Previously it was found only in Africa, Eastern Europe and West Asia. During 1999 the virus was confirmed in both New York and New Jersey. The virus is spreading through the U.S. and Canada along bird migration routes. The first infected crows were confirmed in the Township in September 2001. People are primarily infected from the bite of a mosquito that is infected with the virus.
Mosquitoes get it when they take a blood meal from birds infected with West Nile.
Those mosquitoes then transmit the virus to people and animals when taking a new blood meal. Many species of mosquito are now known to harbor the virus. As most mosquitoes do not travel far from their original breeding area, it is important to eliminate mosquito breeding around the home. People over 50 years of age have the highest risk of developing severe illness because, as we age, our bodies have a harder time fighting off disease. Like most diseases, the very young and the very old are more likely to become ill from infection.