Avian Influenza A(H5N1) in Poultry, Cattle, and Other Animals

What is Influenza A or H5N1?

Avian influenza viruses usually spread between birds. You may have heard it referred to as Highly Pathogenic Avian Influenza or HPAI because of severe infections in birds. In 2022, an emerging strain of avian influenza A virus, called H5N1, was detected in the United States and has since been spreading in wild birds and causing sporadic outbreaks in domestic poultry and dairy cows. In addition to spreading to an increasing number of mammals, including domestic cats, the influenza A(H5N1) virus has caused some rare human infections in people who had contact with infected animals. 

What is the concern?

The influenza A(H5N1) virus was not known to cause infection in cattle until March 25, 2024, when it was confirmed in a dairy herd in Texas and a nationwide outbreak in cattle began. Throughout the course of 2024, human infections with H5N1 began to be detected (most commonly in farm workers exposed to infected animals) for a total of 66 confirmed human H5N1 infections in 2024. The influenza A(H5N1) virus has not been identified to be transmitted from human to human, but two severe H5N1-associated illnesses have occurred in North America with genetic linkages to animals, and one death has occurred. 

What action(s) should I take?

The situation is still evolving, but the overall risk to the general public remains low. Maintain healthy practices, such as avoiding sick or dead animals and avoid consuming unpasteurized (raw) milk or raw cheeses. It is safe to drink commercial milk because products are pasteurized before entering the market. Pasteurization kills bacteria and viruses, like influenza viruses, in milk. CDC has additional guidance available here. As cats appear to be susceptible to the H5N1 virus and birds and waterfowl may carry influenza, it is important to consider actions you might take to limit your cat’s contact with birds and waterfowl and monitor your cat for signs of illness or abnormal behavior. Take personal protective measures such as wearing personal protective equipment and limiting contact, and contact your veterinarian, if you have concerns or your animal has been potentially exposed to H5N1 and you observe illness in your animal. 

What are the symptoms?

The reported signs and symptoms of avian influenza infections in humans have ranged from mild symptoms to moderate to severe disease and complications. Conjunctivitis (redness and swelling of the eye) has been the predominant symptom among human cases caused by this H5N1 strain. Other symptoms typical of influenza infection include cough, fever or feeling feverish, sore throat, runny nose, fatigue, headache, muscle or joint aches, and shortness of breath or difficulty breathing. 

What can medical providers do?

Medical providers should remain vigilant for a patient with both (1) direct contact or consumption of H5N1-infected birds, animals, or their raw food/dairy products, and (2) signs/symptoms of influenza infection. If a patient meets both criteria, isolate the patient, and follow infection control recommendations, notify the South Dakota Department of Health by calling 800-592-1861, collect specimens for testing at the South Dakota Public Health Laboratory, and begin antiviral medication treatment with oseltamivir (twice daily for five days) regardless of time since symptom onset. Additional guidance can be found here.

What can Farmer, Rancher, and other Animal Caretakers do?

To reduce the risk of avian influenza A(H5N1) virus infection, avoid unprotected direct physical contact or close exposure with sick or dead birds or other animals. When in contact with sick or dead birds or other animals, wear personal protective equipment (PPE). CDC has additional guidance available here.

H5N1 Virus Guidance for Farm Workers

Guía sobre el virus H5N1 para trabajadores agrícolas

Protect Yourself From H5N1 When Working With Farm Animals (CDC)