"This is a Japanese political issue," he said. "The Japanese farmers are saying, 'We get our cattle tested 100%, why not the U.S.?' "
Scientists believe that BSE, a fatal disease that rots the brain, is transmitted when cows eat feed contaminated by infected animal parts -- a practice the USDA banned in 1997. A rare and deadly human form of the illness known as variant Creutzfeldt-Jakob disease has been linked to the consumption of contaminated cattle products.
Although not yet confirmed by DNA tests, authorities believe the infected Washington state cow was born in Canada a few months before that government also imposed a feed ban.
U.S. agriculture officials are searching for 73 head of cattle believed to have entered the United States with the diseased animal. Eight other animals that entered the U.S. with the diseased cow have been located and are under quarantine in Washington state.