BURNET — Rabies in coyotes and gray foxes haven’t been choked out yet in Texas, but the noose is tightening, thanks to a third successful year in a cooperative state program.
The Texas Animal Damage Control Service, working with other government agencies, helped lead an aerial assault that spread baited rabies vaccine over 41,000 square miles of South, West and Central Texas.
Concluding in early February, the annual Texas Department of Health program also involved personnel from the Texas National Guard and the Ontario Ministry of Natural Resources. It tightened the “perimeters of immunity,” squeezing just a little more the areas where the rabies cases are centered.
The strategy is to fly in smaller bands around the infected areas each year until the areas have been spread completely with baited vaccine and the disease controlled.
The perimeters serve as buffer zones around the infected areas. Targeted animals generally have a limited range and will not move beyond the buffer zone, said Guy Moore of the Texas Department of Health, West-Central Texas project director for the aerial drop.
In 1995, the assault began with a vaccine drop against coyotes in South Texas, where 21 counties have reported canine rabies cases. In 1996, it expanded to include an area around 48 West and Central Texas counties where rabies in gray foxes is a problem.
January’s South Texas portion covered 21,000 square miles and parts of 29 counties. February’s drop in West and Central Texas covered 20,000 square miles in 52 counties.
As the operation continues in subsequent years, organizers expect the infected areas will become ever smaller. Animal rabies cases fell from 244 in 1995 to 101 in 1996 in the West and Central Texas area. In South Texas, they fell from 142 to 20.
No cases of rabies have been reported in foxes or coyotes outside the perimeters since the program began, Moore said.
Funding for the program runs out in 1998, but the agencies running it hope to be able to secure future funding, he added.
The agencies are working together to stamp out an epizootic, or epidemic in animals, that had spread through 21 South Texas counties and 48 counties in the western and central portions of the state. Gray fox and coyote populations were among the animals most affected, and the coyote rabies problem was quickly moving toward San Antonio when the aerial vaccinations began in 1995.
The difference between the two areas lies mainly in the bait used and the animals targeted. The South Texas bait for coyotes is primarily fish meal, while the fox bait is dogfood laced with aromatic vanilla and a bit of sugar coating.
“Foxes have a sweet tooth,” Moore explained.
Using three bright yellow Twin Otter planes from Ontario, the effort involves teams of pilots, navigators and others who fly for several hours at a time. Planes fly a preplanned path, dropping baits over a quarter-mile wide swath. They parallel the same path on the way back, moving over slightly to cover another quarter-mile area.
On good days, three complete out-and-back tours can be made with each plane. The trips eventually result in an outer perimeter 20 miles wide where bait had been spread.
Crews in the back of the planes man a long conveyor belt, keeping a steady stream of the baits rolling along the belt and eventually out of an apparatus that drops the baits out of the bottom of the plane.
The flight crew controls the apparatus from the cockpit so that it does not drop bait over houses or other populated areas.
The baits might be tasty for coyotes, foxes and other animals happening upon them. However, they’re not so pleasing for flight crews.
“You never forget that smell,” said Moore, who added that most people become nauseated at least once during the operation, but get used to the smell.
“We hear jokes, but very few complaints. Everybody seems to love to do this.”
Crews switch off to avoid consecutive segments and fly either one or two segments each day. More than 50 Texas Animal Damage Control Service employees took part.
“This is a high-manpower operation,” said Gary Lee Nunley, state director of the Texas Animal Damage Control Service. “We supply about 60 percent of the manpower and pay their salaries, but TDH picks up the travel costs.
“We have a common interest, so it’s beneficial for all of us to cooperate.”
Using a mobile command post, the project started in Alice in the second week of January. It moved to Fort Stockton, and then concluded in Burnet a month later.
Airports in all three locations were used for the daily flights along the perimeters.
Ontario contracts out planes and crews because they are not in full- time use in Canada, where rabies problems also occur. That province also has a vested interest in doing so, Moore said.
“The particular strain of rabies in coyotes is found only in Texas, so we don’t want it to break out,” he said. “If it does, it’s conceivable that it could go all the way to Canada.”
Nunley said the Texas Animal Damage Control Service will soon be out in the field conducting surveillance work to monitor the success of the project. Its expertise in collecting animals for surveys and in controlling animal diseases complements the health department’s ability to plan and monitor the large vaccination effort, he said.
Dr. Gayne Fearneyhough, director of the health department’s oral rabies vaccination program, said establishing the perimeter and reducing cases within is important because it reduces the chances of rabies transmission to humans, as well.
“The battle isn’t over, but we’re definitely on the offensive. The program is working,” he said.