Recent studies have highlighted a significant public health concern regarding the H5N1 bird flu virus in raw milk cheese. Here are the key findings and implications:
Key Findings
Stability of the Virus: The H5N1 virus remains stable and infectious in raw milk cheese even after aging for months. This challenges the traditional belief that the aging process alone can eliminate pathogens in cheese made from raw milk.
pH Levels and Virus Survival: The survival of the virus is pH-dependent. At lower pH levels, such as pH 5.0, the virus does not survive, suggesting that increasing the acidity of raw milk cheese could enhance its safety.
Cheese-Making Process: The virus persists throughout the cheese-making process and during the aging period, except at the most acidic pH levels.
Public Health Risks: The persistence of the virus in raw milk cheese poses a potential risk to public health, especially if consumed repeatedly. However, the infectious dose for humans is not well understood.
Regulatory Context
Raw Milk vs. Raw Milk Cheese: While raw milk cannot be sold across state lines, raw milk cheese can be sold nationwide if aged for at least 60 days. This regulation aims to reduce bacterial contamination risks but may not be sufficient for viral pathogens like H5N1.
FDA Recommendations: The FDA advises against manufacturing or selling raw milk products from cows showing symptoms of illness, including avian influenza.
Mitigation Strategies
Pasteurization: Heat-treating raw milk through pasteurization is effective in inactivating the H5N1 virus.
Increasing Acidity: Producing cheese at lower pH levels (e.g., pH 5.0) may help eliminate the virus, enhancing the safety of raw milk cheese.
Despite these findings, some health officials maintain that food does not pose a significant risk for bird flu transmission. However, the studies emphasize the need for additional safety measures in cheese production to mitigate potential health risks.