BSE: Science & research - What is the origin of BSE?
Epidemiological analysis indicates that the primary cause of the spread of the BSE epidemic was the consumption of feed containing ruminant-derived meat and bone meal. However, the initial source of the BSE agent which was then disseminated in feed is unclear. The hypotheses surrounding the origin of BSE have been discussed by the BSE Inquiry and the Horn Review.
Summary of research into the hypotheses
From scrapie in sheep
Defra has funded work to examine if scrapie from UK sheep can be transmitted to cattle. Results to date indicate that scrapie can be transmitted only by intracerebral inoculation but not when given orally. This work does not provide a definitive answer to whether BSE originated from scrapie because it is always possible that a rare BSE-generating form of scrapie was not included in the strains selected for the cattle challenge experiments (projects SE1941, SE1942).
A new strain of scrapie
A new strain of scrapie which was particularly infectious to cattle might have arisen, possibly through a genetic mutation in the prion protein, which then entered the cattle feed chain through meat and bone meal.
Defra is funding research (projects SE1919, SE1938, SE1849) into cataloguing the diversity of scrapie strains in Great Britain and understanding their significance.
A sporadic form of BSE in cattle
As the food-borne BSE epidemic declines, there is an increased probability of detecting a rare disease-causing mutation in the prion protein. To search for this, the DNA sequence of the prion protein gene and its regulatory regions were analysed in BSE cases born after the epidemic (BARBs) but no specific changes were found (project SE0239).
Autoimmune theory
In the past Defra funded research into the hypothesis that BSE could be an autoimmune disease in cattle (project SE1827).
Links to other information
- The hypothesis that the use of organophosphates (in pesticides) contributed to the BSE epidemic was reviewed by the EU Science Steering Committee.
Page last modified: 17 March, 2008