Mosquito traps in Canyon and Payette counties tested positive for West Nile virus this week.
On Tuesday, a mosquito trap in the Jewel Wetlands area, north of Payette, tested positive for the West Nile virus.
On Wednesday, a Canyon County trap located along the Boise River, near Caldwell Ponds and Rotary Pond, north of Caldwell, also tested positive.
Canyon County Mosquito Abatement District Director Ed Burnett said this is one of the earliest detections of West Nile virus since 2006, according to a news release Thursday.
Routine mosquito abatement operations will continue throughout Canyon County, however nighttime ultra-low volume fogging will take place in the affected area and will continue Friday at sundown, if weather permits.
Larvicide operations have been ongoing, but hot temperatures have resulted in a spike in population of the species of mosquitoes that carry West Nile virus, Burnett said.
An aerial mosquito larvae control operation is also being scheduled along the Boise River from Curtis Park along Channel Road to Look Lane, south of Highway 20.
In Payette County, the abatement program is increasing mosquito surveillance in the area and continuing to locate and treat larvae infested waters. In addition, ground adulticide applications, made via truck-mounted sprayers, will be increased in the surrounding areas of Jewel Wetlands.
Officials warned residents of the receding flood waters that are expected to create standing water pools, potentially attracting mosquitoes with West Nile virus. West Nile virus can be transmitted to humans, horses and other animals by infected mosquitoes after the mosquitoes have bitten infected birds, which are the primary hosts of the virus.
Most people bitten by West Nile virus-infected mosquitoes experience either no symptoms, or possibly a short period of mild flu-like symptoms.
Symptoms of human West Nile virus infections typically begin within 14 days following the insect bite and consist of low-grade fever, muscle and joint aches, fatigue, and headaches.