As cases rise across parts of Europe here’s what you need to know
Copenhagen, 24 July 2026
The World Health Organization Regional Office for Europe is urging countries to strengthen mosquito surveillance and public knowledge of protective measures as West Nile virus cases climb in parts of the continent, with the transmission season just getting under way. For most people the risk remains low, but anyone living in or travelling to an affected area should take basic steps to avoid mosquito bites and know the signs of severe illness in case they or someone close to them falls ill.
Current situation
Greece has recorded the steepest recent rise, with 21 human cases confirmed by national health authorities as of 22 July, 14 of them in the past week alone. Twenty of the 21 patients developed neuro-invasive disease, including encephalitis or meningitis, and 13 remain hospitalised. Italy has the widest geographic spread, with 21 cases confirmed in 17 separate areas as of 15 July. Locally acquired human cases have also been reported in Spain (2), Romania (2), and North Macedonia (2).
Mosquito-borne infection
West Nile virus is transmitted through the bite of an infected mosquito. In Europe, most human infections occur during the mosquito season, typically from late spring through autumn, with the highest transmission usually observed between July and September. There is no licensed vaccine for humans and no specific antiviral treatment. Care is limited to managing symptoms and supportive treatment in hospital for severe cases.
“West Nile virus is not a new threat, but the conditions that make it spread are changing rapidly,” said Dr Hans Henri P. Kluge, WHO Regional Director for Europe. “Warmer temperatures and longer summers are giving mosquitoes more time and territory to transmit this virus. Most infections are mild, but roughly 1 in 150 people who contract it will develop a severe infection affecting the central nervous system which can be life-threatening. Simple steps like covering up, using insect repellent, and clearing stagnant water around the home, can make a real difference. Anyone who develops a high fever, rash or neck stiffness after a mosquito bite should see a doctor without delay.”
Mosquitoes acquire the West Nile virus by feeding on infected birds and pass it to humans and other animals through bites. Transmission through organ transplant, blood transfusion, pregnancy and breastfeeding has also been documented, though this is rare. No human-to-human transmission through everyday contact has ever been recorded.
Protecting against infection
WHO/Europe recommends the following measures to the public to reduce the risk of mosquito bites:
- Wear light clothing covering most of the body, including long sleeves and trousers.
- Limit time outdoors at dawn and dusk, when mosquitoes are most active.
- Fit window and door screens to keep mosquitoes out of the home.
- Apply mosquito repellent containing approved active ingredients, according to the manufacturer's instructions. An adult should apply repellent to young children and avoid applying it to their hands or around the eyes and mouth.
- If possible, sleep in an air-conditioned room, use fans, or fit mosquito nets over beds and baby carriers. Spraying sleeping areas with an effective insecticide may also help lower risk.
Removing mosquito breeding sites around the home also cuts risk. This means clearing stagnant water from pots, containers and rubbish, disposing of waste properly, and covering, emptying and cleaning water storage containers regularly.
Communities can also help reduce mosquito breeding by eliminating standing water in public and private spaces wherever possible.
Recognising symptoms
Between 70%-80% of people with West Nile virus infection won’t develop any symptoms. Those who do may experience fever, headache, tiredness, body aches, nausea or vomiting, and sometimes a rash or swollen lymph glands. Severe disease can cause high fever, neck stiffness, disorientation, tremors, convulsions, muscle weakness, paralysis or coma.
If you develop symptoms after returning from an area where West Nile virus is circulating, seek medical care promptly.
Anyone who develops severe symptoms should seek urgent medical care immediately. Care focuses on rest, fluids, pain relief and, in severe cases, hospital-based supportive treatment.
West Nile virus infection can be confirmed by laboratory testing, including detection of virus-specific antibodies or viral RNA, depending on the timing of illness.
Additional resources
ECDC West Nile virus Surveillance Report, week 29
Public health advice on mosquito-borne diseases
Contacts
Bhanu Bhatnagar, bbhatnagar@who.int
Sarah Tyler, tylers@who.int