March 1993
Health
Running Rabid
Five years ago, rabies was rare in South Texas. Now nearly three hundred animals have died and the epidemic is not abating.
The nature and nightmarish potential of the rabies outbreak dawned on South Texans in late 1988 and early 1989, when coyotes were seen trotting through the streets of Rio Grande City. The first of these wayward animals crossed U.S 183, the town’s busy main drag, and sat down in the yard of a highway patrolman. The officer promptly shot it.
The creature’s docile behavior was not atypical. The image of the rabid beast—staggering, snarling, drooling—is accurate but only half true; not all rabies is the furious type. Just as often, infected canids exhibit the lethargic and treacherous symptoms of “dumb” rabies. A few weeks after that first incident, another coyote sat watching cars go by a couple of blocks from the Starr County Courthouse. A resident shot it too.
Although rabies occurs regularly on the Mexican side of the river, the disease has been virtually unknown on the American side for nearly two decades. As of September 3, 1988, eighteen years had passed since the virus had last been detected in Starr and adjacent counties in any animals except bats. Since that date—when a sickly coyote entered a yard near the rural village of Rincon, menaced the owner, and fought with his two dogs while he ran for a gun—96 cases of animal rabies have been confirmed in Starr County alone. In a twelve-county area of South Texas, the number of cases is approaching 300 and shows no sign of slowing down.
The infected animals in Starr County have included a raccoon, a bobcat, a goat, and 3 domestic cats, but the overwhelming majority of cases have involved canids—27 coyotes, 60 dogs. The brush county outbreak has spread in a consistent pattern. In tiny ranching hamlets, there will be no sign of rabies; then, all at once, the areas are besieged. Rabid coyotes show up first. Then, after a lull of eighteen days, to ten months, unvaccinated dogs develop symptoms. Scattered north of Rio Grande City are Starr County’s principle ranching communities. Their names—El Sauz, La Gloria, Santa Elena, La Reforma—reflect the county’s dominant ethnicity. They are friendly little places with tidy homes and well-kept churches, perhaps a store and a school, cemeteries filled with the floral tributes that Hispanics bestow on the dead.
In March 1991 a wave of rabies passed through these enclaves in northern Starr County. The following August, on a ranch between El Sauz and La Gloria, a 55-year-old Hispanic woman fell ill and died of canine rabies. State health investigators could never prove that her tragedy was related to the coyote epidemic; incubation of the virus in humans can take more than a year, making cause and effect hard to pin down. But investigators became suspicious when they learned that the woman’s unvaccinated dog had recently died of unknown causes. A puppy that had played with the dog had later gotten a bone caught in its throat, and the woman had stuck her finger in the pup’s mouth, trying to dislodge the obstruction. Her husband swore that she was not bitten, but then, one doesn’t have to be. The virus can enter through a minor cut or an open sore. It can be transmitted through the mucus membranes of the eyes.
Unlike most viruses, which are blood-borne, rabies travels through the nervous system, reaching the spinal cord and then inching toward the brain. The gruesome vaccination ordeal of dozens of painful shots in the abdomen is an obsolete procedure; a newer and quite effective vaccine can be administered in a series of just six shots in the arm. But doctors have to realize that the shots are required, and rabies is notoriously hard to diagnose. Symptoms can include mental depression and restlessness, sore throat, fever, nausea, and stomach pains; the profile is easily mistaken for appendicitis or inflammation of the kidneys or pelvis. By the time lab testing confirms the disease, it is almost always too late. The patient can suffer seizures, hallucinations, uncontrollable excitement, and excruciatingly painful spasms in the neck and jaws. The spasms can be triggered by the slightest irritation. As a result, the patient is unable to drink, even though he may be consumed with thirst. Death from asphyxiation, exhaustion, or general paralysis usually follows in three to ten days. Rabies is a ghastly way to go.
