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Questions and Answers Regarding Milk Safety During Highly Pathogenic Avian Influenza (HPAI) Outbreaks

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The U.S. Food and Drug Administration (FDA) is working closely with the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS), the Centers for Disease Control and Prevention (CDC), and state partners to investigate an illness affecting dairy cows in multiple states. This illness is causing symptoms such as reduced milk production, poor appetite, and other health issues.

As of Tuesday, April 2, the agencies have confirmed the presence of highly pathogenic avian influenza (HPAI) A (H5N1) viruses in dairy herds in Idaho, Kansas, Michigan, New Mexico, and Texas. The virus was identified in unpasteurized milk, swabs, and tissue samples collected from sick cattle on dairy farms. These samples were submitted as part of the investigation into the illness, which primarily affects older dairy cows but has also been found in some younger lactating cows.

Presumptive positive test results have also been reported for additional herds in Idaho, Ohio, and Texas.

At this time, there is no evidence that this situation poses any risk to consumer health or the safety of the interstate commercial milk supply. All milk products entering the market are pasteurized to ensure their safety.

Only milk from healthy animals is allowed for distribution in interstate commerce for human consumption. Pasteurization is mandatory for all milk in interstate commerce and has been consistently effective in inactivating bacteria and viruses, including influenza, in milk. Milk from symptomatic animals is either diverted or destroyed to prevent it from entering the food supply.

The loss of milk from affected cattle has been minimal and is not expected to significantly impact the overall supply or the price of milk and dairy products. The FDA will continue working with its partners and provide updates as needed.

Highly Pathogenic Avian Influenza (HPAI)

What is HPAI, and why is it a concern?

Highly Pathogenic Avian Influenza (HPAI), also known as bird or avian flu, is a highly contagious disease that affects poultry and is often fatal. It is caused by avian influenza A (H5) and A (H7) viruses. HPAI can be transmitted from wild birds to domestic poultry and other birds and animals.

While bird flu viruses do not typically infect humans, sporadic cases have occurred. It’s important to understand that "highly pathogenic" refers to the severe effects of the disease in birds, not necessarily in humans.

Milk Safety and Supply

Is the milk in stores safe to drink?

The FDA currently has no concerns about the safety or availability of pasteurized milk products across the country. Pasteurization has consistently been effective at inactivating bacteria and viruses, including influenza, in milk. It is a required process for all milk that enters interstate commerce.

Is the milk supply affected?

Currently, milk loss from symptomatic cattle is minimal and not significant enough to impact the overall supply. There is no expected effect on the price of milk or other dairy products. The FDA has not identified any nationwide issues with the availability of pasteurized milk products.

What about cheese sold in stores?

The FDA has no concerns about the safety or availability of pasteurized cheese and other pasteurized milk products sold nationwide. Pasteurization remains a proven method of inactivating bacteria and viruses, including influenza, in milk and milk products like cheese.

Concerns About Raw Milk and Cheese

Is there a risk of HPAI from raw milk?

Currently, there is limited research on whether HPAI A (H5N1) viruses can be transmitted through consuming raw (unpasteurized) milk or products like cheese made from raw milk from infected cows. However, raw milk is already known to pose serious health risks due to the harmful microorganisms it can contain.

The CDC reports that between 1998 and 2018, there were 202 outbreaks linked to raw milk, leading to 2,645 illnesses and 228 hospitalizations. These outbreaks were typically caused by bacteria such as Campylobacter, Cryptosporidium, E. coli, Salmonella, or Listeria monocytogenes.

FDA Recommendations for Raw Milk and Cheese Products

Due to limited information about the potential transmission of HPAI A (H5N1) viruses in raw milk, the FDA advises against the production or sale of raw milk or raw milk cheese made from cows showing signs of illness. This includes cows infected with or exposed to avian influenza viruses. Exposure typically refers to cattle on premises with suspected or confirmed HPAI A (H5N1).

Because farm sizes and state regulations vary, the FDA recommends that producers consult with state regulatory officials and their veterinarians for specific guidance. Milk from exposed but asymptomatic cattle should only be used for pasteurized products, whether intended for human consumption or animal feed. Before resuming the sale of unpasteurized dairy products, the FDA advises testing pooled milk for HPAI viruses once illnesses on the premises appear to have resolved.

