The Labor Day weekend may signal the traditional end of the summer season, but it's still prime time for the ever-present mosquito to take a bite into late-season outdoor plans.

The Wyoming Department of Health reported Friday that cases of West Nile virus continue to climb, with no concrete answers as to when the threat of more cases might end.

To date, 119 cases of the mosquito-carrying disease have been reported in Wyoming residents this year, one of which has resulted in death.

The cases have been reported in 11 of the state's 23 counties, according to the Department of Health.

The number of cases reported this season to the Department of Health by local physicians and county health agencies, however, may not represent the actual number of cases in the state, according to state epidemiologist Dr. Tracy Murphy.

And, with a limited number of years' data to draw upon, the volatility of Mother Nature and other factors - including the severity of the onset of the disease after the fateful mosquito bite and the inconsistencies in reporting the disease - the state and area health officers have a difficult time predicting just how bad the season will turn out to be.

"There is variability around the state in how aggressive health care providers are regarding West Nile virus testing," Murphy said in a statement. "We know many cases are not diagnosed because ill people do not seek care and because some medical professionals do not pursue testing."

Though the calendar may suggest otherwise, it's still warm enough to warrant vigilance when it comes to preventing a mosquito that carries the West Nile strain from biting you, said Kim Deti, public information officer with the Department of Health.

"The main message is that we want people to be aware of the disease and take preventive measures," she said in an interview Friday.

As it did last year, Fremont County leads the list of reported West Nile cases in 2007 with 85, more than six times the amount reported by Campbell County, the second-most affected county.

But those numbers don't necessarily mean Fremont County is a hotbed for insects carrying the disease.

"There's no magic combination allowing us to make a prediction as to where it might be more prevalent," Deti said.

To date, Uinta and Teton counties are the only ones in Wyoming never to have reported a West Nile virus case, she said.

Marty Stensaas, a registered nurse and county manager for Fremont County Public Health, said her office has been aggressively promoting testing of people who believe they might have contracted a form of West Nile virus.

That can be especially tricky, as most people who contract the disease show no symptoms, according to the Department of Health. Those who do can be subject to what's called "West Nile fever," which includes swollen lymph nodes, headache and fever. Nine cases this year have been of the neuroinvasive type, which can include fever, neck stiffness and paralysis.

West Nile virus is carried by the culex tarsalis mosquito, which Stensaas said "is a very prevalent mosquito in Wyoming."

There are many factors as to why Fremont County ranks at the top of the West Nile incidence list, Stensaas said.

"For the last three years, we've really encouraged people to get tested," she said.

The prevalence of multiple bodies of water coursing through Fremont County - the Little Wind and Big Wind rivers, the Popo Agie river and the large concentrations of people living near them - factor into the high numbers, too, she said.

"We're at the right elevation and the right temperatures for (mosquitoes)," Stensaas said.

"The awareness is up, but we never know who's going to get (the disease)," she added.

Like other Wyoming counties, Fremont has its share of brochures and tip sheets to help residents avoid being bitten.

"Maybe we should put up signs that say, 'You're entering mosquito country,'" she joked. "It really is everywhere in this county, but there really isn't an area (in Fremont County) for getting the disease that's worse than others."

Riverton, Shoshoni, Lander and Ethete have routine fogging operations to kill mosquitoes.

In Campbell County, where 13 West Nile cases have been reported, Campbell County Health Department nurse supervisor Della Amend admitted there are probably more cases than are on the books.

The county provides spraying to eliminate mosquitoes and sprays larvacide that kills the juvenile buggers, she said.

"The message (to protect yourself) is out there, but I'm not sure people think about it," she said. "We think there are more people with signs and symptoms of the disease than are tested."

A hard freeze, bitterly cold winter and mild spring could mean a shorter West Nile season, but no one really knows for sure.

"Mother Nature is pushing this much harder than anything else," Stensaas said.