficult because the quantities of infectious agents in the blood are certainly 100-1000 times lower than those present in the brain.

Gravenor, M. B. and R. R. Kao (2003). "Risk assessments on BSE." Vet Rec 152(26): 816.
 
Gravenor, M. B., S. J. Ryder, et al. (2003). "Searching for BSE in sheep: interpreting the results so far." Vet Rec 152(10): 298-9.
 
Grobben, A. H., P. J. Steele, et al. (2003). "Inactivation of the bovine spongiform encephalopathy (BSE) agent by the acid and alkaline processes for manufacturing of bone gelatine." Biotechnol Appl Biochem.
 A validation study was carried out to determine the capacity of the traditional acid and alkaline processes for manufacturing bovine bone gelatine to remove and/or inactivate the transmissible agent that causes bovine spongiform encephalopathy (BSE). Using an accurately scaled down laboratory process that precisely mimicked the minimum conditions of the industrial processes, gelatine was manufactured from industrial starting material that had been spiked with mouse-brain infected with the 301V strain of mouse-passaged BSE agent. Clearance factors were determined by titrating the infectivity levels of the infected mouse brain-tissue, the gelatine extracts, and the final sterilised gelatine solution. The infectivity level of the spiked starting material was 10 8.4 mouse intracerebral ID 50/kg. Clearance factors of 10 2.6 ID 50 and 10 3.7 ID 50 were demonstrated for the first stages of the acid and alkaline processes respectively during which the bones are converted to crude gelatine. It was further demonstrated that the complete acid and alkaline process both reduced infectivity to undetectable levels, giving clearance factors of >10 4.8 ID 50 for the acid process, and >10 4.9 ID 50 for the alkaline process.

Guillaume, E., C. Zimmermann, et al. (2003). "A potential cerebrospinal fluid and plasmatic marker for the diagnosis of Creutzfeldt-Jakob disease." Proteomics 3(8): 1495-9.
 The recent occurrence of the new variant of Creutzfeldt-Jakob disease (CJD), probably transmitted to humans by cattle affected by the bovine form of spongiform encephalopathy, has generated renewed interest in the clinical issues related to human spongiform encephalopathies. Using the current set of diagnostic tools, these rare but devastating conditions may be difficult to diagnose with accuracy before death. The objective of the present communication is to describe the discovery of a potential cerebrospinal fluid (CSF) and plasmatic marker of human transmissible spongiform encephalopathies. A preliminary two-dimensional electrophoresis approach highlighted a potential neurodegenerative disorder marker called the fatty acid binding protein, FABP. Its heart form, H-FABP, was investigated in a small group of CJD affected patients (n = 8 ) by an immunoassay approach. The amount of FABP appeared to be significantly (p< or = 0.05) increased in all tested samples. H-FABP detection could therefore be helpful as a blood screening test for a pre-mortem diagnosis of the disease and also to prevent the risk of iatrogenic transmission of CJD through blood transfusion.

Guy, D. (2003). "Public opinion in a crisis." Hosp Q 6(4): 24.
 
Hamilton, R. L. (2003). "[The other dementias: the neuropathology of the non-Alzheimer's disease dementias]." Rev Neurol 37(2): 130-9.
 Alzheimer's disease (AD) is one of the most common causes of dementia, but requires neuropathological verification for a definitive diagnosis because there are a number of other neurodegenerative diseases that may present with dementia. Some of these disorders have considerable overlap both clinically and pathologically with AD, while others have distinct clinical and pathological profiles. Vascular dementia and dementia with Lewy bodies (DLB) have the greatest overlap with AD and considerable controversy still surrounds the exact contribution of the non AD pathology to the dementia syndrome. The frontotemporal dementias are loosely united by clinical presentation, but are pathologically heterogeneous and include Pick's disease, dementia lacking distinctive histopathology, motor neuron disease inclusion dementia and corticobasal degeneration (CBD). CBD can be difficult to distinguish from progressive supranuclear palsy, especially when the latter lacks the distinctive gaze palsy. Finally, Creutzfeldt Jakob disease (CJD) may be difficult to distinguish from AD when the symptoms progress at an atypically slow pace. Recently, a new variant of CJD (vCJD) that has been linked to bovine spongiform encephalopathy ('mad cow' disease) has heightened awareness of these prion protein disorders. The neuropathological criteria for the diagnosis of these non AD dementia disorders will be reviewed.

Harakeh, S., R. A. Soweid, et al. (2003). "Knowledge, attitude, and behavior of students regarding 'mad cow disease'." Sci Total Environ 312(1-3): 255-60.
 The aim of the current study is to assess the knowledge, attitude and behavior of students enrolled at the American University of Beirut (AUB) in Lebanon, towards mad cow disease (MCD). Three hundred and fifty-six students (199 males and 157 females), ranging in age between 17 and 25 years were randomly selected from various majors and were asked to fill out a self-administered questionnaire. It was found that 99.7% of students had heard about MCD and 85.8% knew that the cow is the host for bovine spongiform encephalopathy (BSE). Seventy five percent reported that animals contract the disease through the consumption of meat and bone meal. Thirty-seven percent wrongly believed that MCD cases were reported in Lebanon and 89% were not satisfied with the measures undertaken by the Lebanese government to curb the disease. Eighty four percent were concerned about the disease and 72% stated having modified their eating habits accordingly. Moreover, students majoring in biology and other health-related majors knew significantly more about MCD compared with students majoring in non-health related majors. A surprising finding was that females were more likely to modify their eating habits than males. Hence, this study provides an insight into the knowledge, attitude, and behavior of AUB students towards MCD. A limitation of this study is that our sample is not representative of all university students in Lebanon. Future surveys should also target students enrolled in other universities in the country.

Hardy, A. (2003). "Professional advantage and public health: British veterinarians and State Veterinary Services, 1865-1939." 20 Century Br Hist 14(1): 1-23.
 At the beginning of the twentieth century, municipal authorities in England and Wales, and in Scotland, began to develop systems of veterinary public health which encompassed both the welfare of animals and the safety of meat and milk intended for human consumption. This paper examines the motives behind veterinary attempts to extend the integration of human and animal health considerations within the public health framework in the inter-war period. In 1938 the Ministry of Agriculture implemented a national administrative structure for the management of animal diseases which absorbed the veterinary personnel of the municipal authorities, whose own veterinary public health activities largely fell into abeyance. As a result, the ideal of veterinary public health disappeared from British public health practice after 1939, and lost its force as a professional political cause. The mid-century disappearance of animal health from consideration in British public health programmes was one of a complex of historical strands which contributed to the late-twentieth-century emergence of public health crises over such animal-borne diseases as salmonellosis, Escherichia coli infection, and bovine spongiform encephalopathy.

Heim, D. and U. Kihm (2003). "Risk management of transmissible spongiform encephalopathies in Europe." Rev Sci Tech 22(1): 179-99.
 Bovine spongiform encephalopathy (BSE) was first described in the United Kingdom (UK) in November 1986. After the introduction of an active surveillance system, most countries in Europe have reported BSE cases in the cattle population. This indicates that the use of active surveillance in addition to passive surveillance is important to assess the true BSE status in a country. Scrapie, a transmissible spongiform encephalopathy (TSE) in sheep and goats, has been reported in countries throughout the world with a few notable exceptions. Concern was expressed that BSE could have been introduced into sheep and goats. Currently, distinguishing between scrapie and BSE in small ruminants is only possible through lengthy experiments in mice. Preliminary results of active surveillance, introduced in 2002, show that significant under-reporting occurred. The history of BSE in cattle shows that risk assessments concerning the risk in a given country were often ignored and subsequent risk management decisions were inaccurate, i.e. although the risk was probable, no measures were taken in terms of either animal or human health. Furthermore, the effect of the measures taken was often overestimated and these had to be amended several times. The most important action to prevent new cases of TSEs occurring is by banning the feeding meat-and-bone meal (MBM) to ruminants. Further measures to be considered are the exclusion of specified risk material and carcasses from rendering, the process parameters for rendering of animal waste and the prevention of cross-contamination of feed with MBM. The most important measures to protect the consumer are the ban on specified risk material, such as brain and spinal cord, which may contain particularly high concentrations of the BSE agent, and the ban on mechanically recovered meat. The most important measures taken in Europe and the scientific background thereof are described and discussed.

Hill, A. F. and J. Collinge (2003). "Subclinical prion infection." Trends Microbiol 11(12): 578-84.
 Prion diseases are transmissible neurodegenerative disorders that include scrapie in sheep, bovine spongiform encephalopathy (BSE) in cattle and Creutzfeldt-Jakob disease (CJD) in humans. The principal component of the infectious agent responsible for these diseases appears to be an abnormal isoform of the host-encoded prion protein (PrP), designated PrP(Sc). Prion diseases are transmissible to the same or different mammalian species by inoculation with, or dietary exposure to, infected tissues. Although scrapie in sheep has been recognized for over 200 years, it is the recent epidemic of BSE that has centred much public and scientific attention on these neurodegenerative diseases. The occurrence of variant CJD in humans and the experimental confirmation that it is caused by the same prion strain as BSE has highlighted the need for intensive study into the pathogenesis of these diseases and new diagnostic and therapeutic approaches. The existence and implications of subclinical forms of prion disease are discussed.

Hill, A. F. and J. Collinge (2003). "Subclinical prion infection in humans and animals." Br Med Bull 66: 161-70.
 Transmission of prion diseases between mammalian species is limited by a so-called 'species' or 'transmission' barrier. Recognition of prion transmission usually relies on the appearance of clinical symptoms in inoculated animals and the interval between inoculation and appearance of clinical disease is designated incubation period. At some point during this clinically silent period, neuropathological and biochemical changes as well as accumulation of prions in the brain can be detected and this stage can be called preclinical prion disease. Recently, several lines of evidence have suggested that subclinical forms of prion disease exist, in which high levels of infectivity and PrP(Sc) are found in animals that do not develop clinically apparent disease during a normal life-span. Such asymptomatic prion 'carrier' states challenge our current understanding of pathogenesis as well as of the molecular basis of barriers to transmission. Subclinical as well as preclinical/clinical prion disease may be relevant when analysing the risk to public health of potential sources of prion exposure.

Hills, D., J. Schlaepfer, et al. (2003). "Sequence variation in the bovine and ovine PRNP genes." Anim Genet 34(3): 183-90.
 A resequencing approach was adopted to identify sequence variants in the PRNP gene that may affect susceptibility or resistance to bovine spongiform encephalopathy. The entire PRNP gene (>21 kb) was sequenced from 26 chromosomes from a group of Holstein-Friesian cows, as well as exon 3 of PRNP (>4 kb) from a further 24 chromosomes from six diverse breeds. We identified 51 variant sequences of which 42 were single nucleotide polymorphisms and nine were insertion/deletion (indel) events. The study was extended to exon 3 of the sheep PRNP gene where 23 sequence variants were observed, four of which were indels. The level of nucleotide diversity in the complete bovine PRNP gene was pi = 0.00079, which is similar to that found at the bovine T-cell receptor alpha delta joining region (pi = 0.00077), but somewhat less than that observed for the bovine leptin (pi = 0.00265). Sequence variation within exon 3 of PRNP in both cattle (pi = 0.00102) and sheep (pi = 0.00171) was greater than that for the complete PRNP gene, with sheep showing greater sequence variation in exon 3 than cattle. The level of sequence variation reported here is greater than previously thought for the bovine PRNP gene in cattle. This study highlights the contribution that recombination plays in increasing allelic diversity in this species.

Hoag, H. (2003). "BSE case rattles Canadian officials." Nature 423(6939): 467.
 
