First West Nile Virus Positive Mosquitoes Detected In Placer County

Placer Mosquito urges County residents to protect themselves from mosquito bites

ROSEVILLE, Calif., July 22, 2020 – The Placer Mosquito and Vector Control District has confirmed the first mosquito sample to test positive for West Nile virus in 2020. The mosquitoes were collected in a mosquito trap in western Placer County near Baseline and Pleasant Grove Roads.

Since spring, District technicians have treated immature mosquito populations to prevent adult mosquito development.  Despite our best efforts, as the temperature continues to rise, adult mosquito abundance and WNV activity in birds and mosquitoes increase at this time of year.

“It is not unusual to detect WNV activity at this time of year. We work hard to conduct prevention measures to limit adult mosquito abundance in summer. Now that WNV risk is heightened, we will analyze what treatments need to be done to help protect residents. We also encourage residents to wear an EPA-registered repellent to protect themselves from mosquito bites,” stated Joel Buettner, Placer Mosquito General Manager.

WNV is a potentially serious illness transmitted through the bite of a mosquito and there is no cure. The best ways to avoid WNV is to prevent mosquito bites with an EPA-registered repellent, dump and drain standing water on your property to prevent mosquito breeding and if you think you have a mosquito problem, contact the District to submit a service request. To date, there has been no information or evidence to suggest that the new coronavirus could be transmitted by mosquitoes.

For more information, contact the Placer Mosquito and Vector Control District at (916) 380-5444 or Follow the District on Facebook, Twitter and Instagram: @placermosquito. For a list of EPA-registered repellents, please visit or