This has been the worst season ever in Clark County for mosquito-borne West Nile virus, but health authorities say they face a challenge convincing local residents that they need to protect themselves against the tiny bloodsuckers.
As of Friday, the Southern Nevada Health District had documented 36 cases of West Nile virus in Clark County, including 26 cases of the more serious neuroinvasive form. The district also has found infected mosquitoes in at least 40 county zip codes.
Despite the risk, “It’s a huge challenge to get people to think about mosquito-borne disease,” said Brian Labus, an assistant professor of epidemiology and biostatistics at UNLV’s School of Public Health.
Experts cite several reasons they have a hard time getting the public to take the threat seriously.
Most people infected with the virus won’t feel sick. But some — about one in 150 — will experience the severe form of the illness that affects the central nervous system and can be fatal or lead to permanent disability.
Mosquitoes also are most active around dusk and dawn, but Labus notes that Southern Nevadans don’t want to “to stay inside when it’s actually nice out” and not too hot.
What’s more, “We tell people we want them to put on clothes that are uncomfortable,” he noted, referring to the guidance from public health officials to wear long sleeves and long pants when temperatures are in the triple digits.
However, outdoor and sporting goods stores offer light-weight protective clothing, and EPA-registered repellents are safe when used as directed, health authorities say.
‘Most dangerous creature’
Joe Conlon with the American Mosquito Control Association warns against underestimating the risk of mosquitoes and forgoing repellent.
“They’re the most dangerous creature on the planet by a long shot,” noted Conlon, a medical entomologist. “It’s not even close. The only creature that comes near it in terms of lethality is humans.”
Conlon was referring to the fact that the insects spread many dangerous diseases beyond the West Nile virus, including the Zika and Chikungunya viruses, dengue and malaria. About 800,000 people each year are killed by mosquito-borne illness. Malaria alone sickened 219 million people in 2017, killing 435,000 of them, mostly children in Africa, according to the Centers for Disease Control.
West Nile virus is the most common virus spread by mosquitoes in the continental U.S. Mosquitoes in 15 different zip codes in Clark County have tested positive for St. Louis encephalitis this year, though no human infections have yet been reported.
Many areas in the country, including Southern Nevada, have the kind of mosquitoes that can spread Zika, which can cause birth defects in the babies born to women infected during pregnancy. However, mosquitoes in Southern Nevada so far have not tested positive for Zika.
While there have been no deaths from West Nile virus this year in Southern Nevada, consider that some research indicates that almost half of all people who have ever lived were killed by mosquitoes. Said Conlon: “People need to treat mosquitoes seriously.”