Rare H5N9 Bird Flu Detected in U.S. Poultry for the First Time

The outbreak at a California duck farm has led to the culling of thousands of birds as experts warn of potential risks from viral reassortment.

The H5N9 strain of highly pathogenic avian influenza (HPAI) was confirmed at a duck farm in Merced County, California, marking the first U.S. case in poultry.
Nearly 119,000 birds were culled at the farm to prevent further spread, alongside the detection of the more common H5N1 strain at the same site.
Experts warn that genetic reassortment between H5N9 and other viruses could increase the risk of creating a more infectious strain, raising pandemic concerns.
Since 2024, 67 human cases of bird flu have been reported in the U.S., with one death linked to exposure to infected birds and animals.
The outbreak has severely impacted the poultry industry, with over 136 million birds lost since 2022, driving up egg prices and straining supply chains.