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West Nile Virus

As our annual mosquito season begins, take steps now to avoid mosquito bites that can transmit this disease-causing virus

What is West Nile Virus?

West Nile Virus (WNV) is a disease carried by mosquitoes that is common in Africa, west Asia, the Middle East and more recently North America. Human infection with WNV may result in serious illness. Experts believe WNV is established as a seasonal epidemic in North America that flares up in the summer and continues in the fall.

How is West Nile Virus Transmitted?

  • Infected Mosquitos. Most often, WNV is spread by the bite of an infected mosquito. Mosquitoes are carriers that become infect when they feed on infected birds. Infected mosquitoes can then spread WNV to humans and other animals they bite.
  • Transfusions, transplants and mother-to-child. All donated blood is checked for WNV before being used. The risk of getting WNV through blood transfusions and organ transplants is very small, and should not prevent people who need surgery from having it. Transmission during pregnancy from mother to baby or transmission to an infant via breastfeeding is extremely rare.
  • Not through touching. WNV is NOT spread through causal contact such as touching or kissing a person with the virus or by breathing the virus.

For more information, visit the CDPH website.