June 28, 2024 at 5:58 pm

Public Health Officials find St. Louis Encephalitis and West Nile Virus in Local Mosquito Pools

IMPERIAL COUNTY- The Imperial County Public Health Department announced today that a mosquito pool tested positive for St. Louis Encephalitis Virus (SLEV) and a separate pool for West Nile Virus (WNV). The SLEV mosquito pool was collected in the City of Imperial, while the WNV mosquito pool was from the Salton Sea Beach area. The samples were collected on June 25th and results were received today, June 28th. This is the first positive mosquito pool for SLEV and second positive mosquito pool for WNV identified in Imperial County this year.

“Mosquitoes become more active during the warmer months of the year, which increases the risk of mosquito- borne diseases. These diseases can be serious; therefore, it is important that individuals protect themselves from mosquito bites,” stated Stephen Munday, M.D., Health Officer.

The Public Health Department’s Vector Control Program has approximately 52 mosquito traps placed in strategic areas throughout the county, mostly within city limits. The traps are checked several times a week and mosquito pools are collected weekly. “Our agency will continue monitoring disease activity and treat affected areas,” said Jeff Lamoure, Deputy Director of Environmental Health. “Although the positive mosquitoes were collected in a specific area, all Imperial County residents should take precautions, like wearing insect repellent and minimizing outdoor activity at dusk and dawn, when mosquitoes are most active.”

Symptoms of Saint Louis Encephalitis (SLE) include fever, headache, nausea, vomiting, and tiredness. Severe neuroinvasive disease (often involving encephalitis, an inflammation of the brain) is more common in older adults. There are no vaccines to prevent nor medications to treat SLE. SLE is transmitted to humans through the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds.

As far as the symptoms of WNV are concerned, these include fever, nausea, vomiting and seizures. Most individuals who are infected with WNV will not experience any illness. Others will have only mild symptoms, such as fever, headache and body aches. However, WNV can be severe in the elderly and individuals with lowered compromised immune system. WNV is transmitted to humans through the bite of an infected mosquito. Mosquitoes can become infected when they feed on infected birds.

Individuals can reduce their risk of mosquito-borne diseases by taking the following precautions:

  • Limit time outdoors during dawn and early evening.
  • When outdoors, wear loose-fitting, light-colored, long-sleeved shirts and pants when mosquitoes are most active (during dusk and dawn).
  • Apply insect repellent that contains DEET, Picaridin, or oil of lemon eucalyptus according to label instructions to prevent mosquito bites.
  • Make sure that doors and windows have tight-fitting screens. Repair or replace screens that have tears or holes.
  • Eliminate all sources of standing water on your property that can support mosquito breeding by:
  • Draining or eliminating, old tires, buckets, plastic covers, toys, or any other container where mosquitos can breed.
  • Emptying and changing the water in birdbaths, fountains, wading pools, rain barrels, and potted plant trays at least once a week to destroy potential mosquito habitats.
  • Draining or filling temporary pools of water with dirt.
  • Keeping swimming pool water treated and circulating.
  • Contact Vector Control if there is a significant mosquito problem where you live or work.

If you think you or anyone in your household has symptoms that are causing you concern, contact your healthcare provider.

The United States Environmental Protection Agency (EPA) has a useful search tool that the public can use to find the repellent products most appropriate for them and their families. The tool is available at https://www.epa.gov/insect-repellents/find-repellent- right-you.


For general information about WNV or to report a problem with mosquitoes in Imperial County please contact Environmental Health Division at (442) 265-1888. For addition information related to West Nile Virus (WNV) or St. Louis Encephalitis Virus (SLEV), please visit California Department of Public Heath’s website:Westnile.ca.gov | California  West Nile Virus Website https://www.cdph.ca.gov/Programs/CID/DCDC/Pages/SLE.aspx