The bacterium of leprosy: slow, curable, and far less contagious than its history suggests. Explore its illustrative 3D model, human context, and sources.
WHO describes leprosy as a chronic infectious disease caused by Mycobacterium leprae that affects skin and peripheral nerves and can cause permanent disabilities if untreated. StatPearls describes M. leprae as a Gram-positive, acid-fast bacillus and an obligate intracellular organism that cannot be cultured with artificial media, with a predisposition to spread more efficiently at cooler regions of the body including skin, superficial nerves and the membranes of the upper respiratory tract, and tropism for Schwann cells and macrophages. LPSN records that no culture is available for this species. WHO states that leprosy is a curable disease and recommends multidrug therapy for 6 months in paucibacillary cases or 12 months in multibacillary cases, and that patients become non-infectious once treatment begins.
WHO states that casual contact does not spread leprosy and that patients become non-infectious after treatment begins, so the historical fear of contagion is not supported by the current description. The real risk is nerve damage accumulating before diagnosis: WHO describes permanent disabilities if the disease is untreated. Roughly 200,000 new cases are reported each year worldwide, so this remains a current disease rather than a historical one.
Mycobacterium leprae · A slender bacillus with a simplified mycolic-acid-rich envelope, authored separately from the TB model. This is a species-informed teaching diagram; colours, proportions, envelope spacing and internal detail are illustrative. The model uses muted illustrative colours; stains, colony pigments and microscopy colourization are not natural cell colours. Anatomy is enlarged for phone viewing. Morphology reference: Leprosy · organism, Ridley-Jopling classification and clinical features.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.