The U.S. Food and Drug Administration (FDA) released findings from two research efforts regarding highly pathogenic avian influenza (HPAI H5N1).

FDA published findings from a recent Cornell University study, in which researchers used HPAI-spiked raw milk to create raw milk cheeses. Results showed that H5N1 virus can remain stable in raw milk cheese throughout the minimum required aging period of 60 days.

Importantly, the study found that virus survival was pH-dependent; virus survived throughout the manufacturing and aging process in cheese groups with a pH of 6.6 or 5.8 but did not survive in cheeses with a pH of 5.0. The study also found that heating raw milk at 54°C (130°F) for at least 15 minutes or 60°C (140°F) for at least 10 seconds inactivated the virus.

In this same study, researchers also looked at commercial raw milk cheese inadvertently produced with naturally contaminated raw milk. This cheese remained positive for active virus throughout the 60-day aging period, validating the controlled laboratory results.

The study did not examine whether H5N1 remains active in raw milk cheeses beyond the 60-day aging period.

Given the results the Wisconsin Cheese Manufacturers Association (WCMA) is urging FDA officials to act quickly to make resources available for raw milk cheesemakers, including testing avenues for finished product and further studies on these initial findings.