West Nile Virus Transmissable To Humans
General Information
  • West Nile Virus (WNV) is a member of the family Flaviviridae and is closely related to several mosquito-transmitted flaviviruses that cause human disease on different continents, including St. Louis encephalitis (SLE) virus, a native North American arbovirus. Both WNV and SLE viruses are maintained in a transmission cycle involving birds and mosquitos.
  • WNV was first isolated in 1937 in the West Nile district of Uganda, Africa. Outbreaks of WNV have occurred in a number of countries including Egypt, Israel, South Africa, and countries in parts of Asia and Europe. Recent outbreaks, outside of North America, have occurred in France and Israel in 2000, Russia in 1999, and Romania in 1996-97.
  • WNV was first detected in the United States in September 1999 during the investigation of an outbreak of encephalitis in humans in New York City.
  • WNV is spread to humans by the bite of an infected mosquito. A mosquito becomes infected by feeding on the blood of a bird that carries the virus. Approximately two weeks must elapse after a mosquito has fed on an infected bird before it is capable of transmitting the virus to a human or animal. There is no evidence to suggest that an individual could get WNV from another person. For example, WNV cannot be spread through touching or kissing an infected person, or from exposure to a health care worker who has treated someone infected with WNV.
  • The number of bird species in North America that play a role in the transmission of WNV is not known at this time, although the virus has been identified in more than 100 species of birds in the USA between 1999-2001. High mortality rates occur in some bird species, particularly the Corvidae (American crows [Corvus brachyrhynchos], blue jays [Cyanocitta cristata], gray jays [Perisoreus canadensis], magpies [Pica hudsonia], and ravens [Corvus corax]). The Canadian Cooperative Wildlife Health Centre is currently involved in collecting dead birds for surveillance of West Nile Virus in Canada. See visit their website for further details.
  • For general information on WNV, visit Health Canada's website.
  • For recent updates on WNV surveillance by province and general information provided by Health Canada, click here.
  • In British Columbia between 2007 and 2014, WNV has been reported in:
    • 25 people, of which 21 cases are suspected of being contracted outside of the province;
    • 5 horses, 6 birds (corvids) as well as in mosquitos.
  • For information on WNV in jurisdictions surrounding BC, see the following:
Further Reading
Return to Manual Home Page Disease List - Body Region Affected Disease List - Causative Agent or Risk Factor Disease Surveillance Form Glossary Contact Information
Return to Manual Home Page Return to Disease List - Body Region Affected Return to Disease List - Causative Agent or Risk Factor Disease Surveillance Form Download Glossary Contact Information