The World Health Organization (WHO) has said a man’s death in Mexico was caused by a strain of bird flu called H5N2 that has never before been found in a human.
The WHO said Wednesday it wasn’t clear how the person became infected. “Although the source of exposure to the virus in this case is currently unknown, A(H5N2) viruses have been reported in poultry in Mexico,” it said in a statement.
Scientists are on alert for changes in the virus that could signal that bird flu is adapting to spread more easily among humans.
But the UN agency said Wednesday said the current risk of the bird flu virus to the general population in Mexico is low.
The 59-year-old man, who had been hospitalised in Mexico City, died on 24 April after developing a fever, shortness of breath, diarrhoea, nausea and general discomfort, the WHO said.
Mexico’s health ministry added in a statement on Wednesday that there had so far been no evidence of person-to-person transmission of bird flu in the case of the man who died, and that he had several prior health conditions. All people who had contact with him have tested negative, it said.
In March, Mexico’s government reported an outbreak of A(H5N2) in an isolated family unit in the country’s western Michoacan state, but said at the time it did not represent a risk to distant commercial farms, nor to human health.
After the April death, Mexican authorities confirmed the presence of the virus and reported the case to the WHO, the agency said.
There had been three poultry outbreaks of H5N2 in nearby parts of Mexico in March, but authorities haven’t been able to find a connection.
Scientists said the case in Mexico is unrelated to the outbreak of a different strain of bird flu – H5N1 – in the United States that has so far infected three dairy farm workers.
Other bird flu varieties have killed people across the world in previous years, including 18 people in China during an outbreak of H5N6 in 2021, according to a timeline of bird flu outbreaks from the US Centers for Disease Control and Prevention.
Andrew Pekosz, an influenza expert at Johns Hopkins University said that since 1997, H5 viruses have continuously shown a propensity to infect mammals more than any other avian influenza virus.
“So it continues to ring that warning bell that we should be very vigilant about monitoring for these infections, because every spillover is an opportunity for that virus to try to accumulate those mutations that make it better infect humans,” he said.
Cases of bird flu have now been identified in mammals such as seals, raccoons, bears and cattle, primarily due to contact with infected birds.
Australia reported its first human case of A(H5N1) infection in May, noting there were no signs of transmission. It has however found more poultry cases of H7 bird flu on farms in the state of Victoria.
With Reuters and Associated Press