Highly pathogenic avian influenza (HPAI) H5N1 has been detected in Indiana dairy cattle for the first time, marking a new development in the ongoing outbreak affecting the United States dairy industry. The US Department of Agriculture’s Animal and Plant Health Inspection Service (USDA APHIS) confirmed the detection on November 2, 2026, following laboratory testing of samples from dairy herds in Newton County, Indiana.
According to the Indiana State Board of Animal Health (BOAH), the virus was detected in two operationally connected dairy herds in late October. The confirmation was made by the National Veterinary Services Laboratories (NVSL) using polymerase chain reaction (PCR) testing, which identified the H5N1 genotype B3.13.
The detection resulted from routine testing under the National Milk Testing Strategy rather than pre-movement surveillance. Following the initial finding, state animal health officials collected additional samples from the affected farms for further investigation and laboratory confirmation.
Disease Surveillance and Investigation Intensified
Indiana’s first reported detection highlights the importance of continued disease surveillance across dairy production systems. Although the two affected herds are operationally connected, authorities have not identified additional cases in Indiana dairy cattle as of the November 2 announcement.
USDA APHIS is working with BOAH to conduct further on-farm investigations, diagnostic testing and epidemiological data collection. These activities aim to improve understanding of the detection, identify potential transmission pathways and reduce the likelihood of further spread.
Regular monthly surveillance of milk storage silos at Indiana dairy processing facilities will continue under the National Milk Testing Strategy. This monitoring approach helps authorities identify potential infections and respond promptly to emerging disease risks.
The detection also reflects the continuing geographical spread of HPAI in dairy cattle. Since the outbreak began in March 2024, dairy cattle infections have been reported across numerous US states. APHIS has continued to identify cases in states that had not previously reported infections, reinforcing the need for sustained monitoring and coordinated animal health responses.
Biosecurity Remains Critical for Dairy Farms
USDA APHIS has stated that the Indiana detection does not change the national HPAI eradication strategy. Strengthening biosecurity remains a central measure for reducing the risk of virus introduction and transmission between dairy premises.
Dairy producers are encouraged to review farm biosecurity protocols, monitor cattle for signs of illness and report suspected infections promptly to state animal health authorities. Particular attention should be given to livestock showing unusual clinical signs and to reports of sick or dead wild birds and other wildlife.
Practical biosecurity measures include limiting unnecessary farm access, maintaining appropriate hygiene for personnel and equipment, managing animal movements carefully and following veterinary guidance on disease prevention and response. Workers who may encounter infected animals should use suitable protective equipment and follow relevant public health recommendations.
For dairy businesses, early detection and effective communication with veterinary authorities can help limit operational disruption and support the protection of neighbouring herds.
Commercial Milk Supply Remains Safe
Authorities have emphasised that the Indiana detection does not affect the safety of the US commercial pasteurised milk supply or pose a new risk to consumers through properly pasteurised milk.
The US Food and Drug Administration (FDA) maintains that pasteurisation effectively inactivates HPAI virus. Dairy regulations and response procedures also require milk from affected animals to be excluded from the commercial milk supply intended for human consumption. Milk from impacted animals is diverted from the commercial milk tank or destroyed to prevent it from entering the human food supply.
The US Centers for Disease Control and Prevention (CDC) assesses the risk to the general public from HPAI viruses circulating in birds and dairy cattle as low. However, individuals with occupational or recreational exposure to infected birds or mammals face greater risks and should follow appropriate precautions.
Implications for the US Dairy Industry
Indiana’s first confirmed detection underscores the importance of coordinated surveillance, transparent reporting and strong farm-level disease prevention. Although the commercial milk supply remains safe when established food safety controls are followed, outbreaks can create additional demands on farm management, veterinary services and dairy processing operations.
Continued cooperation between producers, state authorities and federal agencies will be essential to monitoring the situation and limiting further transmission. For the wider dairy industry, the case reinforces the need to treat biosecurity and animal health surveillance as integral components of sustainable and resilient dairy production.