Countywide : Officials Step Up Attack on Mosquito Population

Due to several cases of mosquito-borne encephalitis last fall--one of which proved fatal--county health officials have expanded a disease surveillance program and are asking the public to help stem the spread of the potentially dangerous insect.

B. Fred Beams, assistant manager and educational coordinator for the Orange County Vector Control District, said backyard containers such as buckets, barrels, old tires, wheelbarrows, fish ponds and neglected swimming pools are favorite haunts for the 21 varieties of mosquitoes found in the county.

One wheelbarrow half full of water can provide breeding grounds for more than 10,000 adult mosquitoes a week. The water does not have to be stagnant--merely standing--for the bloodthirsty insects to thrive, Beams said. As many as 200,000 could breed in a neglected pool during a week, he said.

Last year’s outbreak of St. Louis encephalitis was the first of its magnitude on record in an urban California area, said Charles Myers, regional supervisor for vector biology in the state Department of Health Services.

In 1983, for the first time on record, two cases were diagnosed in Los Angeles. Then, last fall, there were five outbreaks in Orange County, 16 in Los Angeles, four in Riverside County and one in San Diego County. One of 1984’s 26 victims, a woman in her early 60s, died in January, Beams said.

The Orange County Vector Control District has begun using three “sentinel” flocks of chickens to detect the presence of the viral disease, Beams said. There are 20 chickens in each flock, one of which is in Santa Ana Canyon, a second on San Mateo Point near San Clemente and a third at a marsh on UC Irvine land in Irvine.

Moreover, wild birds are being surveyed in an effort to detect the disease early. Adult mosquitoes are also routinely trapped and submitted for laboratory study.

The district is concentrating its mosquito-eradication efforts on roadside ditches and gutters, catch basins, flood control channels, underground drains and natural rainwater depressions.

For more information, call 971-2421.