Indiana confirms first H5N1 infections in two connected dairy herds
The Indiana State Board of Animal Health (BOAH) said the virus was initially found in late October. Samples collected from the herds were examined by the National Veterinary Services Laboratories, where polymerase chain reaction testing identified H5N1 genotype B3.13. The US Department of Agriculture’s Animal and Plant Health Inspection Service (USDA APHIS) subsequently confirmed the findings. State veterinary officials took further samples at the affected premises to support the investigation and laboratory verification.
APHIS and BOAH are carrying out farm investigations, additional diagnostic work and the collection of epidemiological information. Their stated objectives include examining how transmission may have occurred and limiting further spread. At the time of the November 2 announcement, officials had identified no other infected dairy herds in Indiana. The original samples were collected through routine surveillance rather than checks conducted before cattle movements. Monthly testing of storage silos at the state’s milk-processing plants will continue through the national testing programme.
The US outbreak in dairy cattle began in March 2024, with infections subsequently recorded in numerous states. APHIS has continued to confirm infections in states without earlier reported cases. The agency said the Indiana findings would leave its national HPAI eradication strategy unchanged. Measures to prevent the introduction of the virus onto farms and its movement between dairy premises remain central to that strategy.
Producers are being encouraged to reassess their farm-level biosecurity procedures, watch cattle for illness and promptly notify state animal-health officials of suspected infections. The guidance calls for particular attention to unusual symptoms in livestock, as well as sick or dead wild birds and other wildlife. Recommended precautions include restricting non-essential entry to farms, applying hygiene procedures to workers and equipment, carefully controlling livestock movements and following veterinary advice on prevention and outbreak response. Personnel whose work could bring them into contact with infected animals are advised to wear appropriate protective equipment and observe public-health guidance.
Authorities said the findings in Indiana did not compromise the safety of commercially supplied pasteurised milk or introduce an additional consumer risk from milk that has been properly pasteurised. The US Food and Drug Administration maintains that pasteurisation inactivates the HPAI virus. Food-safety rules and outbreak-response procedures require the exclusion of milk from affected cattle from commercial supplies destined for people. Such milk must be kept out of the commercial storage tank or destroyed, preventing its entry into the human food chain.
The US Centers for Disease Control and Prevention rates the danger to the general population from HPAI viruses circulating among birds and dairy cattle as low. People exposed to infected birds or mammals through their jobs or recreational activities face a higher risk, according to the agency, and should take appropriate precautions. The worker-protection advice accompanying the dairy response covers both suitable protective equipment and compliance with relevant health recommendations.
Outbreaks can place additional demands on the management of farms, veterinary services and dairy-processing operations. The response guidance identifies prompt detection and communication with veterinary authorities as measures that can help reduce disruption to dairy businesses and protect nearby herds. Producers are being asked to maintain disease monitoring and farm biosecurity while state and federal officials continue testing and investigative work.
