West Nile virus is extremely common but rarely causes serious illness — about 80% of infections produce no symptoms at all, and most symptomatic cases resemble a mild flu. However, roughly 1 in 150 infections leads to neuroinvasive disease (encephalitis or meningitis), which can be severe or fatal.
The virus is carried by Culex mosquitoes, which bite primarily from dusk through the night. West Nile is widespread across the Americas, Europe (expanding significantly since 2010), the Middle East, and parts of Africa. Peak transmission occurs in late summer and early autumn.
There is no vaccine for humans and no specific treatment. Older adults and immunocompromised individuals are at highest risk of severe disease. Standard evening and nighttime bite precautions are the only defense.
Culex pipiens (Europe/North America) and Culex quinquefasciatus (tropics) — night-biting species.
Adults over 60 and immunocompromised travelers face the greatest risk of severe neuroinvasive disease. There is no vaccine and no specific treatment — taking precautions is your only protection.
West Nile Virus is recorded in 50 countries in our database. Click any country for the full Mozzwise briefing covering local seasonality, regional risk, and prevention.
Disease information is sourced from WHO, CDC, ECDC, and OpenDengue. Not medical advice. Personal decisions on diagnosis, treatment, vaccinations, or medication belong with a qualified healthcare professional.