December 18, 2024
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First severe avian influenza outbreak in the U.S., CDC confirms with latest H5N1 information
Louisiana reports people hospitalized with severe cases of H5N1, USDA begins bulk testing of milk

A person in Louisiana was hospitalized with severe H5N1 influenza after coming into contact with a sick bird in his backyard. This virus is similar to that found in wild birds and some domestic poultry.
The ongoing avian influenza outbreak in the United States has become even more alarming. A person in Louisiana has become the first person in the United States to be hospitalized with a severe case of H5N1 avian influenza virus infection, the Centers for Disease Control and Prevention announced in a statement. Published on Wednesday. California’s governor also declared a state of emergency against bird flu on Wednesday as a precaution.
A total of 61 human cases of H5N1 have been confirmed in the United States this year. Most cases occur in dairy or poultry farm workers, and most cases are mild. The recent Louisiana case, first reported by the Louisiana Department of Health last Friday, is the first known case of H5N1 infection in the United States this year. An investigation is underway, but it appears the individuals involved came into contact with sick or dead birds from the backyard flock. This virus strain is different from the virus strain currently circulating in dairy cows. Preliminary genetic sequencing has revealed that the D1.1 strain, currently circulating in wild birds and poultry in the United States, is likely related to the human cases in Canada.
In addition to the Louisiana case, Delaware recently reported a suspected H5N1 case detected through routine state influenza surveillance. The infected person had no contact with sick animals. As a result of multiple tests, the CDC was unable to confirm the type of influenza A virus, and classified the case as a “high possibility of infection.” There have been at least two known cases of infection in the past, but no infections have been confirmed.
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“These two cases do not change CDC’s current risk assessment for the general population,” Demetre Daskalakis, director of the CDC’s National Center for Immunization and Respiratory Diseases, said in a group call with reporters Wednesday. “It remains low.” Nevertheless, “the large number of animals, such as birds and mammals, infected with H5 avian influenza increases the risk that the virus could infect humans or adapt and cause human-to-human transmission. .”
The H5N1 virus continues to infect dairy cows in at least 16 states, with 860 herds affected as of December 17th. On Dec. 6, the U.S. Department of Agriculture issued a new federal order requiring bulk testing of raw milk from dairy cows. The order will begin in phases in 13 states: California, Colorado, Michigan, Mississippi, Oregon, Pennsylvania, Indiana, Maryland, Montana, New York, Ohio, Vermont and Washington. * Other states will be added as resources allow, Eric says. Deeble, the USDA’s assistant secretary for marketing and regulatory programs, told reporters Wednesday. He added that several field trials of bovine H5N1 vaccines are underway across the country.
Also this week, LabCorp announced it will now offer a human H5 avian influenza test that doctors can order.
*Editor’s Note (December 19, 2024): This text has been updated to reflect the latest states participating in USDA’s Bulk Milk Inspection Program.