The spread of the West Nile virus in California has slowed significantly in recent weeks, prompting experts to believe that the disease will take a far smaller toll here than in other states.
Confirmed human cases of West Nile -- now at 586 -- appeared to have peaked in late July and early August and have been declining steadily since then, according to state statistics. Between Aug. 7 and Aug. 20, officials confirmed that 132 people contracted the virus. Thirty cases were confirmed between Aug. 21 and Sept. 11.
Despite fears that West Nile would sweep across California, the virus appears to have been confined mostly to Southern California -- notably San Bernardino County and eastern Los Angeles County. As a result, total human cases have been less than some expected.
"We feel it could have been far worse," said Dr. Carol Glaser, acting chief of the viral disease section of the state health department. "We think it's settling down, but we're keeping our fingers crossed."
Although 16 Californians have died from complications of the virus, that is far fewer deaths than in other, less populous states hit by West Nile. For example, Colorado recorded nearly 3,000 human cases and 63 deaths last year. In Texas, 37 people died, while Nebraska recorded 29 deaths.
Officials believe California's relatively cool August and September, combined with aggressive efforts to spray wetlands and remove standing water, helped contain the virus. Standing water and wetlands attract mosquitoes, which spread the virus to humans.
West Nile spread this spring and summer from the desert areas of San Bernardino County into other parts of Southern California and then to Northern California.
Health experts believe West Nile will begin to recede by mid-October as the mosquito season ends. But they stressed that it should still be taken seriously.
"People should not relax," said Dr. Jonathan Fielding, Los Angeles County's public health director. "There's been a diminution of West Nile cases, but we really don't know whether it's permanent or temporary."
Most infected people show no symptoms. About 20% experience flu-like symptoms, including headache, fever, rash and weakness. Less than 1% of those infected die from the disease.
Blood banks, which turned to more rigorous testing in late July as increasing numbers of donors tested positive for the virus, have seen rapidly decreasing rates of infected donors.
