Scrapie triggered BSE suggests new research

U.K. research published on Thursday said that an entrenched sheep disease, scrapie, could have triggered mad cow disease, whose human form has killed more than 100 people, primarily in Britain. The government-sponsored study, led by Cambridge University scientist Gabriel Horn, said that meat and bone meal (MBM) infected with scrapie may have caused the 1980s U.K. outbreak of mad cow disease, or bovine spongiform encephalopathy (BSE). Scrapie is a fatal neurological disease similar to BSE that has been present in the U.K. flock for more than 250 years. It is believed to be not harmful to humans. According to the report, a relatively high rate of sheep to cattle in the U.K., as well as high incidence of scrapie, could mean that the U.K. meat-based feed contained a relatively high level of scrapie-infected material. In addition, the U.K. began to feed it to calves for the first 12 weeks of their lives in the 1970s, a practice the report says appears to have been less common in the United States and in continental Europe. "An unusual concatenation of events occurred in the U.K. during the period 1970 to the 1980s. The diet of many calves was changed so that MBM was included in their starter rations,"​ the report said. "Furthermore, the MBM is likely to have included a relatively high level of scrapie-infected material."​ The report speculated that these two factors might help explain why the BSE epidemic developed in the U.K. although other countries have scrapie-infected sheep and used meat-based feed in the latter half of the 20th century. The scientists played down views that meat-based feed was not the only culprit in spreading mad cow disease, which was first found in the British herd in 1986. A decade later it was linked to the deadly brain-wasting human disease, variant Creutzfeldt-Jakob disease. "The evidence is very strong that the spread of BSE to the point at which it became an epidemic arose through the use of meat and bone meal ...in cattle feed,"​the report said. "If transmission from mother to calf, contamination of pastures and/or the use of veterinary preparations played a part in the transmission of BSE, their effects are likely to have been small."​ On Thursday, Britain announced plans to launch a programme aimed at eradicating scrapie in U.K. sheep. The French government is also expected to step up measures to fight scrapie this month, following an opinion issued in February by French food safety agency AFSSA. AFSSA recommended excluding certain sheep and goat organs and tissues from the food chain, after scientists managed to infect sheep with BSE in the laboratory. There has never been a naturally occurring BSE case in sheep. The UK's Spongiform Encephalopathy Advisory Committee will consider the U.K. report in September. The BSE epidemic in the U.K. continues to decline. The number of BSE cases confirmed during 2000 was 1,311, 42 per cent lower than in 1999. The number of BSE suspects reported this year to date, 598, is 45 per cent lower than in the same period last year.