MADERA - Madera County is reporting a fatality from St. Louis Encephalitis Virus (SLEV) in a male in his 90s from August 2020. This is the first confirmed case of SLEV in the state of California in 2020 and the first case in Madera County since 1976. While preliminary testing originally suggested the West Nile Virus, further testing has now confirmed SLEV as the final diagnosis.
Saint Louis Encephalitis is transmitted to people through the bite of an infected mosquito. Testing of mosquitos in Madera had demonstrated one pool testing positive recently for SLEV. Mosquito abatement control was notified at the time of the original diagnosis and has been spraying in the areas where the positive tests were localized. SLEV is similar to West Nile Virus: both can result in infections of the brain, paralysis, and rarely death.