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State Takes Aim Before It Sprays for West Nile

August 08, 2004|Janet Wilson | Times Staff Writer

The truck heads out at 2:20 a.m., creeping through slumbering cul-de-sacs and releasing a colorless pesticide fog.

"[This] is a last resort. I don't like to do it. But we don't have a choice; we're in an epidemic," said Min-Lee Cheng, manager of the West Valley Vector Control District in Chino.

As West Nile virus spreads across California, government officials say spraying pesticides is the most powerful tool they have to wipe out mosquitoes carrying the disease.

But the state, no stranger to pesticide controversy, is taking a significantly different approach from other regions of the country that have grappled with the sometimes deadly but fairly rare new disease.

In the Northeast, the Midwest and the South, officials resorted to mass aerial sprayings to combat West Nile virus. When the disease began killing people in the United States -- in New York City in 1999 -- then-Mayor Rudolph Giuliani ordered wide-scale daytime spraying of city streets. That and similar spraying in New England triggered lawsuits by pesticide crews, fishermen who said catches had been wiped out, and others.

By contrast, California, where the disease arrived last year, has relied so far on ground-level spraying around targeted river beds, flood channels and handpicked neighborhoods in Los Angeles and San Bernardino counties with high counts of infected mosquitoes. The approach has drawn praise from some experts, but criticism from others who say the limited spraying is less effective, and the pesticides being used here may pose health risks.

In recent weeks, workers for the region's vector control districts have used larvicides to target juvenile mosquitoes in sewage ponds, manure pits and other spots they're likely to be found. They have focused spraying efforts to kill adult mosquitoes on Machado Lake in Harbor City, the Rio Hondo and San Gabriel river corridors, and small sections of Fontana, Colton and Chino.

"They're not trying to do a Sherwin-Williams and paint the world" with insecticides, said William Reisen, a UC Davis research entomologist. "They're using ounces per acre."

The West Valley district covers 200 square miles in five cities, which amounts to 128,000 acres, but it is targeting 250 acres in Chino. Crews think stubbornly high counts of infected mosquitoes there may be from industrial cattle yards or a weed-choked flood control channel. Before spraying, district workers sent notices to more than 600 affected homeowners and followed up with door-to-door visits.

"We spray in the middle of the night because the mosquitoes are out, but the humans aren't, unless they're closing down the neighborhood bars," said Cheng.

In Chino on a recent morning, the trucks halted on three occasions -- once when a jogger loped by in the murky darkness at 3 a.m., and twice when lone cars drove by. The rest of the time, the sprayer released a steady mist of Pyrenone 25-5.

The chemical cloud drifted among bushes, houses and the ground, visible only when caught by the yellow blinking light atop the truck or under humming street lights. When a trickle of commuter traffic began to appear on the streets at 4:30 a.m., the operation ended.

Limited ground-level spraying does allow some adult mosquitoes to escape. "The problem is getting them in the backyard, because the house acts as a barrier," Reisen said.

But limited spraying is more acceptable to the public, he said. "Do I want vector control districts to stop all the traffic over LAX

Ramiro Salazar, a mosquito-control worker with the West Valley district, agrees. Sitting with his finger near the trigger of a truck-mounted Pro-Mist pesticide fogger, he said: "People in California don't like chemicals sprayed on them."

Vermin-control districts were set up at the turn of the 20th century in Los Angeles and San Francisco to eliminate insects in swamps that were being developed into housing. When mosquitoes infected with St. Louis encephalitis began killing people in the 1930s, the districts expanded across much of the state.

But spraying became highly controversial in the 1980s and 1990s, when California officials ordered the pesticide malathion sprayed from helicopters and airplanes onto residential neighborhoods to combat the Mediterranean fruit fly. The sticky insecticide coated cars and houses and brought about more than 6,600 claims of poisonings of people and pets. The spraying prompted wide-scale protests and lawsuits.

At that time, state officials said the spraying was needed to protect California's multibillion-dollar agriculture industry. West Nile, though deadly in a small number of cases, has yet to generate a similar level of concern.

According to the state's latest figures, the number of West Nile infections in California has risen rapidly, nearly doubling from 53 cases reported as of July 29 to 103 cases by Aug. 5. Federal and state public health officials have warned that based on the experience of other states, August and September, active mosquito-breeding times, could be the worst months.

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