Mosquito-abatement districts in the Salt Lake area will be aerially spraying for mosquitoes tonight, prompting a warning to residents to stay indoors in certain areas.
Because so many mosquito pools have tested positive for West Nile virus, the Salt Lake Valley Health
Department has recommended that the districts spray. The suggestion follows Centers for Disease Control and Prevention guidelines that set up a "minimum infection rate" of the virus in mosquitoes.
"That formula is based on how many per thousand mosquitoes have infection in how many areas of the valley," said Pam Davenport, spokeswoman for the county health department. "When it reaches a certain point, you need to spray. Right now, the numbers are so high, the risk to humans is great."
The aerial spraying, from 9 p.m. to midnight, weather permitting, will focus on three separate areas that are particularly plagued by the mosquitoes:
2,000 feet on either side of the Jordan River Corridor south from 2100 South to the Salt Lake County/Utah County border,
areas to the north of Magna,
and more than 28,000 acres of marsh area west and north of the Salt Lake City International Airport.
Normally, this is the time of year when human exposure to infected mosquitoes really picks up, said Davenport, because the marshes start to dry up and the mosquitoes move into the city. Recent rain may change that.
But there's no question mosquitoes are also already in urban areas. Of 45 mosquito pools that tested positive for the virus, 28 were in Salt Lake. Updated numbers will be released sometime today by the state Department of Health.
Experts say exposure to the mosquito-control pesticides poses low risk. The CDC says studies in North Carolina, Virginia and Mississippi all found that eating fresh produce and using flea and tick prevention on pets raised pesticide levels more than mosquito spraying did.
But those in the areas set for spraying may want to stay inside during that time. Those who suffer from chemical sensitivities or who feel the spraying may aggravate a preexisting health condition should consult their doctor or the local health department and take special measures to avoid exposure.
Davenport also recommends closing windows and turning off air conditioners during the spraying.
Although public spraying should knock back the mosquito population, people still need to take protective steps, she said. Those include staying inside from dusk to dawn when the mosquitoes that carry the virus are active, wearing longs pants and sleeves, using appropriate mosquito repellent and seeing that water is not allowed to collect near your home.
More information is available online at www.slvhealth.org.
The Salt Lake Valley Health Department says anyone who feels they have health problems because of pesticide exposure should contact the Utah Poison Control Center hotline at 800-222-1222.