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Pasteurization working to kill bird flu in milk and other dairy products, FDA tests find

Dairy cows to be tested for bird flu closely
More dairy cows to be tested for bird flu after findings in grocery store milk 02:45

Results of tests run by the Food and Drug Administration show that pasteurization is working to kill off bird flu in milk and other dairy products, the agency says. 

"In addition to preliminary results released late last week on an initial set of 96 retail milk samples, these results reaffirm our assessment that the commercial milk supply is safe," the FDA said in a statement Tuesday.

The FDA's findings come after the agency disclosed that around 1 in 5 samples of retail milk it had surveyed from around the country had tested positive for highly pathogenic avian influenza, or HPAI H5N1. The U.S. Department of Agriculture also ordered testing requirements on cows in response to the outbreak, which has affected growing numbers of poultry and dairy cows

Positive so-called PCR tests in milk can happen as the result of harmless fragments of the virus left over after pasteurization, officials and experts have said, prompting the additional experiments to verify whether or not the virus found in the milk was infectious. Those tests found it was not.

The FDA said it has also now tested dairy samples from cottage cheese and sour cream, which can be pasteurized differently from milk. 

"We are aware, because there are so many different dairy products, there are probably a few more products that we would look at just so that we make sure that we've got a good national sample," Don Prater, acting director of the FDA's Center for Food Safety and Applied Nutrition, told reporters 

While health authorities have said that milk from visibly sick cows is being discarded before entering the supply chain, officials have acknowledged the possibility that cows could be spreading the virus in their raw milk without symptoms or after they have otherwise appeared to recover. It remains unclear how traces of H5N1 ended up in the milk supply chain.

"FDA is working with our federal partners to analyze the initial data that we've collected through this survey of retail milk. We recognize that processors can receive milk from hundreds of different farms, which may cross state lines, "said Prater.

The FDA said it had also tested several samples of retail powdered infant formula and toddler formula, which the agency said were all negative for the virus. 

No beef cattle have been detected with the virus, the USDA has said. The department has also finished collecting samples of ground beef from stores in states with sick cattle, which will be tested for the virus. 

So far, only one human infection has been reported this year, in a person who had contact with dairy cattle in Texas.

Doctor on bird flu: "So far, no real risk to the human population" 03:32

Though growing evidence is now confirming the safety of pasteurized milk, an additional challenge also remains for health authorities as they grapple with the possibility that dairy industry workers could be unknowingly exposed to the virus. 

Unlike poultry, which quickly die off or are culled after H5N1 infections, cows largely go on to recover after a month or two.

Other animals have also not fared as well during the outbreak: the USDA said that deaths and neurological disease had been "widely reported" in cats around dairy farms. Officials have said they suspect cats had been drinking leftover raw milk from infected cows.

"We know that the illness in cattle can go on for several weeks. So that puts workers at an ongoing risk. And thus, the period for monitoring will be longer," the Centers for Disease Control and Prevention's Sonja Olsen told reporters.

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