County of El Dorado logoEl Dorado County health officials confirmed the first human death related to neuroinvasive West Nile Virus this year. The death occurred at the end of October. The individual was over the age of 55 and resided on the West Slope of El Dorado County. 

West Nile Virus (WNV) is a mosquito-borne virus that causes disease in humans, horses, and birds. WNV spreads to people through the bite of an infected mosquito. While most people  (about 4 out of 5) who are infected with WNV do not have symptoms, some individuals infected with WNV will become very sick. People over the age of 60, individuals with certain types of medical conditions (such as cancer and diabetes) and individuals who have received organ transplants are most at risk for developing severe symptoms from WNV. 

There is no specific treatment or vaccine for WNV, so preventative measures should be taken to minimize risk.  

Mosquito surveillance programs are in place throughout the County. Activities include trapping and identifying mosquitoes, treating neglected swimming pools, and reporting and testing dead birds. Medical providers are required to report all cases of West Nile virus to the El Dorado  County Public Health Division, which will coordinate with the Environmental Management Department to investigate the geographic area (if available) for surveillance activities. 

The following tips are given to help prevent West Nile Virus: 

  • Drain standing water around the property and keep water in swimming pools, ponds and water troughs circulating or treated with “Mosquito Dunks” or mosquito fish.
  • Apply insect repellent that contains DEET or another approved substance (e.g. picaridin, oil of lemon eucalyptus or IR 3535) on exposed skin when outdoors. 
  • Dress in long sleeves and pants when outdoors among mosquitoes. Mosquitoes are most active at dusk and dawn. 
  • Make sure doors and windows have tight-fitting screens, kept in good condition.
  • Report dead birds and tree squirrels to the State WNV hotline at (877) WNV-BIRD (877- 968-2473) or online at Wear gloves and place the dead bird or squirrel in a double plastic bag if you dispose of it yourself. 

Mosquito problems and neglected swimming pools should be reported to the Environmental  Management Department at (530) 621-5300 on the West Slope or (530) 573-3450 in South  Lake Tahoe. Additional WNV information can be found at or