A new study by Cornell University researchers has found that raw cheese made with milk from dairy cattle infected with bird flu can harbor the infectious virus for months, posing a risk to public health. The study, funded by the US Food and Drug Administration, tested the stability of the H5N1 virus in raw milk cheeses aged at least 60 days.
Raw milk cheeses are allowed on store shelves nationwide as long as they are aged for at least two months, but this aging process may not be enough to inactivate the virus. The researchers found that the virus remained infectious for up to eight weeks and even after the cheese was aged for the full two-month period.
However, the study suggests that making raw milk cheese more acidic may kill the virus and make the cheese safer to eat. Cheese produced at a lower pH level had no live virus detected.
Experts say that pasteurization is the most effective way to inactivate the virus and make dairy products safe for consumption. The FDA has sampled over 464 pasteurized dairy products, all of which were negative for viable H5N1.
The study’s findings emphasize the importance of surveillance and not consuming raw milk products during the bird flu outbreak. It is recommended to only consume pasteurized dairy products to minimize the risk of infection.
The researchers also tested real-world samples of raw milk cheese from a farm that had inadvertently produced them with milk from cows infected with bird flu, which confirmed the findings of the study.
Source: https://edition.cnn.com/2025/03/14/health/h5n1-bird-flu-raw-cheese/index.html