Mosquito on human skin.

Not only a nuisance, mosquitoes can pose a serious health threat to people. Disease can be spread to people through the bite of an infected mosquito. Over 40 different mosquito species can be found in Washington, and many are vectors for diseases, such as West Nile virus, western equine encephalitis, and St. Louis encephalitis.

In the past, sporadic outbreaks of western equine encephalitis and St. Louis encephalitis had occurred in Washington afflicting hundreds of people. These mosquito-borne disease outbreaks prompted the development of many mosquito control districts in our state. Today, with the emergence of West Nile virus, mosquito control and bite prevention remain key in protecting public health.

Mosquitoes can also spread Zika. Only two types of mosquitoes, Aedes aegypti and Aedes albopictus, are known to spread the virus to people. These mosquitoes are not found in Washington. Learn how you can help watch for the arrival of these invasive Aedes mosquitoes (PDF) and stop their spread in your community.


The best way to protect against mosquito-borne disease is to prevent mosquito bites. 

Avoid Mosquito Bites

Don't Give Mosquito a Home

Support Your Community


Content Source: Zoonotic Disease Program