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Two More West Nile Virus Cases Detected

September 20, 2010

AUBURN, CALIF. – Two more Placer County residents have become ill from West Nile virus (WNV). The two residents live in Roseville and Lincoln. These mark the second and third detected cases this year of the mosquito-borne disease. Both individuals are recovering at home. In August, another Roseville resident was diagnosed with the first WNV case in the county this year.

Fight The Bite West Nile Virus prevention iconSo far this year in California, there have been 34 counties where the disease has been detected and there have been 45 human cases statewide, including one fatality in Fresno County. Positive dead birds have been found in 25 counties and nine counties have had horses diagnosed with the disease. In 2009, there were no human cases reported in Placer County. In 2008, there were six.

“Even though summer is winding down, mosquitoes are still active and human infections with West Nile virus are not unusual at this time of year,” said Dr. Mark Starr, Placer County Director of Community Health and Clinics. “This disease is preventable if people follow a few simple precautions. First, avoid the outdoors in the morning or evening when mosquitoes are most active. If you’re going to be outside at those times, cover yourself and use an effective mosquito repellant. In addition, check your window and door screens, and drain standing water as it provides a place for mosquitoes to lay their eggs.”

Most people who are infected with West Nile virus will not become ill. However, for certain populations, the disease can cause serious illness and death. 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 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 provider immediately.

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

  • Drain standing water weekly, since that's where mosquitoes lay eggs. Check your yard for water in old tires, flowerpots and bird baths.
  • Avoid mosquito bites by staying indoors at dusk and dawn when mosquitoes are most active, and assure that your window screens are in good condition.
  • If you must be outdoors when mosquitoes are active, wear long sleeves and long pants, and use an insect repellant that contains DEET, picaridin or oil of lemon eucalyptus.
  • 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.
  • Concerned residents may also request an inspection of a property or report a dead bird online through the District’s website: or by calling the District at (916) 380-5444.
  • 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 Community 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 .