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West Nile Fever


West Nile Fever is spread by mosquito bites and can cause a flu-like illness and rarely, severe disease.

Recommendations for Travellers

WNV is rare in travellers. There is no vaccine against WNV.

Travellers should practice Mosquito Bite Avoidance both day and night when visiting areas experiencing an outbreak of WNV.  These outbreaks will be listed on the destination pages of fitfortravel. Medical advice can be sought if symptoms develop following travel to a risk area.

Note for blood donors: If you have travelled to an area with WNV in the past 12 months you may need to be tested for WNV before donating blood. All travel must be mentioned to the Blood Transfusion Service so that they can determine whether you need to be tested. The Scottish National Blood Transfusion Service have produced a leaflet which details information about blood donation after travel:

Overview of Disease

West Nile Fever is caused by West Nile virus (WNV). Until 1999 it was only recognised in Africa, Asia, Middle East, and Europe.  In 1999 the virus appeared in New York City and spread rapidly throughout North America, and is now also found in Central and South America and the Caribbean.

WNV predominantly infects birds and sometimes other animals.  It can be transmitted to humans by the bites of infected mosquitoes. A range of different mosquito species can carry the virus.  Very rarely it can be transmitted by blood transfusion.

The Illness

Most people with WNV have no symptoms. 

Symptoms, when they occur, start 2-14 days after the mosquito bite. Those who become ill, can experience a flu-like illness with fever, headache, body aches and vomiting/diarrhoea.  Some people may develop a rash. Very rarely WNV also causes infection of the brain and its lining, (encephalitis or meningitis) and this may be fatal. 


There is no specific treatment for WNV.  Most people recover without any treatment.  Those who are very ill are treated symptomatically in hospital. 

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