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L.A. Case of W. Nile Suspected

Health: If confirmed, the infection would be the first known to have been acquired in the West.


A Los Angeles County woman "very likely" developed meningitis caused by a West Nile virus infection, suggesting that the disease has completed its cross-country march a mere three years after it first appeared in the United States, health officials said Friday.

The diagnosis of the young woman from the southwestern part of the county would be the first reported case in humans to be acquired west of the Rocky Mountains. It cannot be confirmed, however, until a final set of test results comes back, probably next week, health officials said.

"In discussions with the state and the [federal] Centers for Disease Control, we think it was highly probable ... that this was West Nile virus infection," said Jonathan Fielding, Los Angeles County public health director, at a news conference in Los Angeles on Friday. "We would not be talking to you if we did not think it was very likely that this would be confirmed by the definitive test."

He said health officials decided to alert the public based on results of several tests of the woman's blood and cerebral spinal fluid. A final diagnosis can be made only after a series of tests is done to detect antibodies to West Nile and to rule out other types of infection.

West Nile remains rare and most often produces no symptoms among those infected. In about one in five cases, people experience mild symptoms including fever, headache and nausea. One in 150 require hospitalization. Elderly people are most vulnerable to symptoms.

The disease has attracted strong interest from public health officials and the media because it is so new to the United States and because of its mounting death toll--61 people since the summer of 1999, including 43 this year. Recent infections suggest the possibility that the virus can be spread through transplantation of organs.

The California woman's case is mystifying because health experts here have not detected any evidence of the virus in birds, which harbor West Nile, or in mosquitoes, which transmit it to humans.

State health authorities had not expected West Nile to arrive in California until next year or 2004.

But "we have been preparing for the arrival of West Nile virus, and we are ready," said Diana M. Bonta, director of the state Department of Health Services, who also spoke at the news conference.

In light of the probable California case, county and state officials say they are increasing their surveillance of mosquitoes and birds. Vector-control agencies also plan to intensify spraying of anti-mosquito chemicals in storm drains, pools of standing water and unused swimming pools.

The unidentified woman from Los Angeles County became ill on Aug. 10 with a mild case of viral meningitis, in which the membranes covering the brain become irritated, health officials said. She was hospitalized for five days and has fully recovered. She is expected to suffer no long-lasting consequences.

To protect her privacy, health officials would not release additional details, such as her age or city of residence.

Researchers don't know how the woman may have contracted the virus. She had not traveled out of state and does not recall being bitten by mosquitoes. A sophisticated state monitoring program has picked up no evidence of the virus in animals, which often are the first clue to the virus' arrival in a region.

"Finding a human case before we have evidence in birds or chickens or mosquitoes is rare, but it's not unprecedented," said Fielding. When the virus was first detected in the United States, in New York City in 1999, human cases were confirmed before any were found in mosquitoes or animals. Seven people in the New York area died that year.

In addition to the probable Los Angeles County case, samples from three other people with encephalitis or meningitis are being tested for West Nile, but officials noted that there are other causes of these diseases. At least one of the patients is a visitor from out of state.

Tests on two other people in Los Angeles County have come back negative. Bonta said she is unaware of any other possible cases in the state, but her agency has sent out alerts to doctors, hospitals, health plans and health departments, asking them to watch for infections that could be caused by West Nile.

Bonta and Fielding also suggested preventive measures people can take until the mosquito season is over in late October. These include avoiding mosquito-infested areas at dawn and dusk; wearing long-sleeved shirts and long pants outdoors; using insect-repellent products with no more than 35% DEET for adults and 10% for children; and ensuring that windows have intact screens.

Officials also advised against allowing water to stagnate in old tires, flowerpots, trash, swimming pools, birdbaths and pet bowls. They recommended cleaning and chlorinating swimming pools and draining water from pool covers.

At least four other West Nile cases have been reported in the West, but all the victims are thought to have contracted the virus elsewhere in the country.

The West Nile virus is common in Africa and the Middle East. Since 1999, it has been detected in every state east of the Rockies. This year, there have been 954 infections among humans in 29 states and the District of Columbia, according to the CDC. On Thursday, federal health officials said that "tens of thousands" of Americans probably have been infected.

A vaccine is available to protect horses, but there is no vaccine for humans. Dogs and cats can get the virus but do not become ill.

Bonta urged Californians who see crows, jays, ravens, magpies, sparrows or finches that have been dead for less than 24 hours to report them to health authorities at (877) 968-2473. The department will pick them up and test for the presence of the virus.

Residents who would like general information about West Nile can call (800) 975-4448.

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