West Nile virus may flourish this year

This "manic depressive" spring, dishing up both extra water and sunshine, may portend a bad West Nile virus year. Or not. Health and mosquito experts say there's no way to predict, but people need to reduce the mosquito populations where they live, work and play.

"Right now, pretty much every place that can hold water and produce mosquitoes has water," says Sammie Dickson, director of the Salt Lake City Mosquito Abatement District. "And we're starting to see a lot of the larvae in the water, so we've got a pretty good crew out this spring treating the water. This has been a manic depressive spring, one of the strangest we've had in a long time."

The mosquitoes that are beginning to buzz around — and yes, there are mosquitoes out — are "nuisance mosquitoes," not the critters that may carry West Nile virus. They will likely come later.

But Dickson says his crews already found a few larvae of the C. tarsalis (one of two breeds that carry the virus). So did Davis County Mosquito Abatement crews, says Gary Hatch, abatement district director. Any that survive the larvicide that's being used to kill them before they get started could be biting in as few as 10 days.

In addition, Utah County Health Department spokesman Lance Madigan says, many already-infected mosquitoes may winter over. Hatch says they store fat they need to survive, then hibernate in places like garages or sewers. When they become active, they're already loaded with virus.

First, the experts say, the bugs will go after birds. Humans are unlikely to be the main buffet attraction until later, when it's hot, the marshlands and other water sources dry up and the birds move on. Then the mosquitoes pay more attention to horses and humans. It's worth noting, Dickson adds, that three-fourths of the biting activity for these breeds takes place within 45 minutes of dusk, though they are active from dusk to dawn.

As for prevention, Dickson says there's not much a homeowner can do to prevent C. tarsalis from developing, so in the evenings, wear repellent. Now's the time, too, to get rid of water sources around the yard (even an abandoned tin can will hold enough water to produce mosquitoes) and make sure screens are repaired to keep the bugs out. Bird baths and ornamental ponds need to be rinsed weekly. Mosquito abatement districts can provide mosquito fish for ornamental ponds, which eat the larvae. The fish are 1-2 inches long and aggressive, though, so they should not be put in with smaller fish, Dickson says.