Experimental leprosy infection in a nine-banded armadillo: an early disease-model study
A 1971 experiment reported lepromatoid disease in a nine-banded armadillo about 14 months after inoculation with leprosy bacilli. This archive record summarizes the experiment, its historical role in armadillo research, and what later work established about the model.
What the study did and found
In 1971, Nora Veldin published "Attempts to establish the armadillo (Dasypus novemcinctus Linn.) as a model for the study of leprosy. I. Report of lepromatoid leprosy in an experimentally infected armadillo." in the International Journal of Leprosy and Other Mycobacterial Diseases. The study involved inoculating a nine-banded armadillo (Dasypus novemcinctus) with leprosy bacilli from an untreated case of lepromatous leprosy, placing inoculum in abdominal skin and the ear lobes. About 14 months later the animal had developed lepromatoid infection. The study reported a more than 1,000-fold increase in acid-fast bacteria at the inoculation sites, massive nodular skin lesions, intracellular bacilli in lepra cells, bacilli in cutaneous nerves, and abundant acid-fast bacteria at a normal-looking skin site away from the inoculated areas. Culture and D-dopa observations were consistent with M. leprae, while the mouse foot-pad work provided additional experimental context.
Why it is cited
This paper is recognized as early experimental evidence that the nine-banded armadillo could support disseminated M. leprae infection and therefore could serve as a useful animal model for leprosy research. Its historical importance comes from demonstrating the susceptibility of armadillos to experimental infection and helping establish their role in later investigations of leprosy biology, pathology, and transmission.
The central experimental finding was reinforced by later armadillo research, including post-mortem studies and decades of work using nine-banded armadillos to propagate M. leprae and investigate leprosy pathogenesis. Subsequent field and genomic studies also demonstrated naturally acquired M. leprae infection in wild armadillos and supported zoonotic transmission in parts of the southern United States. These later findings extend the 1971 paper: the original experiment focused on experimental infection rather than natural transmission, human risk, or disease outcomes in people.
The topic today
Nine-banded armadillos remain a recognized animal model for M. leprae research and a nonhuman reservoir relevant to zoonotic leprosy. Modern studies use them to examine bacterial propagation, pathology, peripheral nerve involvement, host responses, and transmission. Genomic methods now allow researchers to compare M. leprae strains from wildlife and people, while surveillance has shown that infection in wild armadillos is geographically variable. The model's current value therefore spans both laboratory research and the ecology of a pathogen that can circulate outside humans.