is occurred worldwide?
             A. See the map describing distribution of flaviviruses, including West Nile virus:
             Q. How long has West Nile virus been in the U.S.?
             A. It is not known how long it has been in the U.S., but CDC scientists believe the virus has probably been in the eastern U.S. since the early summer of 1999, possibly longer.
             Q. I understand West Nile virus was found in "overwintering" mosquitoes in the New York City area in early 2000. What does this mean?
             A. One of the species of mosquitos found to carry West Nile virus is the Culex species which survive through the winter, or "overwinter," in the adult stage. That the virus survived along with the mosquitoes was documented by the widespread transmission the summer of 2000.
             Q. Is West Nile virus now established in the Western Hemisphere?
             A. The continued expansion of West Nile virus in the United States indicates that it is permanently established in the Western Hemisphere.
             Q. Is the disease seasonal in its occurrence?
             A. In the temperate zone of the world (i.e., between latitudes 23.5° and 66.5° north and south), West Nile encephalitis cases occur primarily in the late ummer or early fall. In the southern climates where temperatures are milder, West Nile virus can be transmitted year round.
             Avoid Mosquito Bites to Avoid Infection
             Human illness from West Nile virus is rare, even in areas where the virus has been reported. The chance that any one person is going to become ill from a mosquito bite is low.
             You can further reduce your chances of becoming ill by protecting yourself from mosquito bites. To avoid mosquito bites:
             Essay Bibliography (leave it blank if you don't hav· Apply insect repellent containing DEET (N,N-diethyl-meta-toluamide) when you're outdoors. For details on when and how to apply repellent, see "qa/insect_repellent.htm" in our "q&a.htm" pages. See also "http://www.epa.gov/pesticides/citizens/insectrp.htm" from the EPA l "dis...