The Placer Mosquito and Vector Control District reported today that four mosquito samples have tested positive for West Nile virus over the past week.  The samples were collected from sites 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.  “At this point in the season, we are trying to minimize the number of infected adult mosquitoes around people by doing targeted adult mosquito treatments ,in addition to continuing our preventative larval control activities.” states Joel Buettner, District General Manager, “ We also need everyone to do their part to protect themselves from mosquito bites by wearing protective clothes and repellent if they are outside around dawn and dusk”. Due to this latest development, the District is planning aerial treatments for adult mosquitoes in specific rural areas.  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.


2019 Placer County West Nile virus activity update: 0 dead birds, 0 sentinel chickens, 4 mosquito sample, and 0 humans have tested positive for West Nile Virus to date.