Hogan, R. N. (2003). "Potential for transmission of prion disease by contact lenses: an assessment of risk." Eye Contact Lens 29(1 Suppl): S44-8; discussion S57-9, S192-4.
 Prions are small proteinaceous infectious agents known to cause central nervous system infections in both animals and humans. Interest in the pathogenesis of these diseases has grown since the emergence of bovine spongiform encephalopathy (BSE or "mad cow disease") in the United Kingdom and several other countries in Europe. Ingestion of meat products from animals infected with BSE has resulted in transmission of the disease to humans as a variant form of Creutzfeldt-Jakob Disease (vCJD). CJD has a long asymptomatic incubation period, is untreatable, and universally fatal. Hence concern has arisen over other possible routes of disease transmission. Because it is known that prions are found in low levels in the corneas of animals with experimentally induced prion disease, and that a case of human CJD transmission by corneal transplantation has occurred, the question of possible prion transmission through the reuse of diagnostic fitting of contact lenses has surfaced. This article reviews prion diseases of animals and humans, and the data regarding the presence and location of prions in the eye. Issues inherent in the question of corneal and contact lens transmission are discussed. Although some key information has yet to be derived, it appears that the chance of obtaining prion disease through contact lens use is negligible.

Houston, F., W. Goldmann, et al. (2003). "Prion diseases: BSE in sheep bred for resistance to infection." Nature 423(6939): 498.
 
Houston, E. F. and M. B. Gravenor (2003). "Clinical signs in sheep experimentally infected with scrapie and BSE." Vet Rec 152(11): 333-4.
 
Hueston, W. D. (2003). "Science, politics and animal health policy: epidemiology in action." Prev Vet Med 60(1): 3-12.
 Public policy decisions underlie society's response to current animal health issues ranging from emerging diseases and public health threats to food safety concerns and sustainable animal agriculture strategies. Despite strong calls for "science-based" decisions, animal health policy most commonly emerges at the interface of science and politics. Too often scientists' disdain for politics limits their involvement in formulating policy. By contrast, epidemiologists are ideally qualified to bring scientific skills to complex policy issues through analytical, macro-epidemiological approaches that consider the economic, legal, and cultural context of policy issues as well as the biological and medical aspects. Risk analysis provides a systematic approach to evaluating animal health issues and comparing policy options. Capturing these opportunities for applied epidemiology requires an understanding of the policy-making process as well as the basic principles of epidemiology. Furthermore, epidemiology training programs must incorporate communications skill building and experiential learning opportunities in a team environment.

Hunter, N. (2003). "Scrapie and experimental BSE in sheep." Br Med Bull 66: 171-83.
 Scrapie is a natural disease of sheep, but it can also be successfully transmitted between sheep by experimental inoculation. Although BSE is primarily a disease of cattle, it has also infected humans (causing vCJD) and, in addition, can be transmitted orally to sheep bringing concerns that BSE might naturally have infected the UK sheep population. Because of this, scrapie and BSE are being compared and studied in detail in sheep. PrP genotype controls sheep susceptibility and resistance to scrapie and to BSE, and deposition of the disease-associated PrP(Sc), used as a marker of infection, has the potential to act as a means of identifying BSE-infected animals and describing different pathogenesis mechanisms. Sheep orally dosed with BSE show signs of infection in their blood and this model is of major importance in the study of the safety of blood products for use with human beings.

Irani, D. N. and R. T. Johnson (2003). "Diagnosis and prevention of bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease." Annu Rev Med 54: 305-19.
 An outbreak of bovine spongiform encephalopathy (BSE) arose in the United Kingdom as a result of prions entering and being recycled through the ruminant food chain. Humans have since developed a variant form of Creutzfeldt-Jakob disease (vCJD), also mostly in the United Kingdom, that occurs in younger individuals and causes prominent psychiatric and/or behavioral manifestations early in disease. Laboratory studies now provide strong evidence that the causative agent of BSE in cattle and vCJD in humans share a common origin. Because of a lack of information regarding the incubation period of vCJD and the number of people who may have been exposed, the future scope of this disease remains unknown. Control of the current and any future outbreaks in cattle requires strict measures to prevent contamination of the animal food chain with prions of any species. Prevention of human exposure mandates the avoidance of neural tissue in all human foods.

Ironside, J. W. (2003). "Variant Creutzfeldt-Jakob disease." Vet Res Commun 27 Suppl 1: 11-3.
 
Ironside, J. W. and M. W. Head (2003). "Variant Creutzfeldt-Jakob disease and its transmission by blood." J Thromb Haemost 1(7): 1479-86.
 Variant Creutzfeldt-Jakob disease (vCJD) is a novel acquired human prion disease resulting from human exposure to the agent causing bovine spongiform encephalopathy (BSE). vCJD differs from all other human prion diseases in that the disease-associated form of the prion protein and infectivity are present in lymphoid tissues throughout the body. Lymphoid tissues and lymphocytes are implicated in the peripheral pathogenesis of prion diseases (where infectivity may be detected during the preclinical phase of the illness), giving rise to concerns that blood and blood products may also contain infectivity, thus representing a possible source of iatrogenic spread of vCJD. These concerns have been reinforced by the recent transmission of BSE in an experimental sheep model by blood transfusion from an infected animal in the preclinical phase of the illness. Studies in other animal models suggest that most infectivity in blood may be cell-associated, with lower levels in the plasma, and there is evidence to indicate that any infectivity present may be reduced during the process of plasma fractionation. At present, the attempts to detect disease-associated prion protein and infectivity in buffy coat from vCJD patients have been negative, but these studies have been limited in size and in the sensitivity of the detection systems employed. Further studies are required to develop more sensitive means of detection of disease-associated prion protein in blood; such techniques could also be employed for screening purposes, both individually and to help ascertain more precisely the likely numbers of future cases of vCJD.

Jeffrey, M., S. Martin, et al. (2003). "Cell-associated variants of disease-specific prion protein immunolabelling are found in different sources of sheep transmissible spongiform encephalopathy." J Gen Virol 84(Pt 4): 1033-45.
 Scrapie and bovine spongiform encephalopathy (BSE) are transmissible spongiform encephalopathies (TSEs) or prion diseases affecting domestic and exotic ruminants. In previous immunohistochemical studies, we have shown that different sheep TSE sources may be distinguished by both the proportion of disease-specific prion protein (PrP(d)) accumulation relative to different cell types in the brain (the 'PrP(d) profile') and by different labelling patterns for PrP peptide sequences within phagocytic cells. In the present study, we have further characterized the intracellular accumulation patterns of PrP(d) in the lymphoreticular system (LRS) and in the brain of sheep clinically affected with scrapie or BSE. BSE-infected PrP(ARQ/ARQ) sheep of different breeds were compared with scrapie-infected sheep of different PrP genotypes. Cases of BSE infection could be distinguished from scrapie cases by a marked reduction in labelling of PrP(d) containing the 84-105 amino acid residues in phagocytic cells of the LRS and in neurones and glia of the brain. These results therefore indicate that TSE agent-dependent processing of PrP in specific cell types within the brain and LRS can be used to distinguish between BSE in PrP(ARQ/ARQ) sheep and scrapie in sheep of several PrP genotypes. Three different N-terminal peptide antibody labelling patterns were recognized for different cell types in different tissues of BSE-infected sheep, suggesting that different truncated forms of PrP(d) are formed following infections with this agent strain. These variations in the cleavage sites of BSE PrP(d) may be due to cell-specific variation in endosomal-lysosomal digestion or to cell- and tissue-specific differences in BSE PrP(d) conformation.

Kaneko, K. (2003). "[Creutzfeldt-Jakob disease (CJD), variant CJD, and BSE]." Nippon Rinsho 61 Suppl 3: 9-16.
 
Kao, R. R., F. Houston, et al. (2003). "Epidemiological implications of the susceptibility to BSE of putatively resistant sheep." J Gen Virol 84(Pt 12): 3503-12.
 The experimental infection of sheep with bovine spongiform encephalopathy (BSE) by the oral route and the likelihood that sheep were fed BSE-infected meat and bone meal has led to extensive speculation as to whether or not sheep are naturally infected with BSE. In response, the UK government has initiated the National Scrapie Plan (NSP), an ambitious pound 120 million per year project to create a BSE- and scrapie-resistant national sheep flock, by selectively breeding for a genotype of sheep believed to be resistant to both diseases. This genotype has recently been shown to be susceptible to BSE by intracerebral (i.c.) inoculation. Should these sheep be sufficiently susceptible to BSE via natural transmission, the NSP might fail. Here we estimate the susceptibility of this genotype to horizontal (sheep-to-sheep) transmission of BSE by comparison with more extensive oral and i.c. exposure data for other sheep genotypes. We show that a previous estimate of the risk of BSE transmission to sheep via the feedborne route remains robust. However, using a mathematical model for the within-flock transmission of BSE, we show that, while the best estimate indicates that the NSP should be successful, current data cannot exclude the failure of the NSP.

Kellar, J. A. and V. W. Lees (2003). "Risk management of the transmissible spongiform encephalopathies in North America." Rev Sci Tech 22(1): 201-25.
 As North American Free Trade Agreement partners, Canada, the United States of America (USA) and Mexico apply independent but harmonised transmissible spongiform encephalopathy (TSE) risk management strategies in observance of Office International des Epizooties guidelines. The divergence between bovine spongiform encephalopathy (BSE) risk management approaches in North American and Europe reflects comparatively reduced external and internal BSE risks in North America. The external quarantine and internal surveillance measures adopted for BSE respond to several iterations of national risk assessments initiated in the early 1990s and revised as recently as 2002. Feed bans applied since 1997 to preclude establishment of BSE also bear the potential to limit intra-species and inter-species exposure to scrapie, chronic wasting disease (CWD) and transmissible mink encephalopathy (TME). Surveillance continues for the four TSEs through collaborative efforts of national and sub-national veterinary infrastructures and accompanying laboratory networks. Mexico has never identified the presence of any TSE. The last diagnosed case of TME in North America dates back to 1985. Since the only recognised appearance in Canada through an import from Great Britain in 1993, BSE has not been detected in North America. Scrapie and CWD remain at generally low prevalence in Canada and the USA. Independent but harmonised eradication programmes target elimination of the latter two diseases.

Knight, J. (2003). "Academy calls for improved tests to beat prion disease." Nature 426(6964): 216.
 
Kohler, M. (2003). "[BSE, prions, vCJD and (not only) homologous transfusion]." Anasthesiol Intensivmed Notfallmed Schmerzther 38(1): 43-7.
 
Kubler, E., B. Oesch, et al. (2003). "Diagnosis of prion diseases." Br Med Bull 66: 267-79.
 Prion diseases are usually diagnosed clinically and confirmed by post-mortem histopathological examination of brain tissue. The only reliable molecular marker for prion diseases is PrP(Sc), the pathological conformer of the prion protein that accumulates in the central nervous system and, to a lesser extent, in lymphoreticular tissues. For BSE, several commercial diagnostic kits based on the post-mortem immunochemical detection of PrP(Sc) in brain tissue are now available. These rapid screening tests have been used in active surveillance of BSE and have greatly improved the detection of infected cattle before their entry into the human food chain. At present, no diagnostic test exists for the detection of prion diseases in live animals or humans. New diagnostic techniques aimed at increasing sensitivity and specificity of PrP(Sc) detection in body fluids and at identifying novel surrogate markers are under development. In this report, we review the classical diagnostic methods as well as present and future tools for the diagnosis of prion diseases.

Kuwata, K., T. Matumoto, et al. (2003). "NMR-detected hydrogen exchange and molecular dynamics simulations provide structural insight into fibril formation of prion protein fragment 106-126." Proc Natl Acad Sci U S A 100(25): 14790-5.
 PrP106-126, a peptide corresponding to residues 107-127 of the human prion protein, induces neuronal cell death by apoptosis and causes proliferation and hypertrophy of glia, reproducing the main neuropathological features of prion-related transmissible spongiform encephalopathies, such as bovine spongiform encephalopathy and Creutzfeldt-Jakob disease. Although PrP106-126 has been shown to form amyloid-like fibrils in vitro, their structural properties have not been elucidated. Here, we investigate the conformational characteristics of a fibril-forming fragment of the mouse prion protein, MoPrP106-126, by using electron microscopy, CD spectroscopy, NMR-detected hydrogen-deuterium exchange measurements, and molecular dynamics simulations. The fibrils contain approximately 50% beta-sheet structure, and strong amide exchange protection is limited to the central portion of the peptide spanning the palindromic sequence VAGAAAAGAV. Molecular dynamics simulations indicate that MoPrP106-126 in water assumes a stable structure consisting of two four-stranded parallel beta-sheets that are tightly packed against each other by methyl-methyl interactions. Fibril formation involving polyalanine stacking is consistent with the experimental observations.

