Infection Prevention

U.S. Reports First Outbreak of H5N9 Bird Flu on California Duck Farm

Jan. 27, 2025

The U.S. confirms the first outbreak of H5N9 bird flu on a California duck farm, a rare subtype of influenza A virus causing highly pathogenic avian influenza (HPAI). H5N1 strain was also identified.

Janette Wider

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According to a Jan. 27 article from Newsweek, the U.S. has reported the first outbreak of H5N9 bird flu on duck farm located in California. The World Organization for Animal Health first reported the outbreak on Monday.

The article stated, “H5N9 is a rare subtype of the influenza A virus that can cause highly pathogenic avian influenza (HPAI), also known as bird flu. It's a reassortment strain that originated from the H5N1, H7N9, and H9N2 subtypes.”

Further, “Additionally, U.S. authorities identified the more common H5N1 strain on the same farm in Merced County, California. In a report to the Paris-based WOAH, officials noted that nearly 119,000 birds on the farm had been culled by December 2.”

Newsweek also released a map using data from the U.S. Department of Agriculture on bird flu outbreaks in poultry since 2022.