First serious human case of bird flu, American patient infected with H5N1 virus dies

A first human death linked to bird flu has been recorded in the United States, Louisiana health authorities announced on Monday, specifying that it was an elderly patient who suffered from other pathologies.

This patient, aged over 65, was the first serious human case detected in the United States. He had been infected with the H5N1 virus via backyard and wild birds.

Suffering from a respiratory condition, he was in “critical condition”, health authorities reported in December, when his hospitalization was publicized.

The only human case of H5N1 in Louisiana

The investigation carried out “did not identify other cases of H5N1 or evidence of person-to-person transmission. This patient remains the only human case of H5N1 in Louisiana”, the local Department of Health specified on its site.

Therefore, he believes that the risk posed by bird flu to the general public remains “low”. As for “people who work with birds, poultry or cows, or who are exposed to these animals as part of their leisure activities”, the risk is “higher”.

For several months, the United States has been facing an epizootic – the equivalent of an epidemic in animals – of avian flu.

The virus is circulating in poultry farms and cattle herds and 66 cases of avian flu in humans have been detected since the beginning of 2024, the vast majority being mild and linked to known contact with animals infected.

Although no cases of human-to-human spread have been observed, the level of virus circulation is worrying experts.

“I'm not worried about the average citizen, but about people who come into contact with animals that we know can be infected,” Jennifer Nuzzo, a professor of epidemiology at Brown University, told AFP. And to continue: “It's a nasty virus that no one would like to catch.”

More than 950 cases reported to WHO

“While tragic, a death due to H5N1 in the United States is not unexpected”, the American Centers for Disease Control and Prevention (CDC) also reminded about the death reported in Louisiana.

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“En Outside the United States, more than 950 cases of H5N1 avian influenza have been reported to the World Health Organization, and about half of them have resulted in death,”, they report. they in a press release.

These cases were recorded between 2003 and the end of 2024 in 24 countries, including a large number in China and Vietnam, specifies a document from the WHO.

“The vast majority of cases of contamination and death are linked to exposure” known to a sick animal, notes Mrs. Nuzzo.

As things stand, this epidemic surveillance specialist is especially concerned that more people working in livestock farms or in contact with wild animals “will get sick and die”.

Furthermore, she points out, if the Louisiana patient had other pathologies, the case of a Canadian teenager hospitalized in 2024 for avian flu shows that younger and healthier people can also be seriously affected.

Avian influenza A (H5N1) first appeared in 1996, but since 2020, the number of outbreaks in birds has exploded and an increasing number of mammal species have been affected.

Risk of mutation

Experts worry that the high circulation of the virus could facilitate a mutation that would allow it to spread from one human to another. Some also worry that it could mix with seasonal flu and become more transmissible.

Genetic sequencing of the virus found in the Louisiana patient showed that it was different from the version found in several dairy herds and poultry farms.

And a small portion of the virus had genetic changes that suggested it had mutated inside the body to adapt to the human respiratory tract. This mutation is not, however, the only one needed to make a virus more contagious or transmissible between humans, reassure researchers interviewed by AFP.

As Donald Trump approaches his inauguration, having announced his desire to eliminate an agency responsible for preparing for epidemic risks, the situation is worrying health professionals.

The outgoing administration is also not exempt from criticism, with experts judging its response insufficient and warning of shortcomings in terms of monitoring contamination.

“We could do so much more”, believes Jennifer Nuzzo, who calls in particular for strengthening preventive measures for agricultural workers, including via a vaccination.