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Understanding HPAI in Dairy Cattle

Highly Pathogenic Avian Influenza (HPAI), historically known for its devastating impact on bird populations, has recently emerged as a threat to dairy cattle.

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Updated:

December 16, 2024

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Highly Pathogenic Avian Influenza (HPAI), historically known for its devastating impact on bird populations, has recently emerged as a threat to dairy cattle. The detection of the H5N1 strain in dairy herds across several states has heightened concerns about animal health, food safety, and public health. This unexpected crossover into dairy cattle has prompted urgent attention from the agricultural community, regulators, and public health officials, underscoring the need for comprehensive strategies to manage and mitigate the spread of this virulent disease.

Background

HPAI is caused by influenza A viruses, with the H5N1 strain being particularly virulent. While HPAI is well-known for its impact on poultry, its emergence in dairy cattle is a relatively new phenomenon. The first cases in dairy cattle were reported in March 2024, and since then, the virus has spread to multiple states. Since mid-December 2024, there have been 188 new, confirmed HPAI cases in dairy farms in Idaho (ID), Utah (UT), and California (CA), which means 38% of all cattle cases occurred in about one month. Since February 2024, the number of affected dairy herds has reached 492, with 278 farms in CA alone. With the number of cases awaiting confirmation, CA could see over 300 cases soon. (APHIS, 2024) This significant increase has raised concerns about the potential impact on milk production. For October, there could be an industry-estimated 4% drop in the U.S. milk production, given that CA produces 18% of the nation’s milk supply. This could mean a substantial decline in the country’s milk production.

Clinical Signs and Symptoms

Dairy cattle infected with HPAI may exhibit a range of clinical signs, including:

Reduced appetite: Affected cows often show a decreased interest in feed.
Reduced milk production: There is a noticeable drop in milk yield.
Abnormal milk appearance: The milk may appear thickened or discolored.
Respiratory symptoms: Coughing and nasal discharge can occur.
General malaise: Infected cows may appear lethargic and unwell.
Fever: A low-grade fever may occur (USDA APHIS).

Transmission and Spread

The H5N1 virus can spread through direct contact with infected animals, contaminated equipment, and shared personnel. The movement of cattle between farms is a significant risk factor for disease transmission. Additionally, there is evidence that the virus can spread from dairy cattle premises to nearby poultry facilities. In the same 30-day timeframe, there have been 21 confirmed positive cases in poultry flocks in Washington (WA), Montana (MT), UT, Oregon (OR), and CA, affecting a total of 4.4 million birds. (APHIS, 2024) Poultry farms now face an ongoing double-threat risk from wild bird and dairy cattle introduction.

Pennsylvania Regulations

Pennsylvania has implemented specific regulations to address the threat of HPAI in dairy cattle. As of November 2024, the Pennsylvania Department of Agriculture requires bulk testing of milk from dairy farms. Milk tankers transporting dairy farm milk to processing plants must submit samples to a Pennsylvania Animal Diagnostic Laboratory System lab within 48 hours. This testing is done at no cost to farmers and aims to quickly identify any early cases of HPAI in cattle.

If HPAI is detected, the Department will establish a special quarantine on the farm where the sample originated. All dairy cattle herds inside the quarantine zone will undergo additional sampling and testing. The state has also issued a quarantine order requiring dairy cattle to be tested when entering Pennsylvania from other states, especially from areas with confirmed cases.

Human Health Concerns

Since March 2024, there have been roughly 36 confirmed cases of HPAI in humans. All affected individuals reported mild cases of conjunctivitis and severe red eye. You can visit the Centers for Disease Control and Prevention to read further about how HPAI affects humans. Getting the seasonal flu vaccine, especially for those in direct contact with animals, is important to lower the chances of co-infection and HPAI evolving into a new type of virus.

Food Safety

The Food and Drug Administration (FDA) and USDA have emphasized that the commercial milk supply is safe due to the pasteurization process. Almost all (99%) of the commercial milk supply in the U.S. originates from dairy farms participating in the Grade A Milk Safety Program and adhering to the Pasteurized Milk Ordinance (PMO). These regulations include essential controls to ensure the safety of dairy products. Pasteurization and the diversion or destruction of abnormal milk are key measures within this federal-state milk safety system.

For over a century, pasteurization has played a crucial role in protecting public health. By heating milk to a specific temperature for a set time, pasteurization effectively kills harmful bacteria and viruses. Even if a virus is present in raw milk, the High Temperature, Short Time (HTST) pasteurization process will inactivate it. Similarly, the meat supply is considered safe. Consumers are reassured that there is no risk from consuming dairy or meat products from infected animals.

Biosecurity Measures

To prevent the spread of HPAI, dairy producers are advised to implement stringent biosecurity measures, including:

Isolation of sick animals: Any cow showing symptoms should be isolated immediately.
Minimizing cattle movements: Reducing the movement of cattle between farms can help contain the virus.
Enhanced cleaning protocols: Regularly cleaning and disinfecting equipment and vehicles can prevent contamination.
Personal protective equipment (PPE): Workers should wear appropriate PPE to reduce the risk of infection, such as disposable gloves and protective eyewear.

