First West Nile virus case of the season reported
Health District urges residents to protect themselves from mosquito bites
FOR IMMEDIATE RELEASE:June 3, 2026
LAS VEGAS – The Southern Nevada Health District is reporting the first case of West Nile virus in a Clark County resident this year. 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.”
While no mosquitoes collected in Clark County have tested positive for West Nile virus this year, public health officials are encouraging residents to take steps now to reduce their risk of mosquito-borne illness.
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.
- Prevent mosquito bites by using Environmental Protection Agency (EPA)-registered insect repellent and wearing loose-fitting, long-sleeved shirts and pants when outdoors.
- 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. While most infections are mild or cause no symptoms, some people develop neuroinvasive disease, which can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the membranes surrounding the brain and spinal cord).
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.
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.
In addition to West Nile virus, 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. Although Culex mosquitoes prefer to feed on birds and are responsible for maintaining the virus in avian populations, they also bite people and can transmit mosquito-borne viruses like West Nile virus when they do.
Culex mosquitoes lay eggs on the surface of fresh or stagnant water, including unmaintained swimming pools, horse troughs, ornamental ponds and marshy areas.
Since first being detected locally in 2017, Aedes aegypti mosquitoes have become established throughout Southern Nevada. While best known for transmitting diseases such as dengue and chikungunya, Aedes aegypti mosquitoes collected in Clark County also 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.
For more information, visit the Health District Fight the Bite webpage at www.southernnevadahealthdistrict.org/programs/mosquito-surveillance/mosquito-bite-prevention/ or the Centers for Disease Control and Prevention website at www.cdc.gov/mosquitoes/prevention/index.html.
The Health District’s weekly mosquito surveillance reports are available at www.southernnevadahealthdistrict.org/programs/mosquito-surveillance/arbovirus-update/.
The Southern Nevada Health District serves as the local public health authority for Clark County, Boulder City, Henderson, Las Vegas, Mesquite and North Las Vegas. The agency safeguards the public health of the community’s residents and visitors through innovative programs, regulations, and initiatives focused on protecting and promoting their health and well-being. More information about the Health District, its programs, services, and the regulatory oversight it provides is available at www.SNHD.info. Follow the Health District on Facebook, Twitter, and Instagram.