Indiana confirms first H5N1 dairy herd, the 21st US state affected

USDA's Animal and Plant Health Inspection Service said its National Veterinary Services Laboratories confirmed H5N1 genotype B3.13 in an Indiana dairy herd through polymerase chain reaction testing. The herd was confirmed earlier this month. The detection came through routine testing under USDA's National Milk Testing Strategy, not premovement surveillance, DTN Progressive Farmer reported.

Indiana is the 21st state with infected dairy cattle since the outbreak was first identified in U.S. herds in March 2024, according to DTN. Nationally, USDA had confirmed more than 1,166 infected dairy herds across 19 states as of 22 July 2026, Medical Daily reported. That July count predates the Indiana detection. The Indiana case follows recent detections in Washington, another state that had not previously reported HPAI in livestock, DTN reported.

Why routine milk testing found it

The National Milk Testing Strategy is designed to identify H5N1 in dairy cattle through testing milk samples, allowing animal-health officials to monitor where the virus is circulating, DTN reported. The B3.13 genotype has been associated with most HPAI cases in U.S. dairy herds. USDA said many infections resulted from movements of live cattle linked to the original spillover event detected in the Texas Panhandle in late 2023.

USDA said the Indiana detection highlights another avenue it is using to monitor the virus. Unlike some previous cattle detections prompted by sick animals or testing associated with cattle movement, this case was found through routine milk surveillance.

What USDA is doing next

USDA said it is working with the Indiana State Board of Animal Health on additional on-farm investigations, diagnostic testing and collection of epidemiological information. The work is intended to better understand the detection and limit additional spread. The agency said the newest detection does not change its HPAI eradication strategy. Federal officials continue to emphasize biosecurity to reduce the risk of introducing the virus onto farms or spreading it between operations.

APHIS recommends dairy producers strengthen biosecurity practices and immediately report livestock showing clinical signs of HPAI to state veterinarians. Producers also are urged to report unusual illness or deaths among wildlife, according to DTN.

Milk safety and public risk

Federal officials said the cattle detections do not change the safety of the commercial milk supply. The Food and Drug Administration has said pasteurization is effective at inactivating HPAI virus. Milk from affected cattle is required to be diverted from the commercial milk supply or destroyed, while only milk from healthy animals can be sent for processing for human consumption.

The Centers for Disease Control and Prevention continues to assess the risk from H5N1 to the general U.S. public as low. People who work with or otherwise have exposure to infected birds, cattle or other animals face greater risk, DTN reported.