What is H5N9? US reports first bird flu strain outbreak in poultry U.S. authorities also identified the more common H5N1 strain on the same farm in Merced County, California. Newsweek

he United States has reported its first outbreak of H5N9 bird flu on a duck farm in California, according to the World Organization for Animal Health (WOAH) on Monday.

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.

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Avian flu surge continues on US poultry farms as feds address contamination of raw pet food Over the past few days, the US Department of Agriculture (USDA) confirmed more H5N1 avian flu outbreaks in poultry from eight states, including the first at a commercial farm in Georgia. CIDRAP

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Meanwhile, the Food and Drug Administration (FDA) and the USDA on January 17 announced new steps to step up the safety of raw pet food, following recent reports of H5N1 infections in household cats. ...

The Centers for Disease Control and Prevention on Thursday urged labs nationwide to determine within 24 hours of admission whether people hospitalized with the flu have seasonal influenza or are infected with the bird flu that's behind an escalating outbreak in dairy cows and poultry.

The guidance for labs to do this type of testing has been in place since last fall, but the process has been slow, with many hospitals sending flu samples out for testing in bulk every few days.