MOUNTAIN VIEW, Calif. (KRON) – Mosquitos in the Santa Clara County area have tested positive for West Nile Virus, and the county’s vector control district will be conducting a treatment from trucks on Thursday night.

This map, provided by Santa Clara County, shows the area that will be treated for West Nile Virus on Thursday. (Map courtesy of Santa Clara Co.)

The mosquitos were found “in a small area” that includes ZIP codes 94024, 94040 and 94087 in Mountain View, Los Altos Hills and Sunnyvale.

“Weather permitting, this area will be treated to reduce adult mosquito populations with the use of truck-mounted equipment on Thursday, Sept. 22, starting around 10 p.m. and concluding a few hours later,” a press release stated. “The District’s mosquito management program largely focuses on preventing mosquitoes from reaching the adult biting stage by proactively targeting immature stages of mosquitoes found in standing water. When a mosquito with West Nile Virus (WNV) is detected, however, the District takes the added step of conducting adult mosquito control treatment to reduce the mosquito population in the area, which decreases the risk of a WNV-human infection.”

During the summer and early fall, the presence of warmer water in the area leads to more West Nile Virus.

“The district has a dedicated surveillance program to detect the presence of diseases like West Nile virus, St. Louis encephalitis and western equine encephalitis, all of which are transmitted through the bite of infected mosquitoes,” the press release continued. “The data collected through surveillance is used to predict locations that are more likely to have these disease-transmitting mosquitoes.”

People in the affected zip codes will be alerted via Nextdoor and the county’s emergency alert phone system, and the treatments themselves should last about four hours.

“Mosquito treatments pose minimal risk to people, pets, animals and the environment when applied by a licensed vector control professional following label instructions,” the press release continued. “Those who would like to take extra precautions can keep family members and pets inside during the approximately four-hour treatment, with windows and doors shut. By sunrise, the insecticide will quickly break down with the sunlight.”

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West Nile Virus has killed “nearly 400” Californians since 2003, out of 7,000 confirmed cases, the press release states. There were 12 deaths last year.

“WNV infection does not cause symptoms in most people; however, for some individuals it can cause fever, headache, body aches and, in severe cases, significant neurological damage or death,” the press release continued. “Individuals with certain chronic medical conditions (such as diabetes, high blood pressure, cancer and kidney disease) and the elderly are most at risk for serious complications.”