/Health District identifies first West Nile virus-positive mosquitoes and updates Aedes surveillance

Health District identifies first West Nile virus-positive mosquitoes and updates Aedes surveillance

Southern Nevadans urged to take steps to reduce breeding sources

June 7, 2017

LAS VEGAS — The Southern Nevada Health District’s Vector Surveillance Program identified the first West Nile virus-positive mosquitoes of the season in the 89011, 89110, and 89146 ZIP codes. On June 1, the Health District announced the Aedes aegypti mosquitoes had been identified in the community for the first time in the 89032 ZIP code. During the course of its surveillance activities, the Health District has identified additional Aedes mosquitoes in the 89032 ZIP code and has received species confirmation from the Centers for Disease Control and Prevention. To date, the Aedes mosquitoes have tested negative for the Zika virus. The Health District has reported one case of West Nile virus this season and one travel-related Zika virus case in 2017.

“It has never been more important for residents to take steps to eliminate mosquito breeding sources and to protect themselves from mosquito bites,” said Dr. Joe Iser, Chief Health Officer for the Health District.

“Our staff has been working diligently to determine the extent of Aedes mosquito species in our community and collaborating with homeowners and our jurisdictional partners to employ control measures. Community members can do their part by ensuring their homes are free of standing water, using insect repellent appropriately, and reporting mosquito activity to our agency,” said Iser.

Mosquitoes acquire West Nile virus by feeding on infected birds. The illness is not spread from person to person. Many people with the virus will have no symptoms or very mild clinical symptoms of illness. Mild symptoms include fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach, and back. In some cases, the virus can cause severe illness and even death. The Health District reported its first West Nile virus case in May. In 2016, there were two West Nile cases and three cases of St. Louis Encephalitis.

The Health District’s Vector Surveillance Program is continuing its surveillance and treatment in the area where the Aedes aegypti mosquitoes were found. The species is known to spread the Zika virus as well as chikungunya and dengue. In 2016, the Health District reported 22 cases of Zika virus in Clark County residents, 21 of which were travel-associated, and one was sexually transmitted. For information about prevention tips, visit the Health District’s Mosquito Surveillance page.

In addition to Zika, West Nile virus, and St. Louis Encephalitis, the Southern Nevada Health District’s Vector Surveillance Program regularly tests mosquito pools for Western Equine Encephalitis, which is occasionally identified in Clark County. Residents can report green swimming pools and standing or stagnant water sources to local code enforcement agencies. Contact information for local jurisdictions’ code enforcement is available on the Health District website.

Residents are urged to protect themselves from mosquito bites. Unlike mosquitoes that can transmit West Nile virus and are most active at dawn and dusk, Aedes mosquitoes are more aggressive during the day. They are known to breed near homes and primarily bite humans. Residents are urged to report all mosquito activity to the Health District, particularly day-biting mosquitoes. Mosquito activity can be reported to the Vector Surveillance Program at (702) 759-1633.

Mosquito Control 

    • Check your yard weekly for water-filled containers or after every use of sprinklers or rain.
    • Throw away or recycle water-holding containers that are not needed.
    • If empty containers or large objects, such as boats or old appliances must be stored, they should be covered, turned over, or placed under a roof that does not allow them to fill with water.
    • Clean and scrub bird baths and pet-watering dishes weekly and dump the water from overflow dishes under potted plants and flower pots.
    • Fill tree holes and other cavities in plants with sand or soil.
    • Eliminate areas of standing water around your home, including non-circulating ponds, “green” swimming pools, and accumulated sprinkler runoff, which support mosquito breeding.
    • Check for hidden bodies of water such as wells, septic tanks, manholes, clogged drains, etc.
    • Call the Health District to report mosquitoes.

Prevent Mosquito Bites

    • Use Environmental Protection Agency (EPA)-registered insect repellents containing DEET, Picaridin, IR3535, Oil of lemon eucalyptus (OLE), or 2-undecanone. Always follow instructions when applying insect repellent to children.
    • Do not use insect repellent on babies younger than 2 months old.
    • Do not apply insect repellent onto a child’s hands, eyes, mouth, and cut or irritated skin.
    • Adults: Spray insect repellent onto your hands and then apply to a child’s face.
    • Do not use products containing oil of lemon eucalyptus (OLE) or para-menthane-diol (PMD) on children under 3 years old.
    • Wear pants and long-sleeved shirts to reduce mosquito exposure when outdoors.
    • Make sure doors and windows have tight-fitting screens without tears or holes.
    • If you are outdoors in a mosquito infested area, place mosquito netting over infant carriers.
    • Use mosquito netting when sleeping outdoors or in an unscreened structure.

For more information on mosquito surveillance activities in Southern Nevada access the Southern Nevada Health District website.  For additional information on eliminating breeding sources, access the CDC’s Controlling Mosquitoes at Home webpage.


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.