St. Louis Encephalitis Virus Detected in Indian Wells Mosquitoes

St. Louis encephalitis virus (SLEV) has been detected in a mosquito sample near the area of Vintage Drive and Portola Avenue in Indian Wells. This is the first detection of SLEV for Indian Wells and becomes the furthest west this virus has ever been found in the Coachella Valley since SLEV reappeared in 2015 mosquito samples. So far this year, there have been 95 SLEV positive samples and 509 West Nile Virus (WNV) positive samples. As of today, no human cases of SLEV have been reported in Riverside County this year but the California Department of Public Health has confirmed 11 human cases of WNV in Riverside County. 

District staff will post disease notification signs in communities located near the trap locations and will intensify mosquito surveillance with an increase in traps and inspections for mosquito breeding sites. Technicians will also carry out larval and adult mosquito control as necessary in the surrounding area in an effort to reduce the number of mosquitoes and interrupt further transmission of the virus.

“Mosquitoes and mosquito-borne illnesses are a real threat. You must do everything you can to not get bit.” said Tammy Gordon, Public Information Officer for the District. “It’s not worth the risk. We have not had this amount of virus activity in the valley for either virus since they were detected - and that means the risk a person can get sick is greater.”

 SLEV and WNV are transmitted to humans via the bite of an infected mosquito. Mosquitoes are infected when they feed on birds carrying the virus. Most individuals infected with SLEV or WNV will not experience any illness. Others will have flu-like symptoms, such as fever, headache and body aches. In severe cases, people will need to be hospitalized, and in rare cases the disease can be fatal. People over 50 years old, or individuals with lowered immune systems are at greater risk of experiencing severe symptoms when infected. Anyone with symptoms should contact their health care provider. 

In addition to the SLEV and WNV-positive mosquito samples, detections of the invasive mosquito species Aedes aegypti continue across the Valley. This invasive mosquito species is capable of transmitting deadly viruses including dengue, chikungunya, Zika, and yellow fever. Mosquito control applications have been scheduled in Cathedral City and Palm Desert. See their website for details.

The District is asking the public to do all they can to prevent mosquito breeding in their neighborhoods and to report increased mosquito activity.

Prevent mosquitoes around your home:

  • Inspect yards for standing water sources and drain water that may have collected under potted plants, in birdbaths, discarded tires, and any other items that could collect water.
  • Check your rain gutters and lawn drains to make sure they aren’t holding water and debris.
  • Clean and scrub bird baths and pet watering dishes weekly.
  • Check and clean any new potted plant containers that you bring home because they may have Aedes aegypti eggs. The eggs can remain viable in dry areas for months.

Prevent mosquito bites:

  • Avoid going outside in the hours around dawn and dusk when mosquitoes that can transmit SLEV and WNV are most active.
  • Wear EPA registered ingredients such as DEET, picaridin, oil of lemon eucalyptus, or IR3535 to exposed skin and/or clothing (as directed on the product label).
  • Wear long-sleeve shirts, long pants, socks and shoes when mosquitoes are most active.
  • Be sure window and door screens are in good repair to prevent mosquitoes from entering your home.

For more information contact the Coachella Valley Mosquito and Vector Control District at (760) 342-8287.