The PDA stresses that all farms obtain and maintain an everyday biosecurity plan. This type of plan focuses on preventing a disease outbreak on farms. The Penn State Extension team offers assistance and resources for farmers to develop their own biosecurity plan. Pennsylvania dairy farmers can request, at no cost, biosecurity kits and "No Trespassing" signs through the Center for Dairy Excellence to create their biosecurity protocols and everyday biosecurity plan.

For farmers, treating a biosecurity plan like a living document is key to preventing or containing potential positive cases of HPAI. This means reviewing and revising it continuously and going over it with family members and employees regularly. Developing protocols for visitors and service providers improves a farm's overall efficacy of its biosecurity plan. Also, designating someone who understands the farm as the biosecurity coordinator will ensure implementation.

The PDA emphasizes the importance of obtaining a USDA premise I.D. number, not to be confused with the FDA premise I.D., to help slow and prevent the spread of HPAI. USDA programs do not recognize FDA-issued identifiers. If you receive an official I.D. for your cattle, you most likely already have a USDA-issued federal premise I.D. Check the status of or register for a USDA premise I.D.

Testing and Reporting

Federal and state regulations require testing of lactating dairy cattle for HPAI before interstate movement. Producers must report any positive cases to the appropriate authorities to facilitate rapid response and containment efforts.

The Pennsylvania Department of Agriculture encourages all Pennsylvania dairies to enroll in the voluntary Lactating Dairy Cow Health Monitoring Program. This program will provide critical data on the health status of dairy cattle in Pennsylvania to ensure that the state remains free of Highly Pathogenic Avian Influenza. Enrolled farms will benefit by no longer being required to individually test cattle prior to interstate movement. Testing will be performed at no cost to producers, and the Department or USDA will provide necessary sampling supplies upon enrollment.

Ongoing Surveillance and Support

A Voluntary Multistate HPAI Surveillance Program will be open to Mid-Atlantic dairy processors to collect key data on the presence of HPAI in milk silos in the region. Participating processing plants collect samples regularly for testing and are shipped overnight for PCR and ELISA testing, with results shared with participating states. Currently, dairy processors in Pennsylvania, Maryland, New Jersey, and Delaware are participating. For more information, please contact the Pennsylvania Department of Agriculture (PDA) at RA-ahds@pa.gov.

The PA Department of Health (PA DOH) has various Personal Protective Equipment (PPE) available, including gowns, face shields, and gloves. To request PPE, contact Call 717-772-2852 or Email RA-ahds@pa.gov.

Collaboration is Key to Prevention

The emergence of Highly Pathogenic Avian Influenza (HPAI) in dairy cattle represents a significant and evolving challenge for the agricultural industry, with far-reaching implications for animal health, food safety, and public health. The recent surge in confirmed cases across multiple states, particularly the sharp rise in California, underscores the urgent need for coordinated efforts to mitigate the spread and impact of this virulent disease.

In response to this threat, Pennsylvania has implemented stringent regulations and proactive measures designed to protect its dairy and poultry industries. The state's bulk testing requirement for milk from dairy farms and the establishment of quarantine zones upon detection of HPAI are critical steps in early detection and containment. The encouragement for dairy farms to enroll in the Voluntary Lactating Dairy Cow Health Monitoring Program further strengthens the state's ability to monitor and control the disease effectively.

Biosecurity remains the cornerstone of disease prevention and control. Farmers are urged to treat biosecurity plans as living documents, continuously reviewing and updating protocols to address potential risks. The availability of biosecurity kits and support from the Penn State Extension team and the Center for Dairy Excellence empowers farmers to implement robust biosecurity measures. Request a biosecurity kit from the Dairy Excellent Foundation.

The potential impact on milk production, especially with California being a major producer, highlights the broader economic implications. A significant decline in the U.S. milk supply could affect not only farmers but also consumers and the entire food supply chain. It is crucial to maintain stringent biosecurity and surveillance measures to mitigate this risk. Continued cooperation between state and federal agencies, industry stakeholders, and public health officials is vital. Efforts to navigate trade implications and maintain a secure food supply must be sustained. The USDA's assurance that dairy products remain safe for consumption, combined with proactive state measures, provides reassurance to the public.

As the situation evolves, the importance of timely and accurate reporting, comprehensive testing, and robust biosecurity cannot be overstated. The agricultural community must remain vigilant, adaptive, and committed to safeguarding both animal and public health. Human health concerns, though currently considered low, cannot be overlooked.

By leveraging the collective expertise and resources of agricultural and health institutions, we can effectively manage the current crisis and build resilience against future outbreaks. The collaborative efforts and proactive strategies being implemented set a strong foundation for addressing the challenges posed by HPAI and ensuring the long-term sustainability of the dairy and poultry industries.

If your farm needs assistance creating a Biosecurity Plan, Reach out to Samantha Gehrett, Dairy Educator with Penn State Extension, at 717-706-6034 or email smr5319@psu.edu.