The Placer Mosquito and Vector Control District reported today that a mosquito sample has tested positive for West Nile virus this week.  The sample was collected from a site along the county’s western border.  Mosquito numbers have also increased in the past week, most likely from sustained higher temperatures.  District staff have been aggressively treating immature mosquito populations out in the agricultural areas to the west, in an effort to stem the development of adult mosquitoes.  “This kind of mosquito and West Nile virus activity is not unusual for this time of year. Mosquito abundance is not the only thing that is impacted with hot weather. West Nile virus activity in birds and mosquitoes also tends to increase with higher temperatures,” states Joel Buettner, District general manager.

Due to this latest development, the District is planning ground-based treatments for adult mosquitoes.  More information about the planned treatment is available on the District’s website  The Placer Mosquito and Vector Control District advises the public to implement the 3 Ds of protection:

  • Drain or dump any standing water that may produce mosquitoes.
  • Defend yourself and your home by using a CDC-recommended insect repellent and dressing protectively when outside, and making sure screens on doors and windows are in good condition.
  • Contact the District for any additional help controlling mosquitoes around your home.

For a list of CDC-recommended repellents, please visit the District’s website or the Centers for Disease Control and Prevention: Placer residents can also call Placer County Public Health at 530-889-7141.


2017 Placer County West Nile virus activity update: 0 dead birds, 0 sentinel chickens, 1 mosquito sample, and 0 humans have tested positive for West Nile Virus to date.