Mosquito infection rates across Salt Lake County have surged to seven times their typical level, prompting the county health department to issue a formal warning that Sandy residents who spend evenings outdoors face elevated risk of West Nile virus.

The Salt Lake County Health Department announced Wednesday, Aug. 12, that 35% of mosquito samples collected by the Salt Lake City Mosquito Abatement District tested positive for West Nile, according to a Fox 13 report. Typical rates this time of year run at 5% or less. Two other districts, South Salt Lake Valley and Magna, are showing similar levels.

Two human cases have been confirmed countywide.

Nicholas Rupp, communications director for the health department, said there is now a "significantly higher-than-normal risk of West Nile among local mosquitoes."

Sandy falls within the South Salt Lake Valley Mosquito Abatement District, which is tracking infection rates comparable to the Salt Lake City district's 35%. Residents who walk Dimple Dell Regional Park, use the Jordan River corridor or attend evening events at the Sandy Amphitheater and America First Field face heightened exposure because mosquitoes are most active after dusk.

The warning marks a sharp escalation from the county's first human West Nile case of 2026, confirmed July 30. As we reported July 31, 86 positive mosquito samples had been collected countywide at that point. Statewide, 709 samples have now tested positive in 2026, compared to 108 at the same point in 2025 and 92 in 2024.

Draper City, which borders Sandy to the south, also confirmed Wednesday that West Nile was detected in local mosquito pools, ABC4 reported.

What residents should do

The health department recommends:

• Use EPA-registered repellent containing DEET, picaridin, IR3535 or oil of lemon eucalyptus.
• Wear long sleeves and pants after dusk.
• Drain standing water from yards, including old tires, plant trays, pet dishes and buckets.
• Keep gutters clear and weeds cut short.
• Check door and window screens for holes.

There is no vaccine or specific treatment for West Nile virus. Symptoms, which include fever, headache, body aches and rash, appear within two to 14 days of a bite. Less than 1% of infected people develop severe neurologic disease, but older adults and immunocompromised individuals face the highest risk of serious illness.

In 2025, 49 Utahns contracted West Nile and four died, according to Gephardt Daily.

Mosquito season in Utah continues until the first hard freeze, meaning the risk window for Sandy residents remains open through at least October.