Langeveld, J. P., J. J. Wang, et al. (2003). "Enzymatic degradation of prion protein in brain stem from infected cattle and sheep." J Infect Dis 188(11): 1782-9.
 Prions-infectious agents involved in transmissible spongiform encephalopathies-normally survive proteolytic and mild protein-destructive processes. Using bacterial keratinase produced by Bacillus licheniformis strain PWD-1, we tested conditions to accomplish the full degradation of prion protein (PrP) in brain-stem tissue from animals with bovine spongiform encephalopathy and scrapie. The detection of PrPSc, the disease-associated isoform of PrP, in homogenates was done by Western blotting and various antibodies. The results indicated that only in the presence of detergents did heat pretreatment at >100 degrees C allow the extensive enzymatic breakdown of PrPSc to a state where it is immunochemically undetectable. Proteinase K and 2 other subtilisin proteases, but not trypsin and pepsin, were also effective. This enzymatic process could lead to the development of a method for the decontamination of medical and laboratory equipment. The ultimate effectiveness of this method of prion inactivation has to be tested in mouse bioassays.

Laprevotte, I. and A. Henaut (2003). "The new variant of the Creutzfeldt-Jakob disease accounts for no relative increase of the Creutzfeldt-Jakob disease mortality rate in the United Kingdom; this fits ill with the new variant being the consequence of consumption of food infected with the agent of Bovine Spongiform Encephalopathy." BMC Public Health 3(1): 25.
 BACKGROUND: A new variant of Creutzfeldt-Jakob disease was described in the United Kingdom. It is often claimed that it is caused by consumption of food infected with the agent of bovine spongiform encephalopathy. However, this remains open to question because the number of cases of the variant is, at the present time, less than would be expected from a major food-borne source. DISCUSSION: The EUROCJD cooperative study presents currently available epidemiological data of Creutzfeldt-Jakob disease and its new variant, for nine European countries plus Australia and Canada. Unexpectedly, for the United Kingdom where all but a few cases of the new variant have been reported, these cases have to be included in the incidence curve of the sporadic forms of the disease in order to obtain the best fit with the median curve from all the countries. This variant could be merely a rare clinical phenotype within the sporadic disease. The published clinical and experimental data which suggest that it is linked with bovine spongiform encephalopathy, lead us to propose that this link could be a common etiological origin other than consumption of bovine infected food. In any case, public health recommendations hold and further investigation is required. SUMMARY: The lack of a relative increase of the Creutzfeldt-Jakob-disease mortality rate in the United Kingdom, does not fit well with the new variant being the consequence of consumption of food infected with the agent of bovine spongiform encephalopthy.

Lasch, P., J. Schmitt, et al. (2003). "Antemortem identification of bovine spongiform encephalopathy from serum using infrared spectroscopy." Anal Chem 75(23): 6673-8.
 Since 1986, more than 180 000 clinical cases of bovine spongiform encephalopathy (BSE) have been observed in the U.K. alone. Most of these cases were confirmed by postmortem examination of brain tissue. However, BSE-related risk assessment and risk management would greatly benefit from antemortem testing on living animals. A serum-based test could allow for screening of the cattle population; thus, even a BSE eradication program would be conceivable. Here we report on a novel method for antemortem BSE testing, which combines infrared spectroscopy of serum samples with multivariate pattern recognition analysis. A classification algorithm was trained using infrared spectra of bovine sera from more than 800 animals (including BSE-positive, healthy controls and animals suffering from classical viral or bacterial infections). In two validation studies, sensitivities of 85 and 84% and specificities of 86 and 91% were achieved, respectively. The combination of classification algorithms increased the sensitivity and specificity of BSE detection to 96 and 92%, respectively.

Lezmi, S., A. Bencsik, et al. (2003). "First case of feline spongiform encephalopathy in a captive cheetah born in France: PrP(sc) analysis in various tissues revealed unexpected targeting of kidney and adrenal gland." Histochem Cell Biol 119(5): 415-22.
 Feline spongiform encephalopathy (FSE), affecting domestic and captive feline species, is a prion disease considered to be related to bovine spongiform encephalopathy. Here we report an immunohistological analysis of the first FSE-affected cheetah born in France. The duration of clinical signs, of which ataxia was the main one, was about 8 weeks. The distribution of abnormal prion protein (PrP(sc)) was studied by immunohistochemistry within 27 different tissues. Different antibodies were used to visualise abnormal PrP deposits in situ. PrP(sc )accumulation was detected in the central nervous system (cerebral cortex, cerebellum, brain stem, spinal cord, retina), in peripheral nerves and in lymphoid organs. PrP(sc) deposits were not observed within the enteric nervous system nor in several other organs, such as pancreas, ovary, liver and muscle. More interestingly, unusual PrP(sc )deposits were observed within the zona fasciculata/reticularis of the adrenal gland and within some glomeruli of the kidney raising the question of possible PrP(sc) excretion. The sympathetic innervation of these two organs was visualised and compared to the distribution of PrP(sc) deposits. Our results suggest the possibility that the infectious agent is spread by both haematogenous and nervous pathways.

Ludwig, B., F. B. Kraus, et al. (2003). "Viral zoonoses - a threat under control?" Intervirology 46(2): 71-8.
 Despite intensive research and considerable effort to eradicate infectious diseases, modern medicine has failed to control many infectious diseases which have been thought to be easy to overcome with advances in medical science and technology. In fact, infectious diseases remain a dominant feature in public health considerations for the 21st century. Some infectious agents already known to be pathogenic have gained increasing importance in recent decades due to changes in disease patterns. Furthermore, many new, previously unknown infectious agents with a high pathogenic potential have been identified. Nearly all of these emergent disease episodes have involved zoonotic or species-jumping infectious agents. The complex interaction of factors like environmental and ecological changes, social factors, decline of health care, human demographics and behaviour influences the emergence of re-emergence of such diseases. Viruses, especially RNA viruses with their ability to adapt quickly to changing environmental conditions, are among the most prominent examples of emerging pathogens. In this review, we present the important examples of zoonotic viruses and discuss the factors playing a key role in the emergence and resurgence of these diseases.

Makarov, V. V. (2003). "[Veterinary and epidemiologic aspects of prion infections]." Vestn Ross Akad Med Nauk(1): 35-40.
 
Maraschi, F. and F. Pezza (2003). "BSE: active and passive control system. Data comparison in the district of Lodi." Vet Res Commun 27 Suppl 1: 711-3.
 
Marchal, R., A. Lallement, et al. (2003). "Clarification of Muscat musts using wheat proteins and the flotation technique." J Agric Food Chem 51(7): 2040-8.
 The bovine spongiform encephalopathy (BSE, mad cow) crisis has led some wine-makers to question gelatin as a fining agent and to reject the use of these animal proteins. The search for a substitute for gelatin was begun by comparing vegetable proteins (particularly gluten) with gelatin fining treatments. Clairette de Die (French-controlled appellation) is a sparkling sweet wine. The alcoholic fermentation begins in a tank, continues in a crown-cap bottle, and stops before the complete consumption of sugar. All particles present in the bottle have to be removed before corking, and it is important to have a must as clear as possible. This study concerned the clarifying of a Muscat must, treated with pectinases, using a very efficient flotation technique. The must is fined with bentonite/silica/protein (fish gelatin, wheat gluten, or lupin isolate) to induce flocculation and then pressurized (6 bar). After depressurization, microbubbles cling to flocculates and climb to the top of the flotation tank (this flotation foam is clarified using a rotary filter). At laboratory scale, gluten (20 g/hL) and gelatin (10 g/hL) (each combined with bentonite and silica gel) gave turbidities of 50 and 35 NTU, respectively (6.5 and 4.1% of that of the nontreated must). The Muscat must was also clarified by static settling. The turbidity decreased by 86% for the gluten/bentonite fining and by 60% for the gelatin/bentonite fining. Visually, gluten flocculation takes longer to occur and flocculates sedimentation is longer than with gelati, but the removal of insoluble particles is more complete and leads to lower turbidities. At an industrial scale, gluten (20 g/hL) and gelatin (10 g/hL) (each combined with bentonite and silica gel) gave turbidities of 60 and 48 NTU, respectively. Turbidities measured in the tanks 14 h after the flotation showed a better efficiency for the wheat gluten (24 NTU) compared to gelatin (28 NTU). This is explained by the static settling that completed the clarifying effect of the flotation. The last experiment showed comparable efficiencies for wheat gluten and lupin proteins. BSE caused a situation of crisis (in Europe particularly) leading the public and wine-makers to lose their confidence in the use of gelatin as fining agent and to reject animal proteins in general. It is proposed here that vegetable proteins could efficiently replace gelatin.

Matthews, D. and B. C. Cooke (2003). "The potential for transmissible spongiform encephalopathies in non-ruminant livestock and fish." Rev Sci Tech 22(1): 283-96.
 Pigs and poultry in the United Kingdom have undeniably been exposed to the bovine spongiform encephalopathy (BSE) agent. They consumed the same ruminant protein that gave rise to the BSE epidemic in cattle, but there has been no evidence of an epidemic in these species. Experimental investigations have shown pigs to be susceptible to infection by multiple parenteral challenge, but resistant to oral exposure with BSE-infected cattle brain. Current but incomplete evidence suggests that they are also resistant to oral challenge with sheep scrapie. Studies in domestic chickens indicate that they are resistant to both parenteral and oral challenge. Unfortunately, no published data exists on the susceptibility of fish to infection. Incidental findings in the brains of unexposed pigs are described that could otherwise give rise to concerns aboutthe presence of a transmissible spongiform encephalopathy in pig populations around the world.

Matthews, D. (2003). "BSE: a global update." J Appl Microbiol 94 Suppl: 120S-125S.
 As the British bovine spongiform encephalopathy (BSE) epidemic declines towards extinction, the European epidemic continues to grow. The introduction of active surveillance in Europe and elsewhere makes direct comparison with past events in Britain difficult. BSE is increasingly recognized to be a global problem. While the epidemics in other countries may never reach the scale experienced in Britain, failure to learn from the British experience will prolong consumer concerns and the consequences for international trade for many years. There are still more clinical cases in Britain per year than in any other country. Nevertheless, the risk of exposure of British cattle may for some time have been greatest from imported products. The tightening of British feed controls in 1996 has had a significant effect, but feed controls were only tightened in Europe in 2000 and 2001. The covert nature of exposure means that risks are not recognized until long after the critical event of exposure has occurred. Recent consideration by the European Commission's Scientific Steering Committee (SSC) of the risks of importing BSE suggests that dispersal of infectivity from European countries was wide-spread even before the disease was first recognized in Britain in 1986.

McKintosh, E., S. J. Tabrizi, et al. (2003). "Prion diseases." J Neurovirol 9(2): 183-93.
 Prion diseases are incurable neurodegenerative conditions affecting both animals and humans. They may be sporadic, infectious, or inherited in origin. Human prion diseases include Creutzfeldt-Jakob desease (CJD), Gerstmann-Straussler-Scheinker disease, kuru, and fatal familial insomnia. The appearance of variant CJD, and the demonstration that is caused by strains indistinguishable from bovine spongiform encephalopathy (BSE) in cattle, has led to the threat of a major epidemic of human prion disease in the UK and other countries where widespread dietary exposure to bovine prions has occurred. This article reviews the history and epidemiology of these diseases, and then focuses on important areas of current research in human prion disorders.

