The Fresno Mosquito and Vector Control District has confirmed that Culex mosquitoes in Fresno have tested positive for the Saint Louis Encephalitis (SLE) virus.

According to a press release from the Fresno County Department of Public Health (FCDPH), the infected mosquitoes were found in the areas of East Floradora Avenue and Highway 41, and Shields and Van Ness avenues. The notification was made by the FCDPH Thursday.

SLE virus is mosquito-transmitted and causes inflammation of the brain (encephalitis). Most infected persons have no apparent signs of illness, but symptoms can include fever, headache, dizziness, nausea and fatigue. The time from when an individual is bit by an infected mosquito to onset of illness can range from 5 to 15 days. Signs and symptoms last from a period of several days to a week.

Severe symptoms include fever, headache, stiff neck, confusion, and an altered level of consciousness. Coma, convulsions, paralysis and sometimes death may occur (with a 5-15 percent overall case fatality ratio). Elderly people and those with a weakened immune system are more at risk for developing severe symptoms of the disease.

There is no specific vaccine for SLE and health care providers should evaluate individuals who believe they are at risk. FCDPH has recommended the use of repellent along with permethrin, an insecticide used for clothing. The department further advised to protective clothing and avoiding the peak biting hours between dusk and dawn when possible.

FCDPH also cautioned against leaving standing water around the house and changing whenever possible to avoid the laying of eggs.