Detailed genetic analysis of Mycobacterium leprae isolates from wild armadillos and human patients suggests that leprosy may be a zoonosis in the southern U.S.
Despite suspicion that some leprosy patients in the U.S. might have acquired their disease from armadillos, causality has not been proven. To further explore this possibility, investigators performed an ecologic cohort study that involved skin-biopsy specimens from 50 leprosy patients who lived in the southern U.S. and tissue samples from 33 wild armadillos from the same geographic region.
Whole-genome sequencing, single nucleotide polymorphism typing, and variable-number tandem-repeat analysis were used to molecularly characterize the Mycobacterium leprae strains isolated from these samples.
One genotype, labeled 31-2-v1, appeared to be unique and highly distinctive and was significantly associated with a history of residence in regions where infected wild armadillos have been found (P<0.001). This genotype was recovered from 28 of 33 armadillos and from 25 of the 39 patients who lived in regions where exposure to infected armadillos was possible; the genotype has not been reported from anywhere else in the world. There was some suggestion that contact with an armadillo might increase the likelihood of infection with this unique strain (odds ratio, 4.0; 95% confidence interval, 0.5–35.8).
Comment: The results of this in-depth strain analysis are intriguing and should encourage additional activities to confirm the impression that zoonotic leprosy occurs in the southern U.S.
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