Morley, R. S., S. Chen, et al. (2003). "Assessment of the risk factors related to bovine spongiform encephalopathy." Rev Sci Tech 22(1): 157-78.
 The Office International des Epizooties (OIE: World organisation for animal health) recommends that all OIE Member Countries determine the status of bovine spongiform encephalopathy (BSE) in their cattle populations by conducting a risk assessment and meeting certain BSE surveillance criteria. The OIE has identified and listed the factors and criteria for this in the International Animal Health Code. The factors to be assessed include the consumption of meat-and-bone meal (MBM) by cattle, the importation of cattle and MBM which are potentially infected or contaminated with the BSE agent, the livestock population structure, the rendering processes and the animal feeding practices. In this paper, the authors present an overview of these risk factors and criteria, detailing the relevant components of each. In the second part of this paper, the authors provide a risk assessment to demonstrate the application of the OIE BSE guidelines. This is a probabilistic risk assessment of the factors related to BSE for Canada which conforms to the OIE approach to import risk analysis. The steps include the hazard identification, release, exposure and consequence assessments and the risk estimation. A scenario tree for the release and exposure assessments was used to model the events emanating from the initiating failure event of importing cattle potentially infected with BSE. The consequence assessment describes the costs and losses associated with the introduction and establishment of BSE in other countries. The risk estimate, integrating the release, exposure and consequence assessments, indicates a negligible probability that BSE was introduced and established in Canada; nevertheless, the economic consequences would have been extreme.

Naharro, G., J. Yugueros, et al. (2003). "Prion protein gene polymorphisms in a population of Spanish cows." Vet Rec 152(7): 212-3.
 
Nardone, A. (2003). "Impact of BSE on livestock production system." Vet Res Commun 27 Suppl 1: 39-52.
 The small number of BSE cases diagnosed in Italy from January 2001 to 12 September 2001 (a total of 28, one every 9000 head) does not allow for a statistical analysis of the relationship between this disease and the livestock systems. However, some indications can be noted: (a) only dairy cattle, which represent three-quarters of the cattle raised in Italy, are involved; (b) 58% of the cases belong to medium-large farms that breed 27% of all head; (c) 13 out of 28 cases are 5-year-old animals and 26 out of 28 are between 5 and 7 years of age; (d) 15 of 28 cases come from Lombardia, where 27% of Italian dairy cattle are raised. The following factors may have affected the livestock system: (1) trends of beef meat consumption; (2) changes in livestock management; (3) changes in animal feeding; (4) possible effects on selection. A strong decline in beef meat consumption (4 kg/year) has been observed in the UK and other European countries since 1996 (the year of the discovery of the relationship between BSE and nvCJD). In Italy, from January 2001 the consumption of beef meat has declined as well as slaughter: a drop of 31% in the total slaughtered head in the period January-February, a drop of 14% in January-May. A fall in the price of calves has promoted, in some dairy farms, the start of the production of light beef less than one year old (advantages in the marketing of meat favour this initiative), a phenomenon which is not yet well established. Traceability and certification of meat have improved, thanks to breeders' associations and interprofessional agreements. The breeders associations have also started insurance initiatives against BSE risks. In Italy the employment of plant protein meals would increase the total feedstuff consumption by about 7%. Direct effects of BSE could slow down the genetic progress (GP) of cattle populations within breed and country. Indirect effects on GP may also happen as a consequence of an increase in the replacement rate (rr). This increase in rr reduced the generation interval and will therefore proportionally increase GP. Some important questions for the livestock production system are: Does the vertical transmission of BSE exist? Is there a genetic basis favouring the disease and is it inheritable? Are in vivo diagnostic tests possible? Are vaccination schemes against BSE possible and useful or is it better to pursue eradication?

Nishida, Y. (2003). "Elucidation of endemic neurodegenerative diseases--a commentary." Z Naturforsch [C] 58(9-10): 752-8.
 Recent investigations of scrapie, Creutzfeldt-Jakob disease (CJD), and chronic wasting disease (CWD) clusters in Iceland, Slovakia and Colorado, respectively, have indicated that the soil in these regions is low in copper and higher in manganese, and it has been well-known that patients of ALS or Parkinson's disease were collectively found in the New Guinea and Papua islands, where the subterranean water (drinking water) contains much Al3+ and Mn2+ ions. Above facts suggest that these neurodegenerative diseases are closely related with the function of a metal ion. We have investigated the chemical functions of the metal ions in detail and established the unique mechanism of the oxygen activation by the transition metal ions such as iron and copper, and pointed out the notable difference in the mechanism among iron, aluminum and manganese ions. Based on these results, it has become apparent that the incorporation of Al(III) or Mn(II) in the cells induces the "iron-overload syndrome", which is mainly due to the difference in an oxygen activation mechanism between the iron ion and Al(III) or the Mn(II) ion. This syndrome highly promotes formation of hydrogen peroxide, and hydrogen peroxide thus produced can be a main factor to cause serious damages to DNA and proteins (oxidative stress), yielding a copper(II)- or manganese(II)-peptide complex and its peroxide adduct, which are the serious agents to induce the structural changes from the normal prion protein (PrP(c)) to abnormal disease-causing isoforms, PrP(Sc), or the formation of PrP 27-30 (abnormal cleavage at site 90 of the prion protein). It seems reasonable to consider that the essential origin for the transmissible spongiform encephalopathies (TSEs) should be the incorporation and accumulation of Al(III) and Mn(II) ions in the cells, and the sudden and explosive increase of scrapie and bovine spongiform encephalopathy (BSE) in the last decade may be partially due to "acid rain", because the acid rain makes Al(III) and Mn(II) ions soluble in the subterranean aquifers.

Nitzan-Kaluski, D. and A. Leventhal (2003). "Bovine spongiform encephalopathy in Israel: implications for human health." Isr Med Assoc J 5(9): 662-5.
 Only one case of a cow infected with bovine spongiform encephalopathy has been reported in Israel. Its publication, in 2002, caused both public and professional concern. The inevitable health policy question raised was whether or not to recommend against consuming beef and what public health measures should be taken. In this article we describe the prion diseases among animals and humans, their interaction and the precautionary procedures that were carried out by the state Veterinary Services and the Ministry of Health since 1988. The BSE case (a 10 year old dairy cow) is believed to be the result of local consumption of infected mammalian meat and bone meal more than a decade earlier. The risk assessment took into consideration that no cases of vCJD (a new variant of Creutzfeldt-Jacob disease) have ever been diagnosed in Israel, as well as the low risk of contamination of the meat due to the religious method of slaughtering performed in the country. The policy decision was to implement a contingency plan prepared in advance. Israel was reclassified from the level II category of geographic risk where BSE is unlikely but not excluded in the herds, to level III where BSE is likely but not confirmed, or confirmed at a lower level. No undue damage to the meat industry has occurred. By the end of 2002, despite the examination of more than 3,800 brains from slaughtered cows older than 3 years, no other cases of BSE have been detected.

Nonno, R., E. Esposito, et al. (2003). "Molecular analysis of cases of Italian sheep scrapie and comparison with cases of bovine spongiform encephalopathy (BSE) and experimental BSE in sheep." J Clin Microbiol 41(9): 4127-33.
 Concerns have been raised about the possibility that the bovine spongiform encephalopathy (BSE) agent could have been transmitted to sheep populations via contaminated feedstuffs. The objective of our study was to investigate the suitability of molecular strain typing methods as a surveillance tool for studying scrapie strain variations and for differentiating PrP(Sc) from sheep scrapie, BSE, and sheep BSE. We studied 38 Italian sheep scrapie cases from 13 outbreaks, along with a British scrapie case, an experimental ovine BSE, and 3 BSE cases, by analyzing the glycoform patterns and the apparent molecular masses of the nonglycosylated forms of semipurified, proteinase-treated PrP(Sc). Both criteria were able to clearly differentiate sheep scrapie from BSE and ovine experimental BSE. PrP(Sc) from BSE and sheep BSE showed a higher glycoform ratio and a lower molecular mass of the nonglycosylated form compared to scrapie PrP(Sc). Scrapie cases displayed homogeneous PrP(Sc) features regardless of breed, flock, and geographic origin. The glycoform patterns observed varied with the antibody used, but either a monoclonal antibody (MAb) (F99/97.6.1) or a polyclonal antibody (P7-7) was able to distinguish scrapie from BSE PrP(Sc). While more extensive surveys are needed to further corroborate these findings, our results suggest that large-scale molecular screening of sheep populations for BSE surveillance may be eventually possible.

Nunziante, M., S. Gilch, et al. (2003). "Prion diseases: from molecular biology to intervention strategies." Chembiochem 4(12): 1268-84.
 Prion diseases are fatal neurodegenerative infectious disorders for which no therapeutic or prophylactic regimens exist. Understanding the molecular process of conformational conversion of the cellular prion protein (PrP(c)) into its pathological isoform (PrP(Sc)) will be necessary to devise effective antiprion strategies. In recent years, new findings in the cell biology of PrP(c), in the molecular pathogenesis of PrP(Sc), and in the cellular quality control mechanisms involved in these scenarios have accumulated. A function of the prion protein in signalling, the possible impact of the proteasome, and aggresomes as intracellular waste deposits have been described. Here, important pathogenetic similarities with the more frequent neurodegenerative disorders are evident. The need for therapeutic, postexposure, and prophylactic possibilities was drastically illustrated by the emergence of variant Creutzfeldt-Jakob disease (vCJD), a new human prion disease caused by bovine spongiform encephalopathy (BSE) derived prions. Although prion infectivity in humans is usually restricted to the central nervous system, in vCJD patients prions are present in the lympho-reticular system, posing a theoretical risk of accidental human-to-human transmission. A variety of chemical antiprion substances have been reported in in vitro and cell culture based assays or in animal studies. Occasionally, they have also made their way into the first human trials. In addition, various promising interference strategies have been devised in transgenic models, although they are usually hard to transfer into nontransgenic in vivo situations. New findings in the fields of peripheral prion pathogenesis and immune system involvement fuelled the search for antiprion strategies formerly considered to be entirely impossible. This opened the door towards classical immunological interference techniques. Remarkably, passive and even active vaccination approaches now seem to be realistic goals.

Ozawa, Y. (2003). "Risk management of transmissible spongiform encephalopathies in Asia." Rev Sci Tech 22(1): 237-49.
 A questionnaire-based survey was distributed to the Office International des Epizooties (OIE: World organisation for animal health) Member Countries in Asia to assess the use of risk management for transmissible spongiform encephalopathies. The author presents a summary of 16 responses received in July 2002. The survey revealed that import risk analysis on bovine spongiform encephalopathy (BSE) is not routinely carried out in ten countries, indicating an urgent need for further training courses. Although the number of ruminants imported from Europe is relatively small, significant quantities of feedstuffs of ruminant origin have been imported into Asia, which may mean that the BSE agent could have reached domestic cattle in most countries. The external challenge has been considerably reduced in recent years as most countries in Asia banned the importation of feedstuffs from countries with BSE, but a few weak spots which enable imports of risk materials still persist. Recycling of BSE through rendering plants is unlikely but cannot be totally excluded in some countries such as the People's Republic of China, India, Japan, Pakistan and Taipei China. Therefore, much more stringent management at slaughterhouses and rendering plants, as well as extensive surveillance programmes, are required in those countries. Bovine spongiform encephalopathy is not notifiable in six countries, indicating a total absence of risk management of BSE in those countries. Immediate actions by these governments to declare BSE a notifiable disease are considered necessary. Numbers of specimens tested for BSE are still very small in most countries in Asia, indicating a pressing need to upgrade surveillance programmes by introducing modern (economically affordable) diagnostic methods and by conducting practical training courses on epidemiological surveillance systems. With the exception of Japan, very little work has been performed on scrapie in Asia although the disease has been routinely monitored in the People's Republic of China, India, Myanmar, Pakistan and Taipei China.

