Read condition-specific symptoms and clinical context for Mycobacterium leprae. The bacterium of leprosy: slow, curable, and far less contagious than its history suggests.
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 the disease manifests commonly through skin lesions and peripheral nerve involvement, and that diagnosis requires identifying at least one cardinal sign: loss of sensation in skin patches, thickened nerves with weakness, or bacilli detected in skin samples.
Possible symptoms: Pale or reddish skin patches; Loss of sensation in skin patches; Numbness or tingling; Thickened peripheral nerves with weakness; Painless burns or injuries in the hands and feet; Loss of eyebrows or eyelashes.
WHO states that leprosy is a curable disease and recommends multidrug therapy combining dapsone, rifampicin and clofazimine for 6 months in paucibacillary cases or 12 months in multibacillary cases. StatPearls describes the Ridley-Jopling spectrum from tuberculoid to lepromatous forms, which reflects the immune response rather than separate diseases. Diagnosis and treatment are clinical decisions.
Being near someone with leprosy does not usually lead to disease.
WHO states that casual contact does not spread leprosy and that patients become non-infectious after treatment begins; transmission is believed to occur through droplets from the nose and mouth of an untreated case. There is no symptom list for contact without disease and none is invented here. WHO’s diagnostic requirement of at least one cardinal sign means that, without a skin patch with sensory loss, a thickened nerve with weakness, or bacilli in a skin sample, leprosy is not diagnosed. This profile assigns no human carriage state.
Contact tracing and any preventive measures for household contacts are handled by national leprosy programmes. This app gives no exposure advice and does not assess skin changes.
Source check: 2026-09-20. Educational content; independent scientific review remains pending.