Encephalitis Virus Found in Bird Tests

The discovery of St. Louis encephalitis virus in birds during routine testing in Monterey Park and Orange County has stirred concerns that mosquitoes may transmit the potentially deadly virus to people.

Two chickens in a Monterey Park coop tested positive for the virus earlier this summer, and authorities received confirmation of the test results last week. The virus has also been detected in the blood of finches and sparrows kept in five of Orange County’s nine surveillance traps, authorities said.

While experts emphasize that no human cases of St. Louis encephalitis have been reported in Los Angeles County or Orange County this year, they caution that mosquitoes can carry the virus from birds to people. The virus cannot be transmitted from person to person or from birds to humans.

In Monterey Park, the virus was discovered in two of five so-called sentinel chickens maintained by the San Gabriel Valley Mosquito Abatement District. The chickens are kept in coops and tested periodically as part of an encephalitis warning system.

Confirmation of the test results prompted a widespread search for mosquito breeding grounds in the area, authorities said.

In nearby Montebello, for instance, technicians searched a cemetery and found evidence of mosquito breeding in graveside flower basins. They emptied water and larvae from thousands of basins during a two-day effort by the San Gabriel district and the Greater Los Angeles County Vector Control District, based in South Gate.

“If you find it in the birds, that means the mosquitoes have it. That’s why we use it as an early warning system,” said James P. Webb Jr., vector ecologist with the Orange County Vector Control District, which maintains the five traps where the birds tested positive.

The district announced news of the testing this week, and Webb said it represented the most significant activity in the Orange County trapping program in five or six years.

In response, authorities are urging people to remove potential breeding sites from their yards by properly filtering and covering pools, stocking ornamental ponds with mosquito-eating fish and removing cans, barrels, jars and old tires in which standing water can collect.

“The important message for people is to eliminate places where mosquitoes can breed,” said Dr. Hildy Meyers, an epidemiologist with the Orange County Health Care Agency.

Health experts have been particularly sensitive to the threat of encephalitis since a 1984 outbreak struck 26 Southern Californians, killing six.

Encephalitis can cause brain and spinal-cord inflammation. Mosquitoes in California are known to carry St. Louis encephalitis as well as western equine encephalitis, which can affect horses as well as people.

Residents can protect themselves by applying mosquito repellent, wearing long-sleeved shirts and long pants and by refraining from going outdoors at night in mosquito-infested neighborhoods, health officials said.

To report mosquito problems in the San Gabriel Valley, call the district at (818) 814-9466. In Orange County, call the Vector Control District at (714) 971-2421.

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Backyard Health Hazard

The discovery of St. Louis encephalitis in the blood of house finches and sparrows gives rise to the fear that mosquitoes may transmit the potentially deadly virus from birds to humans. A primer on the disease:

St. Louis encephalitis, so called because it was first isolated in that city in 1933, is the most common of mosquito-borne diseases in the Western U.S. Flu-like symptoms last about two weeks:

* Fever, headache, exhaustion

* Severe cases can lead to coma, brain damage and death

* There is currently no cure

Cutting the Conduit

Mosquitoes breed in one out of 10 backyards. What to look for and how to deal with them:

Signs

* Standing water

* Swarming

* Nearby creeks or channels

Bite Prevention

* Apply repellent when outside

* Burn citronella candles

* Avoid yard work in morning and evening, when mosquitoes are most active

Breeding Prevention

* Dump water from containers; cover them or turn upside down

* Add mosquitofish to ornamental ponds or fountains; they eat mosquito larvae and require no care

* Fill in unused ornamental ponds with sand or dirt

* Cover swimming pools or clean every day with skimmer; chlorine does not kill mosquito larvae

Whom to Call

Report standing water or mosquito swarms to Orange County Vector Control District at (714) 971-2421

Sources: Times reports