PALMDALE, LANCASTER VIRUS SITES.

Byline: Charles F. Bostwick Staff Writer

LANCASTER - West Nile virus or a related disease has been detected in chickens in east Palmdale and east Lancaster.

Further tests are needed to conclude whether the chickens, both in flocks tested regularly for mosquito-borne diseases, were infected with West Nile or by St. Louis or Western Equine encephalitis.

``This is the first indication of (West Nile virus) in Palmdale. Last year all of the positives were in Lancaster,'' said Karen Mellor, entomologist for the Antelope Valley Mosquito and Vector Control District.

A chicken in central Lancaster and wild birds in Rosamond and at Edwards Air Force Base tested positive earlier this year for West Nile virus.

So far this year, 208 Californians have been confirmed with West Nile virus, including six people who died. That is by far the highest incidence in the United States. South Dakota has had 43 cases and Louisiana 36 cases.

The Antelope Valley mosquito abatement district was awarded a grant of $139,070 by the state to increase mosquito-control efforts in outlying areas and to prepare for a possible attack on adult mosquitoes by spraying.

District technicians now spray ditches, gutters, abandoned swimming pools and other stagnant water to kill mosquito larvae. Spraying for adult mosquitoes is the last resort, when everything else has failed, Mellor said.

Potentially fatal to humans - especially chronically ill and elderly people - and to horses, West Nile virus is spread by mosquitoes that extract blood from infected birds and then pass the virus on to people or other animals.

The Antelope Valley mosquito district keeps flocks of chickens around the valley to detect the virus. The virus is not fatal to chickens as it is to ravens, jays and other wild birds, and there is no chance they picked up the disease in another area, as wild birds might.

West Nile virus last year infected more than 300 Los Angeles County residents, including 190 who became ill enough to be hospitalized and 13 who died.

While the Antelope Valley has had no human cases, two horses last year became sick - one so seriously it had to be euthanized.

Health officials say the risk of acquiring the virus is low. About 80 percent of people who become infected with the virus show no symptoms, and most of those who become ill show only mild flulike symptoms.

Charles F. Bostwick, [phone]

chuck.bostwick(at)dailynews.com

AT RISK

--People at the highest risk of life-threatening disease are over age 50 or have weak immune systems from another illness.

--Most mosquitoes do not have West Nile virus.

--Eighty percent of infected people have no symptoms. People typically develop symptoms between three and 14 days after coming in contact with an infected mosquito.

--Mild symptoms include fever, headache, body aches, vomiting and sometimes swollen lymph glands or a skin rash. They pass on their own.

--Of those infected, one in 150 can develop severe symptoms or even die. Severe symptoms can include high fever, neck stiffness, tremors, muscle weakness, vision loss, numbness and paralysis. Neurological effects can be permanent.

--The best way to protect against the disease is to protect against mosquito bites.

Source: Los Angeles County Health Department, Centers for Disease Control and Prevention.

MOSQUITO TIPS

To reduce exposure to the virus, health officials suggest residents follow the precautions recommended for all mosquito-borne diseases:

--Get rid of standing water, where mosquitoes can breed. Empty all small containers at least once a week, keep pools and spas chlorinated or drained, and avoid overwatering that lets water form puddles on lawns or in gutters.

--Get mosquito-eating fish (Gambusia affinis) for free from the mosquito district if you have sources that cannot be drained, such as fish ponds and large horse troughs.

--Wear long-sleeve shirts and pants and use mosquito repellent containing DEET when outdoors during dusk and dawn.

--Keep tight-fitting screens on doors and windows to prevent mosquitoes from entering homes.

--Horse owners should make sure their horses are properly vaccinated.

--Report stagnant pools and other backyard sources to the mosquito district so technicians can treat them. The mosquito district can be reached at [phone]. Its Web site is www.avmosquito.org. Crows and ravens that have recently died - without obvious trauma - can be reported by calling (877) WNV-BIRD. Use gloves, a shovel or an inverted trash bag to pick up any dead bird.

Source: Antelope Valley Mosquito and Vector Control District

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(1 -- ran in AV edition only) AT RISK (see text)

(2 -- ran in AV ediiton only) MOSQUITO TIPS (see text)