Spongiform Encephalopathy Advisory Committee Research Articles

BSE: the further we go, the less we know

BOVINE spongiform encephalopathy (BSE) is a transmissible spongiform encephalopathy (TSE) that during the last three decades has overturned all the paradigms of surveillance, diagnosis, legislation and public concern. Several origins...

Control of classical scrapie in Great Britain

CLASSICAL scrapie has been recognised as a fatal neurological disease in sheep in Great Britain for almost 300 years and, until recently, control at flock level has been difficult to...

Progress and limits of PrP gene selection policy

Classical scrapie has proved to be a notoriously difficult disease to control due to a poor understanding of its natural history. The recognition of disease risk linkage to PrP genotype has offered the prospect of a disease control strategy, viz. genotyping and selective breeding, novel to veterinary medicine when first considered in the 1990s. The UK Spongiform Encephalopathy Advisory Committee recommended the exploitation of this approach in a voluntary, national programme to control classical scrapie and protect the public against food-borne exposure to bovine spongiform encephalopathy, should the national flock have been exposed via contaminated feed. The National Scrapie Plan for Great Britain was launched in 2001 and uptake has been widespread throughout the purebreeding sector of the sheep industry, with membership peaking at over 12 000 flocks in 2006. A total of 700 000 rams from 90 breeds have been genotyped. A comparison of ram lambs born in 2002 with those in 2006 shows evident changes in PrP genotype frequencies which are predicted to be associated with a reduction in disease risk. Various concerns have been raised regarding possible unintended consequences of widespread selection on PrP genotype, including impacts on other performance traits and possible effects on inbreeding and genetic diversity. To date, these concerns appear to be unfounded, as no consistent associations have been found with performance traits, nor are there likely to be any detectable impacts on inbreeding in mainstream breeds. Currently, semen banks have been implemented in Great Britain to store samples from animals of all common PrP genotypes, should these genotypes be required in the future. Various strategies to minimise future disease risks are discussed in the paper.

A laboratory and clinical evaluation of single‐use instruments for tonsil and adenoid surgery

To compare the quality and consistency of single-use adenotonsillectomy instruments available in the UK with reusable instruments and examine their performance in a clinical setting. A laboratory assessment of each reusable instrument created a detailed specification for the respective single-use equivalent. A surveillance system monitored the performance of a selected set of specified single-use instruments. Single-use instruments were withdrawn shortly after their introduction in 2001. Persisting concerns from the Spongiform Encephalopathy Advisory Committee led to an investigation into the feasibility of continuing to use such instruments. The numbers of instruments from each set judged as unacceptable or as good as the original. The number and cause of instrument failure during clinical surveillance. Between 40% and 93% of the instruments on each set were as good as the original and between 0% and 40% of the instruments were unacceptable from six sets of steel and one set of polymer instruments. 4151 procedures were monitored between 1 February 2003 and 31 March 2004 using a total of 41 376 instruments. Problems were reported with 335 (0.8%) instruments, 46% attributable to instrument design, 14% to poor design control and 13% to instruments escaping quality control systems. Following correction of the faults, between 1 January 2004 and 31 March 2004 the problem rate fell to 0.4%. High quality single-use instruments for tonsil and adenoid surgery are available in the UK. Some companies offered inferior instruments not fit for their purpose. The procurement, introduction and subsequent clinical approval of single-use instruments requires a radically different approach to that currently applied to the purchase of reusable surgical equipment. Careful monitoring of their introduction is essential.

Creutzfeldt-Jakob disease: implications for gastroenterology.

The current clinical views regarding variant Creutzfeldt-Jakob disease, and in particular transmission via endoscopy, of those representing both gastroenterology and the Spongiform Encephalopathy Advisory Committee are presented in an attempt to guide clinicians as to "best practice" given the current state of our knowledge.

More on BSE/vCJD

More on BSE/vCJD

Pulvinar sign on MRI images in variant Creutzfeldt-Jakob disease.

A non-invasive investigation that gave a reliable sign of variant Creutzfeldt-Jakob disease (vCJD) would help in the diagnosis of this disorder and reduce the need for tonsillar biopsy or other open procedures with all their attendant safety risks and difficulties in the disposal of hazardous tissues. 1 Transmissible spongiform encephalopathy agents: safe working and the prevention of infection. Advisory Committee on Dangerous Pathogens Spongiform Encephalopathy Advisory Committee. HMSO, Norwich1998 Google Scholar Prompted by the lack of such a test, Martin Zeidler and colleagues looked at the posterior thalamus (pulvinar) on magnetic-resonance-imaging (MRI) scans to find out whether changes in this area were a potential diagnostic aid. Since the number of people incubating or at risk of vCJD is still unknown, 2 Cousens SN Vynnyeky I Zeidler M Will RG Smith PG Predicting the CJD epidemic in humans. Nature. 1997; 385: 197-198 Crossref PubMed Scopus (189) Google Scholar such a study is timely and appropriate. The pulvinar sign on magnetic resonance imaging in variant Creutzfeldt-Jakob diseaseIn the appropriate clinical context the MRI identification of bilaterally increased pulvinar signal is a useful non-invasive test for the diagnosis of vCJD. Full-Text PDF

