West Nile is spreading throughout Utah County, but it hasn't spread beyond mosquitoes yet.

Lance Madigan, public information officer for the Utah County Health Department, said a mosquito pool near Lehi tested positive for the virus. The first positive test came from a mosquito pool in Goshen, at the south end of Utah Lake, in the middle of June.

That test came in earlier than previous years, and health officials prepared for the typical chain of events -- first mosquitoes, then a week or so later the sentinel chickens, followed by horses and then humans. But it's been three weeks, and only the mosquitoes are testing positive for the virus.

"This year is really playing out kind of funny," Madigan said, adding the unanticipated lapse doesn't mean the virus isn't a threat. "That's all the more reason people should be really conscious when they go out."

In addition to the slow passage to animals, the statewide spread of the disease is unusual. In the past it has started in the east and the south first and slowly spread, Madigan said. This season it seems to be appearing first in central Utah -- Utah and Salt Lake counties have both reported positive tests -- and moving outward.

"That's probably indicative because of our weather," he said.

This summer's warmer weather has brought out the Hulex tarsalis mosquitoes early. The bugs, which are out feeding between dusk and dawn, have a blood meal before laying eggs, which is when the virus is passed on. The mosquitoes that are out in swarms in the evening, especially around the lake, are usually not those bugs.

"They bite, they itch, but they're not the disease carriers," Madigan said.

According to the state's Division of Wildlife Resources, there were 285 positive tests for the virus in 2005, including humans, birds, horses and mosquitoes. Of the 52 human cases, one, an elderly man in Uintah County, died of West Nile.

This report is the fourth in Utah this season; two magpies in Salt Lake City tested positive for the virus in early June.

To avoid West Nile:

Wear bug repellent with DEET.

Avoid being outside during the hours in between dusk and dawn.

Wear long sleeves and long pants when outside.

Get rid of standing water in yards or work areas.

Source: Utah County Health Department

This story appeared in The Daily Herald on page A1.