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fitfortravel

Travel health information for people travelling abroad from the UK

West Nile Fever

Introduction

West Nile Fever is a viral infection first identified in Uganda in 1937.  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 found in Central and South America and the Caribbean.

Transmission

West Nile Virus (WNV) mainly infects birds and sometimes other animals.  WNV is usually transmitted to humans by mosquito bites.

The Illness

Most people with WNV have no symptoms.  Symptoms, when they occur, start 3-14 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 meningitis or encephalitis (infection of the brain) can occur and may be fatal.         

Treatment

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

Recommendations for Travellers

There is no vaccine against WNV.

Travellers should practice Mosquito Bite Avoidance 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 4 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:

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