Updates on Highly Pathogenic Avian Influenza (HPAI)

On this page: 

• Highly Pathogenic Avian Influenza (HPAI)
• Milk Safety and Supply
• Raw Milk/Cheese Concerns
• Industry Involvement
• Federal Government Response

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Highly Pathogenic Avian Influenza (HPAI) 

What is HPAI and why is it a problem?

Highly Pathogenic Avian Influenza (HPAI) is a disease of poultry that is highly contagious and often deadly in poultry, caused by highly pathogenic avian influenza A (5) and A (7) viruses; it is also known as bird or avian flu. HPAI viruses can be transmitted by wild birds to domestic poultry and other bird and animal species. Although bird flu viruses do not normally infect humans, sporadic human infections have occurred. It is important to note that “highly pathogenic” refers to severe impact in birds, not necessarily in humans.

Milk Safety and Supply

Is the milk available in the retail market safe to drink?

The FDA and USDA have indicated that based on the information we currently have, our commercial milk supply is safe because of both the pasteurization process and that milk from sick cows is being diverted or destroyed. The federal-state milk safety system, and the Grade “A” Pasteurized Milk Ordinance, have proven effective for decades against a wide range of pathogens. Data from previous studies shows that pasteurization is very likely to effectively inactivate heat-sensitive viruses in fluid milk. Furthermore, thermal inactivation of HPAI has been successful during the pasteurization process for eggs, which occurs at lower temperatures than what is used for fluid milk. Given this is a novel and evolving situation, the FDA and USDA are working closely to collect and evaluate additional data and information specific to HPAI A (H5N1) to support our state co-regulators as they manage this emerging disease in dairy cattle.  

U.S. government partners are working with all deliberate speed on a wide range of studies looking at milk along all stages of production, including on the farm, during processing and on shelves. This work is a top priority and we are proceeding in an efficient, stepwise and scientific fashion to ensure the continued effectiveness of the federal-state milk safety system and reinforce our current assessment that the commercial milk supply is safe. These important efforts are ongoing and we are committed to sharing results as soon as possible. 

Is this situation impacting the availability of milk?

At this time, milk loss resulting from symptomatic cattle is too limited to have a major impact on supply and there should be no impact on the price of milk or other dairy products. The FDA is not aware of any impact on the availability of pasteurized milk products nationwide. We will continue to monitor the supply chain impacts and will update this page as necessary.

What about cheese sold at retail?

The FDA does not currently have concerns about the safety and availability of pasteurized milk products, including pasteurized cheese, sold nationwide. Pasteurization has continually proven to inactivate bacteria and viruses, like influenza viruses, in milk and milk products such as cheese. We are continuing to monitor the situation and will provide updates on our website if necessary. Also, see Q/As 5 and 6 regarding cheese made from raw/unpasteurized milk. 

Raw Milk/Cheese Concerns 

Are there concerns about HPAI and raw, unpasteurized milk?

Based on the limited research and information available, we do not know at this time if HPAI A (H5N1) viruses can be transmitted through consumption of unpasteurized (raw) milk and products (such as cheese) made from raw milk from infected cows. However, we have long known that raw milk can harbor dangerous microorganisms (germs) that can pose serious health risks to consumers. According to the CDC, from 1998 through 2018, there were 202 outbreaks linked to drinking raw milk, resulting in 2,645 illnesses and 228 hospitalizations. These outbreaks have typically been caused by the presence of bacteria such as Campylobacter, Cryptosporidium, E. coli, Salmonella, or Listeria monocytogenes in the raw milk. For more information about how consumers can protect themselves from these risks see our website: Raw Milk. 

Because of the limited information available about the possible transmission of HPAI A (H5N1) viruses in raw milk, the FDA recommends that industry does not manufacture or sell raw milk or raw milk cheese products made with milk from cows showing symptoms of illness, including those infected with avian influenza viruses or exposed to those infected with avian influenza viruses. By exposure, we generally mean cattle located on a premises with cattle with suspected or confirmed HPAI A (H5N1). Given the variety of premises sizes and the potential for state requirements, the FDA recommends producers consult with state regulatory officials and their veterinarian for further guidance. Accordingly, the FDA recommends that milk from exposed, asymptomatic cattle only be used for pasteurized milk and milk products whether for human or animal feed channels. The FDA recommends that premises test for HPAI viruses in pooled milk prior to resuming commerce in unpasteurized dairy products following apparent resolution of illnesses on the premises.

Additionally, as it is prohibited to sell raw milk for human consumption in interstate commerce, each state has its own regulations regarding the sale and distribution of raw milk within the state. Therefore, we defer questions or concerns about raw milk to the state authorities in which the raw milk is sold.

What about raw, unpasteurized cheese that has undergone aging?