Papacchini, M., A. Mansi, et al. (2003). "[Prevention of transmissible spongiform encephalopathy and methods for prion inactivation]." Med Lav 94(3): 271-84.
 BACKGROUND: Transmissible Spongiform Encephalopathies (TSEs) are infectious, progressive, lethal neurodegenerative diseases which affect both human and other mammalian species. The knowledge on the agent responsible for the infection and its pathogenetic mechanism is still limited. Specific diagnostic tests are currently not available; diagnosis is based on clinical symptoms and confirmed by a post-mortem examination which can reveal the typical brain lesions. There is some evidence on the relationship between the agent responsible for Bovine Spongiform Encephalopathy (BSE) and the new human variant of the Creutzfeldt-Jakob disease (nvCJD). The TSEs agents have some peculiarities: they overcome the interspecies barriers and are resistant to the normal disinfections and sterilization procedures. OBJECTIVES: On the basis of current scientific evidence, the aim of this article was: to make an excursus on the efficacy of inactivation methods and to give an overview of what has been issued by International and Italian Regulatory Agencies for the prevention of such diseases in hospital and occupational environments. METHODS: We examined current scientific literature on inactivation of TSEs by physical or chemical methods or combinations thereof. We also reviewed the most relevant guidelines on exposure risk, containment and occupational exposure to TSEs agents. RESULTS AND CONCLUSIONS: Due to the peculiarity of the prion protein and its transmission, it is very important to have effective methods to inactivate the TSE agents and to prevent them spreading. At present, no certain data are available on TSE development in occupational environments, while sources of exposure risk are known for several occupational categories, such as health-care personnel, pathologists, technicians in diagnostic and research laboratories, farmers, veterinary surgeons, slaughter house operators. For these workplaces, after an accurate risk assessment, it is necessary to implement certain precautionary measures, based on containment procedures and on the adoption of specific inactivation protocols.

Pollera, C., G. Carcassola, et al. (2003). "Development of in vitro cell cultures for the evaluation of molecules with antiprionic activity." Vet Res Commun 27 Suppl 1: 719-21.
 
Prince, M. J., J. A. Bailey, et al. (2003). "Bovine spongiform encephalopathy." Rev Sci Tech 22(1): 37-60.
 Early epidemiological studies identified bovine spongiform encephalopathy as a feed-borne infection associated with infected meat-and-bone meal in animal feed. The infection may have derived from scrapie in sheep, a spontaneous genetic mutation in cattle, or a transmissible spongiform encephalopathy in another mammalian species. Experimental work on the risk of transmission has necessarily tried to identify risk materials and their infectivity levels, the nature and size of species barriers, the infectious dose, the route of infection, the strain of the agent and the genotype of the animals at risk. The identification of levels of infection in cattle tissues has aided the removal of risk materials from the human and animal food chains. Maternally associated transmission is unlikely to maintain an outbreak, but the offspring of clinical cases appear to be at greater risk when the rate of food-borne exposure is high. Studies of embryo transfer have not shown infection to be transmitted by this means. While the control measures appeared to be straightforward, compliance has at times proved difficult to enforce and quantify. This has necessitated more extensive prohibitions, aggressive enforcement and thorough auditing of compliance levels.

Priola, S. A., A. Raines, et al. (2003). "Prophylactic and therapeutic effects of phthalocyanine tetrasulfonate in scrapie-infected mice." J Infect Dis 188(5): 699-705.
 The transmissible spongiform encephalopathy (TSE) diseases are rare, neurodegenerative diseases that include scrapie in sheep, bovine spongiform encephalopathy, and Creutzfeldt-Jakob disease in humans. There are no effective treatments available for clinical use in humans. We now demonstrate that, in 2 different rodent models of scrapie, multiple pretreatments with the cyclic tetrapyrrole phthalocyanine tetrasulfonate (PcTS) were as effective at delaying disease as multiple treatments starting at the time of infection. At low doses of scrapie infectivity, PcTS also protected some mice from peripheral scrapie infection, even if treatment was initiated several weeks after infection. Furthermore, PcTS completely inactivated low levels of scrapie infectivity when incubated with the infectious inoculum. Thus, PcTS has a broad range of antiscrapie activities. These findings suggest that cyclic tetrapyrroles may be useful both prophylactically and therapeutically against TSE diseases in vivo, as well as for inactivation of TSE infectivity suspended in solution.

Quirk, M. (2003). "Mad cow in Canada." Lancet Infect Dis 3(7): 397.
 
Roels, S., K. Walravens, et al. (2003). "Mycobacterium bovis meningitis in a cow with clinical signs of BSE." Vet Rec 152(26): 807-8.
 
Rowell, A. (2003). Don't worry, it's safe to eat : the true story of GM food, BSE, & Foot and Mouth. London ; Sterling, VA, Earthscan Publications.
 
Sachse, C., M. H. Groschup, et al. (2003). "Role of variant Creutzfeldt-Jakob disease for safety of treatment with blood components: screening of lymphatic tissue is a potential tool for risk assessment." Eur J Haematol 70(1): 11-6.
 BACKGROUND: Transmissible spongiform encephalopathies (TSEs) are neuropathological diseases caused by prions. Prions are infectious particles (PrPSc) which can induce bovine spongiform encephalopathy and most likely also the related infectious disease, variant of Creutzfeldt-Jakob disease (vCJD). The exposure of humans to orally ingested BSE agent in contaminated meat products presumably led to the emergence of vCJD. In vCJD, prions can be detected immunohistochemically not only in neuronal tissue but also in lymphoreticular tissue. vCJD is of significance in transfusion medicine because of the hypothetical transmission of prions by blood products. METHODS: An immunohistochemistry method was used to allow screening for vCJD in human lymphoreticular tissue. RESULTS: PrPSc can be detected in the cerebrum and cerebellum of patients with sporadic Creutzfeldt-Jakob disease (sCJD) and in the lymph nodes, tonsils, and spleen of vCJD patients. This method has the major advantage of working in fixed specimens which are routinely saved in departments of pathology and therefore allows screening of large numbers of archived human lymphoreticular tissues in different regional areas and from different time points. Scrapie-positive lymphoreticular sheep tissue reacts similarly to human tissue of vCJD affected patients and is available in sufficient amounts to be used as positive control in screening programs. CONCLUSION: A method is provided which is a feasible tool for an epidemiological screening program to assess the prevalence of the assumed infectious agent of vCJD, PrPSc, in various populations.

Saegerman, C., L. Claes, et al. (2003). "Differential diagnosis of neurologically expressed disorders in Western European cattle." Rev Sci Tech 22(1): 83-102, 61-82.
 A classification of neurological or neurologically expressed disorders that occur in Western European cattle aged 12 month and over has been established on the basis of aetiology, frequency and conditions of appearance, age and type of animals concerned and the main clinical signs observed. Neurologically expressed disorders have been classified according to different groups of causes: biological, non-biological and non-specific or unknown. Differential diagnosis of neurologically expressed disorders is an essential element in the clinical epidemiological surveillance of bovine spongiform encephalopathy. A growing number of aetiologies are described in the scientific literature. The identification and centralised management of neurological disorders will make it possible, one the one hand, to take account of the inherent variability in the clinical forms encountered and in the diagnostic approaches of the observers and, on the other hand, to identify new risk factors in order to control them.

Schatzl, H. M. (2003). "[Present-day knowledge of BSE and Creutzfeldt-Jakob disease]." Gesundheitswesen 65 Suppl 1: S13-9.
 
Schreuder, B. E. and R. A. Somerville (2003). "Bovine spongiform encephalopathy in sheep?" Rev Sci Tech 22(1): 103-20.
 Bovine spongiform encephalopathy (BSE) in sheep has not been identified under natural conditions at the time of writing and remains a hypothetical issue. However, rumours about the possible finding of a BSE-like isolate in sheep have led to great unrest within the sheep industry, among the general public and within governmental and regulatory bodies. The difficulties of implementing a proper risk assessment and pre-emptive measures, in the absence of a confirmed case, are described. The authors attempt to list what is known about experimental BSE in sheep, the distribution of infectivity in the host, some aspects of risk assessment and management and the most promising methods for differentiating BSE from scrapie in the same host. As for the latter, new and promising methods are being developed and appear suitable for initial screening of isolates of transmissible spongiform encephalopathies, but in the absence of proper validation, use of the 'classical' strain-typing in a mouse panel is still indicated.

Sellier, P. (2003). "Protein nutrition for ruminants in European countries, in the light of animal feeding regulations linked to bovine spongiform encephalopathy." Rev Sci Tech 22(1): 259-69.
 The outbreak of bovine spongiform encephalopathy (BSE) and the discovery of the central role played by meat-and-bone meal (MBM) as the vehicle of infection resulted, from the late 1980s onwards, in the implementation of new regulations on the incorporation of animal proteins, and then of most fats of animal origin, into diets fed to ruminants and other farmed animals. The BSE-related feed ban, which has gradually been reinforced over time, has led to the investigation of cost-effective routes for adequately replacing MBM and tallow by new sources of dietary proteins, minerals and lipids in the formulation of manufactured concentrates. As far as the technical fulfilment of the nutritive requirements of growing and lactating ruminants is concerned, efficient alternative solutions, based principally on recourse to food materials from vegetals already exist or hopefully will soon be available in most of the situations prevailing in Europe. However, related aspects, such as animal feed-processing, availability and traceability of certain food materials, quality of animal products, environmental constraints or disposal of animal waste from the meat industry give cause for concern. The expected consequences of the BSE-related feeding regulations on the organisational and economic framework of animal and crop production sectors throughout Europe and at world level must also be evaluated.

Shaked, G. M., R. Engelstein, et al. (2003). "Dimethyl sulfoxide delays PrP sc accumulation and disease symptoms in prion-infected hamsters." Brain Res 983(1-2): 137-43.
 PrP(Sc), an aberrantly folded protein, is the only identified component of the prion, an agent causing fatal neurodegenerative diseases such as scrapie and bovine spongiform encephalopathy. Dimethyl sulfoxide (DMSO) has been shown to reduce the accumulation of PrP(Sc) in scrapie-infected (ScN2a) cells, and to inhibit its aggregation in vitro. In humans, DMSO was used successfully in the treatment of various peripheral amyloidotic diseases. Here we show that administration of DMSO to scrapie-infected hamsters significantly prolonged disease incubation time, as well as delayed the accumulation of PrP(Sc) in Syrian hamster brains. Interestingly, administration of DMSO to scrapie sick hamsters resulted in increased clearance of protease-resistant PrP in their urine. We conclude that although DMSO by itself may not be sufficient to cure prion diseases, it may be considered as a component in a 'cocktail' drug approach for these disorders. Also, urine PrP testing should be considered for the assessment of treatment efficacy.

Sigurdson, C. J. and M. W. Miller (2003). "Other animal prion diseases." Br Med Bull 66: 199-212.
 In addition to bovine spongiform encephalopathy (BSE) of cattle and scrapie of sheep and goats, a few other animal prion diseases have been reported. These include feline spongiform encephalopathy of zoological and domestic cats (FSE) and transmissible spongiform encephalopathy (TSE) of zoological ruminants and non-human primates, as well as chronic wasting disease of deer and elk (CWD) and transmissible mink encephalopathy of farmed mink (TME). The origins of TSE in cats, zoo bovids, and non-human primates are clearly linked to the BSE epidemic; however, the origins of CWD and TME are less clear, but are not epidemiologically linked to the BSE epidemic. Here we review the epidemiology, transmission, clinical features and pathology of these other animal prion diseases.

Smith, P. G. and R. Bradley (2003). "Bovine spongiform encephalopathy (BSE) and its epidemiology." Br Med Bull 66: 185-98.
 Since the recognition of BSE in 1986, over 180,000 cattle in the UK have developed the disease and 1-3 million are likely to have been infected with the BSE agent, most of which were slaughtered for human consumption before developing signs of the disease. The origin of the first case of BSE is unknown, but the epidemic was caused by the recycling of processed waste parts of cattle, some of which were infected with the BSE agent, to other cattle in feed. Control measures have resulted in the consistent decline of the epidemic in the UK since 1992. Cattle and feed exported from the UK have seeded smaller epidemics in other European countries, where control measures were applied later. If the control measures now in place to protect public and animal health are well enforced, the epidemic in cattle should be largely under control and any remaining risk to humans through the consumption of beef should be very small.

