West Nile Virus Data

2022 West Nile Virus Activiy

The map and table indicate where West Nile virus activity is occurring in Washington state. Human cases are shown by county where the infected person was most likely exposed to the virus and by county where the infected person lives.

Ongoing West Nile virus monitoring for infected dead birds and mosquitoes is limited to a few counties due to lack of resources. West Nile virus activity may not be indicated in your county, however, it's likely to be widespread in our state.

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2022 West Nile Virus Activity Map

2019 West Nile Virus Activity
Map of Washington where people may have gotten west nile virus with no counties colored in.
Map of Washington with counties that have cases of red nile virus in red.
Map of Washington where there are infected houses/other mammals, birds, and vector mosquitoes.
West Nile Virus-Positive Cases in Washington, 2022
County   Human  Horse/Other Mammal    Bird    Mosquito Sample  
By County of Likely Exposure  By County of Residence 
Benton 0 0 0 0 5
Clallam 0 1 0 0 0
King 0 1 0 0 0
Kittitas 0 0 0 0 1
Pierce 0 1 0 0 0
Spokane 0 1 0 0 0
Multi-county Exposure* 0        
In-state Acquired 0        
Out-of-state Acquired 3        
Unknown Exposure Location ** 1        
Total 4 4 0 0 6***

* "Multi-county Exposure" represents human cases that had potential exposure in more than one county.

** "Unknown Exposure Location" represents human cases that had potential exposure in other states or countries in addition to Washington State. These cases are not shown on Map 1. Human Cases by County of Likely Exposure.

*** Of these 6 positive pools, one is a pool of Aedes vexans collected in Kittitas County tested positive for West Nile virus (WNV). Aedes vexans is not considered to be directly involved in the maintenance of WNV in the bird-mosquito cycle.

Maps and statistics are updated daily by 3 PM. This table shows cases of West Nile virus reported in the state.

Past West Nile Virus Activity

Final annual West Nile virus surveillance maps and statistics for 2002-2021

Find more surveillance data

The Washington Tracking Network presents 2006-2021 vector mosquito species, Culex pipiens and Cx. tarsalis, test data by county. It also shows bird and mammal test data. View data in a table, chart, and map format and export data for your own use.

See Washington Tracking Network - mosquito samples, birds, and mammals tested for West Nile virus.

National Surveillance Maps & Statistics

CDC West Nile Virus Statistics & Maps

West Nile virus surveillance data and maps on human infections and activity by state.

More Information