According to British scientists, Mad Cow disease may have originated from animal feed contaminated with human remains washed ashore after being floated down river in Indian funerals.
At present the cause of mad cow disease, or bovine spongiform encephalopathy (BSE), which infected an estimated 2 million cattle during an epidemic in Britain, is unknown, but it is thought to have resulted from cattle being fed material containing the remains of sheep infected with scrapie.
Professor Alan Colchester of the University of Kent in England says he believes it may have been caused by the tonnes of animal bones and other tissue imported from India for animal feed, which also may have contained the remains of humans infected with Creutzfeldt-Jakob disease (CJD).
All three diseases, Scrapie, BSE and CJD are illnesses caused by brain proteins that transform themselves into infectious agents.
Professor Colchester says he is not convinced by existing theories of the original causes of BSE, the bovine disease.
He says they have identified the fact that a large amount of imported animal feeding material was brought into Britain during the period when BSE must first have occurred and the largest source coming to the UK was from the Indian subcontinent.
Professor Colchester and his daughter Nancy, of the University of Edinburgh, say that many human and animal corpses were disposed of in rivers in India in accordance with Hindu custom, and the remains subsequently washed ashore in poor areas where bone collectors work.
He says they know that there is a considerable risk of the incorporation of human remains with the animal remains that are collected and are processed locally, and some have been exported.
He has found that over 10 years, more than a third of a million tonnes of material from these areas was imported into the UK.
The scientists believe the contaminated feed led to BSE, as humans acquired variant Creutzfeldt-Jakob disease (vCJD) from eating meat from infected cattle.
More than 150 people have died of the illness since vCJD was first detected in the mid-1990s, but the scientists say the risk of a load of animal by-products being infected with human material would be very small.
However as importing animal material went on for decades, so the cumulative risk could become significant over time.
The father, daughter team say they doubt BSE resulted from scrapie, because material infected with the disease has been fed to cattle for many decades, without any sign of BSE arising.
According to Susaria Shankar of the National Institute of Mental Health and Neurosciences in Bangalore, India, one case of scrapie, which was probably imported, has been reported from the Himalayan foothills.
Shankar says that scientists should be cautious about hypothesizing about a disease that has such wide geographic, cultural and religious implications, and facts to support or refute their hypothesis now needs to be produced carefully and urgently.
The report is published in the Lancet medical journal.