Smith, A. J., J. Bagg, et al. (2003). "Prions and the oral cavity." J Dent Res 82(10): 769-75.
 Prion diseases have recently emerged as a significant challenge to health-care workers, including those involved in dentistry. Abnormal prion proteins are resistant to complete inactivation by conventional sterilization techniques. In the last decade, a new form of prion disease emerged in the UK, termed "variant CJD", thought to be acquired by consumption of bovine spongiform encephalopathy-contaminated food products. At present, CJD is an invariably fatal disease with no immediate prospect of treatment or vaccination. Of concern with the variant form of CJD, unlike the more classic forms of the disease, is the appearance of significant levels of infectivity outside the central nervous system. This raises concerns for the potential transmission of prion proteins via surgical procedures from individuals in the asymptomatic stage of the disease. This article reviews the existing knowledge base on the nature of prions, their distribution in oral tissues, and the implications for dental treatment.

Smith, P. G. (2003). "The epidemics of bovine spongiform encephalopathy and variant Creutzfeldt-Jakob disease: current status and future prospects." Bull World Health Organ 81(2): 123-30.
 The large epidemic of bovine spongiform encephalopathy (BSE) in the United Kingdom has been in decline since 1992, but has spread to other countries. The extensive control measures that have been put in place across the European Union and also in Switzerland should have brought the transmission of BSE under control in these countries, provided that the measures were properly enforced. Postmortem tests on brain tissue enable infected animals to be detected during the late stages of the incubation period, but tests that can be performed on live animals (including humans) and that will detect infections early are urgently needed. The number of infected animals currently entering the food chain is probably small, and the controls placed on bovine tissues in the European Union and Switzerland should ensure that any risks to human health are small and diminishing. Vigilance is required in all countries, especially in those in which there has been within-species recycling of ruminant feed. Fewer than 150 people, globally, have been diagnosed with variant Creutzfeldt-Jakob disease (vCJD), but there are many uncertainties about the future course of the epidemic because of the long and variable incubation period. Better control measures are necessary to guard against the possibility of iatrogenic transmission through blood transfusion or contaminated surgical instruments. These measures will required sensitive and specific, diagnostic tests and improved decontamination methods.

Solassol, J., C. Crozet, et al. (2003). "Prion propagation in cultured cells." Br Med Bull 66: 87-97.
 Cell cultures represent relevant and useful experimental models of transmissible spongiform encephalopathies (TSEs). They are able to promote, upon subpassaging, stable and persistent replication of PrP(Sc) as well as infectivity. To date, only a few cell culture models permissive to prion replication are available. Among them, mouse neuroblastoma cell lines (N2a) are most commonly used. While they correspond to homologous models supporting propagation of mouse-adapted scrapie strains, recent studies have reported heterologous models sensitive to natural occurring disease. Infected cell culture models have provided some valuable insights into the biogenesis of PrP(Sc) in terms of conversion, subcellular localisations, physiopathological consequences and species-barrier determinants. They have also contributed to the screening and the study of possible therapeutic compounds and to the development of new strategies for the investigation of TSE-specific diagnostic markers.

Stassano, P., A. Musumeci, et al. (2003). "Can epsilon-aminocaproic acid balance the off-pump bleeding advantage?" Cardiovasc Surg 11(3): 219-23.
 BACKGROUND: Aprotinin improved the control of bleeding in patients undergoing surgery with cardiopulmunary bypass, but its use was halted because of the risk of bovine spongiform encephalopathy. We then started to use epsilon-aminocaproic acid and the results in the control of bleeding were satisfactory. To assess its effectiveness in the control of postoperative bleeding precisely, we compared the results for patients operated on for myocardial revascularization on-pump and treated with epsilon-aminocaproic acid with those for patients who decidedly bleed less: off-pump patients. METHODS: Two groups of patients who had had either on- or off-pump double aortocoronary bypass surgery were retrospectively reviewed for postoperative bleeding. These two almost homogeneous group had two grafts only: left anterior descending and circumflex arteries operated on with cardiopulmonary bypass and treated with the epsilon-aminocaproic acid, and left anterior descending and right coronary arteries operated on off-pump. RESULTS: Postoperative bleeding through chest drainage at 4 h was 265+/-91.7 mL in the off-pump group and 328.4+/-131.4 mL in the on-pump group (p=0.004). But at 24 h it was 671.6+/-311.5 mL in the off-pump group and 827.8+/-514.4 mL in the on-pump group (p=0.07). CONCLUSIONS: epsilon-Aminocaproic acid is effective in controlling postoperative bleeding in patients operated on for myocardial revascularization with the aid of cardiopulmonary bypass.

Tabrizi, S. J., C. L. Elliott, et al. (2003). "Ethical issues in human prion diseases." Br Med Bull 66: 305-16.
 Prion diseases or transmissible spongiform encephalopathies are a group of closely related transmissible neurodegenerative conditions of humans and animals, all of which are incurable. In recent years, they have captured public attention with the emergence of the bovine spongiform encephalopathy (BSE) epidemic in Europe, and more recently with the appearance of variant CJD (vCJD) in humans, a novel form of Creutzfeldt-Jakob disease (CJD) that is linked to dietary exposure to BSE. In this chapter, we outline ethical questions posed by research, diagnostic procedures and therapy in the field of prion diseases.

Taylor, D. M. (2003). "Preventing accidental transmission of human transmissible spongifom encephalopathies." Br Med Bull 66: 293-303.
 The mechanism by which humans became infected with the BSE agent is discussed, and the matter of potential person-to person transmission of TSEs through contagion or medical procedures is considered. There is some discussion regarding the current evidence relating to whether or not the blood of humans infected with TSEs is infectious. Considerable emphasis is placed on the fact that TSE agents are known to be relatively resistant to decontamination by procedures that are effective with conventional micro-organisms, including (under worst-case conditions) the autoclaving procedures used to sterilise surgical instruments. Methods for providing additional re-assurance with regard to the safety of instruments are described. Safety in the pathology laboratory is discussed extensively because TSE agents are not inactivated by the usual processes used to fix tissues, and such laboratories will receive fixed tissues that are still highly infectious as far as TSE agents are concerned.

Taylor, D. M. and S. L. Woodgate (2003). "Rendering practices and inactivation of transmissible spongiform encephalopathy agents." Rev Sci Tech 22(1): 297-310.
 The authors describe the historic form of rendering and provide details on present-day practice. Possible future directions for the rendering industry are considered. The role of rendered meat-and-bone meal (MBM) as a dietary supplement in propagating the United Kingdom (UK) epidemic of bovine spongiform encephalopathy (BSE) is discussed, together with the role of MBM in spreading BSE outside the UK. Evidence that customarily used rendering processes did not substantially inactivate the agents of BSE or scrapie is presented. In addition, the influence that the abandonment of solvent extraction (as an adjunct to rendering) in the UK might have had on BSE infectivity levels in MBM is discussed. The BSE-related safety of tallow and by-products of tallow are considered. Data that associate the BSE agent with a new variant form of Creutzfeldt-Jakob disease in humans, predominantly but not exclusively, in the UK, are also discussed.

Taylor, D. M. (2003). "Inactivation of TSE agents: safety of blood and blood-derived products." Transfus Clin Biol 10(1): 23-5.
 Evidence relating to whether the blood of individuals with sporadic Creutzfeldt-Jakob disease is infectious is discussed. The conclusion is that this is unproven. Similar consideration is given to the blood of individuals with variant Creutzfeldt-Jakob disease; it is concluded that there is no convincing evidence that the blood is infectious but reasons for caution are presented. There is discussion regarding factors that add to the safety of plasma-derived therapeutic products, including the capacity of the manufacturing processes to inactivate or remove infectivity by the chemical and physical processes involved. There is extended discussion regarding the inactivation of these types of agents and the few reliable options available in worst-case scenarios such as the processing of instruments used neurosurgically on known or suspected cases. The most effective method is exposure to 1 M sodium hydroxide during autoclaving at 121 degrees C. The inappropriateness of applying any of the most effective methods to blood and blood-products because they are harsh and denaturing is discussed. Nevertheless, such procedures have potential application to the plant used in the manufacture of plasma-products. Evidence is presented which suggests that even more modest treatments (the use of lower concentrations of sodium hydroxide at lower temperatures) are effective when applied to surfaces that are free from any tissue contamination, as is the case with plant used to manufacture plasma-derived products. This evidence has come from studies carried out by the gelatin manufacturers of Europe regarding the capability of their manufacturing systems to inactivate the causal agent of bovine spongiform encephalopathy.

Terry, L. A., S. Marsh, et al. (2003). "Detection of disease-specific PrP in the distal ileum of cattle exposed orally to the agent of bovine spongiform encephalopathy." Vet Rec 152(13): 387-92.
 The immunohistochemical localisation of the disease-specific protein, PrP(Sc), was examined in the distal ileum of cattle up to 40 months after they had been exposed orally to the agent of bovine spongiform encephalopathy (BSE), in the intestines and mesenteric lymph nodes of an additional group of cattle, killed six months after a similar exposure, and in the distal ileum of naturally occurring clinical cases of BSE. PrP(Sc) was detected, mainly in macrophages, in a small proportion of the follicles of Peyer's patches in the distal ileum of the experimentally exposed cattle throughout much of the course of the disease. The observations are in agreement with the infectivity data derived from mouse bioassays of the distal ileum. At the later stages of the disease, the proportion of immunostained follicles increased as the total number of follicles decreased with age. In the additional experimental group of cattle, PrP(Sc) was confined to the Peyer's patches in the distal ileum. No immunostaining was detected in the lymphoid tissue of the distal ileum of naturally occurring clinical cases of BSE. In some of the clinically affected experimentally induced and naturally occurring cases of BSE there was sparse immunostaining of the neurons of the distal ileal myenteric plexus.

Thackray, A. M., J. Y. Madec, et al. (2003). "Detection of bovine spongiform encephalopathy, ovine scrapie prion-related protein (PrPSc) and normal PrPc by monoclonal antibodies raised to copper-refolded prion protein." Biochem J 370(Pt 1): 81-90.
 Prion-related protein (PrP) is a glycosylphosphatidylinositol-linked cell-surface protein expressed by a wide variety of cells, including those of the nervous system and the immune system. Several functions of normal cellular PrP (PrPc) have been proposed that may be associated with the capacity of this protein to bind copper. In the present study, we describe the generation of a panel of monoclonal antibodies raised to copper-refolded PrP, which may be used to analyse the normal and disease-associated forms of this protein. The anti-PrP monoclonal antibodies were reactive by Western blot and ELISA with recombinant murine PrPc refolded in the presence or absence of either copper or manganese, and with the disease-susceptible allelic form V136R154Q171 ('VRQ'; where single-letter amino-acid notation has been used) and disease-resistant allelic form A136R154R171 ('ARR') of recombinant ovine PrPc. FACS analysis of lymphoid cells using these monoclonal antibodies showed that wild-type non-activated mouse lymphocytes expressed little, if any, PrPc. These monoclonal antibodies were shown to react with the unglycosylated and monoglycosylated forms of PrPSc (abnormal disease-specific conformation of PrP) in prion-infected tissue samples from all of the different species tested by Western blot. In addition, this analysis allowed one to make a distinction between bovine spongiform encephalopathy ('BSE') and scrapie PrPSc) isolates from experimentally infected sheep on the basis of their different electrophoretic mobilities.

