2 Encephalitis Cases in July Spark Concern

Confirmation of the first two cases of St. Louis encephalitis this year in Los Angeles County has sparked concern that a larger number of cases than usual may occur during the coming months, health officials said Thursday.

“We’re concerned because the cases were reported earlier in the season than usual and may mean that we will see more cases than in 1984, which was more severe than usual,” said Dr. Steve Waterman of the county Department of Health Services. Sixteen cases and one death occurred in the county in 1984. Only one case was reported last year.

St. Louis encephalitis, caused by a virus, is transmitted to humans by mosquitoes that become infected when they bite birds carrying the virus. In humans, it causes inflammation of the brain and the nervous system. Symptoms range from fever and headache in mild cases to delirium, seizures and death in severe ones.

Waterman said the two cases this year occurred in July. One case was a 66-year-old male resident of Norwalk. The other was a 59-year-old Covina man. Both were hospitalized for several weeks and have recovered, Waterman said.

The Department of Health Services, the Southeast Mosquito Abatement District and the state Department of Health Services have begun studies on adult mosquitoes to determine the extent of the virus in the county.

Officials are encouraging county residents to help control mosquitoes by getting rid of breeding sites such as pools of water in planters, discarded tires, cans, buckets and other sources around homes.

Residents should also avoid evening activities in mosquito-infested areas, or wear long-sleeve shirts and pants and use insect repellents, they said.

An aggressive mosquito known as the tiger mosquito, which spreads tropical fevers in Asia, was reported by federal health officials Thursday to have recently formed breeding colonies in seven southeastern states. The tiger mosquito has not been detected in California.