As selling raw milk for human consumption across state lines is prohibited, states have their own regulations for its sale and distribution. Questions about raw milk should be directed to the relevant state authorities.

Raw, Unpasteurized Cheese, and Aging

FDA regulations require unpasteurized cheese to undergo a 60-day aging process to enhance food safety by reducing bacteria and viruses. However, due to limited research on whether HPAI A (H5N1) viruses can be transmitted through raw milk or raw milk products like cheese, the FDA advises against producing or selling raw milk or raw milk cheese made from cows showing signs of illness. This includes cows infected with or exposed to HPAI viruses, even if the cheese will be aged for 60 days.

Exposure typically refers to cattle on premises with suspected or confirmed cases of HPAI A (H5N1). Given the differences in farm sizes and state regulations, producers are encouraged to consult with state regulatory officials and veterinarians for specific guidance.

The FDA recommends using milk from exposed but asymptomatic cattle only for pasteurized products, whether for human consumption or animal feed. Additionally, premises should test pooled milk for HPAI before resuming the sale of unpasteurized dairy products once illnesses appear to have resolved.

Consumer Guidance on HPAI in Food

Currently, the FDA is not aware of any milk or milk products from symptomatic cows entering interstate commerce. Milk from affected animals is being diverted or destroyed to prevent it from entering the human food supply. Pasteurization, which is mandatory for all milk in interstate commerce, has consistently been shown to inactivate bacteria and viruses, including influenza viruses, in milk.

The FDA continues to emphasize that unpasteurized, raw milk can carry harmful microorganisms that pose significant health risks. In light of HPAI detections in dairy cows in some states, the FDA reminds consumers of the risks associated with consuming raw milk.

Industry Involvement

What steps should dairies take to protect the food supply?

Dairies should continue monitoring their cows for any signs of illness to ensure that milk from sick animals does not enter interstate commerce. If illness is detected, producers should work with their State Animal Health Official’s office to submit samples for diagnostic testing.

Protecting Dairy Cows

What additional steps should dairies take to safeguard their cows?

Farmers should prioritize strong biosecurity practices and contact their State Animal Health Official or Area Veterinarian in Charge for guidance on preventing the spread of HPAI viruses. Resources on biosecurity for dairies provide helpful precautions.

Producers should closely monitor their cattle for signs of illness, including reduced milk production, and immediately isolate any sick animals. Milk from symptomatic cows should be discarded. If this milk is to be fed to calves or other animals (e.g., cats on the farm), the FDA strongly recommends pasteurizing or heat-treating it to kill harmful bacteria or viruses, including influenza. Many State Cooperative Extension Service programs, such as Penn State’s guidance on pasteurizing non-saleable milk, offer detailed instructions for treating waste milk effectively before use.

How should dairies manage milk from affected cows?

The FDA advises producers to take steps to ensure that discarded milk from affected cows does not contribute to the spread of disease. Producers should consult their state regulatory authorities for specific guidance, but precautions may include heat-treating or pasteurizing the milk before disposing of it in lagoons or applying waste solids.

Additionally, biosecurity measures should be implemented around lagoons to prevent access by animals or birds, reducing the risk of further spread.

Handling Milk from Symptomatic Cows

The FDA advises producers to discard milk from cows showing symptoms of illness. Young calves are vulnerable to diseases, and raw milk can transmit harmful pathogens. If milk from symptomatic cows, including those infected with HPAI A (H5N1), cannot be discarded and is intended for feeding calves or other animals (like farm cats), the FDA strongly recommends heat treating the milk. This process should follow time and temperature guidelines similar to commercial milk pasteurization to eliminate harmful bacteria or viruses, such as influenza.

Raw milk or milk products from exposed cattle – those on premises with suspected or confirmed HPAI A (H5N1) infections – should also be heat treated or pasteurized before being fed to calves or other animals. Many State Cooperative Extension Service programs, such as Penn State's guidance on pasteurizing non-saleable milk, provide detailed instructions for effectively treating milk to ensure it is safe for animal feeding. This guidance applies to feeding both calves and other animals.