Thomzig, A., C. Kratzel, et al. (2003). "Widespread PrPSc accumulation in muscles of hamsters orally infected with scrapie." EMBO Rep 4(5): 530-3.
 Scrapie, bovine spongiform encephalopathy and chronic wasting disease are orally communicable, transmissible spongiform encephalopathies (TSEs). As zoonotic transmissions of TSE agents may pose a risk to human health, the identification of reservoirs for infectivity in animal tissues and their exclusion from human consumption has become a matter of great importance for consumer protection. In this study, a variety of muscles from hamsters that were orally challenged with scrapie was screened for the presence of a molecular marker for TSE infection, PrPSc (the pathological isoform of the prion protein PrP). Sensitive western blotting revealed consistent PrPSc accumulation in skeletal muscles from forelimb and hindlimb, head, back and shoulder, and in tongue. Previously, our animal model has provided substantial baseline information about the peripheral routing of infection in naturally occurring and orally acquired ruminant TSEs. Therefore, the findings described here highlight further the necessity to investigate thoroughly whether muscles of TSE-infected sheep, cattle, elk and deer contain infectious agents.

Torrence, M. E. and R. E. Isaacson (2003). Microbial food safety in animal agriculture : current topics. Ames, Iowa, Iowa State Press.
 
Travis, D. and M. Miller (2003). "A short review of transmissible spongiform encephalopathies, and guidelines for managing risks associated with chronic wasting disease in captive cervids in zoos." J Zoo Wildl Med 34(2): 125-33.
 The transmissible spongiform encephalopathies (TSEs) represent an emerging group of diseases that have been labeled as "prion diseases" because of the recent characterization of the infectious agent. TSEs are caused by prions, which induce neurodegenerative fatal diseases in humans and animals. Some TSEs (scrapie and kuru), have existed in both animals and humans for a very long time, whereas others such as bovine spongiform encephalopathy and variant Creutzfeld-Jakob disease have either recently emerged or are more thoroughly described and recognized. It is obvious that the medical community will be forced to consider these diseases in humans and animals for the future. This article offers a short review of the TSEs of immediate concern to zoo and wildlife veterinarians and wildlife biologists and suggests risk management strategies for the prevention of these diseases, with special focus on chronic wasting disease of cervids in North America.

Trevitt, C. R. and P. N. Singh (2003). "Variant Creutzfeldt-Jakob disease: pathology, epidemiology, and public health implications." Am J Clin Nutr 78(3 Suppl): 651S-656S.
 Prion diseases, or transmissible spongiform encephalopathies, include Creutzfeldt-Jakob disease (CJD) in humans and scrapie and bovine spongiform encephalopathy (BSE) in animals. These neurodegenerative diseases are invariably fatal and can be transmitted by inoculation or dietary exposure. They are associated with the accumulation of an altered, disease-associated form of the normal prion protein. Pathologically, prion diseases result in neuronal cell death and a characteristic spongiform appearance of the brain tissue. The emergence of a variant form of CJD (vCJD) in the United Kingdom in 1996 has been causally and experimentally linked to the UK BSE epidemic in the 1980s and early 1990s. The finding that BSE is transmissible to different animal species, unlike previously characterized prion diseases such as sheep scrapie, has raised enormous public health concerns worldwide. Although it is not yet possible to gauge the size of a potential vCJD epidemic, preliminary data indicate a significant dietary exposure to BSE-infected material in Britain and wider implications of the transmissibility of prion diseases. The threat to public health has intensified research efforts to understand the molecular basis of prion diseases, understand their transmission between species, improve methods of diagnosis, and develop therapeutic strategies for treatment and prevention of disease. In this review, we summarize current data on the pathology of BSE and vCJD and the epidemiology of vCJD, and we outline public health implications based on these data, emphasizing preventative measures and areas of research for screening and diagnosis.

Valfre, F. and V. M. Moretti (2003). "The 'BSE Strategic Project' of the National Council of Research: results of four years of research." Vet Res Commun 27 Suppl 1: 57-62.
 
van 't Hooft, A. J. (2003). "[BSE-blood test in living animals]." Tijdschr Diergeneeskd 128(20): 636.
 
van 't Hooft, A. J. (2003). "[BSE-decision of minister Veerman a step in the right direction]." Tijdschr Diergeneeskd 128(14-15): 461.
 
van Gelderen, C., E. J. Gimeno, et al. (2003). "Bovine spongiform encephalopathy in South America: a regional preventive approach." Rev Sci Tech 22(1): 227-36.
 Bovine spongiform encephalopathy (BSE) is a neurodegenerative disease of cattle caused by prions that was first described in the United Kingdom (UK) in 1986. The BSE epizootic that commenced in the UK in the 1980s has since spread into other countries in Europe and Asia through exports of contaminated meat-and-bone meal or infected cattle. Over the past few years, other emerging or reemerging diseases have spread into previously free countries or regions through international trade. This negative effect of globalisation means that to implement successful preventive and strategic programmes to safeguard animal health, such programmes must, as a priority, take a regional approach. Global thinking, regional planning and local performance constitute the key factors for the successful control of animal diseases. In South America, initial preventive actions against BSE were adopted in 1989. Further measures adopted since then and based on new scientific and technical findings, have led to the demonstration that the region is free of BSE. These early preventive actions have reliably protected the region from importing BSE-infected material. An integral part of the project to determine the BSE status of South America was the training of personnel, the incorporation of technology and the provision of updated information through close relationships with international organisations and prominent international researcher workers. Regional activities aimed at harmonising BSE prevention programmes, producing objective and transparent data on the equivalence of regional BSE status and facilitating regional and international trade have recently been launched. Maintaining the BSE-free status of the region must be given high priority by the beef agro-industrial sectors.

van't Hooft, A. J. (2003). "[BSE: an additional explanation]." Tijdschr Diergeneeskd 128(4): 124.
 
Volkel, D., K. Zimmermann, et al. (2003). "Immunochemical detection of prion protein on dipsticks prepared with crystalline bacterial cell-surface layers." Transfusion 43(12): 1677-82.
 BACKGROUND: Transmissible spongiform encephalopathy (TSE) represents a spectrum of diseases affecting humans and animals. A definitive diagnosis of TSEs is only possible by postmortem identification of pathologic prion protein in brain tissue that has been treated with protease. The pathologic protein is detected by Western blot analysis or ELISA methods. The bovine spongiform encephalopathy crisis and occurrence of a new variant of CJD has increased demand for rapid and simple assays. STUDY DESIGN AND METHODS: A dipstick assay has been developed for prion diagnosis based on a sandwich ELISA specific for prion protein, and crystalline bacterial cell-surface layers (S-layers) were used as an immobilization matrix. The usefulness of the dipstick assay was evaluated by determining the detection limit, comparison with other methods, and analysis of CJD samples. RESULTS: The sensitivity of the prion dipsticks was similar to that published for time-resolved fluorescence ELISA methods. After protease treatment, pathologic prion protein could be detected specifically. CONCLUSION: The dipstick assay is a sensitive and specific test useful for the detection of prion protein. The simplicity of the S-layer dipstick lends itself to a variety of potential applications including field diagnostics.

Vorberg, I., M. H. Groschup, et al. (2003). "Multiple amino acid residues within the rabbit prion protein inhibit formation of its abnormal isoform." J Virol 77(3): 2003-9.
 Transmissible spongiform encephalopathies (TSEs) are neurological diseases that are associated with the conversion of the normal host-encoded prion protein (PrP-sen) to an abnormal protease-resistant form, PrP-res. Transmission of the TSE agent from one species to another is usually inefficient and accompanied by a prolonged incubation time. Species barriers to infection by the TSE agent are of particular importance given the apparent transmission of bovine spongiform encephalopathy to humans. Among the few animal species that appear to be resistant to infection by the TSE agent are rabbits. They survive challenge with the human kuru and Creutzfeldt-Jakob agents as well as with scrapie agent isolated from sheep or mice. Species barriers to the TSE agent are strongly influenced by the PrP amino acid sequence of both the donor and recipient animals. Here we show that rabbit PrP-sen does not form PrP-res in murine tissue culture cells persistently infected with the mouse-adapted scrapie agent. Unlike other TSE species barriers that have been studied, critical amino acid residues that inhibit PrP-res formation are located throughout the rabbit PrP sequence. Our results suggest that the resistance of rabbits to infection by the TSE agent is due to multiple rabbit PrP-specific amino acid residues that result in a PrP structure that is unable to refold to the abnormal isoform associated with disease.

Wadsworth, J. D., A. F. Hill, et al. (2003). "Molecular and clinical classification of human prion disease." Br Med Bull 66: 241-54.
 While rare in humans, the prion diseases have become an area of intense clinical and scientific interest. The recognition that variant Creutzfeldt-Jakob disease is caused by the same prion strain as bovine spongiform encephalopathy in cattle has dramatically highlighted the need for a precise understanding of the molecular biology of human prion diseases. Detailed clinical, pathological and molecular data from a large number of human prion disease cases have shown that distinct abnormal isoforms of prion protein are associated with prion protein gene polymorphism and neuropathological phenotypes. A molecular classification of human prion diseases seems achievable through characterisation of structural differences of the infectious agent itself.

Walker, J. A., D. A. Hughes, et al. (2003). "Quantitative intra-short interspersed element PCR for species-specific DNA identification." Anal Biochem 316(2): 259-69.
 We have designed and evaluated four assays based upon PCR amplification of short interspersed elements (SINEs) for species-specific detection and quantitation of bovine, porcine, chicken, and ruminant DNA. The need for these types of approaches has increased drastically in response to the bovine spongiform encephalopathy epidemic. Using SYBR Green-based detection, the minimum effective quantitation levels were 0.1, 0.01, 5, and 1 pg of starting DNA template using our bovine, porcine, chicken, and ruminant species-specific SINE-based PCR assays, respectively. Background cross-amplification with DNA templates derived from 14 other species was negligible. Species specificity of the PCR amplicons was further demonstrated by the ability of the assays to accurately detect trace quantities of species-specific DNA from mixed (complex) sources. Bovine DNA was detected at 0.005% (0.5 pg), porcine DNA was detected at 0.0005% (0.05 pg), and chicken DNA was detected at 0.05% (5 pg) in a 10-ng mixture of bovine, porcine, and chicken DNA templates. We also tested six commercially purchased meat products using these assays. The SINE-based PCR methods we report here are species-specific, are highly sensitive, and will improve the detection limits for DNA sequences derived from these species.

Wang, J., B. Xu, et al. (2003). "[Detection of bovine-derived materials in import animal feeds and food by PCR assay]." Wei Sheng Yan Jiu 32(1): 26-9.
 A PCR assay for detection and identification of bovine--derived materials in import animal feeds and food is developed. A 271 bp sequence from bovine specific mitochondrial DNA is amplified. The amplified specific sequence of the bovine mtDNA from meat and feed samples is demonstrated by both direct sequencing and restriction endonuclease digestion yield analysis. This method can detect bovine mtDNA in those less than 0.125% of bovine meat. Owing that this method is specific, rapid and sensitive, it can be utilized as a routine control assay in prevention of spreading of bovine spongiform encephalopathy in China caused by imported food and animal feeds especially meat and bone meals.

Weiss, R. A. (2003). "Cross-species infections." Curr Top Microbiol Immunol 278: 47-71.
 Animals have always been a major source of human infectious disease. Some infections like rabies are recognized as primary zoonoses caused in each case by direct animal-to-human transmission, whereas others like measles become independently sustained within the human population so that the causative virus has diverged from its morbillivirus progenitor in ruminants. Recent examples of direct zoonoses are variant Creutzfeldt-Jakob disease arising from bovine spongiform encephalopathy, and the H5N1 avian influenza outbreak in Hong Kong. Recent epidemic diseases of animal origin are the 1918-1919 influenza pandemic, and the acquired immune deficiency syndrome pandemic caused by human immunodeficiency virus. Some retroviruses move into and out of the chromosomal DNA of the host germline, so that they may oscillate between being an avirulent inherited Mendelian trait in one species and an infectious pathogen in another. Cross-species viral and other infections are reviewed historically with respect to the evolution of virulence and the concern about iatrogenic enhancement of cross-species transfer by medical procedures akin to xenotransplantation.

