the west nile virus is closely related to the japanese encephalitis virus and the st. louis encephalitis virus which are found in the southeastern and midwestern united states. these viruses are also mosquito-borne and have a similar life cycle in birds and mosquitoes and occasionally strike people. a major difference is that st. louis encephalitis is "silent" in birds generally not killing them so there is usually no warning before a human case occurs. with the west nile virus (at least the american strain) birds particularly crows become ill or die and therefore offer an early warning system.
are there other viruses like the west nile virus?