Leprosy results from infection with Mycobacterium leprae, an obligate intracellular bacterium. It is an infectious disease, not a heritable genetic condition, and is not caused by an inherited genetic change. Factors that determine individual susceptibility and the spectrum of clinical disease presentations remain an area of active scientific investigation, with host immune response playing a central role in determining the subtype and severity of disease.

Diagnosis of leprosy is established through clinical evaluation combined with laboratory assessment. Research is ongoing to improve diagnostic accuracy and to identify biomarkers predictive of treatment response and disease monitoring. Studies are examining polymerase chain reaction techniques applied to nerve-adjacent tissue and novel diagnostic tools designed for use in endemic settings, including AI-assisted skin disease identification approaches.

No treatments are specifically FDA-approved for leprosy as a designated rare disease in the United States. Standard therapeutic approaches for leprosy have been established through international health programs and are widely used in endemic regions. One investigational compound, dovramilast, has received orphan drug designation for leprosy treatment from the U.S. FDA; it has not yet received FDA marketing approval. Additional therapeutic strategies, including adjunct pharmacological combinations, are being evaluated in ongoing clinical trials.

Prognosis in leprosy varies by disease subtype, timing of identification, and response to treatment. Different subtypes carry different risks of peripheral nerve damage and associated disability. Early identification and treatment are associated with reduced risk of irreversible nerve damage. Precise global prevalence estimates for leprosy are not well established, with the condition listed as UNKNOWN in certified prevalence databases. Disease burden and distribution vary considerably by geographic region.

Leprosy is an active area of clinical investigation, with several trials currently examining new interventions and diagnostic approaches. Active research includes Phase 1 through Phase 3 studies evaluating prophylaxis strategies such as bedaquiline post-exposure prophylaxis, diagnostic accuracy tools, and adjunct treatment combinations including metformin for multibacillary disease. A vaccine candidate (LEP-F1 plus GLA-SE) is under Phase 1 evaluation. Published research on leprosy spans epidemiology and natural history, biomarker identification, and recent trial-related publications across a classified body of literature.