At least one in five Utah Valley mosquitoes is now West Nile positive.

Robert Mower, manager of Utah County Mosquito Abatement, said Friday that while there is much good news in the war on the mosquitoes that carry the potentially deadly virus -- including the fact that the number of mosquitoes here has been significantly reduced by a $100,000 nighttime aerial spraying program -- the virus is still surging, and tests confirm it is now infecting a minimum of one in five mosquitoes.

That number may be higher, he said, but it is better than Salt Lake County, where one in two mosquitoes is positive.

This year is the first in 20 years that aerial mosquito spraying has been done in Utah County, he said. The $100,000 project was made possible by a special budget allotment from county commissioners over and above the abatement program's annual quarter-million dollar budget.

On Thursday night 7,500 acres were sprayed from Provo Bay to Lincoln Beach. No residential areas are being sprayed.

A total of 50,000 acres in Utah County have been aerial sprayed so far. Much of it, such as areas around Goshen and Genola, Provo Bay and Lake Shore, have been sprayed week after week to constantly suppress mosquito populations.

The number of special requests from residents for the county to spray for mosquitoes has plummeted from a high of 140 requests in one week last year to about 80 requests in one week this year, he said. Last year the average number of requests per week was 50-70. This year it has been 30-40.

The decline is more proof, along with the declining number of mosquitoes in county traps, that the aerial spraying is working, he said.

Traditionally, the mosquito season begins tapering off in the second or third week of August, and with that in mind the aerial spraying program will end next week, he said, noting he expects the mosquito population will not surge again this year. Crews will continue spreading larvacide in standing water and morning and evening spraying by truck.

New diagnoses of human cases of West Nile are expected to continue to surge for several more weeks as the virus incubates in people and symptoms begin showing up, he said.

Concerned about escalating numbers of human cases, including six new cases reported in Utah Valley this week, rumors and concerns about mosquitoes have been rampant, and calls and emails for information have been coming into both the Daily Herald and the county health department.

State and local officials should be giving residents more information about where West Nile is occurring, said Keith Horton of Goshen. So far, the state has declined to name the cities where cases are occurring, giving out only the county of origin.

"We keep hearing reports over word of mouth that people have it, and then we hear they don't, so you don't really know if people are getting it here or not," Horton said. "I understand wanting to keep people's privacy, but I don't understand why the state can't say what city the cases are in."

The state does not give information by city because if people hear cases are not in their city it may give "a false sense of relief," said Lisa Wyman, epidemiologist with the State of Utah. "We don't want people to get caught up in a cycle of thinking 'I don't live in those towns so I'm not going to get it.' It is safe to assume the rise in cases is everywhere in Utah County."

Horton also wondered why his area is only sprayed by truck once a week. Mower said weather and staffing plays a part, as well as recommendations about how often to use the spray.

Caleb Warnock can be reached at 443-3263 or This e-mail address is being protected from spam bots, you need JavaScript enabled to view it