"There is a concern because we are on the corridor to Las Vegas, but it's not as big of a threat as it's looking like," Amodt said. Aedes aegypti mosquitoes "are getting closer but it's a question of if they can establish themselves here."
Counties across the state started surveillance for mosquitoes carrying the Zika or West Nile viruses at the end of May and will continue through mid-October. No mosquitoes testing positive for the viruses have been reported yet this season, according to the Utah Department of Health.
The Salt Lake City Mosquito Abatement District started its monitoring in mid-March, earlier than usual, given the valley's fluctuating temperatures, wet spring and runoff, said Ary Faraji, manager and entomologist for the district.
Wet weather and warmer temperatures usually yield a larger mosquito population but don't increase the likelihood that mosquitoes carrying one of the viruses will be found, Faraji said.
While Aedes aegypti mosquitoes are not established in Utah, the two varieties of mosquitoes that carry West Nile virus live throughout the state. Last year, there were 13 human cases of West Nile virus in Utah, with 11 in Salt Lake County, UDOH reported. Seven of those cases involved a serious form of the illness and one person died.
Most people infected with West Nile virus do not exhibit symptoms, according to the Centers for Disease Control and Prevention. Others may have body aches, fever and headaches. Severe cases can include high fever, tremors, disorientation, coma and muscle weakness.
Utah has reported 31 cases of Zika virus to date, and all but one involved patients who had traveled to an area where Zika virus was being actively transmitted. The remaining case was a caregiver. No cases have been reported to the CDC from Utah so far in 2017, according to the CDC.
The infection can cause a birth defect called microcephaly among babies born to mothers with the virus, according to the CDC. Thirteen of Utah's cases were pregnant women; two lost their babies in the first trimester, eight did not pass on the virus to their children, and one woman left Utah and wasn't tracked.
Six Aedes aegypti mosquitoes were trapped four years ago in Washington County, Amodt said, prompting abatement districts in southwestern Utah to build more traps specifically designed to catch them. The district urges residents to dump out water that collects in artificial containers such as old tires and birdbaths.
Southwest Utah's mosquito season is longer than other areas of the state because of its warmer temperatures, making it imperative for residents to remain vigilant throughout the season, said spokesman David Heaton. Washington County has seen between five and 11 mosquito samples test positive for West Nile virus each year from 2014 to 2016, UDOH data showed.
Taking preventive measures such as using insect repellent, getting rid of standing water and wearing long-sleeved shirts and long pants from dusk to dawn are the best ways to protect against Zika or West Nile viruses, Faraji said.
"From my perspective, mosquito control is a job for everyone," he said.