Detection of Highly Pathogenic Avian Influenza in Dairy Herds

Beginning in 2022, the U.S. has experienced the largest and longest outbreak of Highly Pathogenic Avian Influenza (HPAI) among wild birds, poultry, and domestic birds. There have also been detections in many species of wild mammals and recently in goats and dairy cows. The young goats were on a poultry farm in Minnesota that was under quarantine due to HPAI outbreak in the flock. Now HPAI H5N1 has been confirmed in dairy cattle herds in Texas, Kansas, New Mexico, Idaho, Michigan, and Ohio. The cows showed signs of decreased lactation, low appetite, mild fever, and other symptoms. The virus was detected in the raw, unpasteurized milk and occasionally on nasal swabs collected from the cows. The virus that was identified in cows was similar to those previously found among wild birds, so it is likely that the cattle were infected by the migratory waterfowl. The outbreak in Michigan was found in a resident herd that had recently imported some dairy cattle from Texas. The possibility of cow to cow transmission is being investigated. When the cattle were moved from Texas to Michigan, the cattle were not symptomatic and did not appear ill. The H5N1 virus has affected several other wild and domestic mammals, and it was reported that some cats on one dairy farm in Texas were affected.

Avian influenza (H5N1) is caused by a contagious flu virus that can spread among wild and domestic birds, including poultry, as well as to other mammals. Occasionally it can infect people exposed to infected animals, though it is extremely rare for it to be transmitted from one person to another. To date there have been only 2 cases reported in the U.S. One person was exposed to infected poultry and the second person was a worker exposed to an infected cow at a Texas dairy. Both cases were very mild and no indication of human-to-human transmission. Initial testing shows that the H5N1 virus has not adapted or changed in a way to make it more transmissible among humans. Therefore, the public health risk associated with HPAI remains low.

The avian influenza virus was detected in the raw milk from these dairy herds, but the commercial milk supply remains safe. The federal Grade “A” Pasteurized Milk Ordinance (PMO) prohibits milk from sick cows from entering the food supply chain. Sick or affected dairy cows are segregated on farms, and their milk does not enter the food supply. Milk from affected cows should not be used a food for other animals. In addition, pasteurization has continually proven to inactivate bacteria and viruses, like influenza, in milk.

State and federal agencies, as well as other dairy groups (International Dairy Foods Association) strongly recommend that all raw milk and raw milk components be heat-treated to a temperature and duration that kills harmful pathogenic bacteria and other microorganisms, including viruses. USDA, CDC and FDA remind consumers that raw milk should not be consumed due to the possible presence of human pathogens, such as: E. coli O157:H7, Campylobacter spp., Listeria monocytogenes, and Salmonella spp., among others and now to include HPAI with the recent detections.

If farmers note any illness in their animals, they should contact their local veterinarian. Signs of HPAI in poultry are increased morbidity or mortality. Dairy cows affected with H5N1 show signs of sudden drop in production with milk appearing thicker, concentrated (colostrum-like); decrease in feed consumption; abnormal feces, lethargy, dehydration, and fever.

If HPAI is suspected call the Office of the State Veterinarian (OSV) (907)-375-8215 or contact Dr. Coburn at (907) 375-8213. You can find more information about HPAI and detections in Alaska at the OSV Avian Influenza webpage.

Division of Environmental Health Office of the State Veterinarian

Detection of Highly Pathogenic Avian Influenza in Dairy Herds

USDA, FDA and CDC Share Update on HPAI Detections in Dairy Cattle:

References: