US records first fatal bird flu case amid growing concern over virus

The United States has recorded its first fatal case of H5N1 bird flu, in a person from Louisiana who contracted the virus from infected chickens and wild birds in a backyard flock. The death was reported Monday by the Louisiana Department of Health.

The unidentified person was described as being over the age of 65 and reportedly had underlying medical conditions. What these conditions were and whether they put the person at increased risk of developing a serious infection from the flu is not clear.

While the H5N1 virus has claimed over 450 lives globally since 2003, this is the first death from the virus in North America. The United States has recorded 67 human cases of H5N1, all but one of which occurred in 2024. All of the other cases have involved only mild symptoms.

Analysis of virus samples taken from the individual showed that the virus had developed some mutations that are thought to increase its ability to bind to cells in the upper respiratory tract. These changes were not seen in viruses from the birds in the person’s backyard flock, a fact the Centers for Disease Control and Prevention said likely means they developed in the individual during the course of the infection.

Similar mutations were found in virus samples from a teenager in British Columbia, Canada, who also became seriously ill with H5N1. The teenager, a 13-year-old girl, spent several weeks in critical care but is now recovering.

The statement from the Louisiana Department of Health said no additional cases have been detected among contacts of the person who died.

H5N1 has long been at or near the top of the list of viruses that concern pandemic planners. Infections in wild birds have moved it around the world, and newer versions of the virus have shown a disturbing ability to infect several species of mammals, including dairy cows.

The outbreak in cows, which was first discovered in late March, has spread to over 900 herds in 16 states. Forty of the 66 human cases detected in 2024 were among farm workers exposed to infected cows.