Five additional mosquito samples in Placer County have tested positive for West Nile virus (WNV) today, bringing the count to 27 WNV-positive mosquito samples in the county for the year.

“This increase of activity is not unexpected.  With temperatures high enough for mosquitoes to thrive, but not high enough to keep people indoors, we must remind folks that West Nile virus is still a threat and that precautions  need to be taken to reduce risk for exposure,” stated Joel Buettner, General Manager of the Placer Mosquito and Vector Control District.  Total mosquito numbers are significantly up and West Nile virus activity is widespread along the western part of the county according to Buettner.

Due to this latest development, the District is responding with aerial treatments in the agricultural areas in the western county and ground-based treatments in Sheridan, Lincoln, and Roseville in the following days.

The District hopes that its adult treatments, combined with its proactive approach to controlling immature mosquitoes can stem the spread of WNV to other areas in Placer County.  The District is also recruiting the public’s help in identifying additional areas of increased virus activity by reporting dead birds, standing water, or other mosquito issues.

The Placer Mosquito and Vector Control advises the public to implement the 3 Ds of protection:

  • Drain any standing water that may produce mosquitoes.
  • Defend yourself and your home by using an effective 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 more detailed information on the planned treatments, visit

2013 Placer County West Nile virus activity update: 5 dead birds, 0 sentinel chickens, 27 mosquito samples, and 0 humans have tested positive for West Nile Virus to date