Is there a new strain of bird flu to be worried about? On Wednesday, the World Health Organization reported the first confirmed human case of the H5N2 type of bird flu in a 59-year-old man in Mexico who died in April. The case adds to growing anxiety about the risk of bird flu spreading among people, especially because the man had no history of exposure to poultry or other animals, according to WHO. The strain is different from the outbreak of bird flu virus, called H5N1 , that is circulating among herds of dairy cows in the United States and has caused mild infection among three farm workers .
What is H5N2? H5N2 is just one of several kinds of avian influenza viruses. Does it actually pose a significant health risk to humans? An exposure to H5 virus in Mexico isn’t surprising, said Dr. Troy Sutton, an assistant professor of veterinary and biomedical sciences at Penn State.
H5 viruses have been circulating among poultry and wild birds in Mexico since the mid-1990s. However, unlike other avian influenza strains that have caused outbreaks in humans — such H1 and H3 viruses — H5 viruses rarely infect humans. The viruses are classified based on two types of protein on their surfaces: hemagglutinin, or H, which plays a crucial role in allowing the virus to infect cells, and neuraminidase, or N, which helps the virus spread.
Many different combinations of H and N proteins are possible. H5N2 belongs to a family of bird flu viruses called H5, which primarily infects wild birds..