Pathfinder
Editor, Senior Moderator
Investigation of Avian Influenza A (H5N1) Virus in Dairy Cattle
The U.S. Department of Agriculture (USDA), the U.S. Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC), along with state partners, continue to investigate an outbreak of Avian Influenza A (H5N1) impacting poultry, dairy cows, and people in multiple states.
The responsibility of the FDA is to protect the public health by ensuring the safety of the milk, dairy products, and animal feed supply. The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service is leading the response from the animal health perspective while coordinating closely with the FDA and with the Centers for Disease Control and Prevention.
Status of the Milk SupplyWhat's New
FDA H5N1 Communications | Research & Studies
Resources for Producers | Resources for Consumers
Additional Information
What's New
Update on Ongoing Research Exploring if Aging Raw Milk Cheese Can Reduce or Eliminate Viable H5N1 Virus
March 14, 2025
Interim Results from FDA 60-day Aged Raw Milk Cheese Research Don’t Detect H5N1 in Samples Collected to Date
Beginning in December 2024, the FDA initiated an assignment sampling 60-day aged raw milk cheese. The first sample was taken January 2, 2025, and sample collections are anticipated to be complete by the end of March 2025. As of March 10, 2025, 110 samples of the planned 299 have been collected. Of those 110 samples, 96 were negative by PCR (meaning that H5N1 was not detected in the analyzed samples), and 14 are still in progress. Final results are expected later this spring.
Research Results from Cornell University Suggest that the Aging Process Alone May Not Be Effective in Eliminating Viable H5N1 in Raw Milk Cheese
The FDA is continuing to work with Federal and state partners to address the ongoing outbreak of HPAI A (H5N1) in dairy cattle. The FDA has sampled a total of 464 pasteurized dairy products, including milk, cheese, butter, and ice cream, all were negative for viable H5N1. In addition, multiple research studies have confirmed that pasteurization inactivates the virus.
FDA and New York State funded research conducted at Cornell University to assess whether aging raw milk cheese for at least 60 days is effective in reducing or eliminating viable H5N1.
Research on Aged Raw Milk Cheese
To better understand whether aging raw milk cheese is effective at reducing or eliminating viable H5N1, the FDA funded specific research at Cornell University. Aging is a minimum process specific raw milk cheeses must undergo to meet standard of identity regulations before entering interstate commerce. While the research did not represent all commercial processes for producing raw milk cheese, results being previewed in a pre-printExternal Link Disclaimer suggest that aging raw milk cheese for 60 days or longer is not effective at eliminating viable H5N1 in the cheese. H5N1 survived (i.e., was viable) in non-heat-treated raw milk cheese through and beyond the 60-day aging process. However, heating raw milk at 54°C (130°F) for at least 15 minutes or 60°C (140°F) for at least 10 seconds inactivated H5N1 in this research.
Information for Consumers
The FDA is confident that pasteurization is effective at inactivating H5N1, and that the commercial, pasteurized milk supply is safe. To date, FDA testing of pasteurized dairy products and aged raw milk cheese intended for retail has not detected infectious H5N1.
Consumers who want to know if their cheese has been made with raw milk may check the product label. While there is no express Federal requirement for the labeling of cheeses to disclose on the ingredient list whether the milk used in manufacture was raw or pasteurized, many cheeses do disclose on the ingredient list (or elsewhere on the product label) if the milk used is pasteurized or raw. The FDA is not aware of any H5N1 illnesses to date from the consumption of aged raw milk cheese products. The FDA is continuously monitoring the HPAI situation and working together with USDA, CDC, state partners, academia, and industry on ways to mitigate the impact of this ongoing outbreak using a One Health approach to understand and reduce H5N1.
Information for Industry
The FDA continues to recommend that dairy producers monitor herds for H5N1 infection by enrolling in USDA or state testing programs. If a herd becomes infected with H5N1, the USDA recommends that dairy producers segregate clinically ill cows from the rest of the milking herd. The FDA recommends dairy processors not use milk from infected cows in the production of raw milk products, such as raw milk cheese, and reminds manufacturers that heat treating or pasteurization are both effective measures that inactivate H5N1. Research to date has demonstrated heating raw milk at 54°C (130°F) for at least 15 minutes or 60°C (140°F) for at least 10 seconds inactivates H5N1 in raw milk. Additionally, the researchers determined that manufacturing non-heat-treated raw milk cheese at a pH of 6.6 or 5.8 did not inactivate H5N1, whereas a pH of 5.0 led to rapid inactivation of H5N1. Additional research is needed to determine if pH adjustment is a practical intervention.
Status of the Milk Supply
After the first detection of HPAI H5N1 in dairy cattle in March 2024, the FDA has engaged in research and other efforts with industry, federal, and state partners to ensure the continued effectiveness of the federal-state milk safety system.
Nearly all (99%) of the commercial milk supply that is produced on dairy farms in the US comes from farms that participate in the Grade A Milk Safety Program and follow the Pasteurized Milk Ordinance (PMO), which includes controls that help ensure the safety of dairy products. Pasteurization and diversion or destruction of abnormal milk are two important measures that are part of the federal-state milk safety system.
The process of pasteurization has helped to ensure the health of the American public for more than 100 years. Pasteurization kills harmful bacteria and viruses by heating milk to a specific temperature over time. Even if the virus is detected in raw milk, the current pasteurization process (HTST – High Temperature, Short Time) will inactivate the virus.
