Grant County Mosquitoes Test Positive for West Nile Virus

Mosquitoes in Grant County have tested positive for West Nile virus.

The samples were collected north of Moses Lake and confirmed by the Grant County Health District. Grant is the third county in Washington with positive mosquito tests this year, joining Benton and Yakima.

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No human or animal cases have been reported in Washington in 2025, though neighboring states have seen infections, including a West Nile–related death in Idaho last month. The last human case in Grant County was in 2015.

West Nile is the leading mosquito-borne disease in the U.S. Most people show no symptoms, but about one in five develop mild illness such as fever, aches, or rash. Roughly one in 150 experience severe complications, which can be fatal.

Health officials urge residents to take precautions—avoid outdoor activity at dawn and dusk, wear long sleeves, use EPA-approved repellents, and eliminate standing water where mosquitoes can breed.