Theory: Mad Cow Disease May Have Come From Humans

LONDON — A new theory proposes that mad cow disease may have come from feeding British cattle meal contaminated with human remains infected with a variation of the disease.

The hypothesis, outlined this week in The Lancet medical journal, suggests 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 pointed out weaknesses in the theory but agreed it should be investigated.

The cause of the original case or cases of mad cow disease, or bovine spongiform encephalopathy, is unknown, but it belongs to a class of illnesses called transmissible spongiform encephalopathies, or TSEs.

Such illnesses exist in several species. Scrapie is a TSE that affects sheep and goats, while chronic wasting disease afflicts elk and deer. A handful of TSEs are found in humans, including Kuru, Alper’s disease and Creutzfeldt-Jakob disease, or CJD.

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

The disease was not known to infect cows until 1986, when the first cases were noticed in Britain. About a decade later, a new permutation of CJD, which scientists dubbed variant CJD, started showing up in people there.

A popular theory on how cows got the disease is that cattle, which are vegetarian, were fed meal containing sheep remains, passing scrapie from sheep to cows, where it eventually evolved into 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.