In March 2024, highly pathogenic avian flu (H5N1) infected dairy cows in Texas, marking the first known spread to cattle. The virus later affected about 200 animals and three people across 12 states, as reported by the CDC.
Researchers, including USDA virologist Erica Spackman, investigated whether H5N1 could be transmitted through dairy products. Testing nearly 300 milk samples from 132 processors, they found no live virus, confirming in this week’s Journal of Virology that milk is safe due to effective sanitation processes eliminating pathogens like bacterial and viral threats.
According to Spackman, the milk processing process has multiple safeguards. Microbiological monitoring detects pathogens, and milk from cows with diseases like mastitis is not used for food. Pasteurization, which involves heating, destroys H5N1 and other common bacteria.
Avian influenza typically infects migratory birds and can spread to domestic poultry and animals like cats, dogs, young goats, polar bears in Alaska, and elephant and fur seals in Antarctica. However, the discovery of H5N1 on dairy farms in March was unexpected, as the virus had never been seen in dairy cows before.
After discovering an infectious virus in raw milk, the FDA and USDA investigated if pasteurization removes risks to consumers. From April 18 to 22, 2024, researchers analyzed 297 samples of pasteurized milk products across 17 states using PCR.
Despite sensitive tests, they found no live virus but detected viral genetic material in 20% of samples. Spackman confirmed that pasteurization effectively deactivated the virus. She emphasized that these results reassure that pasteurization effectively safeguards against unknown threats.
In conclusion, this study demonstrates that pasteurization effectively neutralizes highly infectious avian flu in milk. Testing revealed no live virus in pasteurized milk samples, although genetic material was detected in some cases.
These findings firmly reassure us that current milk processing practices, including pasteurization, protect consumers from the potential risks of avian flu contamination in dairy products.
Journal reference:
- Erica Spackman, Deana R. Jones et al., Characterization of highly pathogenic avian influenza virus in retail dairy products in the US. Journal of Virology. DOI: 10.1128/jvi.00881-24.
