Louisiana health authorities on Monday reported the first human death in the United States linked to bird flu, while noting that the patient had underlying medical conditions and that general risks to the public remained "low."

The patient, aged over 65, had been hospitalized in the southern state since at least mid-December, when the US Centers for Disease Control and Prevention (CDC) announced it as the country's first serious case of human infection from the H5N1 virus.

"While the current public health risk for the general public remains low, people who work with birds, poultry, or cows, or have recreational exposure to them, are at higher risk," the Louisiana Department of Health said in a statement announcing the death.

It said the patient had "contracted H5N1 after exposure to a combination of a non-commercial backyard flock and wild birds," but had detected no further H5N1 infections nor evidence of person-to-person transmission in the state.

The news comes just days after the federal government awarded an additional $306 million to bolster H5N1 surveillance programs and research, amid some criticism of President Joe Biden's administration over its response to the simmering issue.

The amount of bird flu circulating among animals and humans has alarmed scientists over concerns it could mutate into a more transmissible form -- potentially triggering a deadly pandemic.

"While the risk to humans remains low, we are always preparing for any possible scenario that could arise," Health Secretary Xavier Becerra said in a statement announcing the funding on Friday.

Death 'not unexpected'

The CDC said in December that genetic sequencing of the H5N1 virus from the Louisiana patient was different from the version detected in many dairy herds around the country.

A small part of the virus in the patient had genetic modifications that suggested it could have mutated inside the body to adapt to the human respiratory tract.

However, such mutations are not the only things that could make the virus more contagious or transmissible between humans, according to researchers interviewed by AFP.

H5N1 was first detected in 1996, but since 2020, the number of outbreaks among bird flocks has exploded, while a growing number of mammal species have been affected.

Since the beginning of 2024, the CDC has recorded 66 cases of bird flu in humans in the United States.

"While tragic, a death from H5N1 bird flu in the United States is not unexpected because of the known potential for infection with these viruses to cause severe illness and death," the agency said.

The World Health Organization has meanwhile recorded over 950 cases since 2003 in 24 countries, including a large number in China and Vietnam.

"If you have been exposed to sick or dead birds or other animals or work on a farm where avian influenza has been detected, watch for respiratory symptoms or conjunctivitis," the Louisiana Health Department warned Monday.

If symptoms do develop, it said to alert medical providers to the possibility of bird flu exposure, adding: "Stay home and away from others while you have symptoms."