LAS VEGAS (FOX5) — The Southern Nevada Health District is reporting this year’s first case of West Nile virus in a Clark County resident.
The patient, a woman in her 40s, was diagnosed with the neuroinvasive form of the illness. She was hospitalized and has since recovered. The patient reported travel to another state where multiple human West Nile virus cases have been reported and was also present in Clark County during the incubation period.
“Most people infected with West Nile virus experience mild symptoms or no symptoms at all, but some infections can result in serious illness,” said Dr. Cassius Lockett, District Health Officer for the Southern Nevada Health District. “Taking simple precautions to avoid mosquito bites and eliminate mosquito breeding areas around your home or while traveling can significantly reduce your risk.”
No mosquitoes collected in Clark County have tested positive for West Nile virus this year.
Protecting against mosquito bites
The Health District’s Fight the Bite campaign encourages residents to eliminate standing water by removing or emptying containers that collect water around homes and businesses. Mosquitoes can breed in items as small as bottle caps, plant saucers, toys and wheelbarrows.
The campaign also encourages residents to prevent mosquito bites by using Environmental Protection Agency-registered insect repellent and wearing loose-fitting, long-sleeved shirts and pants when outdoors.
Residents can report mosquito activity to the Health District’s surveillance program at (702) 759-1633. Residents should report green pools to their local code enforcement agency.
West Nile virus is spread through the bite of an infected mosquito. Some people develop neuroinvasive disease, which can cause encephalitis or meningitis.
No human cases of West Nile virus were reported in Clark County in 2025. In 2024, 26 human cases were reported, including 14 neuroinvasive cases and 12 non-neuroinvasive cases.
Mosquito surveillance
The Health District conducts mosquito surveillance throughout Clark County to monitor mosquito populations and test for mosquito-borne diseases. As of June 1, staff had set 920 mosquito traps throughout the county and submitted 957 mosquito pools representing more than 20,000 mosquitoes for testing. No mosquito samples have tested positive for West Nile virus this year.
The Health District monitors mosquitoes for St. Louis encephalitis and Western equine encephalitis. The majority of mosquitoes trapped by the Health District that test positive for West Nile virus are Culex species. Culex mosquitoes lay eggs on the surface of fresh or stagnant water, including unmaintained swimming pools, horse troughs, ornamental ponds and marshy areas.
Aedes aegypti mosquitoes have become established throughout Southern Nevada since first being detected locally in 2017. Aedes aegypti mosquitoes collected in Clark County tested positive for West Nile virus in 2024.
Aedes aegypti mosquitoes lay eggs on the inner walls of small containers that collect water. Their eggs can remain dry and dormant for months before hatching when water is present again.
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