Transmissible Spongiform Encephalopathy as a Zoonotic Disease

ILSI Europe Report Series

Transmissible spongiform encephalopathy (TSE) is a slowly progressive, uniformly fatal neurodegenerative disease that affects several animal species as well as humans. The prototype TSE is scrapie, a naturally occurring disease of sheep and goats that has been recognized in Europe since at least the middle of the 18th century and was shown to be transmissible in 1936. The most important human TSE is Creutzfeldt-Jakob disease (CJD), which was first described in the 1920s and shown to be transmissible in 1968. No direct causal connection between these two diseases has ever been documented, and the concept of any form of human TSE as a zoonotic disease lay latent in scientific thinking for decades. The landscape changed dramatically in 1996 with the suggestion that several cases of a variant form of CJD (vCJD) in young people in the United Kingdom might have resulted from exposure to bovine spongiform encephalopathy (BSE, or “mad cow disease”), itself probably the result of cattle having been exposed to scrapie infected sheep carcasses rendered to produce meat and bone meal dietary supplements. Considering the large-scale human exposure to bovine products and the extraordinary commercial and public health consequences of BSE as a danger to humans, the suggested BSE-vCJD connection was not proposed without a solid epidemiological basis, and it has since been confirmed by biological and molecular studies. This report places these concerns in the historical context of TSE and attempts to distil the essence of what has become an intimidating volume of intermingled fact and fiction surrounding the story of “mad cow disease” and its consequences to human and animal well-being, with particular attention to food.

The report was prepared under the guidance of the ILSI Europe Emerging Pathogens Task Force and has been reviewed by the International Forum for TSE and Food Safety (TAFS).

To download this publication, click here.

Hard copies can be ordered free of charge by sending an email to: