Temporal Aspects of Leprosy Infection in a Wild Population of Nine-Banded Armadillos

Although Dasypus novemcinctus (Nine-banded Armadillo) is the only vertebrate other than humans to exhibit naturally occurring infections with Mycobacterium leprae, the causative agent in producing leprosy, little is known about patterns of infection in wild populations. Here we provide data on some temporal aspects of infection, obtained from sampling a population of armadillos in western Mississippi from 2005–2010. Annual prevalence of infection varied between 4.5–15%. Incidence density estimates calculated over progressively longer time intervals generated values ranging from 0.11–0.61 new cases of infection/1000 animal days. Of 77 animals that tested seropositive over the course of the study, 14 (18.2%) were seropositive in two consecutive years. Four of these animals were seropositive in three consecutive years, but no armadillos tested positive in >3 straight years. Finally, the proportion of seropositive animals increased with the number of years individuals were enrolled in the study. Together, these data indicate a substantial potential for transmission of infection within this population and confirm the view of leprosy as a slow-acting disease that is largely manifested in older individuals.