H5N1 Avian Influenza Persistence in Raw Milk Cheeses Challenges Safety Standards

Recent findings indicate that the H5N1 avian influenza virus can survive in raw milk cheeses for as long as 120 days, posing a significant challenge to existing food safety standards. Researchers led by virologist Diego Diel from Cornell University discovered that the virus remains viable in certain cheese varieties, questioning the adequacy of the current 60-day aging requirement set by the FDA for raw milk cheeses.

The study identifies pH levels as a crucial factor in the virus's persistence. It was observed that the virus stays active in cheeses with pH levels between 5.8 and 6.6, while it becomes inactivated in cheeses with a pH of 5 or lower. Cheeses like feta, which have a naturally lower pH around 4.6, are considered safer options.

The persistence of H5N1 in raw milk cheeses underscores the need for the artisanal cheese industry and regulators to reassess existing protocols. The research emphasizes that pasteurization at standard temperatures effectively inactivates the virus, ensuring the safety of pasteurized dairy products.

This study is a wake-up call for the global dairy community to consider additional thermal processing or focus on producing high-acidity cheeses to maintain public health safety and consumer confidence.

The risk of avian influenza persistence is limited to products made with raw milk. Previous research confirms that pasteurization at 63°C for 30 minutes or 72°C for 15 seconds is fully effective in inactivating the H5N1 virus.