The East Side and Turlock Mosquito Abatement Districts (MADs) have received confirmation that a mosquito sample from Stanislaus County has tested positive for St. Louis Encephalitis Virus (SLEV). SLEV is related to West Nile Virus (WNV) and is transmitted via the bite of Culex mosquitoes, the same mosquitoes that transmit WNV.
Like WNV, most people who become infected with SLEV will never feel sick. Most people who do feel sick will have mild flu-like symptoms. A small number of people will have severe disease with headache, confusion, disorientation, and dizziness. Seizures, paralysis, coma, and sometimes death may occur. Severe disease is more likely in people who are older and those with weakened immune systems.
There is no specific treatment for SLEV.
“It is very important that people take precautions to protect themselves and their families from mosquito bites,” advised Dr. Julie Vaishampayan, Stanislaus County Public Health Officer.
This is the first detection of SLEV in Stanislaus County in over 40 years. Statewide, there have been 17 mosquito samples that have tested positive for SLEV this year. They are from four counties including Fresno, Kern, Kings and Riverside. There have been no reports of SLEV in people this year. During 2016 there were three reports of people with SLEV in California. These were the first cases in California since 1997.
WNV detection in mosquitoes is increasing; a total of 80 mosquito samples have tested positive this year in Stanislaus County. WNV has also been confirmed in two dead birds.
The MADs will continue with their surveillance programs identifying mosquito breeding sources and mosquito-borne disease activity. They will treat according to their surveillance results. The districts anticipate more SLEV and WNV detections in the coming months and remind residents they can help by taking the following precautions:
• Dump or drain standing water. These are places mosquitoes like to lay their eggs.
• Defend yourself against mosquitoes by using repellants containing DEET, Picaridin or Oil of Lemon Eucalyptus.
• Avoid being outdoors at dusk and dawn. These are the times when WNV carrying mosquitoes are generally most active.
• Report neglected swimming pools to your local MAD.
• Use tight fitting door and window screens to keep mosquitoes from entering your home.
For additional information or to request service, residents should contact their local Mosquito Abatement District. Stanislaus County residents north of the Tuolumne River contact: Eastside Mosquito Abatement District at (209) 522-4098; www.eastsidemosquito.com; those south of the Tuolumne River contact: Turlock Mosquito Abatement District at (209) 634-1234; www.turlockmosquito.org.
Resources for additional information on St. Louis Encephalitis are California Department of Public Health, https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/SLE.aspx and Centers for Disease Control and Prevention, https://www.cdc.gov/sle.