But Robbins cautions, "We're making an educated guess, and each time somebody has guessed, the armadillos kept moving north." The previous prediction set the limit in central Arkansas, "and they just plowed right on past that."
Robbins expects Missouri's armadillo population to increase and "fill in the gaps" in its range except for the bootheel, because of lack of burrow sites above the water table.
He thinks they won't do as well in broad expanses of farmland as they will where woods are available. Armadillos like the softer earth of fields and lawns, but when that open ground freezes, they head for the woods and feed under the leaf litter, where soil doesn't freeze as readily.
LEPROSY AND ARMADILLOS
The nine-banded armadillo is the key to a worldwide effort to eliminate Hansen's disease (leprosy), the ancient malady of the tropics and subtropics that affects cooler areas of the human body.
The leprosy bacillus was discovered in 1872, but scientists couldn't grow it in the laboratory. Research in treatment and prevention didn't take off until 100 years later, when scientists found an ideal host with a relatively cool body temperature - the nine-banded. Organisms grown in laboratory armadillos were distributed to research facilities, and the animal itself became a model in development of new drugs. As research continues, three medications are being tested in humans in clinical trials sponsored by the World Health Organization.
During this period of progress, two disconcerting mysteries arose in Texas and Louisiana. First, in the 1970s, leprosy was found in 15 to 20 percent of wild armadillos in those states, with the origin of their infection unknown.
Bob Howard, a spokesman for the National Center for Infectious Diseases, says the center has no information showing leprosy in armadillos in other states. "The armadillo is one of those animals that is studied pretty extensively," he explained, "so if there were indications it was occurring elsewhere, it would be picked up and studied." Florida Institute of Technology researchers found no leprosy among 3,000 armadillos, according to Dr. Arvind Dhople, research professor.
Then, in the mid-1980s, medical journals began to report diagnosis of leprosy in a few people in Texas and Louisiana who had no contact with leprosy patients but handled armadillos. Dhople estimates the number of diagnosed cases at five to ten per year. Contact included racing the armadillos, extracting meat and making souvenirs from the shells. The exact mode of transmission of leprosy, even from human to human, has not been clearly established, but Howard says, "We believe those particular behaviors would put one at risk."
As far as scientists know, both problems - leprosy in armadillos and in people who have handled them - are restricted to Texas and Louisiana.