The simplest and most effective way of preventing a West Nile virus infection is to avoid being bitten by mosquitoes - this is done by using an insect repellent containing an EPA-registered active ingredient when outdoors, especially at dusk and dawn when many mosquitoes are most active - wearing long sleeves and pants at these times or staying indoors during these hours - and ensuring there are good screens on windows and doors to keep mosquitoes out.

The Centers for Disease Control and Prevention (CDC) recommends using products that have been shown to work in scientific trials which contain active ingredients which have been registered with the US Environmental Protection Agency (EPA) for use as insect repellents on skin or clothing - EPA registration ensures a repellent has been evaluated for efficacy and safety and the potential effects on human beings and the environment.
 

EPA registration means that EPA does not expect a product, when used according to the instructions on the label, to cause unreasonable adverse effects to human health or the environment. Of the active ingredients registered with the EPA, the CDC believes that two have demonstrated a higher degree of efficacy. These products contain active ingredients which provide longer-lasting protection than others and they are :- DEET (N,N-diethyl-m-toluamide) and Picaridin (KBR 3023).

Also registered with EPA is Oil of lemon eucalyptus [active ingredient: p-menthane 3,8-diol (PMD)], a plant- based repellent - recent research has found it provided protection similar to repellents with low concentrations of DEET. These products are available as lotions, creams, gels, sprays, and towelettes.

It is also important to rid yards and garden areas of potential mosquito breeding sites by emptying standing water from flower pots, buckets and barrels, regularly changing the water in pet dishes and bird baths, emptying out any containers which might inadvertently store water such as tyres, toys and garden equipment, blocked gutters, poorly maintained pools, and any type of receptacle with decaying organic matter.