Fortunately, very few mosquitoes are infected, so the chance of being bitten by an infected mosquito is very small. However, if an infected mosquito does bite a person, it would take 5-15 days to develop the infection. In many cases, the WNV may cause no symptoms at all or may cause only mild flu-like illness. In more severe and rare cases (less than 1% infected), a person may develop encephalitis. Encephalitis can be a serious health threat for the elderly or people with weakened immune systems.
Currently there is no vaccine for humans against the West Nile virus, nor is their specific treatment. However, the symptoms and complications of the disease can be treated.