New research, funded by the Government, implicates lax regulation in the meat-processing industry for spreading "mad cow disease" in British herds.
Laboratory experiments have shown that meat from sheep and cows infected with the disease remains infectious to other animals, unless treated at high temperatures for long periods - which was not done in the years before Bovine Spongiform Encephalopathy (BSE) became an epidemic.
The news emerged as another person died from the human equivalent of BSE, known as Creutzfeldt-Jakob Disease (CJD). The death occurred at Gloucestershire Royal Hospital, but no further details of the patient were released.
The latest research into the possible dangers from beef infected with BSE was carried out by the Institute of Animal Health in Edinburgh. Scientists there reproduced the techniques used by commercial meat-recovery plants, which strip meat and protein from sheep and cattle carcasses and then use steam and solvents to kill any infectious agents.
"Recovered meat" has been mixed back in to cattle feed for decades, but in the late 1970s government regulations on how long and at what temperature recovered meat had to be treated were relaxed. The first cases of BSE were identified in British herds in 1986. The scientists, writing in the latest Veterinary Record, comment that the agent causing BSE may have become conditioned to survive these lowered temperatures. In four of the 16 different heat treatments they tried, meat contaminated with the BSE agent caused BSE when given to mice.