Ada County Officials Urge Precautions Following West Nile Virus Detections

The Ada County Mosquito Abatement District (ACMAD) has confirmed the presence of West Nile virus (WNV) in 11 mosquito populations collected in traps across Ada County as of August 12, 2025. West Nile virus is the leading cause of mosquito-borne illness in the United States.

While most people infected show no symptoms, serious cases-including encephalitis and meningitis-can occur. There is currently no specific treatment or cure for the disease.

WNV has been discovered in Ada County nearly every year since its detection locally in 2005. ACMAD uses a scientifically informed Integrated Mosquito Management program to protect people and livestock from contracting WNV in Ada County, but public participation is essential. Mosquitoes need only about a bottle cap's worth of water to breed, and there are many ways to prevent the formation of mosquito habitat. The best way to reduce the risk of WNV this summer is to follow the simple steps outlined below:

• Dump & drain standing water weekly - birdbaths, toys, flowerpots, buckets, old tires, rain gutters, etc.
• Keep window and door screens in good condition
• Avoid overwatering your lawn and garden
• Limit time outdoors at dusk and dawn - peak mosquito activity times
• Wear long sleeves and pants (light-colored clothing is best)
• Use an EPA-approved insect repellent and follow label directions

Following a WNV detection, ACMAD will treat areas within 1 mile of each detection to reduce adult mosquito populations and help prevent WNV in people and livestock. Monitoring and treatment will continue through the remainder of the 2025 mosquito season. To learn more about ACMAD operations, watch the ACMAD Operations Video.

To see where ACMAD has detected WNV so far in 2025, visit the Ada County Mosquito Tracker. You can also be notified of WNV Detections via the ACMAD Facebook and NextDoor pages.