The U.S. Food and Drug Administration has begun testing more dairy products for evidence of the bird flu virus as outbreaks spread among dairy herds across the country.
More than 120 dairy herds in 12 states have tested positive for bird flu since March, according to the U.S. Department of Agriculture. Federal officials have warned that further spread among dairy cows could heighten the risk of human infections.
The risk to the general public from bird flu remains low, federal officials have said, though it is higher for workers on dairy farms, who should wear personal protective equipment to reduce the risk of infection.
The focus of additional testing, which will sample 155 products, is to ensure that pasteurization inactivates the virus, said Don Prater, acting director of the FDA's Center for Food Safety and Applied Nutrition, on a call with reporters.
Prior FDA testing of 297 retail dairy samples came back negative for evidence of the virus.
The agency continues to strongly advise against consumption of raw milk products, Prater said.
No infected dairy cow herds are known to be contributing to the raw milk supply, said Eric Deeble, USDA's acting senior adviser for its bird flu response.
More than 690 people who were exposed to infected or suspected infected animals have been monitored for flu symptoms, and 51 people who developed flu-like symptoms have been tested, Demetre Daskalakis, director of the U.S. Centers for Disease Control and Prevention's National Center for Immunization and Respiratory Diseases, said on the press call.
The CDC is providing technical support to the state of Michigan as it begins serological testing of farm workers for signs of prior infection by the virus and will ensure the testing can be completed in other states, Daskalakis said.
The USDA is conducting research on how dairy cattle contract the virus through contact with infected milk or respiratory droplets, Deeble said.
The development of a bird flu vaccine for dairy cows "is going to take some time," and the agency hopes to eradicate the virus in dairy cattle without the use of a vaccine, Deeble said.
Agriculture Secretary Tom Vilsack told Reuters on June 12 that the agency is in talks with two dozen companies on the development of a bird flu vaccine for cattle.
