BRIGHTON - After five years of declining confirmed cases of West Nile virus in Colorado, conditions this year have health officials concerned.

Colorado Mosquito Control monitors mosquito populations throughout the state. They are seeing an increasing number of mosquitoes that have tested positive for the West Nile virus.

"Traditionally in Colorado the hot zones have been Boulder County, Larimer County and Weld County. There is no exception this year. Those three counties tend to have the highest incidence in the Front Range," said Doc Weissmann, surveillance manager for Colorado Mosquito Control.

Weissmann says the first mosquito tested positive for West Nile in early June. He says the weather conditions have played a role in an ever increasing number of mosquitoes.

"A lot of it has been the high temperatures. It makes the mosquito life cycle go faster. The hotter the temperature, the warmer the water is, the faster they go through their life cycle," says Weissmann.

The first confirmed case of West Nile virus in Colorado this year occurred in Delta County. The Colorado Department of Public Health and Environment also confirmed that a Llama in Delta County has been diagnosed with West Nile.

"We know those mosquitoes are out there now. We know that there are a certain percentage of the mosquitoes that carry the virus, so we expect to be seeing more human cases," said Dr. Lisa Miller, state epidemiologist for the Colorado Department of Public Health and Environment.

"I think it would be a mistake for people to think this is just isolated to one geographic area. It looks like it is fairly widely dispersed as far as where we're seeing positive mosquitoes," Dr. Miller said.

The increased number of mosquitoes carrying West Nile increases the chances of transmission to humans.

"Your odds are higher. In a year like this where we're seeing a lot of West Nile activity the odds are certainly higher of getting bit by a West Nile positive mosquito," Weissmann said.

Health officials are encouraging people to remove standing water from their property. The standing water, even small amounts, can serve as a breeding ground for mosquitoes. They also advise people to avoid being outdoors at dusk and dawn, which is when mosquitoes are active. If you do need to be outdoors at dusk or dawn, wear mosquito repellent, long pants and long sleeved shirts.

For more information visit the Fight the Bite Colorado website at: