According to a JRA statement, one horse has developed fever. The positive results were revealed after testing 163 samples from horses stabled at Japanese facilities.
The cancellation affects live race meetings at Sapporo, Niigata and Kokura Aug. 18-19. Officials said the cancellations were necessary to avoid an increasing risk of secondary infections.
Reuters reported all horses registered with the JRA have been vaccinated for the virus. According to the news agency, the last time JRA canceled live racing across the nation was in 1971, when about 1,800 horses were infected with influenza.