About 60 more cases of mad cow disease are expected to occur in Japan, with the number likely to peak in 2005 and 2006, according to a Cabinet Office report.
The report was complied by an expert panel under the government's Food Safety Commission, which met Friday.
Japan has so far confirmed 11 cows to have been infected with the disease, officially called bovine spongiform encephalopathy, since the first case in September 2001.
Although cows are unlikely to be newly infected in Japan due to effective countermeasures already in place, testing of all cattle is expected to uncover more cases as the brain-wasting disease has an average incubation period of five years, the office said.
The report assumes the presence of 60 more infected cows because one case of infection is estimated to have led to four more infections in countries such as Britain.
The report also estimates that about half of the possible 60 cases will be cows at least 30 months old.
As seven years are needed to confirm the elimination of mad cow, testing of cattle for the disease should continue until around 2015, the office said.