North of the Starr County settlements, the chaparral stretches virtually unbroken for fifty miles before reaching the Jim Hogg county seat of Hebbronville. Late one afternoon in September 1991, a month after the death of the woman who handled the puppy, a three-year-old child was playing on her porch in Hebbronville. Inside the house, her mother heard the child suddenly begin to scream. She ran outside and saw blood and a nasty wound on her daughter’s back. This time the victim did not die, but the source of the bite was undisputable. In the yard was a rabid coyote that had come right up out of the brush.
Fortunately for humans and their domestic livestock and pets, the dozen or so known strains of rabies tend to be host specific. Dogs have dog rabies, raccoons have raccoon rabies. A particular strain can be transmitted to another species of mammal but not as readily as to the same species. In Texas, skunks are the creatures most often afflicted, accounting for about half of the more than four hundred positive tests recorded by the Texas Department of Health each year. Bats come in a far distant second. Like humans and cats, coyotes have not developed an endemic rabies strain and until now were rarely affected by rabies. The animal’s behavioral traits may help to account for that. Nimble and canny creatures, coyotes are hard to corner and have been clocked running 35 miles per hour. It is possible that they might just have a keen eye for sick animals acting crazy and have learned to avoid them.
The first crossover infection may have occurred long before the fall of 1988 and scores of miles from Starr County. Whenever it was, and wherever, a coyote contracted the strain of the rabies virus that U.S. scientists have named—with undiplomatic bluntness—Urban Mexican Dog. It is a particularly virulent strain of rabies, and once it jumped into the coyote population, a vicious cycle of coyote-to-dog transmission was established. In this part of the country, where vaccination of pets is not consistently practiced, the disease spread readily in populous areas.
Through 1990 the outbreak was confined to Starr and its downstream neighbor, Hidalgo County. In 1991 it abruptly leapt one hundred miles north of the Rio Grande. The outbreak has since spread through twelve of the state’s southernmost counties—roughly following a line from Corpus Christi to Laredo. In those counties, state health officials have now confirmed a total of 130 rabid coyotes and 149 dogs, only two of which had been vaccinated. Recently, a rabid coyote was killed on the beach near Port Aransas. As conditions now stand, there is no reason to believe the spread will stop short of the city limits of Victoria and San Antonio.
The present epidemic did not happen in a vacuum. Over the last several decades, coyotes have proliferated throughout North America as their chief natural rivals, wolves, have been eradicated. No habitat suits coyotes better than the brush country of South Texas, but as the incidence of rabies has grown, local residents have come to believe that the number of coyotes is way up. The past two years have brought unusually abundant rain and mild winters, and many species are doing well, among them cottontail rabbits, the primary prey of coyotes in the chaparral. With more rabbits for the adults to eat, more pups are likely to survive. Females are fertile at seven months and give birth to litters of six or seven pups.
But whether the coyote population is up or down, the incidence of rabies is definitely up. At the Texas Department of Health in Austin, Keith Clark, a Marble Falls rancher and veterinarian has been calling for emergency vaccination drives. A widely recognized authority on rabies, Clark says of the situation in South Texas, “We’re up against something that’s entirely new. Rabies is established in coyotes now. It’s not going to go away.”
“Here, hold this,” says Rio Grande City veterinarian Roberto Margo, placing a white plastic-foam container in the hands of a visitor. Margo turns to his paperwork with a slight smile. “It’s the head of a dog that died of rabies—probably.”
Packed in ice, the mongrel pup’s head will go by Greyhound bus freight to the Department of Health, where Keith Clark’s technicians will subsequently confirm it as the first case of rabies in Starr County in 1993.
In addition to operating a private practice, Margo serves as the Starr County veterinarian. His position sums up some of the problems facing the impoverished county. Rio Grande City (population 9,900) is the seat of Starr County but is unincorporated. Because of that, the city cannot effectively enforce measures such as mandatory pet-vaccination drives. All services, from water and sewage lines to public health and animal control, are administered by the county. But the county itself is so poor that it has no money to pay the county vet. Therefore, Margo does not earn a salary for his work. His situation has been frustrating.
