A Louisiana resident has died after being hospitalized with bird flu in December of last year, marking the first known U.S. death from the virus.
The patient who, “was over the age of 65 and was reported to have underlying medical conditions,” state health officials announced in a statement, tested positive for the virus and developed severe illness after exposure to wild birds and a personal backyard poultry flock that was infested with H5N1.
No other human cases have been identified in the state.
“CDC has carefully studied the available information about the person who died in Louisiana and continues to assess that the risk to the general public remains low. Most importantly, no person-to-person transmission spread has been identified,” the U.S. Centers for Disease Control and Prevention (CDC) said in a statement.
The case involved the D1.1 strain of H5N1, the same subtype that caused the severe condition of a 13-year-old girl in Canada late last year.
Genetic sequencing of the Louisiana patient’s virus revealed rare mutations that likely developed during the course of infection, a news release shows.
However, the changes were not found in the animals believed to have transmitted the virus.
“Although concerning, and a reminder that A(H5N1) viruses can develop changes during the clinical course of a human infection, these changes would be more concerning if found in animal hosts or in early stages of infection,” the CDC noted late last year.
Most other bird-to-human cases have occurred in workers at major poultry farms; “this is the first case of H5N1 bird flu in the U.S.
The CDC has previously stated that exposure to a backyard flock has been linked to cases of severe H5N1 avian flu in the United States. The agency emphasized that while such cases were not unexpected, they serve as a reminder for individuals with close contact to birds to take precautions. The majority of human bird flu cases in the U.S. have been in California and Washington, primarily affecting workers who have been in contact with infected poultry or dairy cows.
There is currently no evidence of person-to-person spread of the virus, with most cases being mild and manifesting as conjunctivitis. A case in California involving a child with no known exposure to infected animals raised concerns, although tests revealed similarities to viruses found in livestock. Health officials maintain that the immediate risk to the general public remains low.
Investigations into how the child was exposed to bird flu are ongoing, with the child having since recovered after receiving antivirals. Virologists suggest that other animals like cats, dogs, or rodents may be contributing to the spread of the virus. Despite the spread of bird flu in poultry and dairy cows since 2022, no person-to-person transmission has been detected in the California case.
Human bird flu cases have been confirmed in 10 states, with California reporting the highest number of infections. The outbreak has affected over 915 dairy herds in 16 states, with avian influenza spreading in wild and domestic birds across the country. Experts urge caution and vigilance in light of the ongoing situation.
