Hansen's Disease (Leprosy)

Current and Future Pharmacotherapy and Treatment of Disease-related Immunologic Reactions

Davey P. Legendre, Pharm.D.; Christina A. Muzny, M.D.; Edwin Swiatlo, M.D., Ph.D.


Pharmacotherapy. 2012;32(1):27-37. 

In This Article


Hansen's disease occurs in both tropical and subtropical temperate climates. Worldwide, it remains an important public health problem, especially in Asia, Africa, and South America, including India, Brazil, Indonesia, Democratic Republic of the Congo, Bangladesh, Nepal, Angola, China, Madagascar, Mozambique, Nigeria, the Philippines, and the United Republic of Tanzania.[3] Nevertheless, the annual case detection rate of new infections with M. leprae has declined over the past decade as a result of more intensive infection control programs and the use of multidrug therapy.[3] In the United States, immigrants from endemic countries constitute the vast majority of cases diagnosed annually (85–95%).[4] Endemic foci do exist, however, mainly in parts of Texas, Louisiana, Florida, and California.[5] A total of 150 endemic cases in the United States were reported to the National Hansen's Disease Registry in 2008.[5] The annual number of endemic cases reported in the United States has remained relatively stable since 1988. The incidence of disease peaks in the age groups of 10–15 and 30–60 years, and the male:female ratio of infection is ~2:1.[1] No racial predilection for acquisition of this disease is known.

Humans are the primary reservoir for M. leprae. Besides man, only wild nine-banded armadillos (Dasypus novemcintus) are known to be natural hosts of M. leprae.[6] Several cases of suspected zoonotic transmission from armadillos to humans have been reported.[7,8,9,10] Infected armadillos have been found in Alabama, Arkansas, Louisiana, Mississippi, Texas, and Mexico.[11] Whole-genome sequencing of M. leprae from infected wild armadillos and patients with leprosy in the United States has revealed a unique M. leprae genotype (3I-2-v1) that has not been reported elsewhere in the world, lending further evidence to the hypothesis that M. leprae is a zoonosis in this region.[12]


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