CDC Surveillance
...
https://www.fda.gov/food/alerts-adv...ation-avian-influenza-h5n1-virus-dairy-cattle
- Content current as of:
03/14/2025 - Regulated Product(s)
- Food & Beverages
The U.S. Department of Agriculture (USDA), the U.S. Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC), along with state partners, continue to investigate an outbreak of Avian Influenza A (H5N1) impacting poultry, dairy cows, and people in multiple states.
The responsibility of the FDA is to protect the public health by ensuring the safety of the milk, dairy products, and animal feed supply. The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service is leading the response from the animal health perspective while coordinating closely with the FDA and with the Centers for Disease Control and Prevention.
Status of the Milk SupplyWhat's New
FDA H5N1 Communications | Research & Studies
Resources for Producers | Resources for Consumers
Additional Information
What's New
Update on Ongoing Research Exploring if Aging Raw Milk Cheese Can Reduce or Eliminate Viable H5N1 Virus
March 14, 2025
Interim Results from FDA 60-day Aged Raw Milk Cheese Research Don’t Detect H5N1 in Samples Collected to Date
Beginning in December 2024, the FDA initiated an assignment sampling 60-day aged raw milk cheese. The first sample was taken January 2, 2025, and sample collections are anticipated to be complete by the end of March 2025. As of March 10, 2025, 110 samples of the planned 299 have been collected. Of those 110 samples, 96 were negative by PCR (meaning that H5N1 was not detected in the analyzed samples), and 14 are still in progress. Final results are expected later this spring.
Research Results from Cornell University Suggest that the Aging Process Alone May Not Be Effective in Eliminating Viable H5N1 in Raw Milk Cheese
The FDA is continuing to work with Federal and state partners to address the ongoing outbreak of HPAI A (H5N1) in dairy cattle. The FDA has sampled a total of 464 pasteurized dairy products, including milk, cheese, butter, and ice cream, all were negative for viable H5N1. In addition, multiple research studies have confirmed that pasteurization inactivates the virus.
FDA and New York State funded research conducted at Cornell University to assess whether aging raw milk cheese for at least 60 days is effective in reducing or eliminating viable H5N1.
Research on Aged Raw Milk Cheese
To better understand whether aging raw milk cheese is effective at reducing or eliminating viable H5N1, the FDA funded specific research at Cornell University. Aging is a minimum process specific raw milk cheeses must undergo to meet standard of identity regulations before entering interstate commerce. While the research did not represent all commercial processes for producing raw milk cheese, results being previewed in a pre-printExternal Link Disclaimer suggest that aging raw milk cheese for 60 days or longer is not effective at eliminating viable H5N1 in the cheese. H5N1 survived (i.e., was viable) in non-heat-treated raw milk cheese through and beyond the 60-day aging process. However, heating raw milk at 54°C (130°F) for at least 15 minutes or 60°C (140°F) for at least 10 seconds inactivated H5N1 in this research.
Information for Consumers
The FDA is confident that pasteurization is effective at inactivating H5N1, and that the commercial, pasteurized milk supply is safe. To date, FDA testing of pasteurized dairy products and aged raw milk cheese intended for retail has not detected infectious H5N1.
Consumers who want to know if their cheese has been made with raw milk may check the product label. While there is no express Federal requirement for the labeling of cheeses to disclose on the ingredient list whether the milk used in manufacture was raw or pasteurized, many cheeses do disclose on the ingredient list (or elsewhere on the product label) if the milk used is pasteurized or raw. The FDA is not aware of any H5N1 illnesses to date from the consumption of aged raw milk cheese products. The FDA is continuously monitoring the HPAI situation and working together with USDA, CDC, state partners, academia, and industry on ways to mitigate the impact of this ongoing outbreak using a One Health approach to understand and reduce H5N1.
Information for Industry
The FDA continues to recommend that dairy producers monitor herds for H5N1 infection by enrolling in USDA or state testing programs. If a herd becomes infected with H5N1, the USDA recommends that dairy producers segregate clinically ill cows from the rest of the milking herd. The FDA recommends dairy processors not use milk from infected cows in the production of raw milk products, such as raw milk cheese, and reminds manufacturers that heat treating or pasteurization are both effective measures that inactivate H5N1. Research to date has demonstrated heating raw milk at 54°C (130°F) for at least 15 minutes or 60°C (140°F) for at least 10 seconds inactivates H5N1 in raw milk. Additionally, the researchers determined that manufacturing non-heat-treated raw milk cheese at a pH of 6.6 or 5.8 did not inactivate H5N1, whereas a pH of 5.0 led to rapid inactivation of H5N1. Additional research is needed to determine if pH adjustment is a practical intervention.
Status of the Milk Supply
After the first detection of HPAI H5N1 in dairy cattle in March 2024, the FDA has engaged in research and other efforts with industry, federal, and state partners to ensure the continued effectiveness of the federal-state milk safety system.
Nearly all (99%) of the commercial milk supply that is produced on dairy farms in the US comes from farms that participate in the Grade A Milk Safety Program and follow the Pasteurized Milk Ordinance (PMO), which includes controls that help ensure the safety of dairy products. Pasteurization and diversion or destruction of abnormal milk are two important measures that are part of the federal-state milk safety system.
The process of pasteurization has helped to ensure the health of the American public for more than 100 years. Pasteurization kills harmful bacteria and viruses by heating milk to a specific temperature over time. Even if the virus is detected in raw milk, the current pasteurization process (HTST – High Temperature, Short Time) will inactivate the virus.
CDC Surveillance
...
https://www.fda.gov/food/alerts-adv...ation-avian-influenza-h5n1-virus-dairy-cattle