Weissmann, C. and E. Flechsig (2003). "PrP knock-out and PrP transgenic mice in prion research." Br Med Bull 66: 43-60.
 Spongiform encephalopathies such as scrapie in sheep, bovine spongiform encephalopathy (BSE) in cattle or Creutzfeldt-Jacob disease (CJD) and Gerstmann-Straussler-Scheinker syndrome (GSS) in humans is caused by a transmissible agent designated prion. The 'protein only' hypothesis proposes that the prion consists partly or entirely of a conformational isoform of the normal host protein PrP(C), designated PrP(*)(1) and that the abnormal conformer, when introduced into the organism, causes the conversion of PrP(C) into a likeness of itself. PrP(*) may be congruent with PrP(Sc), a protease-resistant, aggregated conformer of PrP that accumulates mainly in brain of almost all prion-infected organisms. PrP(C) consists of a flexible N-terminal half, comprising Cu(2+)-binding octapeptide repeats, and a globular domain consisting of three alpha-helices, one short antiparallel beta-sheet and a single disulphide bond. It is anchored at the outer cell-surface by a glycosyl phosphatidylinositol (GPI) tail and is present in almost all tissues, however, mainly in brain. Compelling linkage between the prion and PrP was established by biochemical and genetic data and led to the prediction that animals devoid of PrP should be resistant to experimental scrapie and fail to propagate infectivity. This prediction was indeed borne out, adding substantial support to the 'protein only' hypothesis. In addition, the availability of PrP knock-out mice provided an approach to carry out reverse genetics on PrP, both in regard to prion disease and to its physiological role.

Weitkunat, R., C. Pottgiesser, et al. (2003). "Perceived risk of bovine spongiform encephalopathy and dietary behavior." J Health Psychol 8(3): 373-81.
 The German BSE crisis in early 2001 can be considered as a natural experiment with strong behavioral consequences. The present study investigated psychological and other factors associated with reduced meat consumption compared to the first months of the previous year. As expected, all types of meat, with the exception of poultry and game, were eaten less often. The effect was strongest in beef, where almost half of the sample reported reduced meat consumption. As predicted by the health belief model, perceived threat was associated with subjective vulnerability. It was not, however, strongly associated with perceived seriousness of BSE, probably due to the ubiquitous public discussion of the topic. Reduced beef consumption has three to four times more frequent in the event of subjective threat.

Wells, G. A. (2003). "Pathogenesis of BSE." Vet Res Commun 27 Suppl 1: 25-8.
 Before the emergence of bovine spongiform encephalopathy (BSE) and recognition of its zoonotic potential, the major example of the transmissible spongiform encephalopathies (TSEs) of animals was scrapie of sheep. But there is no evidence that scrapie transmits naturally to any species other than sheep and goats. The pathogenesis of scrapie has been studied most in experimental laboratory rodent species. In most experimental models of scrapie, after peripheral non-neural routes of infection, replication of the agent can first be detected in lymphoreticular system (LRS) tissue. When the route of introduction of agent into the body is localized, initial involvement will be in LRS tissue draining the infection site. Thereafter, there is a striking amplification of the agent in the LRS and spread by lymphatic/haematogenous routes, giving widespread dissemination in the LRS. This precedes replication in the CNS, but is not the means by which infection reaches the CNS. There is now substantial evidence from experimental models of scrapie that involvement of the CNS is by peripheral nervous system (PNS) pathways. In some models employing oral exposure the earliest localized LRS replication is in the gut-associated lymphoid tissue (GALT) and autonomic PNS routing to the CNS has been implicated. However, the relative importance of different routes of spread of TSEs within the body is determined by a number of host- and agent-dependent factors and, therefore, generalizations from an experimental model to a natural disease across a species barrier may not be appropriate. With the occurrence of BSE and recognition of its food-borne route of transmission via meat and bone meal, has come greater awareness of the probable importance of the oral route of infection in ruminant species affected by TSEs. In consequence, studies have increasingly focused on the natural host species to examine pathogenetic events.

Wells, G. A., S. A. Hawkins, et al. (2003). "Studies of the transmissibility of the agent of bovine spongiform encephalopathy to pigs." J Gen Virol 84(Pt 4): 1021-31.
 Studies to test the transmissibility of the bovine spongiform encephalopathy (BSE) agent to pigs began in 1989. Parenteral inoculation of the agent by three routes simultaneously (intracranially, intravenously and intraperitoneally) produced disease with an incubation period range of 69-150 weeks. Pre-clinical pathological changes were detected in two pigs killed electively at 105 and 106 weeks post-inoculation. Infectivity was detected by bioassay in inbred mice in the CNS of those pigs that developed spongiform encephalopathy. Infectivity was also found in the stomach, jejunum, distal ileum and pancreas of terminally affected pigs. These findings show that pigs are susceptible to BSE. In contrast, disease failed to occur in pigs retained for 7 years after exposure by feeding BSE-affected brain on three separate days, at 1-2 week intervals. The amounts fed each day were equivalent to the maximum daily intake of meat and bone meal in rations for pigs aged 8 weeks. No infectivity was found in tissues assayed from the pigs exposed orally. This included tissues of the alimentary tract. It is suggested that these pigs did not become infected. The relatively high oral exposure used in these experiments compared with feed-borne exposure in the field may explain the absence of an epidemic of spongiform encephalopathy in domestic pigs concurrent with the BSE epidemic in the UK.

White, A. R., P. Enever, et al. (2003). "Monoclonal antibodies inhibit prion replication and delay the development of prion disease." Nature 422(6927): 80-3.
 Prion diseases such as Creutzfeldt-Jakob disease (CJD) are fatal, neuro-degenerative disorders with no known therapy. A proportion of the UK population has been exposed to a bovine spongiform encephalopathy-like prion strain and are at risk of developing variant CJD. A hallmark of prion disease is the transformation of normal cellular prion protein (PrP(C)) into an infectious disease-associated isoform, PrP(Sc). Recent in vitro studies indicate that anti-PrP monoclonal antibodies with little or no affinity for PrP(Sc) can prevent the incorporation of PrP(C) into propagating prions. We therefore investigated in a murine scrapie model whether anti-PrP monoclonal antibodies show similar inhibitory effects on prion replication in vivo. We found that peripheral PrP(Sc) levels and prion infectivity were markedly reduced, even when the antibodies were first administered at the point of near maximal accumulation of PrP(Sc) in the spleen. Furthermore, animals in which the treatment was continued remained healthy for over 300 days after equivalent untreated animals had succumbed to the disease. These findings indicate that immunotherapeutic strategies for human prion diseases are worth pursuing.

Will, R. G. (2003). "Acquired prion disease: iatrogenic CJD, variant CJD, kuru." Br Med Bull 66: 255-65.
 Human prion diseases can be classified as sporadic, hereditary or acquired. The cause of sporadic Creutzfeldt-Jakob disease (CJD) is unknown, hereditary cases are associated with mutations of the prion protein gene (PRNP) and acquired forms are caused by the transmission of infection from human to human or, as a zoonosis, from cattle to human. Although acquired forms of human prion disease are rare, the transmission of a fatal and untreatable neurological disorder has had major implications for public health and public policy.

Willerroider, M. (2003). "Routine tests reveal unknown strains of BSE prions." Nature 425(6959): 648.
 
Williams, E. S. and M. W. Miller (2003). "Transmissible spongiform encephalopathies in non-domestic animals: origin, transmission and risk factors." Rev Sci Tech 22(1): 145-56.
 The transmissible spongiform encephalopathies (TSEs), scrapie and bovine spongiform encephalopathy (BSE), are serious diseases of domestic animals. Although not as significant in terms of numbers of animals affected or geographical distribution, TSEs also affect non-domestic animals. Transmissible mink encephalopathy (TME) was the first TSE to be identified in non-domestic animals. This disease of captive mink (Mustela vison) is very rare and is associated with exposure through feed contaminated by a TSE agent. The second TSE to be identified in non-domestic animals was chronic wasting disease (CWD) of deer and elk. This disease is not known to be associated with feedstuffs contaminated with the agent of CWD, but the natural route of exposure appears to be oral, possibly through direct interaction between animals or through environmental contamination. Over the last five years, the known distribution of CWD across North America has expanded, increasing concerns over the impact of this disease on populations of free-ranging cervids and the viability of game farming industries. Concurrent with the epidemic of BSE, a variety of non-domestic ruminants and felid species were also affected in the United Kingdom, presumably through exposure to the agent in contaminated feed. These examples illustrate that when non-domestic animals are held in captivity, they depend upon feeds supplied by their caretakers and may show degrees of susceptibility to infectious agents in feeds which vary from those of domestic species. Although humans have less influence over exposure of free-ranging species to infectious agents, monitoring these populations for diseases may be important for managing the health of these animals. It is important to institute or continue surveillance for an entire range of infectious diseases, including TSEs, in free-ranging and captive non-domestic species. Study of diseases in these species may provide important information about infectious agents of concern for domestic animals and humans.

Wolferstan, F. (2003). "Slow neurodegeneration and transmissible spongiform encephalopathies/prion diseases. Hypothesis: a cycle involving repeated tyrosine kinase A activation could drive the development of TSEs." Med Hypotheses 60(1): 52-64.
 Neurons are specialised non-mitogenic cells. They cannot be replaced after damage, but most survive the lifetime of the individual. This is achieved by a very specialised process of repair and regeneration.During this process, a phase of degeneration in the distal end of the damaged neuron occurs in response to tyrosine kinase activation by nerve growth factor, which results in removal of neuronal detritus from within the cell membrane. As this phase is completed the activity of tyrosine kinase is modulated and the regeneration phase begins.It is postulated that normal prions play a part in the modulation of tyrosine kinase activity; that abnormal prion isoforms may be damaged in the process releasing a few fragments of prion PrP106-126 and that these stimulate release of nerve growth factor, which activates tyrosine kinase once more, setting up the vicious spiral of slow neurodegeneration found in the transmissible spongiform encephalopathies.

Yin, S. M., Y. Zheng, et al. (2003). "On-column purification and refolding of recombinant bovine prion protein: using its octarepeat sequences as a natural affinity tag." Protein Expr Purif 32(1): 104-9.
 Prion protein has a key role in the occurrence of transmissible spongiform encephalopathy (TSE) and development of these diseases. Here, we provide a convenient procedure for on-column purification and refolding of the full-length mature bovine prion protein (bPrP) from Escherichia coli using immobilized metal (Ni) affinity chromatography, based on the metal-binding property of its unusual octarepeat sequences containing six tandem copies. Following extensive washing, the bPrP pellet was solubilized by guanidine hydrochloride and subjected to Ni-NTA agarose column. Purification and refolding were achieved by stepwise gradient washing with reduced guanidine hydrochloride concentrations. Triton X-100 and beta-mercaptoethanol were required in this rapid refolding process. The isolated prion protein was identified by monoclonal antibodies and its integrity was monitored by mass spectroscopy. Its correct folding was confirmed from circular dichroism (CD) experiments. Moreover, thioflavin T-binding assay showed that the recombinant bPrP could be transformed into amyloid fiber structures like that of the infectious prion isoform PrP(sc).

Zaaijer, H. L. (2003). "[ 'Severe acute respiratory syndrome' (SARS) in perspective]." Ned Tijdschr Geneeskd 147(18): 846-8.
 In the Netherlands, the risk of an outbreak of the severe acute respiratory syndrome (SARS) appears to be limited, if people in contact with a possibly imported case observe strict measures to prevent contamination. SARS may well be a zoonosis. Bovine spongiform encephalopathy and outbreaks of virus infections in the bioindustry, such as swine fever, foot-and-mouth disease and classical avian influenza, have led to massive killing of cattle, swine and fowl in the Netherlands. The possibility that the bioindustry constitutes a risky microbiological 'experiment' makes a discussion as to its future in the Netherlands urgent.

Zou, W., M. Colucci, et al. (2003). "Characterization of prion proteins." Methods Mol Biol 217: 305-14.

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