Highly pathogenic avian influenza (HPAI) H5N1, often called “cow flu,” has emerged as an animal health concern, particularly affecting dairy cattle across the United States. The virus’s presence in livestock also presents a public health consideration. Understanding this influenza strain is important.
Understanding Bovine Influenza
“Cow flu” refers to the highly pathogenic avian influenza A(H5N1) virus, recently identified in dairy cows. This virus, traditionally known for its impact on poultry and wild birds, now threatens bovine health.
Infected dairy cows may exhibit a decrease in milk production, with the milk often appearing thicker, discolored, and colostrum-like. Cows may also show lethargy, a reduced appetite, and decreased rumination. Animals may experience fever, changes in manure consistency, and a clear nasal discharge. These symptoms last between 6 to 17 days.
How it Spreads and Affects Humans
The HPAI A(H5N1) virus spreads among cattle through direct contact with infected animals, which is a main mode of transmission within herds. Contaminated equipment, including shared milking equipment, can also spread the virus between cows and dairy farms. Small mammals like skunks, raccoons, and cats, along with waterfowl and other birds, can transmit the virus to cattle.
The potential for zoonotic spillover to humans exists, though the risk to the general public is currently low. Human exposure occurs through direct contact with infected animals, unpasteurized milk, or contaminated environments. Human infections have been linked to occupational exposure, especially among dairy farm workers with close contact.
The few reported human cases of H5N1 linked to dairy cattle exposure have presented with mild symptoms. These include conjunctivitis (eye irritation, redness, and discharge). Some individuals report mild respiratory symptoms, such as a sore throat, runny nose, or shortness of breath, along with fever, body aches, headaches, and fatigue. Human-to-human transmission of this H5N1 strain has not been observed.
Protecting Animals and Public Health
Implementing biosecurity measures on farms is important to prevent the spread of the HPAI A(H5N1) virus among animals. This includes cleaning and disinfection protocols for equipment and facilities. Limiting visitor access to farms and isolating sick animals are important steps to contain the virus. Proper disposal of contaminated materials helps prevent environmental spread.
For the general public, safe food handling practices are recommended to minimize risk. Consuming only pasteurized milk and dairy products is advised, as pasteurization inactivates the virus. Thoroughly cooking meat also ensures safety. Also, avoid contact with sick or deceased animals and practice good personal hygiene, including frequent handwashing, especially after exposure to animals or their environments.