The World Health Organization said Wednesday a person in Mexico had died in the first confirmed human case globally of infection with the H5N2 variant of bird flu.

The patient, who died on April 24 after developing fever, shortness of breath, diarrhea and nausea, had "no history of exposure to poultry or other animals" and "multiple underlying medical conditions," the WHO said.

Mexican health authorities reported the confirmed case of human infection with the virus to the U.N. health body on May 23, after a 59-year-old was taken to a hospital in Mexico City.

The WHO said the case was the "first laboratory-confirmed human case of infection with an influenza A(H5N2) virus reported globally".

The source of exposure to the virus was unknown, the WHO said, although cases of H5N2 have been reported in poultry in the country.

According to the U.N. health body, H5N2 cases affected poultry in the state of Michoacan in March, with other outbreaks identified in the state of Mexico.

But it said establishing a link between the human case and the poultry infections was so far impossible, estimating the risk to people as "low."

A different variant of bird flu, H5N1, has been spreading for weeks among dairy cow herds in the United States, with a small number of cases reported among humans.

But none of the cases are human-to-human infections, with the disease instead jumping from cattle to people, authorities have said.