The U.S. has recorded its first death of a person infected with bird flu.
The patient was a resident of southwest Louisiana who was hospitalized last month with the first known severe case of bird flu in the country.
On Monday, the Louisiana Department of Health said the person had died from the illness but shared few other details because of patient privacy rules.
The patient was over 65 and had underlying medical conditions.
The patient contracted the illness after being exposed to "a combination of a non-commercial backyard flock and wild birds," according to a news release. An "extensive public health investigation" did not turn up any other cases of H5N1 in a person or evidence of human-to-human spread.
More than 65 people have caught bird flu during the current outbreak, primarily from close contact while working with infected dairy cattle or poultry.
While these cases have largely led to mild illness, historically other strains of bird flu have proved quite deadly in humans. Of the more than 950 cases reported to the World Health Organization, about 50% have resulted in death.
"We have 20-plus years of data showing that it's a pretty nasty virus," said Jennifer Nuzzo, director of the Pandemic Center at the Brown University School of Public Health. "I am not counting on future infections all being mild."
In November, a 13-year-old girl in British Columbia, Canada, was hospitalized with bird flu. How she caught the virus isn't clear. But her illness was so serious she required extracorporeal membrane oxygenation (ECMO) to keep her alive.
That case underscores that it's "very difficult to predict who will become severely ill after an infection," said Nuzzo. "We should not discount this latest death in Louisiana because the patient had underlying health conditions."
Genetic sequencing from the Centers for Disease Control and Prevention indicates the H5N1 virus responsible for both of these severe illnesses belongs to the D1.1 genotype. While this is a different genetic lineage from the virus infecting dairy cattle, it's still part of the same strain circulating globally in wild birds and U.S. dairy herds — technically known as clade 2.3.4.4b.
The virus appears to have picked up some worrisome mutations during the course of the Louisiana patient's illness.
The same may have happened in Canada. In both cases, there's no indication others were infected, though.
In a statement on the Louisiana death, the CDC reiterated that the risk to the general public is still considered low, saying there are no "concerning virologic changes actively spreading in wild birds, poultry, or cows that would raise the risk to human health."
The outbreak in dairy cattle recently led California to declare a state of emergency and kept public health officials on edge because of the increased potential for the virus to spill over into humans.
Their advice is to avoid contact with wild birds, poultry and rodents and to wash your hands after touching feces or objects that could be contaminated with saliva or mucus, such as bird feeders.
Pets can also catch the virus, particularly by consuming raw meat or raw milk, which can also harbor high loads of the virus.
Edited by Jane Greenhalgh
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