With a Denver media outlet calling Colorado the “bird flu epicenter,” that state has mandated dairies to perform weekly testing on milk for the presence of avian influenza (H5N1).
Bird flu has been confirmed in 47 dairy herds in the state since the U.S. outbreak in cows began in late March, with about 60% of the cases detected in the past month, according to U.S. data. The disease has wiped out 3.1 million egg-laying chickens in Colorado in recent weeks, about 70% of the state's laying hens, and at least eight poultry or dairy workers also tested positive.
Reuters reported the largest cluster of human cases to date in the U.S. occurred on a Colorado farm this month. Six farm workers tested positive for bird flu in July after culling chickens at an infected egg farm, the Colorado Department of Public Health and the Environment said on July 19. All had mild symptoms, including conjunctivitis (pink eye) and common respiratory infection symptoms. None was hospitalized.
USDA dispatched an epidemiological "strike team" to Colorado this week to assist. Nationally, 13 states have reported infections in about 168 herds since spring.
The FDA perfomed sample testing of grocery store milks back in April and found "inactive fragments" of avian influenza in about 20% of pasteurized milk in retail stores. But the agency reaffirmed earlier statements that pasteurization appears to kill the highly pathogenic avian influenza (HPAI), and the country’s milk supply remains safe.