Mosquitoes carrying the West Nile virus have been identified in the Logandale area, meaning that infected mosquitoes probably are present throughout the Las Vegas Valley, according to the Southern Nevada Health District.
Wednesday's announcement was intended to remind people about the steps they can take to curb the mosquito population and reduce the risks of encountering the virus, health district spokeswoman Jennifer Sizemore said.
"It's a confirmation that it's in the community," she said. "Sometimes people, when it's off the radar, don't take the proper precautions."
Those include eliminating standing water, such as birdbaths and sprinkler runoff, and reporting "green" pools to code enforcement authorities.
People also should use an insect repellent containing DEET and avoid spending time outside at dawn and dusk, when mosquitoes are most active.
Mosquitoes pick up the virus by feeding on infected birds and can spread it to humans by biting them.
The virus does not spread person to person.
It often causes no symptoms or mild ones such as fever, aches, nausea, vomiting and swollen lymph glands.
In some cases, the virus causes severe illness or death.
"The vast majority of people who get West Nile have mild symptoms, so it often goes undiagnosed," Sizemore said. "Just because we haven't seen cases doesn't mean people shouldn't be protecting themselves."
West Nile was first detected in Southern Nevada in 2004, when 23 cases of human infection were reported.
That's by far the highest number of infections in a year since, and in 2010, no one reported a West Nile infection.
Contact reporter Alan Choate at achoate@ reviewjournal.com or 702-477-3861.