First severe H5N1 bird flu case reported in the U.S.

A patient in Louisiana has been hospitalized with a severe case of H5N1, commonly known as bird flu, according to the Centers for Disease Control and Prevention (CDC). This marks the first instance of severe illness caused by the virus in the United States.

The case involved direct exposure to sick and dead birds in backyard flocks, also making this the first U.S. case of H5N1 bird flu linked to such exposure, the CDC said in a statement on Wednesday. “This case does not change CDC’s overall assessment of the immediate risk to the public’s health from H5N1 bird flu, which remains low.”

The patient, who is experiencing severe respiratory illness, is over 65 years old and has underlying medical conditions, Emma Herrock, a spokeswoman for the Louisiana Department of Health (LDH), told BNO News. LDH also confirmed on Friday that the individual is from southwestern Louisiana.

“Partial viral genome analysis revealed that the virus responsible for this case belongs to the D1.1 genotype, which has been previously detected in wild birds, poultry, and recent human cases in British Columbia, Canada, and Washington state,” the CDC stated. “This H5N1 bird flu genotype is different than the B3.13 genotype detected in dairy cows, sporadic human cases in multiple states, and some poultry outbreaks in the United States.”

A newer strain of H5N1 bird flu – clade 2.3.4.4b – has raised concern due to its global spread and the rising number of cases in mammals, including hundreds of outbreaks among dairy cows in the U.S. This year has also seen a limited but growing number of human cases after contact with birds or cows.

There have been 69 confirmed human cases of H5N1 in the U.S., including today’s first case in Wisconsin. Most cases are linked to poultry or dairy exposure. However, three cases—one in California, one in Missouri, and Canada’s first reported case—have no known connection to poultry or dairy, sparking concerns that the virus may be spreading through other mammals or alternate transmission methods.