Avian & other zoonotic influenza

Influenza viruses that normally circulate in birds or other animals (e.g. H5N1, H7N9, H9N2) occasionally infect humans. Sustained human-to-human spread has not been seen, but these viruses are closely monitored for pandemic potential.

How it spreads

Most human cases follow contact with infected live or dead poultry, contaminated environments such as live-bird markets, or other infected animals.

Common symptoms

Ranges from conjunctivitis and mild influenza-like illness to severe pneumonia and respiratory failure; some subtypes (e.g. H5N1) have had a high case fatality among reported human cases.

When to seek care

Fever, cough or breathing difficulty after recent contact with birds or travel to an affected area — seek care promptly and mention the exposure.

Prevention & treatment

Avoid contact with sick or dead birds and live-bird markets, cook poultry and eggs thoroughly, wash hands after handling birds; there is currently no routine human vaccine for the general public.

Unknowns & ongoing research

Whether these viruses will acquire sustained human-to-human transmission cannot be predicted; the public-health significance of infections in mammals (e.g. dairy cattle) is still being assessed.

Global disease data

Source: WHO Global Health Observatory (annual estimates or officially reported figures; global and WHO-region level). Estimates carry uncertainty intervals; reported counts reflect national surveillance capacity and are not the true number of infections.