On the Origin of Leprosy

TLDR

Leprosy is a chronic human disease caused by the unculturable Mycobacterium leprae, whose genome has undergone extensive reductive evolution with many pseudogenes. The study aimed to determine the evolutionary origin and global spread of leprosy by showing that all current cases derive from a single clone traced via rare SNPs. The authors used comparative genomics to analyze rare single‑nucleotide polymorphisms and trace the worldwide dissemination of a single leprosy clone. The analysis indicates that leprosy originated in Eastern Africa or the Near East and spread through successive human migrations, with Europeans or North Africans introducing it to West Africa and the Americas within the last 500 years.

Abstract

Leprosy, a chronic human disease with potentially debilitating neurological consequences, results from infection with Mycobacterium leprae. This unculturable pathogen has undergone extensive reductive evolution, with half of its genome now occupied by pseudogenes. Using comparative genomics, we demonstrated that all extant cases of leprosy are attributable to a single clone whose dissemination worldwide can be retraced from analysis of very rare single-nucleotide polymorphisms. The disease seems to have originated in Eastern Africa or the Near East and spread with successive human migrations. Europeans or North Africans introduced leprosy into West Africa and the Americas within the past 500 years.