Epidemic Strikes Alligators At Popular Farm, Says UF Researcher

February 27, 1997

GAINESVILLE — A mysterious infectious disease is killing captive alligators and may threaten their estimated 1.5 million counterparts in the wild, says a University of Florida biologist.

The new epidemic of bacteria is destroying even the largest of the ancient reptiles at the St. Augustine Alligator Farm and Zoological Park, killing more than three-quarters of the alligators that have been exposed to the disease, said Kent Vliet, a UF alligator expert and member of a team of researchers studying the problem.

A treatment is being tried, but Vliet says it’s too early to tell wether it works. While it provides a means to control the disease among captive alligators, he said it likely would be impractical for treating alligators in the wild.

“We thought alligators were incredibly resilient animals, with surprisingly few cases of disease,” he said. “We were wrong. Unfortunately, these infected animals made up the core display group at the alligator farm. Many were more than 60 years old, 11 or 12 feet long and weighed 700 or 800 pounds.”

Beginning in fall 1995, large male alligators in one enclosure at the farm suddenly began getting sick and dying at the alarming rate of about a half dozen a day, Vliet said.

About 77 of these 89 alligators died, and the disease since has spread to a second enclosure of 160 alligators, both male and female, he said.

UF’s wildlife veterinarians immediately began performing necropsies — animal versions of autopsies — and discovered the culprit was a new strain of Mycoplasma bacteria, Vliet said. Mycoplasmas cause arthritis and pneumonia in humans and animals and are responsible for upper respiratory infections in the endangered desert tortoise of the American Southwest and the Florida gopher tortoise, he said.

The Mycoplasma infects the respiratory tract and the joints. The infected alligators become extremely sluggish and stop moving.

“If you distress them enough, they’ll get up and walk away or take a swing at you,” he said. “But for the most part they stay on the ground so long that slight movements of their arms or heads kind of wallow out a little area in the sand, like a snow angel. One researcher calls this condition the sand angel syndrome.’”

Although the only other documented case of Mycoplasma infection among crocodilians affected Nile crocodiles at a Zimbabwe farm, there easily could be others among some of the isolated cases of alligator die-offs in farms and in the wild, Vliet said.

The researchers have not done specific work on the alligators’ immune systems, but

based on the effects of other kinds of Mycoplasma, Vliet believes the bacteria compromises the alligator so other secondary bacterial or viral invaders of the body are able to overwhelm the alligator and kill it.

Alligators are not routinely checked for Mycoplasma in necropsies because the conditions necessary to isolate and culture the bacteria in the laboratory are fairly rigorous and few laboratories are equipped to do it, Vliet said. A UF team led by Mary Brown and Elliott Jacobson, professors at UF’s College of Veterinary Medicine, has worked for several years on Mycoplasma and was able to identify the organism quickly and begin combating the disease, Vliet said.

After conducting a series of antibiotic trials, Vliet and veterinary researchers began the difficult task of treating a large group of the alligators with regular injections. “It really points out how little we know about the effects of antibiotics and the proper dosages to give these very large cold-blooded animals,” Vliet said. “It has forced us to go back and do some

basic research.”

The epidemic has been difficult for the century-old alligator farm, the world’s oldest.

“When the farm moved to its present location in the 1920s, an enclosure was built for the largest animals and it has been the focal point of the farm for seven decades,” Vliet said. “People come from up North just to see this huge collection of very big alligators. Now the vast majority of these animals are gone.”