WHO confirms first-ever human death of bird flu in Mexico

More than four million chickens in Iowa will have to be killed after bird flu was detected at a large farm. (Charlie Neibergal / AP Photo)

The World Health Organization on Wednesday said a person's death was caused by the first laboratory-confirmed human case of infection with the A(H5N2) subtype of bird flu reported globally, and the first human infection with the H5 strain of the virus reported in Mexico.

The 59-year-old, who had been hospitalized in Mexico City, died April 24 after developing a fever, shortness of breath, diarrhea, nausea and general discomfort, WHO said.

"Although the source of exposure to the virus in this case is currently unknown, A(H5N2) viruses have been reported in poultry in Mexico," WHO said in a statement.

The victim had no history of exposure to poultry or other animals, but had multiple underlying medical conditions and had been bedridden for three weeks, for other reasons, prior to the onset of acute symptoms, the United Nations agency 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 this 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.

Based on available information, WHO assesses the current risk to the general population posed by this virus as low.

No further cases have been reported during an investigation that tested people who had come into contact with the victim for types of influenza, as well as for COVID-19, it said.

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Cases of bird flu have now been identified in mammals such as seals, raccoons, bears and cattle, primarily due to contact with infected birds.

Scientists are on alert for changes in the virus that could signal it is adapting to spread more easily among humans.

The United States has reported three cases of human infection after exposure to cows since an outbreak was detected in dairy cattle in March. Two just had symptoms of conjunctivitis, while the third also had respiratory symptoms.

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 Victoria state.