Mad cow disease may have originated from animal feed contaminated with human remains washed ashore after being floated downriver in Indian funerals, British scientists said on Friday.

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.

It is thought to have resulted from cattle being fed material containing remains of sheep infected with scrapie.

But Professor Alan Colchester of the University of Kent in England says it may have been caused by the tonnes of animal bones and other tissue imported from India for animal feed that also may have contained the remains of humans infected with Creutzfeldt-Jakob disease (CJD).

Scrapie, BSE and CJD are all illnesses caused by brain proteins that transform into infectious agents.

“Existing theories of the original causes of BSE, the bovine disease, we don’t find convincing,” Colchester said in an interview.

“We 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,” he added.

MIX OF REMAINS

In a report in The Lancet medical journal, Colchester and his daughter Nancy, of the University of Edinburgh, explained that many human and animal corpses were disposed of in rivers in India in accordance with Hindu custom.

The remains washed ashore in poor areas where bone collectors work.

“We are aware of a considerable risk of the incorporation of human remains with the animal remains that are collected. They are processed locally and some have been exported. In 10 years, more than a third of a million tonnes of material from these areas was imported into the UK,” Colchester said.

The scientists believe the contaminated feed led to BSE. Scientists believe humans acquired variant Creutzfeldt-Jakob disease (vCJD) from eating meat from infected cattle.

Since vCJD was first detected in the mid-1990s, more than 150 people have died of the illness.

The scientists said the risk of a load of animal by-products being infected with human material would be very small. But importing animal material went on for decades so the cumulative risk could become significant over time.

Colchester and his daughter 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.

In another journal editorial, Susaria Shankar of the National Institute of Mental Health and Neurosciences in Bangalore, India, said one case of scrapie, which was probably imported, has been reported from the Himalayan foothills.

“Scientists must proceed cautiously when hypothesizing about a disease that has such wide geographic, cultural and religious implications,” Shankar said.

“We agree that the idea proposed by the Colchesters needs to be probed further. Facts to support or refute their hypothesis now need to be gathered with urgency and great care.”