The World Health Organization confirmed the first human case of H5N2 bird flu in a 59-year-old man in Mexico who died in April.
The man had no known exposure to poultry or other animals.
The H5N2 strain differs from H5N1, which has affected dairy cows and farm workers in the U.S.
H5N2 is one of several avian influenza viruses, raising concerns about human health risks.
Dr. Troy Sutton noted that H5 viruses have been present in Mexican poultry and wild birds since the mid-1990s.
H5 viruses rarely infect humans, unlike other avian influenza strains like H1 and H3.
Avian influenza viruses are classified by hemagglutinin (H) and neuraminidase (N) proteins on their surfaces.
H5N2 belongs to the H5 family, which primarily infects wild birds and has nine known subtypes.
H5N1, detected in U.S. dairy cows, is part of the highly contagious "Goose Guangdong lineage."
The "Goose Guangdong lineage" has caused numerous poultry outbreaks and sporadic human infections over the past 20 years.
Click here to read more articles