NEWTON COUNTY, Ind. — The H5N1 influenza virus was detected in two Newton County dairy herds in late October, the Indiana State Board of Animal Health said Monday.
The detections came through routine National Milk Testing Strategy surveillance at a dairy processing facility in another state. After receiving notice, the state board collected samples from the farms for follow-up testing at the Indiana Animal Disease Diagnostic Laboratory. The USDA’s National Veterinary Services Laboratories confirmed the findings.
Highly pathogenic avian influenza has been detected at more than 2,200 poultry premises in all 50 states since February 2022. The virus has also been found in wild birds and mammals. Wild birds were the initial source of infection in the first detection of H5N1 in dairy cows, in Texas in March 2024. Since then, the virus has been detected on more than 1,100 dairy farms in 21 states. Data on detections in wild birds are available on the state board’s website.
The state board called the current outbreak the largest animal health emergency in U.S. history.
The two dairies are operationally connected. No other cases in Indiana dairy cattle have been detected.
When H5N1 is confirmed on a dairy farm, the state board quarantines all lactating dairy cows at the site. Under its response plan, the farm will be tested weekly until lactating cattle in the herd receive two consecutive negative test results. The state board will then lift the quarantine.
The state board will also test all Grade A dairies and commercial poultry premises within a 10-kilometer surveillance zone around the affected farm to check for community spread. Testing in the zone will continue every 28 days until the quarantined farm is cleared, the state board said.
Avian influenza does not pose a food safety risk, the state board said. Cooked poultry, beef and eggs, along with pasteurized dairy products, are safe to eat. Pasteurization kills the H5N1 virus.
The virus can cause particularly severe illness in cats. Pet owners should not feed cats raw or undercooked food, including unpasteurized milk.
Recent detections of H5N1 in wild birds, poultry, and cattle pose a low risk to the general public, the state board said. Human infections are expected to be rare and are most likely among people who have prolonged, unprotected close contact with infected birds or cattle, or with contaminated environments, through recreational or work-related activities.
The Indiana Department of Health offers guidance for farmers. The state board’s website has an H5N1 dairy detection dashboard and updates on Indiana’s National Milk Testing Strategy surveillance.
