PROVO — A 15th human case of West Nile virus in Utah County was detected Monday, accounting for 75 percent of the state's confirmed cases and matching the county's total in 2005.

The latest case involves an adult over age 65 in the south Utah County area, said Lance Madigan, spokesman for the county health department.

Madigan learned of the confirmed case from state health officials Monday afternoon — just hours before a planned West Nile virus update during a meeting of the Utah County Board of Health.

"Utah County is really being hit with West Nile virus," said Dr. Joseph Miner, executive director of the Utah County Health Department. "We had 15 total (human cases) last year out of 52 (statewide). This year, we're already at 15 and we still have half of August left."

This year's confirmed human cases have been scattered throughout the county, from as far south as Payson to Lehi and Saratoga Springs in the north end, Miner said. Twelve of those cases have popped up in the past two weeks.

And No. 15 likely won't be the last, he said. All of the Utah County cases in 2005 were identified in August or early September.

Bob Mower, director of Utah County mosquito abatement, said field work and surveillance have shown that about 20 percent of the active night mosquitos that spread the virus are infected in Utah County.

"That really is a high infection rate," Mower said.

And that's despite increased efforts to combat the spread of the virus. Immediately following "mosquito season" of 2005, county heath department officials began working on a plan for 2006.

The county added aerial spraying and regular concentrated spraying — or fogging — at night, targeting areas of concern around Utah Lake. The Utah County Commission supported the plan with an additional $100,000 in funding.

The county's game plan has been successful in reducing the number of mosquitos, Mower said, but it hasn't limited the human cases of West Nile as much as health officials had hoped.

Miner said the county's goal for 2006 was to match or reduce the number of human cases of '05.

"We're going to be worse than last year, so it won't be as successful as we thought," he said.

Mower said weekly fogging will continue in Utah County's three West Nile hot spots — Provo Boat Harbor and nearby subdivisions; Saratoga Springs and Lehi; and the area of Lakeshore, Palmyra, Benjamin and West Mountain.

Mosquito abatement crews also are expected to do a sixth aerial spraying of the season in late August or earlier September.

There have been 20 confirmed cases of West Nile virus in Utah so far this year.

West Nile is a mosquito-born virus that affects the central nervous system in humans. In 2005, there were 52 identified cases in Utah, including one death.

Symptoms vary from case to case, and 80 percent of people who are infected with West Nile show no symptoms at all, according to the Centers for Disease Control and Prevention.

Only about one in 150 people who are infected with West Nile virus develops severe illness, the CDC says.

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