LONDON (Reuters) - Mad cow disease may be even more infectious
and persistent than experts had thought, U.S. scientists said on
Wednesday. They found that prions -- the tiny mutated brain
proteins that cause the brain-wasting disease -- can exist
undetected for long periods in animals that were thought to be
resistant to the disorder. The research raises the possibility
that infected animals other than cattle could be linked to
Creutzfeldt-Jakob disease (CJD), the human form of bovine
spongiform encephalopathy (BSE) or mad cow disease. ``We report
results that raise concern over the possible long-term
persistence of infectivity in such clinically resistant species
which may have implications for the control of BSE,'' Richard
Race and Bruce Chesebro, of the National Institute of Allergy
and Infectious Diseases in Hamilton, Montana, said in a letter
in the science journal Nature. So far there is no evidence that
BSE can be transmitted from resistant animals, such as chickens
or hamsters, to more susceptible spe