SALT LAKE CITY — Utah's mosquito season has begun, and the Utah Department of Health is advising people to take extra precaution after last summer's increase in West Nile virus cases.
Dallin Peterson, an epidemiologist with the Utah Department of Health, said human West Nile virus cases last year reached Utah's highest number in a decade, with 62 people who tested positive and five who died from the virus. Peterson said Utah usually only records about 10 cases of the virus a year.
Though there's no clear factor causing an increase in mosquitoes and West Nile virus cases, Peterson said, wet springs and hot summers play a significant role in mosquito populations.
The state Department of Health oversees mosquito research with laboratory work and coordination with zoos, blood donation centers and other departments to track signs of West Nile virus in animals and people.
"A lot of the mosquito-born diseases affect animals, so usually when an area does have mosquitoes carrying West Nile, the animals get it first," Peterson said, adding birds and horses are especially susceptible. He said all blood samples they receive from blood donation centers are tested for West Nile virus as well.
Davis, Salt Lake and Utah counties each have their own mosquito abatement districts spraying in areas showing high mosquito populations.
"Right now we're in full swing," said Gary Hatch, Davis County's abatement district manager. "We're out spraying for mosquito larvae in the water and also spraying for adults."
Hatch said he has day and night teams working this month, handling areas with both larvae and adult mosquitoes.
"We have known habitats, so we spend a lot of time out there inspecting," he said. "They go through, dipping through the water, seeing if larvae is present."
Hatch said if they find larvae, they treat it with spray either by hand, backpack sprayer, ATV or airplane, depending on large the area is.
Aislynn Tolman-Hill, public information officer for the Utah County Department of Health, said one thing many people don't consider in mosquito prevention is standing water around their home.
"If you have a fountain that is not circulating, that is a perfect breeding place for mosquitoes, or a little kiddy pool that has not been dumped out," Tolman-Hill said. "It doesn't have to be a huge area — even just a can or a bucket."
She said Utahns should also make sure to use repellent with deet and apply especially during times when the sun is down.
"When we think about going into the sun, it's common knowledge to use a sunblock," she said. "We're trying to instill that way of thinking in our community, during dawn and dusk time, using repellant just as you would sunscreen during the summer."
Utah county has experienced a spring with above-average moisture, increasing the likelihood of mosquitoes and mosquito-spread viruses, according to the Utah County Health Department.
Peterson said the first cases of human West Nile virus usually begin around the end of June or beginning of July. Last year, the first reported case of the virus was at the end of June and the first mosquito pool that tested positive in their lab work was on June 25.
Since they've started testing mosquito pools at the end of May, Peterson's department has not yet had a sample come back positive for West Nile virus.
Peterson said the beginning signs of West Nile virus are usually generic — fever, body aches and muscle aches — and many people don't know they have the virus. In small percentage of cases, people experience neurological symptoms, such as brain swelling, and paralysis. These can result in death or long-term effects.
Peterson said the five people who died from the virus last year experienced brain swelling.
Peterson said they've started testing mosquito pools slightly earlier than usual this year because there were large numbers of mosquitoes available to trap at the end of May.
Residents who have concerns about mosquitoes in their areas can contact their county's Mosquito Abatement District.