Know how to use "fewer" and "less"? Find out.
a type of flavirus mainly infecting birds and mosquitos but also transmitted by them to humans and other animals, causing flu-like symptoms (West Nile fever) which may lead to encephalitis and meningitis and having no known treatment
West Nile virus (wěst nīl)
A viral disease of varying severity, occurring in Africa, Asia, the Mediterranean, and parts of North America, that is transmitted by a culex mosquito.