SMITH VALLEY - Even though mosquitoes near the west end of Wilson Canyon were found with St. Louis encephalitis, it is not likely to develop into a serious health problem
"Because of enhanced surveillance, we were able to catch it early on and with an immediate and adequate response, we knocked it out," said Bud Stinson, district manager for the Mason Valley Mosquito Abatement District.
Last week the district, in its regular trapping and testing of mosquitoes in Smith and Mason valleys, found some of the insects were carrying the illness.
"We trap them every two weeks in the area and the state does the testing," he said.
According to the Centers for Disease Control and Prevention Web site, St. Louis encephalitis is a flavivirus spread by mosquitoes. The insects pick up the virus from feeding on infected birds, similar to West Nile virus.
The disease is not transmitted from person to person and isn't transmitted directly from birds to people. The CDC estimates that 3 percent to 30 percent of cases are fatal.
"A migratory bird with the virus probably came back from down south and nested in that area, and got bit by the mosquitoes," Stinson said.
Symptoms of St. Louis encephalitis include infections, fever and headaches. A severe case may also include neck stiffness, stupor, disorientation, coma, tremors, convulsions and spastic paralysis.
The incubation period for St. Louis encephalitis is usually 15 days.
There is no vaccination and no therapy for treatment.
Stinson said the district would continuing monitoring the area's mosquito population.