Poised to Swat the West Nile Virus

Anticipating the arrival of the West Nile virus in California this year, Orange County pest control officials will double the number of mosquito traps they set in an effort to detect infectious swarms.

Experts don’t know when the sometimes-deadly virus will reach the state. But it has migrated steadily west since its 1999 appearance in the United States. Orange County experts say this year’s mosquito season -- from late spring to early summer -- will probably bring it here.

The Vector Control District places about 30 traps weekly, year round, to identify mosquitoes carrying viruses and isolate their breeding areas. The traps are randomly placed around residential areas and wetlands

Beginning Monday, as many as 70 traps will be set in the hope of quickly pinpointing the virus’ arrival and eradicating the infected mosquitoes, said James Webb, the district’s technical director.

Last year, the virus caused 277 deaths out of 4,161 reported cases nationwide, according to the Centers for Disease Control and Prevention. But medical authorities believe most people who become infected may mistake it for the flu and don’t report their illness.

On rare occasions, infections can lead to severe, sometimes fatal, illnesses.

Symptoms range from fever, headaches and body aches to encephalitis. People 50 and older and those with weakened immune systems are particularly susceptible. Horses also can be infected, Webb said.

The virus, commonly found in Africa, western Asia and the Middle East, first hit the U.S. in New York City, causing an encephalitis outbreak that killed seven people.

The virus has infected six Californians, including a 70-year-old Newport Beach man, but all but one were stricken while out of state.

Late last year, Los Angeles County reported that a 31-year-old woman may have been the first local infection, but officials have been unable to determine how she was infected.

Webb said vigilance can prevent a serious outbreak, but mild infections are inevitable.

Vector control employees will place traps in backyards, Webb said. The slender 4-inch tubes are attached to a canister of dry ice that emits carbon dioxide to mimick the breath of a warm-blooded animal. When the mosquito approaches the trap, a fan pulls it into the tube. The traps are collected after 24 hours and examined.

Vector control spokesman Michael Hearst issued the yearly warning for people to prevent mosquito-breeding conditions.

“People think [those conditions are only] old tires and half-empty swimming pools,” Hearst said. “It is also the saucer underneath a potted plant, a folded tarp, a clogged rain gutter. Those are probably present in every backyard.”