W. NILE FLARE-UP FEARED RAINS MAY BRING MOSQUITO DELUGE.

Byline: Troy Anderson Staff Writer

This season's near-record rainfall has spawned fears of a widespread outbreak of potentially deadly West Nile and more than a dozen other mosquito-borne viruses, experts said Tuesday.

Researchers at the UC Davis Center for Vectorborne Diseases said at least 18 mosquito-borne viruses have been detected in California and many of these pose increasing threats to public health.

Among these are Western equine, Venezuelan equine encephalitis and St. Louis encephalitis, a historically rural disease that has expanded into the metropolitan Southern California area.

Dengue fever that invaded Los Angeles County on international shipments of ornamental plants in 2001 now appears to have become established in the region, UC Davis researchers say.

``There is always the possibility that new viruses or new vectors will be introduced into California, but in terms of (mosquito-borne viruses) in California, the West Nile virus poses the greatest risk,'' said Vicki Kramer, head of the Vector Borne Disease Program at the state Department of Health Services.

The experts predicted that mosquito-borne illnesses will cause more illnesses and deaths as national and international travel becomes faster and cheaper, commerce proliferates and population centers expand into new areas.

``Now that we're testing for West Nile, it won't be surprising that we pick up more cases of St. Louis encephalitis,'' said Dr. Laurene Mascola, chief of Los Angeles County's Acute Communicable Disease Control Program. ``We could also see California equine. We know that California has these vectors and the possibility of these (mosquito-borne diseases).''

Of the 18 mosquito-borne viruses, the state usually tests only for Western equine and St. Louis encephalitis.

Meanwhile, the fight against another deadly year of West Nile virus has started.

Workers have increased treatments of underground storm drains and are stepping up the public education campaign.

``We are preparing for the season,'' said Jack Hazelrigg, general manager of the Greater Los Angeles County Vector Control District. ``We certainly have our surveillance lined up for this time of the year.''

Last year, 23 California counties had 830 human cases of West Nile - the highest number in the nation - and 28 deaths. Los Angeles County was the epicenter of the state's outbreak, with 330 people infected.

Although no confirmed human cases have been reported yet this year, the virus has been detected in 21 counties and 58 dead birds have tested positive, including three in Santa Clarita.

Nine more infected dead birds were found in Orange County, two in Riverside County, and the rest in Central and Northern California counties.

``We anticipate West Nile virus activity will increase in the central and northern parts of the state relative to 2004,'' Kramer said. ``As far as the southern portion of the state, that is more difficult to predict.''

West Nile usually infects mosquitoes, birds, horses and other mammals and can be transmitted to humans through mosquito bites. While most people show no signs or display only flulike symptoms, about one in 150 people bitten by an infected mosquito will develop encephalitis, a potentially deadly brain infection.

Hazelrigg said he expects to see the emergence of infected mosquitoes once the temperatures warm up in late spring and early summer. ``We didn't get our first human cases until mid-May last year,'' he said.

Last week, the state obtained $2.16 million from the federal government to improve lab testing, track the virus and evaluate mosquito-control efforts. Gov. Arnold Schwarzenegger is petitioning Congress for more funding to kill mosquitoes.

``We anticipate an increase in West Nile virus activity this year so Californians must continue to be vigilant and fight the bite,'' state health department Director Kimberly Belshe said.

One of Hazelrigg's main concerns is that his workers are finding an increasing number of stagnant backyard swimming pools - the result of the heavy rainfall - where female mosquitoes lay their eggs.

Although no fines were issued last year in the city of Los Angeles, vector-control officials can fine people $100 a day if they don't take care of stagnant pools or standing water.

And last week, the U.S. Centers for Disease Control and Prevention recommended the use of mosquito repellents containing Picaridin or the oil of lemon eucalyptus. That follows years of promoting the chemical DEET as the best defense against West Nile.

Because Picaridin is odorless and has a lighter, cleaner feel, it will be an appealing alternative for consumers who are dissatisfied with the way DEET-based repellents smell and feel, CDC officials say. It does not need to be washed off after returning indoors.

The manufacturer of the only Picaridin-based repellent sold in the United States is Rayovac, which markets Cutter Advanced Insect Repellent.

Troy Anderson, [phone]

troy.anderson(at)dailynews.com