New Strain of Bird Flu Found on California Duck Farm – Gizmodo

It looks like H5N1 isn’t the only kind of bird flu that Americans should be worried about. Federal officials have just reported finding highly pathogenic H5N9 avian influenza among ducks at a commercial meat farm in California.The U.S. Department of Agriculture (USDA) notified the World Organization for Animal Health (WOAH) about the detection of H5N9 this past weekend, though the outbreak itself dates back to last November. Worryingly, both H5N9 and H5N1 were found on the farm, located in Merced County. These are the first reported cases of H5N9 ever found in U.S. poultry.H5N1 bird flu has become a serious public health concern in the past few years, thanks to continued outbreaks in wild birds and poultry, as well as the more recent emergence of H5N1 in dairy cows starting early last year. More than 60 human cases of H5N1 in the U.S. have been documented since 2024, most linked to contact with infected cows or poultry. Recent H5N1 human cases have typically been mild and the risk of bird flu to the general public is still considered low, though there was a recent death tied to H5N1 in Louisiana reported earlier this month.Bird Flu Emerges as Key Reason Behind U.S. Egg ShortageAs this recent duck outbreak shows, however, H5N1 isn’t the only variant of highly pathogenic influenza A virus circulating in the world (highly pathogenic refers to the virus’s potential to cause severe disease in birds specifically). According to the WOAH report filed by the USDA, the outbreak was detected in late November, following increased duck deaths at the farm. Tests of the sickened birds conducted by the USDA’s National Veterinary Services Laboratory initially detected an unknown type of H5 influenza. Later genetic testing, completed by mid-January, identified cases of H5N9 and H5N1 influenza. Both strains appear to belong to the same broad clade of highly pathogenic avian influenza viruses, called 2.3.4.4b.“This is the first confirmed case of HPAI H5N9 in poultry in the United States,” the WOAH report said.According to the report, state officials quarantined the farm following the detection of the outbreak. In early December, a culling of the farm’s nearly 120,000 birds was performed. Officials with the USDA’s Animal and Plant Health Inspection Service (APHIS), along with state animal health and wildlife officials, are reportedly working together to investigate the situation.The larger implications of this outbreak are unclear at this point. One reason why influenza is dangerous is that different variants can sometimes infect the same host and mix together, producing a new strain with unpredictable properties—including changes that could make it more adaptable to human transmission. This process, known as reassortment, is exactly what led to the emergence of H5N9 in this outbreak, according to APHIS (which is not the first time such an event has happened). But the combination appears to have only involved other strains of avian influenza. A more worrying scenario might involve H5N1 mixing with flu strains already adapted to humans.“The case of H5N9 confirmed in backyard ducks at a facility in California was a reassortment of the H5N1 D1.1 virus that has been circulating in U.S. birds. The finding was not unexpected, as it is not uncommon to see reassortments and ducks are reservoir hosts for influenza A viruses,” an APHIS spokesperson told Gizmodo in an email. “APHIS reported the detection to the WOAH, as is done for all cases of HPAI in domestic birds in the United States.”Ducks are a concerning host for avian influenza, since they often don’t show signs of illness; that in turn could make them more proficient vectors of infection to other birds and animals. At the same time, this outbreak may be an isolated incident, as no additional cases of H5N9 have been detected elsewhere.While the USDA is still talking to the WOAH, the Trump administration has ordered all of its federal health agencies to cease most external communication for the time being. Neither the USDA nor APHIS appear to have provided a public update on the outbreak as of yet. But the agency says that it will still be keeping a close eye on bird flu.“APHIS will continue to conduct comprehensive epidemiological investigations and enhanced surveillance in response to detections of HPAI and will continue reporting cases to WOAH,” the APHIS spokesperson said.This article has been updated to include comments from the APHIS.
bird fluinfectious diseasesoutbreaks
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Source: https://gizmodo.com/new-strain-of-bird-flu-found-on-california-duck-farm-2000555762