That's why members of county and city agencies have joined a new West Nile task force in an effort to inform the public, share information with one another and prevent the spread of the virus.

The mosquito-borne disease first appeared in the United States in 1999 and has spread quickly since then. According to data from the Centers for Disease Control and Prevention, 149 human cases were reported from 1999 through 2001. That number rose to more than 4,100 in 2002 alone and to nearly 10,000 in 2003. There have been 564 deaths from the virus.

Representatives from the county Department of Environmental Health, the vector control district, the water district and several other county and city agencies met April 13 to discuss their roles in preventing human harm from West Nile virus. As of that date, six birds with the virus had been found in Riverside, Los Angeles and Orange counties this year.

Tim Mulligan, manager of the vector control district—an Environmental Health subdivision that works to prevent and control rodent- and insect-borne disease—said effective communication between both agencies in this county and others will be key to minimizing harm.

"Mosquitoes don't enjoy political boundaries," Mulligan said. "A problem in Alameda County may spill over here. It's in our best interest to coordinate."

Kriss Costa, community resource specialist for vector control, agreed that coordinating information about when, where and how the virus spreads through the state is the best defense against it. She also stressed that keeping residents informed may prevent hysteria and panic.

"History with West Nile virus has showed us that communication, information and knowledge have played a big part in containing it," she said. "We want our residents to face it with knowledge and not with fear."

County health officer Dr. Marty Fenstersheib said medical professionals will also need to stay informed, as they will likely hear from many patients who believe they have the disease. But since many West Nile patients display no symptoms at all, other factors will determine whether patients should be tested for the virus.

"The hard thing for physicians is that the symptoms aren't distinguished in any way," he said. "It's not really about what patients are reporting, it's about the likelihood of exposure."

Fenstersheib and other health-care professionals at the meeting said most people who get the virus display mild flu-like symptoms such as fever, if any. But about 1 in 150 people with the virus experience more serious nervous system problems, including inflammation of the brain.

Still, Mulligan was confident that Santa Clara County is in a better position to defend itself than other areas. He said Colorado experienced a great number of West Nile infections and deaths last year because it had no vector-control or mosquito-abatement programs. New York faced a similar situation several years ago for the same reason.

While John Cherbone, public works director for Saratoga, said by phone that the city is currently distributing county pamphlets and information about the West Nile virus, Costa said her department would soon arrange meetings with city representatives about more specific actions to take. For now, though, informing residents is one of the more helpful things cities can do.

County vector ecologist Dan Strickman said that while residents may not pay attention to West Nile virus prevention tips such as wearing long-sleeved shirts and trousers right now, keeping them informed when the virus approaches the area will probably prompt more action.

"If we expose the public to this information, they'll be more motivated to protect themselves," he said.

The task force is tentatively scheduled to meet again May 11.

The Santa Clara County Vector Control District recommends taking the following actions to fight West Nile virus and protect yourself and family:

* Regularly check for and dump any standing water around your home—even very shallow puddles can produce hundreds of mosquitoes.

* If you find a bird that has been dead less than 24 hours, especially a crow, sparrow, jay, hawk, magpie or finch, report it to the district at 408.792.5010.

* Use Bti larvicides (available at hardware stores and nurseries) or mosquito-eating fish (available from the district) in ponds or unused pools.

* Wear long-sleeved shirts and long pants when outdoors.

* Apply insect repellent with DEET to exposed skin when you will be outdoors. Apply repellant with permethrin to clothing, as mosquitoes can bite through fabric.

* When possible, avoid going outside at dawn, dusk and in the early evening, when mosquitoes are most likely to bite.

* Report any neglected pools and ponds or any problems with storm drains to the district.