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West Nile Virus

What is West Nile Virus?

West Nile Virus (WNV) is a virus spread primarily through the bite of an infected mosquito. The virus usually circulates among birds and mosquitoes. Animals and humans are only occasionally infected.

In most cases the virus causes mild flu like symptoms 3-14 days after the bite from an infected mosquito. Other symptoms might include eye pain, vomiting and a rash on the skin. These symptoms usually last 3-6 days.

Only 1 in 150 infected persons can go on to develop a more severe form of the disease, with increased age (over 50) being an indicator for higher risk. Severe symptoms include fever, weakness, vomiting and a change in mental behaviour. These symptoms can eventually lead to death.

Who is at risk of West Nile Virus?

Up until 1999 this disease was mainly found in Africa, Egypt, South-east Asia and the Southern parts of France. The first recorded cases in the Western Hemisphere were reported in New York in 1999 and since 2000 many cases have been reported throughout the United States and Canada. Any person travelling to these areas is at risk of the disease.

Risk is seasonal in most places and will therefore vary at different times of the year - however those travelling to the Southern States of the United States should be aware that the risk remains all year. The CDC website can provide up to date information on currently infected areas.

What can I do to prevent West Nile Virus?

There is no vaccine to prevent WNV in those travelling to high-risk areas. While there have currently been no recorded cases of WNV in those travelling to the United States (Oct 2002) prevention of bites from mosquitoes is the best line of protection. Most of the mosquitoes bite from dusk to dawn and a good repellent should be used during this time, however in some areas day biters have been found so use repellent accordingly.