The ongoing outbreak of highly pathogenic avian influenza (HPAI; H5N1) has emerged as a concern in the agricultural industry.
Since early 2022, poultry has been impacted, and in early 2024, a strain of the H5N1 virus was identified in cattle. The current outbreak of highly pathogenic avian influenza (HPAI; H5N1) impacting poultry has been ongoing since early 2022. A strain of the H5N1 virus was identified in cattle in early 2024. Since that time, nearly 1,000 dairy herds in 16 states have been identified with the virus. Virginia has not yet had a case identified in cattle, but has had multiple poultry outbreaks, including the most recent outbreak in January 2025. HPAI testing has been required for interstate movement of lactating dairy cattle since last year. As the situation unfolds, it becomes increasingly important for those involved in agriculture to stay informed about the implications of this virus.
The Emergence of H5N1 in Cattle
The virus looks different in cattle than in poultry. While morbidity (the number of cattle affected) can be high, mortality plus cull rate in cattle is typically less than 2%. Most cattle make a full recovery. Because the virus is shed heavily in the udder, lactating dairy cows have been the center of the outbreak in cattle. However, it is likely that non-lactating dairy cattle, as well as beef cattle can be infected.
Symptoms may be more subtle in these classes of animals. Decreased milk production and appetite are primary symptoms in dairy cattle. Abortion, especially late-gestation abortion in first lactation animals, has also been reported. A flu outbreak will also exacerbate any pre-existing issues in a herd, such as mastitis or transition cow disease. It is critical to minimize stress during an outbreak and provide supportive care for clinical cases.
The Broader Impact on Other Species
One of the major concerns with the flu virus is its ability to mutate and jump from species to species. Humans, birds and swine are major species of concern. So far, with one or two exceptions, the humans impacted by this strain are dairy farm workers infected by cows. Symptoms have been mild and human-to-human transmission does not appear to be a current concern. There has been an infected pig in a backyard herd housed with poultry in Oregon. There are no known commercial swine cases at this time. Over a dozen other mammalian species have tested positive around the country, including raccoons, skunks and bears.
The most significantly impacted species outside of cattle and poultry currently are cats. In fact, sick cats are often an early sign of a dairy farm outbreak. In addition to respiratory symptoms, infected cats have exhibited neurologic symptoms including tremors, seizures, blindness and sudden death. Cats exhibiting these symptoms should be handled with caution, as the symptoms are also consistent with rabies infection. Cats can be tested post-mortem for both diseases. These symptoms should be taken seriously, especially for cats on dairy farms. Potential transmission between cats and humans is a public health concern at this time.
Human Cases and Public Health Concerns
It is important to state that food products, including both properly cooked meat and pasteurized dairy products, have been shown to be safe for human consumption. Anyone involved with livestock and agriculture should stay aware of these developments and remain vigilant when symptoms of disease arise.
The CDC continually emphasizes that poultry, beef and pasteurized dairy products remain safe for human consumption.
Final Thoughts on HPAI and Animal Health
Regularly check updates from local agricultural extensions, veterinarians, and the CDC about new findings related to HPAI and any changes in regulations.
Remember, the sooner symptoms are addressed, the better the outcomes for both animals and their human caretakers.
ODVS will continue to provide updates as they arise.
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