OMAHA (DTN) -- Highly pathogenic avian influenza (HPAI) was confirmed for the first time in an Indiana dairy herd earlier this month, adding another state to the list of those affected by H5N1 in cattle as animal-health officials continue monitoring detections in livestock and poultry.

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 (PCR) testing.

Unlike some previous cattle detections prompted by sick animals or testing associated with cattle movement, the Indiana case was detected through routine testing under USDA's National Milk Testing Strategy. It was not found through premovement surveillance.

Indiana becomes the latest state to report HPAI in dairy cattle since the outbreak was first identified in U.S. herds in March 2024. Dairy cattle in 21 states have now been affected during the outbreak.

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 Indiana case follows recent detections in Washington, another state that had not previously reported HPAI in livestock.

WASHINGTON DAIRY HERDS AFFECTED

USDA initially announced HPAI detections in two Washington dairy herds after cattle showed clinical signs consistent with the disease. Before becoming sick, the herds had consistently tested negative through routine National Milk Testing Strategy surveillance.

Whole-genome sequencing later confirmed the Washington virus as H5N1 genotype B3.13. USDA said its analysis indicated the infections were consistent with transmission from Idaho to Washington, likely through movement of cattle.

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.

The Indiana detection through routine milk surveillance highlights another avenue USDA is using to monitor the virus. 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.

USDA 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.

POULTRY CASES CONTINUE

HPAI also continues to circulate in poultry and wild birds, as migratory birds begin their journey south.

The Iowa Department of Agriculture and Land Stewardship and USDA confirmed H5N1 in a commercial turkey flock in Sac County on Oct. 28. It was Iowa's eighth HPAI detection of 2026.

Iowa Gov. Kim Reynolds issued a disaster proclamation for Sac County following the detection. The proclamation, effective through Nov. 27, allows state resources to assist with monitoring, rapid detection, containment, disposal and disinfection related to the outbreak.

The Sac County case followed a September detection in a multi-species backyard flock in Boone County. H5N1 can be carried by wild birds without the birds appearing sick, while the disease can be fatal to domestic poultry, including chickens and turkeys. Animal-health officials have repeatedly encouraged commercial poultry farms and backyard flock owners to strengthen biosecurity, particularly during periods of wild-bird migration.

In the past 30 days, poultry cases of HPAI have also been found in California, Illinois, Minnesota, Wisconsin, South Dakota, North Dakota and Kansas, among others.

FOOD, PUBLIC HEALTH RISK REMAINS LOW

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.

Iowa officials similarly said recent poultry detections do not present an immediate public-health concern, and poultry and eggs remain safe to eat when properly handled and cooked. Poultry and egg products should be cooked to an internal temperature of 165 degrees Fahrenheit.

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 and are advised to follow recommended precautions.

With cases now appearing in previously unaffected states, federal and state animal-health officials continue to emphasize surveillance, rapid reporting and stronger farm biosecurity as key tools for limiting further spread.

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Editor's Note: This article was produced with the assistance of artificial intelligence and reviewed by DTN editorial staff.

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