By the early 20th century, the critters had expanded their range across much of southern and central Texas, including a westward extension along the Pecos River nearly to the border with New Mexico. Eastward extension into Louisiana and into southern
and western Mississippi and parts of Alabama came later. Meanwhile, 3 purposeful introductions of armadillos were made in Florida in the 1920s and 1930s, facilitating their rather rapid colonization by 1972 of all of the state except the Everglades and the Panhandle Region. Southern Arkansas, Oklahoma and Georgia soon followed. The current range extends to Kansas, Missouri and most of South Carolina. Outliers beyond that range may or may not represent real range extension. Global warming would favor range expansion in response to decreasing number of freeze-days even though it seems unlikely to explain the initial expansion out of Mexico. See S. R. Humphrey (BioScience vol. 24, pages 457-462, 1974) for further discussion of range extension and climatic effects.
Undoubtedly the armadillo’s least attractive feature is its vulnerability to leprosy or Hansen’s Disease. In fact, this dreaded bacterial disease which destroys the liver and kidney if not treated early, infects only armadillos and humans, no other species! Perhaps thought of as a problem restricted to the tropical regions, 150 to 250 human cases occur annually in the U.S. About a third of these are traceable to contact with infected armadillos. Many cases are found in Louisiana and Texas where armadillos are hunted, skinned and eaten! Leprosy thus has joined the growing list of diseases like West Nile Virus that have spread from animals to humans. In armadillos, leprosy is apparently much more recent than in humans. The disease is believed to have been unknown in the New World prior to the trans-Atlantic voyages of Columbus and other explorers, but has a long history in the Old World in humans, but, of course, not in armadillos, which are found only in the Americas. Thus we have a seldom discussed aspect of the Columbian Exchange!