FDA regulations require a 60-day aging process for unpasteurized cheese, as the aging process may inactivate some bacteria and viruses. However, these regulations are not safety standards, and some pathogens may survive the 60-day aging process. Because we have limited research and information on whether HPAI viruses can be transmitted through raw milk or raw milk products, such as cheese, the FDA recommends that industry does not manufacture or sell raw milk or raw/unpasteurized milk cheese products made with milk from cows showing symptoms of illness, including those infected with HPAI viruses or exposed to those infected with avian influenza viruses, even if the cheese will undergo the 60-day aging process. By exposure, we generally mean cattle located on a premises with cattle with suspected or confirmed HPAI A (H5N1). Given the variety of premises sizes and the potential for state requirements, the FDA recommends producers consult with state regulatory officials and their veterinarian for further guidance. Accordingly, the FDA recommends that milk from exposed, asymptomatic cattle only be used for pasteurized milk and milk products, whether for human or animal feed channels. The FDA recommends that premises test for HPAI in pooled milk prior to resuming commerce in unpasteurized dairy products following apparent resolution of illnesses on the premises.

Do consumers need to do anything different to protect against HPAI in food?

At this time, the FDA is not aware that any milk or milk products from symptomatic cows is entering interstate commerce as milk from impacted animals is being diverted or destroyed so that it does not enter the human food supply. Additionally, pasteurization has continually proven to inactivate bacteria and viruses, like influenza viruses, in milk. Pasteurization is required for any milk entering interstate commerce. FDA’s longstanding position is that unpasteurized, raw milk can harbor dangerous microorganisms that can pose serious health risks to consumers, and FDA is reminding consumers of the risks associated with raw milk consumption in light of the HPAI virus detections in dairy cows in some states. Safe food handling and preparation is always important and more information about best practices can be found at Safe Food Handling.

Industry Involvement

Is there anything more that dairies should be doing at this time to protect the food supply?

Farms should continue to monitor their dairy cows for signs of illness to ensure that milk from sick cows does not enter into interstate commerce. Producers that identify illness in their cows should work with the State Animal Health Official’s office to submit samples for diagnostic testing. 

Is there anything more dairies should be doing at this time to protect their dairy cows?

It is critically important that farmers practice good biosecurity measures and contact their State Animal Health Official and/or Area Veterinarian in Charge with concerns about preventing the spread of HPAI viruses. Additional general information about biosecurity on dairies precautions are available at Enhanced Biosecurity Training | Secure Milk Supply. Producers should continue to closely monitor their cattle for illness, including decline in milk production, and immediately separate sick animals. Milk from these cows should be discarded. If this milk is intended to be used to feed calves or other animals (such as cats living on the dairy farms), the FDA strongly encourages that it be pasteurized or otherwise heat treated to kill harmful bacteria or viruses, including influenza viruses, before it is fed. Many State Cooperative Extension Service programs have published detailed information on how to pasteurize or otherwise effectively treat waste milk before using it to feed calves (for example, Penn State - Pasteurization of Non-Saleable Milk).

How should dairies handle the disposal of milk from affected cows?

The FDA recommends producers take precautions when discarding milk from affected cows so that the discarded milk does not become a source of further spread. Producers should consult with their state regulatory authorities for specific recommendations or requirements, however, such precautions could include heat-treatment or pasteurization of discarded milk prior to dumping in lagoons or application of waste solids and ensuring biosecurity around lagoons (e.g., ensuring that animals and birds do not have access to lagoons). 

The FDA recommends producers discard milk from symptomatic cows. Young calves are susceptible to disease and disease-causing pathogens can be transmitted through raw milk. If milk from cows showing symptoms of illness, including those infected with HPAI A (H5N1), cannot be discarded and is intended to be used to feed calves (or other animals, such as farm cats), the FDA strongly encourages that it be heat treated to kill harmful bacteria or viruses, such as influenza, before calf feeding. This heat treatment should be similar to times and temperatures commonly found in commercial milk pasteurization processing.  

Any raw milk or raw milk products from exposed cattle that are fed to calves (or to other animals, such as farm cats) should be heat treated or pasteurized. By exposed, we mean cattle located on a premises with cattle with suspected or confirmed infections with HPAI A(H5N1) viruses. Many State Cooperative Extension Service programs have published detailed information on how to pasteurize or otherwise effectively treat milk before using it to feed calves (for example, Penn State - Pasteurization of Non-Saleable Milk). This information also applies to ways to render the milk safe before feeding to other animals.

What should dairy farms with affected cows do to protect their workers?

For information on recommendations for preventing exposures to HPAI A (H5N1) viruses, use of protective equipment, antiviral treatment, and similar topics visit CDC’s webpage Highly Pathogenic Avian Influenza A(H5N1) Virus in Animals: Interim Recommendations for Prevention, Monitoring, and Public Health Investigations.

Federal Government Response

Which federal agencies are involved with this response?

The US Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS) is leading this response from the animal health perspective while coordinating closely with FDA concerning milk and animal feed safety, and the Centers for Disease Control and Prevention (CDC) who is monitoring this incident from a disease control and prevention aspect. For additional information see USDA, FDA, and CDC Share Update on HPAI Detections in Dairy Cattle.