West Nile virus has reared its ugly head for the first time this year in Utah County.

The county will respond by doing extra testing in south Utah County and intensifying its chemical spraying efforts there, he said.

"We are doing additional spraying, which we were semi-planning on doing anyway just going into the holiday weekend," Madigan said.

Madigan said workers will be aided by airplanes, which drop chemicals from above. The planes will focus on the shore of Utah Lake, a known breeding ground where it's harder for ground crews to work, he said.

It's tough to predict if or when the virus will show up in humans or animals, Madigan said. Generally, it appears one to two weeks after the first positive mosquito test, but the trend has been less predictable lately, he said.

"We've kind of been breaking expectations in the last few years," he said.

The virus has not shown up in "sentinel" chickens placed in key areas around the county as indicators, Madigan said. With the march of the virus being harder to predict, it's anybody's guess when it may spread, he said.

"Hopefully, it won't, but we could start seeing it anytime," Madigan said.

Utah County Mosquito Abatement Director Bob Mower did not return a phone call for comment.

The state's first case of West Nile this year appeared June 4 in a dead crow in Kane County on the state's southern edge.

The Associated Press reported Tuesday that health officials had confirmed the first case of West Nile virus in a person in Salt Lake County this year.

The Salt Lake Valley Health Department says the case involves a child who was exposed while camping in the Uintah Mountains.

The child was diagnosed with West Nile fever, a less severe form of the virus, the AP reported. The child was not hospitalized.

There were only two confirmed cases among humans in Utah County last year, down from 65 in 2006.

• Ace Stryker can be reached at 344-2556 or at This e-mail address is being protected from spam bots, you need JavaScript enabled to view it