A Louisiana resident was hospitalized with “severe illness” due to the bird flu virus, the most serious U.S. case since the viral disease appeared in wild birds in the South nearly three years ago, said the Centers for Disease Control on Wednesday. Meanwhile, Gov. Gavin Newsom declared a state of emergency as bird flu outbreaks in dairy herds, previously limited to the Central Valley, were detected in Southern California.
To date, 62 people in eight U.S. states have been diagnosed with bird flu — 61 of them this year. Their symptoms have been mild, most often conjunctivitis, until the Louisiana case. It is the first U.S. case linked to exposure to sick or dead birds in backyard flocks.
“We can share the patient was in fact hospitalized with severe illness related to their flu infection,” said Dr. Demetre Daskalakis of the CDC. “It is believed the patient had exposure to sick and dead birds on their property.”
As in a recent Canadian case, the illness was caused by an H5N1 strain found in wild birds and poultry rather than the strain that has been hitting dairy herds.
Asked about the patient’s condition, Daskalakis said hospitalization for the flu “is something we would consider severe.” The Louisiana Department of Health reported the case last week, saying that a resident of southwestern Louisiana had been hospitalized with highly pathogenic avian influenza. The infection was discovered through routine testing for flu.
Wisconsin reported its first “presumptive positive human case” of bird flu on Wednesday, in Barron County, in the state’s northwest. “The human case follows an infected flock of commercial poultry identified in Barron County. The person had exposure to the infected flock,” said the Wisconsin Department of Health Services.
In the past 20 years, nearly half of the people in other countries — largely in Asia and the Middle East — who have contracted bird flu have died of the disease. Still, the CDC said the risk to the general population remained low because the virus has not evolved to become more communicable and there has been no person-to-person spread. It advised people to avoid contact with sick or dead birds and to wear protective equipment if they work with animals that may be infected. All but two of this year’s human cases were in dairy and poultry workers.
Some 34 of this year’s human cases were in California.
Newsom said in the state of emergency proclamation that outbreaks in four dairy herds in Southern California a week ago necessitated “a shift from regional containment to statewide monitoring and response to active cases.” The proclamation “is a targeted action to ensure government agencies have the resources and flexibility they need to respond quickly to this outbreak,” he said in a statement.
Since late summer, bird flu has been detected in 649 California dairy herds, more than half of the roughly 1,100 dairies in the state. Nationwide, bird flu has infected 865 herds in 16 states since it was identified as the mystery disease affecting dairy cows in the Texas Panhandle in late March. It struck domestic flocks in February 2022 and was found in wild birds in South Carolina in January 2022.
The USDA has paid $51 million to dairy farmers in compensation for milk production lost because of bird flu, said Eric Deeble, the USDA’s bird flu adviser. Thirteen states are enrolled in a program of weekly testing for bird flu in milk fresh from the farm; the program began operating this week. And the USDA has approved seven field trials of candidate vaccines to shield cattle from bird flu, he said.
“No, we have not seen reinfection of herds that were previously infected and cleared,” said Deeble.