Mosquitoes and West Nile Virus


  • Ability of different mosquito species to acquire and transmit WNV is highly variable
  • Mosquitoes are critical for the transmission of WNV from birds to humans and horses
  • In North America, large number of Culex species are involved in WNV transmission
  • WNV is transmited when mosquito injects infected saliva into host
  • Primary vector for WVN in the prairie provinces of Manitoba, Saskatchewan, and Alberta is Culex tarsalis
  • Cx. tarsalis is one of the most competent WVN vectors evaluated to date in laboratory studies
  • Cx. tarsalis has been found as far north as the southern boundary of the boreal forest transition zone
  • Grassland and agriculture area is the preferred area of distribution of Cx. tarsalis in Western North America and other regions of the Great Plains
  • Cx. tarsalis, as well as many other mosquitoe species, lay eggs in stagnant water bodies with high organic content, such as artifical containers, water-filled hoof prints, and weedy roadside ditches
  • Factors that facilitate transmission of WNV in Cx. tarsali:
  • Note: Cx. tarsalis is also the primary vector for St. Louis and Western Equine Encephalitis viruses in North America
  • Many factors contribute to the spatial and temporal distribution of vectors and vector-borne disease
  • Climate conditions such as temperature and precipitation influence:
  • Purpose of targeted surveillance for virus within mosquito population is to detect virus prior to outbreaks in humans and horses, and to establish a base-line of mosquito-born activity so we can monitor changes in their population over time
  • Note: WNV has also been detected in ticks!

    Engler, O., et al. (2013) European Surveillance for West Nile Virus in Mosquito Populations. Int. J. Environ. Res. Public Health. 10:4869-95.
    Chen, CC., et al. (2013) Climate Change and West Nile Virus in a Highly Endemic Region of North America. Int. J. Environ. Res. Public Health. 10:3052-71.
    Nelms, BM., et al. (2013) Overwintering Biology of Culex (Diptera: Culicidae) Mosquitoes in the Sacramento Valley of California. J. Med. Entomol.. 50(4):773-90.