St. Louis encephalitis resurfaces in Orange County

Mosquitoes collected in Anaheim and Westminster have tested positive for St. Louis encephalitis — the first occurrence in those cities in three decades, Orange County officials announced Tuesday.

The mosquitoes were collected late last week along Old Bolsa Chica Road in Westminster and near Dale and Orange avenues in Anaheim, according to Heather Hyland of the Orange County Mosquito and Vector Control District.

The last time any St. Louis encephalitis-positive mosquitoes were found in those areas was 1987, according to the district. Mosquitoes testing positive for the virus
were found in 2017 near the vector control offices in Garden Grove, the agency said.

Most people bitten by a St. Louis encephalitis-infected mosquito do not become ill, but those who do will experience symptoms such as fever, headache, nausea, vomiting and fatigue. Older adults can experience inflammation of the brain, and in rare cases a person can sustain a long-term disability or die.

The last time anyone in Orange County was afflicted with
the virus was in the fall of 1984. There were six positive samples St. Louis encephalitis in mosquitoes from 1984 through 1987 in the county.

Vector control officials encouraged residents to dump any standing water around their homes to stymie breeding grounds for the insects.