Mad cow disease may come from people, not animals

New theory proposes that mad cow disease may have come from feeding British cattle with meal contaminated with human remains infected with a permutation of the disease.

The hypothesis, outlined this week in The Lancet medical journal, suggests that the infected cattle feed came from the Indian subcontinent, where bodies sometimes are ceremonially thrown into the Ganges river.

Indian experts not connected with the research exposed weaknesses in the theory, but agreed it should be investigated, the AP reports.

The cause of the original case or cases of mad cow disease, or bovine spongiform encephalopathy, is unknown.

It belongs to a class of illnesses called transmissible spongiform encephalopathies, or TSEs. They exist in several species. Scrapie is a TSE that affects sheep and goats, while chronic wasting disease is one that afflicts elk and deer. A handful of TSEs are found in humans, including Kuru, Alper's disease and Creutzfeldt-Jakob disease, or CJD.

All the TSEs are fatal, untreatable and undiagnosable until after death. They are called spongiform encephalopathies because the diseases involve spongy degeneration of the brain.

But where the cows got their disease in the first place remains a mystery. The most popular theory is that cattle, which are vegetarian, were fed meal containing sheep remains, passing scrapie from sheep to cows, where it eventually evolved to become a cow-specific disease. Another theory is that cows just developed the disease spontaneously, without catching it from another species.

However, a pair of British scientists now propose the origin may be the bones of people infected with classical CJD, which they theorize ended up in cattle feed imported from South Asia.