A Louisiana patient hospitalized with severe bird flu has died, the first death in the United States, state health officials announced Monday.
Officials said the patient was over 65 years old and had underlying health conditions. This person contracted the avian influenza virus H5N1 after being exposed to backyard flocks and wild birds.
There is no sign that the virus is spreading from person to person anywhere in the country, and Louisiana officials have not confirmed any other cases in the state. Pasteurized dairy products are safe to consume.
“We still think the risk is low,” said Dr. Diego Diehl, a virologist at Cornell University.
“However, it is important that people remain vigilant and avoid contact with sick animals, sick poultry, sick dairy cows, and also avoid contact with wild birds,” he added.
The news followed reports that virus samples taken from patients contained mutations that could make it easier to infect people.
Late last month, the U.S. Centers for Disease Control and Prevention announced that the mutations were not present in virus samples taken from backyard herds, suggesting the mutations may have developed in patients as the disease progressed.
One of the mutations was also present in a virus taken from a 13-year-old Canadian girl who was hospitalized and required respiratory support. She then recovered.
Both patients carried a version of the virus circulating in wild birds, which is different from the virus that causes outbreaks in dairy cows.
Experts say these are isolated cases, but together they show the virus could morph into dangerous new forms.
The news “should remind us that H5N1 influenza has been and continues to be a dangerous virus,” said Dr. James Lawler, director of the Global Center for Health Safety at the University of Nebraska.
“The more widely a virus spreads, especially among humans and other mammals, the greater the risk that the virus will acquire mutations that adapt it to human disease and transmission,” he said. “This puts us all at risk.”
That risk is especially heightened as the country faces a severe flu season.
People who are infected with both avian influenza viruses and seasonal influenza at the same time may provide ample opportunity for H5N1 to acquire the mutations it needs to spread efficiently between people.
H5N1 has been circulating in wild birds for several years and in dairy cattle for about a year. The outbreak shows no signs of slowing down, affecting more than 900 herds in 16 states. The virus has spread from dairy farms to poultry farms and is still prevalent among wild birds.
California, the state hit hardest by the cattle outbreak, declared a public health emergency in December.
At least 66 people in the United States have contracted the virus in 2024, according to the CDC. Almost all cases occurred in people who worked on farms raising infected cattle or poultry.
Most people experience mild symptoms such as conjunctivitis, conjunctivitis, and respiratory symptoms. Approximately 500 deaths have been reported worldwide in the past 20 years, most of them in Southeast Asia.
The Louisiana patient was reportedly hospitalized last month. But state officials have declined to release further details, citing patient confidentiality.
Until last year, only one case of H5N1 infection in humans had been reported in the United States (in 2022, in a poultry worker in Colorado).
Experts have warned against drinking raw milk, which may contain high concentrations of the virus. Although there have been no human cases linked to raw milk, cats in several states have died after drinking milk containing the virus.
