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Public Urged to Take Precautions Against West Nile Virus

August 08, 2013

With the warm summer weather upon us, Placer County Public Health officials are reminding the public to take precautions against West Nile virus (WNV), a preventable, mosquito-borne disease that can infect humans. The disease is typically spread when a mosquito bites an infected bird, then bites a human. While most people who are infected with the virus will not become ill, in certain populations the disease can cause serious illness and even death. 

The Placer Mosquito and Vector Control District has advised that there is increased mosquito activity and is conducting additional control activities and surveillance in and around areas where they have detected WNV. The District has also been taking appropriate control measures to limit the numbers of mosquitoes in areas with a higher risk of WNV transmission. 

In Placer County, most human cases have occurred between mid-July and the end of August the last few years. 

“The Placer County Division of Public Health would like to remind our residents to be aware of a few simple precautions that can lower or eliminate the possibility of becoming infected with West Nile virus,” said Wesley G. Nicks, Placer County Public Health Division Director. “First, avoid the outdoors in the morning or evening when mosquitoes are most active. If you’re going to be outside anytime mosquitoes are present, cover yourself and use an effective mosquito repellent. In addition, check your window and door screens to ensure they are intact and drain standing water as it provides a place for mosquitoes to lay their eggs.”  

About 20 percent of those infected with WNV may experience mild to moderate flu-like symptoms, called West Nile fever, which may be prolonged. About one in 150 infected people will become very ill. People over 50 and people with suppressed or compromised immune systems are more likely to become seriously ill. West Nile virus is rare, but people with symptoms, including high fever, severe headache and stiff neck, should contact their health care providers immediately.  

The Placer County Division of Public Health and the Placer Mosquito and Vector Control District offer the following reminders and information about preventing the spread of West Nile virus:

  • 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. 
  • If you know of swimming pools that are not maintained and become “neglected,” report them to the District at (916) 380-5444. These pools are ideal breeding grounds for mosquitoes.
  • As dead birds are a surveillance tool to help track West Nile virus, you are encouraged to report them by calling the California WNV hotline at 1-877-WNV-BIRD (1-877-968-2473), or online at
  • Horses are vulnerable to West Nile virus, and the mortality rate for unvaccinated horses is very high. Contact your veterinarian about protective immunizations. West Nile does not spread between humans and horses.  

Placer County residents with questions about West Nile virus can call Placer County Public Health, or visit If residents have questions about mosquitoes, are having mosquito problems, or need mosquito fish, they should call the Placer Mosquito and Vector Control District or visit the District’s website at