First West Nile-positive mosquito of 2018 found in Clark County| Las Vegas, NV

For the first time this year, a mosquito in the Las Vegas Valley has tested positive for the West Nile virus, the Southern Nevada Health District said Friday.

The district’s Mosquito Surveillance Program found the mosquito carrying the virus in the 89122 zip code, near Clark County Wetlands Park in the southeast Las Vegas Valley, according to a press release. No human cases of the West Nile virus had been reported as of Friday.

Mosquitoes that can transmit the West Nile virus are most active at dawn and dusk and become infected by feeding on infected birds. People who are bit by the bloodsuckers often develop very mild or no symptoms. Mild symptoms include fever, headaches, body aches, nausea, vomiting and occasionally swollen lymph glands or rashes on the chest, stomach and back.

But the West Nile virus can cause severe illness and death in some cases. The health district reported three cases of the virus in 2017, according to the release.

The mosquitoes capable of transmitting the West Nile virus are not the same as those that can carry the Zika virus, which are active during the day. Mosquitoes able to carry Zika have been found in four zip codes in North Las Vegas since 2017, though no cases of the disease are known to have been transmitted locally.

The health district regularly tests mosquitoes for West Nile virus, Zika, St. Louis Encephalitis and Western Equine Encephalitis, all of which can be fatal and have been found in Clark County.

Residents can report green swimming pools and standing or stagnant water sources to local code enforcement agencies. They are also urged to report mosquito activity, especially day-biting mosquitoes, to the health district’s Mosquito Surveillance Program at 702-759-1633. More information can be found at the health district’s website,

Contact Katelyn Newberg at or 702-383-0240. Follow @k_newberg on Twitter.