Tests Detect Growing Threat of Encephalitis

Chances of catching a mosquito-borne encephalitis virus that can lead to serious illness or death are increasing throughout Southern California, according to state and county health authorities.

Signs of the growing presence of the disease have been picked up from laboratory tests of so-called sentinel flocks of chickens maintained by vector control officers in various counties.

After what he called a “sort of a surprise epidemic” of the virus in 1984 that killed one person in Los Angeles County and affected 26 others in Los Angeles, Orange, Riverside and San Diego counties, Don Woneldorf, chief of the vector surveillance and control branch of the state Department of Health Services, said Friday that it appears there could be an “avalanche” of cases later this summer.

Didn’t Look for It

“We actually didn’t know about (the presence of) this encephalitis in the southern part of the state until recently, after 1984’s figures came in,” he said. “There was one case in 1957 (in the Orange County-Los Angeles metropolitan area) and none at all until last year. We really didn’t look for it.”

Gilbert Challet, manager of the Orange County Vector Control District, said three sentinel flocks, located in Irvine, San Clemente and at Featherly Regional Park northeast of Anaheim, are being monitored. Five flocks are in Los Angeles County, and others are in Ventura, Riverside and San Diego counties.

The chickens are immune to the virus, but the encephalitis strains show up in their blood, indicating the presence of the disease-carrying mosquitoes.

It was in the Irvine flock last September that proof was first found that such mosquitoes were in heavily populated neighborhoods in the southern part of the state.

Point Mugu Report

Woneldorf and Challet said flocks checked this spring at the Colorado River communities of Palo Verde and Needles, and Heber and Seeley in the Imperial Valley, provided “positive signs of the virus.” They added that the most recent report came from Point Mugu in Ventura County, and said they were disturbed that the mosquitoes are appearing in the coastal zone.

“And it’s all happening much earlier this year than in 1984,” Woneldorf said.

Art Tilzer, head of the Los Angeles County Vector Control District, said the “bottom line in heading off diseases is to eliminate mosquitoes.”

To help accomplish this, he and Challet urged people to get rid of water that collects in various kinds of containers in their yards. The insects breed in still water.

Fred Beams, another official at the Orange County Vector Control District, suggested that campers near the Colorado River this summer take special precautions to protect themselves from mosquito bites.

A spokeswoman for the Los Angeles County Health Department compares the onset of encephalitis to that of flu, meaning anything like a bad cold or diarrhea, with symptoms that may include fever, headaches, stiff joints, and changes in mental state and physical condition.

She said encephalitis can be treated only in a “supportive way,” and just has to run its course because there are no drugs or antibiotics to treat it.