SAN ANGELO — Rabies cases in animals are spreading at a surprising rate this year in South and West Central Texas, and state officials are warning hunters in particular to be alert for unusual animal behavior in the wild.
The fall hunting seasons are expected to send more than one million hunters into the Texas brush, increasing the chances that people who don’t take simple precautions may be bitten and infected.
“Use a little common sense,” advises Dr. Dale Rollins, wildlife specialist for the Texas Agricultural Extension Service in San Angelo.
“If you encounter a fox, coyote, or any other animal exhibiting unusual behavior, stay away from it. This behavior could include activity during daylight or showing no fear of humans. If you’re a quail hunter, make sure your bird dogs have current vaccinations.”
Rabies carried primarily by coyotes and dogs has been found in four new counties in South Texas this year, indicating that the disease has continued moving north to within a county of the San Antonio metropolitan area.
Meanwhile, rabid gray foxes have turned up in 12 new counties in West Central Texas and appear to be spreading north and east toward San Antonio, Austin, Abilene, Fort Worth and Dallas.
Rabies is a viral disease that is almost always fatal, but human deaths in Texas continue to be few. Since 1990, three persons have died from exposure to rabid animals in Texas; none died during the 1980s.
Even so, the seriousness of the two rabies epidemics in Texas led Gov. Ann Richards in July to declare both to be state health emergencies. State authorities are moving to increase public awareness of the problem and to urge vaccinations of pets and livestock.
In the gray fox rabies epidemic, 215 rabid animal cases have been reported this year through mid-September. Tom Green County with 69 confirmed cases and McCulloch County with 67 lead the state. No other county comes close.
Dr. Keith Clark, director of the Texas Department of Health’s Zoonosis Control Division, attributes the increase directly to a loss of fur markets over the last five years. The relaxed trapping pressure has led to a virtual explosion in all fur-bearer numbers.
“When there’s a population explosion in any species, problems occur,” said Clark. “Nature’s way of keeping a population healthy is spatial separation. When overpopulation occurs, rabies and other diseases flourish; it’s harsh but very effective.”
“South Texas has received a lot of attention because the coyote strain readily infects dogs and can be transmitted from dog to dog. For every single exposure to a wild animal, we have five from a domestic animal.
“While the number of rabies cases are almost equally divided between coyotes and dogs, over 90 percent of the human exposures are from the dogs. Simply put; the more people and unvaccinated dogs in an area, the more chance of exposure.”
In all, 71 canine rabies cases have been reported this year, with half of them found in three counties: Kleberg, 13; Webb, 12, and La Salle, 11.
Clark said that fox rabies cases were virtually unheard of in Texas prior to 1946, when an outbreak from Louisiana crossed into Shelby County. The disease was almost forgotten by the late 1970s, but a small pocket remained in the rough country in Val Verde, Real and Uvalde counties.
After fur prices fell in 1988, the resulting fox population explosion triggered the current outbreak, Clark said.
“Once rabies hits an area, it kills off the susceptible animals, and the area remains relatively trouble free until populations again boom,” he said. “As a rule, though, the subsequent outbreaks rarely equal the initial one. Unfortunately, problems quickly occur in neighboring counties. For example, the Tom Green-McCulloch County episodes probably are on the decline. Neighboring counties will be the next areas hit, but Tom Green and McCulloch counties will probably be relatively rabies-free for at least the next two years.”
Clark admits the rabies increase is alarming, but added that caution tempered with a little common sense can save people a lot of grief.
“Vaccinate all your dogs and cats annually,” he advised. “In fact, all domestic animals receiving regular human contact should be vaccinated, including saddle horses and show stock. By law, all rabies vaccinations in Texas must be performed by a licensed veterinarian.”
Clark’s department is working on an oral vaccine that would immunize animals in the wild to try and stem the rabies tide. The project involves cooperative efforts with, among others, Texas Animal Damage Control, the U.S. Army, the Texas A&M University School of Veterinary Medicine, Texas A&M at Kingsville, U.S. Department of Agriculture, Centers for Disease Control and Prevention, and Rhone- Merieux Inc.
Baits laced with the vaccine are air-dropped over a wide area where they are eaten by coyotes, dogs, foxes, and other carnivores. Clark said the technique has been successful on red fox in Canada and Europe. An initial test project, using bait without the vaccine, yielded promising results with coyotes in South Texas.
Research on the baits is still under way, Clark said, but the health department hopes to have the coyote bait deployed by February and the bait for the foxes out by next fall.
If the vaccine baits work, Clark said, rabies on an epidemic scale could be a thing of the past within five to seven years.
Texas counties in which canine rabies were found during 1988-1993 were Brooks, Cameron, Duval, Hidalgo, Jim Hogg, Jim Wells, Kenedy, Kleberg, LaSalle, Nueces, Starr, Webb, Willacy and Zapata. The four new counties added to the list this year were Dimmit, Frio, Live Oak, and McMullen.
Texas counties in which fox rabies were found during 1987-1993 were Bandera, Brewster, Concho, Crockett, Edwards, Irion, Kendall, Kerr, Kimble, Kinney, Medina, Menard, McCulloch, Pecos, Presidio, Real, Schleicher, Sutton, Terrell, Tom Green, Upton, Uvalde and Val Verde. The 12 new counties added in 1994 were Bexar, Brown, Coke, Coleman, Crane, Lampasas, Mason, Mitchell, Reagan, Runnels, San Saba and Sterling.
-30-
