Kern County Public Health Services has received confirmation of the first Kern County St. Louis Encephalitis-associated death this year. The Kern County resident had pre-existing health conditions.


“This is a tragic reminder that serious diseases can be transmitted by mosquitoes,” says Matt Constantine, Director of Kern County Public Health Services. “We strongly encourage residents to protect themselves and family members from mosquitoes.”

Related: 13 Diseases You Can Get From Mosquitoes

St. Louis encephalitis virus (SLEV) is transmitted to humans by the bite of an infected Culex mosquito, the same mosquito that transmits West Nile virus. Like West Nile virus, SLEV is not transmitted person to person. SLEV has been found historically in many regions of California, such as the Central Valley and southern California, but has been detected rarely.

Most people bitten by an SLEV-infected mosquito will have few to no symptoms. Others will develop mild flu-like symptoms, including fever and headache from 5 to 15 days after being infected. Severe SLEV can result in serious symptoms that affect the central nervous system such as stiff neck and mental confusion. Elderly people and those with weakened immune systems are more at risk for developing severe symptoms of the disease.

There is no specific treatment for SLEV. Severe SLEV illness is treated by supportive therapy that may include hospitalization, respiratory support, IV fluids, and prevention of other infections.