Climate change might bring more West Nile virus-carrying mosquitoes

SALT LAKE CITY — Warmer temperatures and disappearing wetlands are creating conditions where the mosquitoes that spread West Nile virus could thrive this summer. That’s the assessment of experts cited in an article from Kaiser Health News as reported in the Salt Lake Tribune.

Gary Hatch, the director of the Davis Mosquito Abatement District, agreed.

Increasing populations

Hatch said his crews have had to continue their spraying efforts later in the year to control the Culex mosquitoes that spread the virus, and they’ve seen more and more of them.

“Last year, we had 301 positive mosquito pools, which is more than double what we’ve had in the past,” Hatch told KSL NewsRadio.

Hatch said the mosquitoes love warm weather when the daytime and nighttime temperatures average 70 degrees.

“We’ve seen an increase in those 70-degree days, which makes the virus amplify and grow faster and make the mosquito able to transmit the virus quicker,” he said.

The district’s efforts focus on two species of mosquito.

Culex tarsalis lives in wetland areas, and the district’s spraying efforts focus on eliminating them. The other, Culex pipiens, lives and breeds in urban areas, taking advantage of standing water in yards and gardens. Hatch said its numbers diminished last year, partly because residents weren’t watering their properties as much during the drought.

What West Nile virus does

While West Nile virus typically causes mild symptoms in most people, it can turn into a neuroinvasive disease that can cause serious illness and even death. Hatch said its early symptoms are similar to COVID-19, and some people with the disease may not have known they had it.

“They go in for testing for COVID. They’re told they don’t have COVID, and so they just go home,” he said.

KSLTV.com reported that the Utah Department of Health confirmed 11 cases of West Nile virus last summer, with one fatality.

Experts recommend wearing long-sleeved clothing, avoiding outdoor exposure at dawn and dusk, and using mosquito repellents with DEET to avoid bites from mosquitoes that carry West Nile and other disease-causing germs.

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