The concern over bird flu extends beyond the H5N1 strain, as a highly pathogenic strain of H7N9 bird flu has been detected on a poultry farm in Mississippi, according to animal health officials. This strain is different from the H5N1 flu that has been spreading among cows and poultry since last year.

The World Organization for Animal Health (WOAH) released a report on the H7N9 outbreak, based on data provided by the U.S. Department of Agriculture and local officials. This marks the first poultry outbreak of H7N9 in the U.S. in nearly a decade.

Highly pathogenic avian influenza viruses (HPAI) pose a significant public health threat. These viruses spread rapidly among wild birds and poultry, often causing widespread die-offs, and can also jump to other animal species, including humans. The fear is that one strain will develop the wrong combination of mutations, allowing it to spread widely and cause severe illness in people, potentially leading to a deadly pandemic.

The most well-known HPAI subtype currently circulating is H5N1, which has been causing outbreaks among cows across the country since early 2024. However, other HPAI subtypes, including H7N9, are also circulating.

H7N9 was first discovered in China in 2013 and is concerning due to its high deadliness when transmitted to humans. According to the World Health Organization, most reported human H7N9 cases have resulted in severe illness, with a 39% fatality rate among the 1,568 total cases documented globally since 2013.

The last known U.S. outbreak of H7N9 among poultry occurred in 2017. However, in early March, the strain was detected again on a farm in Noxubee, Mississippi, in a flock of nearly 50,000 commercial broiler breeder chickens.

“The USDA Animal and Plant Health Inspection Service (APHIS), in conjunction with State Animal Health and Wildlife Officials, are conducting a comprehensive epidemiological investigation and enhanced surveillance in response to the detection,” WOAH stated in its report.

To contain the outbreak, the farm’s population of exposed chickens is being culled, which may prevent the outbreak from spreading further. However, the overall threat of bird flu is increasing, with WOAH’s latest situation report indicating that there have been more poultry outbreaks of HPAI strains worldwide in the first five months of the current seasonal wave than there were total outbreaks during the entire previous season.

These outbreaks have contributed to surging egg prices, although prices are beginning to drop back down, according to the USDA. However, the ability of health officials to contain H5N1 and other bird flu strains in the U.S. is uncertain, given the Trump administration’s actions, including the recent layoff of bird flu experts under the orders of Elon Musk’s DOGE, which has since been reversed with the USDA scrambling to rehire these experts.