USDA tests confirm that pasteurization kills the bird flu virus in milk

New USDA research confirms pasteurized milk is safer against H5N1 bird flu - Photo by Nathan Anderson on UnSplash

Tests were conducted after the virus showed up in dairy cows this year

Raw, unpasteurized milk is increasingly popular but new research from the U.S. Department of Agriculture (USDA) suggests pasteurized milk is much safer, especially against germs like avian flu, or H5N1 bird flu.

The pathogen has been found in dairy cattle in Texas and at least three people. The virus was also detected in raw milk, leading researchers to investigate whether dairy products pose a risk to consumers. 

"How far is the virus getting through?" asked Erica Spackman, Ph.D., a virologist at USDA in Athens, Ga. 

To find out, she and her collaborators tested nearly 300 milk products from 132 processors. The researchers found no infectious virus in the samples.

"Milk is safe," Spackman said. "Just like bacterial pathogens that occur in milk, or other viruses that could occur in milk, the sanitation processes that are in place are getting rid of the pathogens."

Spackman says the milk processing pipeline includes multiple layers of protection. She said microbiological surveillance of milk products can identify pathogens, and ensure that milk from cows with mastitis or other disease conditions does not enter the food supply. Finally, heating during the pasteurization process can destroy H5N1 and other, more common bacterial pathogens.

Major impact on the food supply

Bird flu has had a major impact on the U.S. food supply in recent years, resulting in a huge surge in egg prices after millions of chickens were culled. The virus typically spreads among migratory birds and can be transmitted to domestic poultry, but the virus has been detected in other animals as well. 

Recently, animals diagnosed with avian flue have included cats, dogs and juvenile goats, as well as a polar bear in Alaska and elephant and fur seals in the Antarctic. 

However, agriculture officials said the discovery of H5N1 on dairy farms in March was a surprise—the virus had never been found in dairy cattle before.

Soon after the discovery, diagnostic testing revealed that an infectious form of the virus was present in raw milk, suggesting the virus passes from cow to milk. That finding led the U.S. Food and Drug Administration (FDA) and the USDA to investigate whether pasteurization killed the virus and protected consumers.

Their conclusion? It does. Between April 18 and April 22, 2024, researchers analyzed 297 samples of pasteurized retail milk products, including 23 types of products, collected from 17 states, finding no trace of the virus.

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