West Nile quiet so far this year

By: DAVE DOWNEY - Staff Writer
But wave of foreclosures has spawned bumper crop of mosquitoes | Sunday, August 26, 2007 10:33 PM PDT ∞

Despite a surge of West Nile infections across California this summer, state officials report that so far not a single Riverside County resident has gotten sick as a result of the mosquito-borne virus that just a couple of years ago spread fear far and wide.

For the year to date, 53 percent more cases have been reported statewide this summer than in 2006. Authorities had confirmed, as of Friday, that 147 Californians had contracted the virus. This time last year, 96 cases had been reported, according to the California Department of Public Health.

As well, eight deaths have been blamed on West Nile virus so far this year, already exceeding the total of seven for all of 2006, the state agency reported. The surge has prompted Gov. Arnold Schwarzenegger to pump more than $11 million in emergency funding into attacking the problem.

Even so, cases have been concentrated in the Central Valley and Southern California hasn't been hit nearly as hard as it was a short time ago.

Riverside County was hit particularly hard, with 112 infections in 2004 -- the third highest total of all California counties -- and 104 in 2005, the second highest. The number of infections plummeted to four last year, albeit with one death. And the downward trend appears to be continuing.

Still, the trend is no reason for anyone to let his or her guard down, said Barbara Cole, director of disease control for the county Department of Public Health.

"We're hopeful that it will stay quiet," she said. "But I certainly cannot predict what the rest of the season will be like. We can't rule out the possibility that we might see some human cases."

The season when the virus strikes is far from over. Steve Van Stockum, the county's deputy director of environmental health, said mosquitoes are active through October.

Indeed, the disease is beginning to spread to counties that had escaped infection until recently. For example, San Bernardino County reported its first case of the summer last week.

And even if Riverside County residents somehow manage to elude the virus the rest of the season, don't think for a moment that West Nile has packed up and left the area, state officials advise.

"It's fortunate that you haven't seen a resurgence of West Nile in that area," said Vicki Kramer, chief of the state's vector-borne disease program, in a telephone interview. "But that doesn't mean that in subsequent years it can't flare up again."

Here to stay

Far from fading, West Nile is going to pose a threat to human health for years to come, Kramer said.

"The bottom line is, West Nile virus is well established in California. We can expect activity every summer, every year," she said. "We cannot predict the level of activity that we will see each year, nor predict exactly where that activity will occur. This virus will be cycling with ebbs and flows throughout the state of California. We can't become complacent. It is here to stay."

The virus has been in California four years. It arrived in July 2003 in Imperial County and spread to six Southern California counties by the end of that year, Kramer said. A year later, it was in every county in the state.

According to the Centers for Disease Control and Prevention, the virus showed up in the United States along the East Coast and has spread to every state except Oregon, Alaska and Hawaii.

The name of the virus stems from a 1937 discovery in the West Nile district of Uganda.

For most people, exposure is of little concern. State and local officials say about eight in 10 people aren't affected, and most of the rest develop mild symptoms such as headache and fever.

But, for some, exposure is fatal.

Experts say infection can develop into encephalitis, inflammation of the brain; meningitis, inflammation of the tissue surrounding the brain and spinal cord; or myelitis, inflammation of the spinal cord.

Those most vulnerable to complications include the elderly, very young and people with compromised immune systems.

'Green' pools

Because of the risk, health officials urge people to continue taking measures to protect themselves from the spindly, blood-sucking insects that carry the virus.

Residents should empty fountains and bird feeders, replace damaged window and door screens, stay indoors around dawn and dusk when mosquitoes are active and spray insect repellent on exposed skin, officials say.

While Riverside County has yet to confirm any West Nile infections -- for either humans or horses -- mosquito sightings have soared in recent months.

Barry Hess, a biologist and county environmental health specialist, said sightings have more than quadrupled in the territory covered by the Department of Environmental Health's vector control program.

The county hunts and kills mosquitoes in much of western Riverside County, although not in Lake Elsinore and Corona, which are covered by the Northwest Mosquito and Vector Control District.

Hess said the county, which serves Temecula, Murrieta and nearby unincorporated communities, logged 195 reports for all of 2006. In sharp contrast, for the year to date, already about 875 complaints have been received, he said.

A large chunk of the increase is due to the flurry of foreclosures across western Riverside County, Hess said. Many people are walking away from homes -- and from swimming pools that are turning green with algae and becoming mosquito breeding grounds, he said.

"We're just being swamped with all the green pools," said Kelly Kersten, an environmental health technician, saying about 80 percent of his calls are about abandoned homes.

When the calls come in, Kersten goes out and treats the mosquito-infested, pea-soup-colored water with chemicals. It's important to respond immediately, he said, because in one week an abandoned pool can go from clear to green, and become a hatchery for 1,000 mosquitoes.

"That can affect an entire neighborhood," Kersten said.

However, the county isn't waiting for reports to come in. Hess said the county takes aerial photographs regularly to spot "green" pools, as well as standing water in flood-control channels and fields.

Kern County hot spot

It also helps to have local officials act as eyes and ears. For example, Temecula recently asked the county to check out ponds formed by the city's construction of a road across the bed of Murrieta Creek at Via Montezuma.

Kersten said the county plans to set a trap early this week using dry ice in a can to troll for mosquitoes, as a first step toward determining if the pools should be treated. Dry ice is frozen carbon dioxide and the insects are attracted to carbon dioxide gas.

"Green" pools have been a major problem in Kern County, which also has been hit hard by foreclosures, Kramer, of the state health department, said. She said those pools are to blame for much of the West Nile surge statewide, which is concentrated in Bakersfield.

As of Friday, 78 of the 147 infections statewide were in Kern County where Bakersfield sits.

According to the state health department, there have been eight fatalities: three in Kern and one each in Los Angeles, Fresno, Colusa, Kings and San Joaquin counties.

After the virus's arrival in California, confirmed West Nile infections statewide spiked at 830 in 2004 and 935 in 2005, then declined to 292 in 2006.

For more information, go to www.westnile.ca.gov. To report a dead bird that could be carrying the virus, call 1(877) WNV-BIRD.

-- Contact staff writer Dave Downey at (951) 676-4315, Ext. 2623, or ddowney@californian.com.