Local News in Brief : Mosquitoes at Sepulveda Dam Found to Bear Encephalitis

A strain of encephalitis virus believed to have caused at least one death in Los Angeles County last year has been found in mosquitoes at Sepulveda Dam near Encino, county health officials said Wednesday.

The mosquitoes, which bear St. Louis encephalitis, were collected from the dam area July 16 as part of the county’s mosquito abatement program, Dr. Shirley Fannin of the county Department of Health Services said.

No human cases of St. Louis encephalitis have been reported this year, but Fannin said it may take several weeks for the virus to show up in humans. Last year, two weeks elapsed between the time the virus was identified in mosquitoes and the first human case was reported.

St. Louis encephalitis is a viral inflammation of the brain and central nervous system transmitted by the bites of infected mosquitoes. In mildest cases, victims may suffer severe headaches, fever and nausea, according to Fannin. Severe cases can lead to paralysis, coma and death.

Health officials said 26 cases of the virus were reported in Southern California last year, including 16 cases in Los Angeles County, with as many as eight of those in Reseda, Encino and Van Nuys.

County health officials said they have been testing mosquito pools more often since the virus-bearing insects were found at Point Mugu in Ventura County two weeks ago.

Fannin said mosquitoes active at night are likely carriers of the virus. She said residents can eliminate potential breeding sites in their backyards by getting rid of standing water in which the mosquitoes breed.