Purpose of review: After tuberculosis, leprosy (Mycobacterium leprae) and Buruli ulcer (M. ulcerans infection) are the second and third most common mycobacterial infections in humankind, respectively. Recent advances in both diseases are summarized.
Recent findings: Leprosy remains a public health problem in some countries, and new case detections indicate active transmission. Newly identified M. lepromatosis, closely related to M. leprae, may cause disseminated leprosy in some regions. In genome-wide screening in China, leprosy susceptibility associates with polymorphisms in seven genes, many involved with innate immunity. World Health Organization multiple drug therapy administered for 1 or 2 years effectively arrests disseminated leprosy but disability remains a public health concern. Relapse is infrequent, often associated with higher pretreatment M. leprae burdens. M. ulcerans, a re-emerging environmental organism, arose from M. marinum and acquired a virulence plasmid coding for mycolactone, a necrotizing, immunosuppressive toxin. Geographically, there are multiple strains of M. ulcerans, with variable pathogenicity and immunogenicity. Molecular epidemiology is describing M. ulcerans evolution and genotypic variants. First-line therapy for Buruli ulcer is rifampin + streptomycin, sometimes with surgery, but improved regimens are needed.
Summary: Leprosy and Buruli ulcer are important infections with significant public health implications. Modern research is providing new insights into molecular epidemiology and pathogenesis, boding well for improved control strategies.