HEALTH : Rabies Outbreak in Texas Carried North by Coyotes : Two persons have died, and 1,600 have been treated for exposure to the virus in one of the worst flare-ups in recent U.S. history.

Here in the dusty plains of South Texas, the piercing howl of coyotes competes with the rumble of 18-wheelers barreling through town. But the unearthly wail that jolted a neighborhood one morning last month came from a large stray dog, which sat on its haunches and keened like a wolf gone berserk.

Neighborhood kids who threw rocks at the stray knew it had attacked two dogs and bitten a boy the day before. Now they saw white foam dripping from its mouth.

By the time police--and a throng of breathless onlookers--chased the snarling stray into a chicken coop, it was obvious what analysis of the dog’s brain would later confirm: One of the worst rabies outbreaks in modern U.S. history had reached San Diego, a poor ranching community.

Since 1988, when rabid coyotes from Mexico are believed to have entered South Texas in the floodwaters of Hurricane Gilbert, a rare strain of canine rabies has moved steadily north at about 50 miles a year. Two South Texans have died, and more than 1,600 have received treatment for exposure to a virus thought virtually eradicated in the United States by pet vaccines in the 1950s.

Unlike the rabies outbreak among raccoons in New England, the South Texas canine strain is considered threatening because it moves very quickly from coyotes to dogs. “This one is particularly dangerous--it’s adapted to exist in dogs, our own pets,” said Dr. Gayne Fearneyhough, director of the oral rabies vaccination project for the Texas Department of Health. “It is the strain historically most often associated with human deaths. The canine variant is unique because it exists nowhere else in the U.S. right now.”

Since 1988, 547 cases of canine rabies have been confirmed in a 19-county area of South Texas. As the epizootic--an epidemic among animals--nears San Antonio, officials are taking drastic measures to contain the virus. In a two-week period in February, two airplanes dropped 830,000 lard-scented biscuits containing a coyote rabies vaccine over a 15,000-square-mile crescent from Laredo to Corpus Christi. The idea is to create a buffer of immune animals between the infected counties and unaffected areas to the north.

“Right now the outbreak is confined to a narrow and lightly populated part of the state. If we miss this year, it could very possibly be too geographically large to contain anymore,” Fearneyhough said.

Residents of San Diego, population 5,225, have their own problems as they struggle to contain rabies in a town that has no dog pound or veterinarian. City Administrator Jose Jimenez now doubles as the dogcatcher. His first line of defense is a battered yellow Ford pickup toting a wire cage donated by a farmer. An animal snare is fashioned from sturdy cord threaded through an old conduit pipe and held together by a clump of black duct tape.

“It’s a homemade deal, but it works real good,” Jimenez said as he dangled the contraption to form a loop with the cord. With a nod of satisfaction, he snapped back the pipe to show how the noose tightens around an animal’s neck. “The cavalry’s not going to land here, you have to make do with what you have.”

While city fathers dither over the design and cost of a dog pound, vicious strays are caught and driven 10 miles east to the pound in Alice. Docile strays, many abandoned on country roads near town, are left to roam the streets. “Without a dog pound, it’s like having a town without a jail,” Jimenez said.

At the Marcos BBQ, waitress Tina Morin is exasperated. “There are more dogs around here than people--just look outside,” she said, jerking her head toward the window.

Restaurant manager Elda Olvera owns one cat but feeds seven strays. “These cats are so wild and mean they won’t let you near them to pet them, much less vaccinate for rabies,” she said.

After a rabid dog bit 6-year-old Jose Ramon Pena last month, San Diego police officers went door-to-door with flyers warning of the outbreak. Schools sent notes to parents with an urgent message: Vaccinate your pet. On a recent Saturday, nearly 400 people lined up in the pouring rain at the Gonzales Farm and Ranch Feed store to have their dogs, cats, horses and goats vaccinated by a traveling veterinarian.

Similarly heavy turnouts were seen last fall at vaccination clinics in South Texas border towns hit hard by the rabies outbreak. In Edinburg, south of San Diego, residents were near panic when eight rabid animals were found near Zavala Elementary School in January. A fence now circles the school grounds.

Elsewhere near the Mexican border, ranchers shot coyotes on sight. Others tried leg-hold traps, but with little effect as the virus continued north. The problem was compounded by a drought that forced coyotes closer to populated areas and the reluctance of many to vaccinate strays kept as watch dogs.

The state health department, under fire for failing to stop the outbreak, points out that an oral coyote vaccine did not exist until now. “The technology just wasn’t there,” said Dr. Keith Clark, director of the department’s zoonosis control division. Working with Texas A&M; University and other groups, the health department adapted to coyotes an oral rabies vaccine fed to raccoons.

Officials will begin to measure the success of the $2.3-million bait-drop program next month by monitoring coyotes in the buffer zone. “The infected animals south of the area will die within days of exhibiting symptoms,” Clark said.

That’s cold comfort for San Diego Mayor Alfredo Cardenas. “It seems to me they ought to be dropping the vaccine in the affected areas, not farther north. It’s like they think we’re too far gone to help, so they leave us to suffer.”

In a decaying neighborhood behind City Hall, three dogs dozing on a sagging porch shift lazily as one rouses itself to gnaw at a bleeding sore.

Belinda Everett, 25, the mother of two toddlers, is frightened. “Some of these dogs bark real ugly. They will put their heads up and cry like a coyote. My boys like to run around with their cousins all day, but now I won’t let them go outside without me. I spend more than $10 a day for videotapes so that they’ll stay inside.”

In a mobile home next door, Jose Ramon Pena, called J.R., shyly raises his left thumb, which still bears a nick from the rabid dog shot by San Diego police last month. J.R. was riding the dog like a pony when he jumped off and gleefully clapped his hands. That’s when the dog nipped him. His parents drove 60 miles to Corpus Christi to find a hospital that stocked the vaccine.

Unlike horror stories involving long needles and painful injections in the stomach, modern rabies treatment consists of five separate shots in the arm with a purplish serum called HDCV. A needle of standard length is used, but treatment must begin quickly because the dormant rabies virus can become active at almost any time.

Once the virus moves from muscle cells to nerve tissue, there is no way to stop it. By the time clinical symptoms--such as lack of coordination and mood swings--appear, the virus has already traveled up the spinal cord and into the brain, causing swelling and, within weeks, certain death. J.R., who usually cries at the sight of a needle, quietly laid his head on the examining table and waited for the injection, said his mother, Victoria Pena.

“He heard the doctor say he would die without the medicine,” she said. “It scared him.”

J.R. announced he will stay away from the strays. “If a dog bites me, they’ll put more shots in,” he said gravely. Outdoors, two strays paw through an overturned garbage can.