County of Monmouth
Mosquito Control Division

West Nile Virus (WNV) 

West Nile virus (WNV), a mosquito-borne flavivirus, is related to St. Louis encephalitis virus. WNV is found in Africa, Europe, and Asia (primarily in countries bordering the Mediterranean Basin). Typically, this virus results in clinical disease in only a very small percentage of humans infected. The general symptoms of West Nile fever, resulting from infection with WNV, range from fever, rash, and headache to meningitis, encephalitis, coma, and death. The fatality rate is approximately 10%.

There are no reports of WNV causing disease in domestic animals, with the exception of the horse. In contrast, there is a considerable body of serological evidence for infection of many species of wild birds and animals. It is generally accepted that birds are the principal vertebrate hosts of WNV. Migration of infected birds is the most probable mode of virus dispersion. A variety of mosquito species have been shown to transmit WNV, most notable are species of Culex and Aedes. In addition, WNV is also known to replicate in ticks, which may serve as an alternate means of transmission under certain circumstances.

Note: If you find a dead crow, report it to your local health department as soon as possible. If the crow is in an early stage of decay, it can be collected and submitted to the NJ Department of Health for West Nile virus testing.