Bovine spongiform encephalopathy (BSE) – a review

Summary Bovine spongiform encephalopathy (BSE) incidence. The number of new cases continues to fall as forecast (from the peak of 37 487 in 1992 to 13 825 in 1995, to 7406 in 1996 to 3980 in 1997) and is on track to bring the epidemic to an end. BSE/nvCJD. Findings since 1996 indicate that the agents of BSE and new‐variant Creutzfeldt—Jakob disease (nvCJD) possess the same ‘fingerprint’. This is consistent with the transmission of BSE infection to humans. Although it remains possible that both BSE and nvCJD may have been triggered by some currently unknown cause, it is difficult to conceive what that might be. nvCJD incidence. The UK Department of Health reported 24 cases of nvCJD up to the 6 April 1998. Assuming that nvCJD is the result of consumption of BSE infective materials before 1989, it is too soon to draw any conclusions about likely future incidence. Infectivity of bovine materials. In its report dated 9 December 1997, the EU Scientific Steering Committee has set out the most up‐to‐date information and assessment of the infectivities of various bovine materials. Beef, milk and bones. Assays in mice have not detected BSE infectivity in muscle meat (beef) or milk from confirmed cases. The more sensitive assay in calves is yet to be concluded, but to date results are negative. Thus, although low levels of infectivity cannot be excluded, the risk from beef or milk is currently considered to be extremely small. Calf experiments have detected infectivity in the dorsal root ganglia, the trigeminal ganglia and the bone marrow. The risk involved to people eating beef is extremely low, about one case of nvCJD in a billion years per person. However, this estimate has a wide range of uncertainty, and the UK government has responded by banning the sale of beef on the bone. Galatin and tallow. In its report of 19–20 February 1998, the EU Scientific Steering Committee carried out risk assessments of various raw materials and production processes for gelatin and tallow, and has issued ‘scientific opinoins’ thereon. Blood. Recent research on mice shows that the lymph system is involved in the passage of infectivity from gut to brain. This implicates the lymphoreticular system and suggests that circulating lymphocytes may carry infectivity. Infectivity has been found in the tonsils of nvCJD victims. Thus, the Spongiform Encephalopathy Advisory Committee (SEAC) has suggested the leucodepletion of blood supplies as a precaution. Official Inquiry into BSE and CJD. The Institute of Food Sciecne and Technology (IFST) welcomed the official independent enquiry into BSE and has made a written submission.

Bovine spongiform encephalopathy

Bovine spongiform encephalopathy

A Bayesian Approach to Modelling the Observed Bovine Spongiform Encephalopathy Epidemic

The threat of Bovine Spongiform Encephalopathy (BSE) to humans was realized in March 1996, when the Spongiform Encephalopathy Advisory Committee (SEAC) reported to the government that the most likely explanation of the new variant Creutsfeldt–Jakob Disease (nvCJD) in humans was exposure to the BSE agent. To assess the potential risk of nvCJD, it is necessary to understand the development of the BSE epidemic within the cattle population. This paper reports on work undertaken to model the observed BSE epidemic in the UK using established Bayesian methodology. © 1997 John Wiley & Sons, Ltd.

Meltdown: the media and mad cows

Newspapers, whose columnists had been burbling on about the delights of eating British beef only weeks before, cleared their front pages for what they said might be the biggest public health calamity this century. They took their lead from the previous night's television programmes. In successive appearances, an increasingly palefaced Stephen Dorrell reprised his Commons statement of that afternoon (p 795). Professor John Pattison, head of the government's Spongiform Encephalopathy Advisory Committee, refused to offer much reassurance other than attributing the 10 new cases of Creutzfeldt-Jakob disease (CJD) to exposure to affected beef before 1989. (No one probed the plausibility of this attribution hard enough.) The opinions of Professor Richard Lacey, who had been consigned to the scientific wilderness for his views on spongiform encephalopathies, were suddenly of interest. But few newspapers could bring themselves to quote his upper estimate of 500000 new cases of CJD a year. Thursday was human victims day, with the blurred family snaps of those who had succumbed to CJD staring out from the front pages. One of them was repeatedly referred to as a vegetarian—which he had been at the time of his death—despite his distraught mother telling television audiences the night before that his favourite snack was hamburgers. This “it's all so confusing; even the experts can't agree” line can be reliably depended on to cloud public understanding of any complex scientific issue. The Daily Telegraph argued that any alarm should be kept in perspective. “Life is a hazardous business. But among all the hazards we face, eating beef must rank as minor, even after yesterday's news.” …

BSE linked to new variant of CJD in humans

Children are no more susceptible to the new variant of Creutzfeldt-Jakob disease than the rest of the population, the British government announced this week (see pages 790, 791, and 854). The Spongiform Encephalopathy Advisory Committee considered further genetic information on the 10 new cases of CJD reported last week and consulted with a paediatrician, immunologist, and gastroenterologist before reaching its decision last weekend. It repeated its view that the most likely explanation for the 10 new cases is exposure to the agent that causes bovine spongiform encephalopathy in cattle that occurred before the ban on the use of cow offal was introduced in 1989. In accepting the committee's opinion, the government has for the first time acknowledged that BSE could be transmissible to humans. There were 40 cases of CJD in Britain last year according to government statistics, compared with 54 in 1994. About 15% of these have a genetic basis; others are sporadic, for which no cause is known—these usually occur in people aged over 60. …