1st severe human case of H5N1 bird flu confirmed in U.S. | CBC News

The U.S. reported its first severe human case of bird flu on Wednesday in a Louisiana resident who is hospitalized in critical condition, the U.S. Centers for Disease Control and Prevention (CDC) said.

Agency officials didn't immediately detail the person's symptoms, but the Louisiana Department of Health said the patient is suffering severe respiratory illness.

The person is reported to have underlying medical conditions and is over the age of 65, putting the patient at higher risk, the department said.

California, the country's most populous state, declared an emergency later Wednesday as the H5N1 virus spreads more widely in dairy herds. Data has shown 649 herds have tested positive since late August — roughly 60 per cent of the state total.

This year, more than 60 bird flu infections have been reported, and more than half of them in California. In two cases — an adult in Missouri and a child in California —  health officials have not determined how they caught it.

Previous illnesses in the U.S. had been mild and the vast majority had been among farm workers exposed to sick poultry or dairy cows.

WATCH | WHO calls for animal surveillance of H5N1: 

Dr. Maria Van Kerkhove, the World Health Organization's director of epidemic and pandemic preparedness, is calling for increased surveillance globally of animal populations that are known to be susceptible to H5N1, including wild birds, poultry, swine and cattle.

The CDC confirmed the Louisiana infection on Friday, but did not announce it until Wednesday. It's also the first U.S. human case linked to exposure to a backyard flock.

Partial viral genome data of the H5N1 avian influenza virus that infected the patient in Louisiana indicates the virus belongs to a genotype related to viruses recently detected in wild birds and poultry in the U.S. and in recent human cases in British Columbia and Washington state.

The D1.1 genotype of the virus differs from the one detected in dairy cows in the U.S. as well as human cases in multiple states and some poultry outbreaks in the country, the CDC said.

Bird flu has infected more than 860 dairy herds in 16 states since March and killed 123 million poultry since the outbreak began in 2022.

B.C.'s Office of the Provincial Health Officer said it won't be providing any updates on the status of the teenaged patient in the province who contracted bird flu unless there is a need from a public health perspective to do so.

U.S. health officials say bird flu is still mainly an animal health issue, and the risk to the general public remains low. There's been no documented spread of the virus from person to person.

"The best way to prevent H5 bird flu is to avoid exposure whenever possible," the CDC said. "Infected birds shed avian influenza A viruses in their saliva, mucous and feces."

Other infected animals may shed avian influenza A viruses in respiratory secretions and other bodily fluids such as in unpasteurized cow milk or raw milk.