Bovine spongiform encephalopathy
CMAJ 1997;156(4):481
In regard to the article "Bovine spongiform encephalopathy and CreutzfeldtJakob disease: implications for physicians" (CMAJ 1996;155:52936 [full text / résumé]), by Drs. Chris MacKnight and Kenneth Rockwood, I have several questions. What of the beef handlers and especially meat-cutters working in the United Kingdom since 1985? With their frequent skin cuts, incurred while dressing beef, have they had neurologic changes? It has been at least 11 years now that they would have been exposed to bovine spongiform encephalopathy (BSE).
And what of brain eaters living in the United Kingdom?
Also, what of the meat-processing plants that have processed the cattle that are carriers? If we are to destroy surgical instruments because of the lack of knowledge concerning proper sterilization techniques, what has been done with the machinery and instruments that have processed these cattle in the past?
David Mallek, MD
Vancouver, BC
[The authors respond:]
Dr. Mallek asks several relevant questions. If BSE and the new variant of CreutzfeldtJakob disease (CJD) are related, should there not be an increased risk among abattoir workers? Similarly, should consumers of beef brains in the United Kingdom not be at a higher risk of CJD than those outside the United Kingdom?
The peripheral route of inoculation, as opposed to inoculation into the central nervous system, is a relatively inefficient method of transmission. Sporadic CJD has not been identified in abattoir workers; however, in addition to reports of cases in farmers,[1] a case has been reported in a handler of animal feed.[2] Among the cases of the new variant of CJD, 1 patient had worked as a butcher and 1 had visited an abattoir.[3] None of the variant cases had a history of brain consumption. This background suggests that the pathogenesis of these diseases is more complex than a simple doseresponse relation.
Stronger evidence that BSE and the new variant of CJD are linked has come from molecular analysis of the prion protein.[4] Western blot analysis of prion protein from BSE transmitted to laboratory animals and from variant CJD has shown that the 2 are similar, suggesting that they share the same source.
Canada has initiated several programs to investigate CJD and the risk of its transmission through blood transfusion.[5] Any cases should be reported to the Laboratory Centre for Disease Control of Health Canada.
Chris MacKnight, MD
Clinical Fellow
Kenneth Rockwood, MD, MPA
Associate Professor
Division of Geriatric Medicine
Dalhousie University
Halifax, NS
References
- Young GR, Fletcher NA, Zeidler M, Estibeiro KL, Ironside JW. CreutzfeldtJakob disease in a beef farmer [letter]. Lancet 1996;348:610-1.
- Weis J, Kretzschmar HA, Windl O, Podoll K, Schwarz M. Fatal spongiform encephalopathy in a patient who had handled animal feed [letter]. Lancet 1996;348:1240.
- Will RG, Ironside JW, Zeidler M, et al. A new variant of CreutzfeldtJakob disease in the UK. Lancet 1996;347:921-5.
- Collinge J, Sidle KCL, Meads J, Ironside J, Hill AF. Molecular analysis of prion strain variation and the aetiology of "new variant" CJD. Nature 1996;383:685-90.
- Laboratory Centre for Disease Control. CreutzfeldtJakob disease in Canada. Can Fam Physician 1996;42:2223-4.
Letters