Miss. reports first case of H7N9 in commercial poultry in 8 years

The Mississippi Board of Animal Health has confirmed the presence of highly pathogenic avian influenza H7N9 in a commercial broiler breeder chicken flock in Noxubee County for the first time in eight years.

The U.S. Department of Agriculture’s National Veterinary Services Laboratory verified the positive test results.

While low pathogenicity avian influenza H7N9 has been previously detected in wild birds through surveillance efforts, this marks the first documented case of highly pathogenic H7 in U.S. commercial poultry since 2017. The strain, of North American wild bird origin, is unrelated to the Eurasian H5N1 virus that has been circulating in the country.

The affected flock exhibited high mortality rates, prompting diagnostic testing at the Mississippi Veterinary Research & Diagnostic Laboratory. Following presumptive positive results, the USDA Animal and Plant Health Inspection Service confirmed the presence of H7N9 at its National Veterinary Services Laboratories.

In response, the Mississippi state veterinarian placed the premises under quarantine, and MBAH initiated a joint response with federal animal health officials. The flock was depopulated to prevent further spread of the virus. None of the affected birds entered the food supply.

This latest detection marks the third case of HPAI in commercial poultry in Mississippi since the spring of 2023. Since November 2024, HPAI has also been found in migratory waterfowl across multiple areas of the state.

According to the Centers for Disease Control and Prevention, the risk to public health remains low. Proper handling and cooking of poultry and eggs to an internal temperature of 165°F continue to be recommended food safety measures.

To mitigate further outbreaks, MBAH is increasing statewide monitoring and emphasizing the importance of biosecurity measures. Poultry producers and hobby flock owners are urged to remain vigilant, report bird illness or mortality, and practice strict biosecurity protocols.