Forms of Leprosy
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By Liji Thomas, MD
Leprosy is a chronic granulomatous infection. It is caused by the slow-growing organism Mycobacterium leprae, which is an obligate intracellular parasite. It affects chiefly the skin and peripheral nerves.
Leprosy has a wide range of clinical manifestations, which depend upon the host immune response more than the virulence or multiplication rate of the bacillus. It has a long incubation period, from two to seven years, ranging between six months and 20 years. Seropositivity may occur months or years before a clinical diagnosis is made.
Closeup hands of asian old man suffering from leprosy, Thailand - Image Credit: Bidarat Tiemjai / Shutterstock
Closeup hands of asian old man suffering from leprosy, Thailand - Image Credit: Bidarat Tiemjai / Shutterstock
The typical manifestations of leprosy include:
Hypoesthesia of skin lesions with the decrease in sensitivity – this follows the sequence of heat-pain-light touch insensitivity.
The disease spectrum ranges from tuberculoid to lepromatous, corresponding to a high and low cellular immunity (Th1 and Th2 response) respectively.
Cytokines released in tuberculoid disease include interferon (IFN)-γ, IL-2 and lymphotoxin-α with high phagocytic activity and granuloma formation due to macrophage and T-cell aggregation. In lepromatous disease, granuloma formation is reduced, and CD8+ cells are predominant. Patients in the borderline forms move between these two ends as the immune status shifts, and leprosy reactions are a characteristic feature of this state.
http://www.news-medical.net/health/Forms-of-Leprosy.aspx
