The H5N1 virus, or bird flu virus, has raised fresh concerns for humans with reports of spillover to mammals like domestic cats and mice, infectious disease experts said on June 12.

The World Health Organization on June 11 confirmed a human infection with bird flu caused by the H9N2 virus in a four-year-old child in West Bengal.

It is the second human infection of H9N2 bird flu from India, with the first in 2019, the agency said.