West Nile Virus

West Nile virus (WNV) is a disease caused by a virus that is spread through mosquito bites. WNV is found on every continent except Antarctica. It was first detected in North America in 1999, and has since spread across the continental United States and Canada and is well established. Maricopa County had its first WNV outbreak in 2004. See current case counts.

Fight the Bite - Day or Night
  1. Transmission
  2. Signs & Symptoms
  3. Treatment
  4. Prevention

WNV is spread primarily through mosquito bites. WNV is spread to people primarily through the bite of infected Culex species mosquitoes. Culex mosquitoes are found in Maricopa County and other parts of Arizona and we do have mosquitoes infected with WNV. These mosquitoes generally bite from evening to early morning so it is important to protect against mosquito bites whenever you are outside.

WNV can be spread in other ways, too. In rare cases, WNV also can be transmitted during blood transfusions, organ transplants, or from a mother to her baby during pregnancy, delivery, or breastfeeding.