St. Louis Encephalitis has traveled to Tulare County

Tulare County sees the first case of mosquito transmitted disease St. Louis Encephalitis which has few symptoms other than mild flu like symptoms, but could leave a harmful stamp on infected individuals

TULARE COUNTY –Tulare County warns residents to watch for mosquito breeding grounds as the public health department announces its first confirmed case of St. Louis Encephalitis, a disease similar to West Nile Virus.

Tulare County Public Health has confirmed the first human case of St. Louis Encephalitis (SLEV) in a Tulare County resident. The virus presents itself similar to that of West Nile Virus, which has also been seen in the county this year. County residents are urged to take the necessary precautions against mosquito bites as SLEV is present and mosquito samples positive for West Nile Virus have been detected in multiple locations within the county.

“Due to this increased activity and these reported cases, we strongly encourage residents to use safeguards to reduce their risk of contracting both West Nile Virus and SLEV through mosquito bites,” Dr. Karen Haught, Tulare County public health officer said.

There are currently an additional five cases under investigation and may result in illness due to either SLEV or West Nile Virus. SLEV is in the same virus family as West Nile and as a result, both viruses are similar and transmitted to humans when bitten by the same type of mosquito. Horses are also particularly susceptible to infection from West Nile virus.

According to the Centers for Disease Control and Prevention (CDC) there is no vaccine or medication to treat the virus for humans. Those infected with SLEV will have few to no symptoms, same goes for those infected with West Nile. The most common symptoms for those infected with SLEV appear five to 15 days after being infected. The symptoms will appear as mild, flu-like symptoms, including fever and headache. In severe cases, SLEV can affect the central nervous system, resulting in meningitis and/or encephalitis and can result in death or long-term disability. 

Those infected with West Nile rarely show symptoms, but one in five people will develop a fever along with additional symptoms as soon as two days after being infected or as late as 14 days after being infected. Similar to SLEV, severe cases of West Nile Virus can affect the central nervous system, resulting in meningitis and/or encephalitis and can result in death or long-term disability.

Residents are urges to increase their awareness of potential breeding grounds on or around their properties.  Tulare County Public Health Department advised residents to be on the lookout for homes that are unoccupied, since they may have swimming pools or backyard ponds that are breeding grounds for mosquitoes. 

It is recommended that residents take the following precautions to avoid being bitten, thereby reducing their risk for exposure to both West Nile Virus and SLEV: 

  • Use EPA-registered insect repellent such as DEET. Always follow label instructions carefully. 
  • Dress in long sleeves and pants during dawn and dusk or in areas where mosquitoes are active. 
  • Drain standing water that may produce mosquitoes. 
  • Repair or replace door and window screens that have tears or holes

Contact your local mosquito abatement district if you see areas of standing water that may be a breeding area for mosquitoes. Tulare County has three mosquito abatement districts providing abatement services to residents: 

  • Delta Vector Control (Mosquito Abatement District) – Covering the northern portion of Tulare County. Contact the Visalia Office at (559) 732-8606 or visit online at: 
  • Tulare Mosquito Abatement District – Covering the western portion of Tulare County. Contact the Tulare Office at (559) 686-6628 or visit online at: 
  • Delano Mosquito Abatement District – Covering the southern portion of Tulare County. Contact the Delano Office at (661) 725-3114 or visit online at: 

For horses, there is a vaccine to prevent these diseases, and horse owners should have their horses vaccinated annually and keep vaccinations up to date as a preventive measure. For more information, visit the California West Nile website at 

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