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Medical Author:

Charles Patrick Davis, MD, PhD

Charles Patrick Davis, MD, PhD

Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

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Medical Editor:

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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In this Article

• Leprosy (Hansen's disease) facts
• What is leprosy?
• What is the history of leprosy (Hansen's disease)?
• What causes leprosy?
• What are the risk factors for leprosy?
• What are leprosy symptoms and signs?
• Are there different forms (classifications) of leprosy?
• How is leprosy transmitted?
• How is leprosy diagnosed?
• What is the treatment for leprosy?
• What are the complications of leprosy?
• How is leprosy prevented?
• What is the prognosis (outcomes) of leprosy?
• Where can I find more information on leprosy?
• Leprosy Index

Unfortunately, the early signs and symptoms of leprosy are very subtle and occur slowly (usually over years). The symptoms are similar to those that may occur with syphilis, tetanus, and leptospirosis. Numbness and loss of temperature sensation are some of the first symptoms that patients experience. As the disease progresses, the sensations of touch, then pain, and eventually deep pressure are decreased or lost. Signs that occur, such as relatively painless ulcers, skin lesions of hypopigmented macules (flat, pale areas of skin), and eye damage (dryness, reduced blinking) are experienced before the large ulcerations, loss of digits, and facial disfigurement develop. This long-term developing sequence of events begins and continues on the cooler areas of the body (for example, hands, feet, face, and knees).

There are multiple forms of leprosy described in the literature. The forms of leprosy are based on the person's immune response to M. leprae. A good immune response can produce the so-called tuberculoid form of the disease, with limited skin lesions and some asymmetric nerve involvement. A poor immune response can result in the lepromatous form, characterized by extensive skin and symmetric nerve involvement. Some patients may have aspects of both forms. Currently, two classification systems exist in the medical literature: the WHO system and the Ridley-Jopling system. The Ridley-Jopling system is composed of six forms or classifications, listed below according to increasing severity of symptoms:

• Indeterminate leprosy: a few hypopigmented macules; can heal spontaneously, this form persists or advances to other forms
• Tuberculoid leprosy: a few hypopigmented macules, some are large and some become anesthetic (lose pain sensation); some neural involvement in which nerves become enlarged; spontaneous resolution in a few years, persists or advances to other forms
• Borderline tuberculoid leprosy: lesions like tuberculoid leprosy but smaller and more numerous with less nerve enlargement; this form may persist, revert to tuberculoid leprosy, or advance to other forms
• Mid-borderline leprosy: many reddish plaques that are asymmetrically distributed, moderately anesthetic, with regional adenopathy (swollen lymph nodes); the form may persist, regress to another form, or progress
• Borderline lepromatous leprosy: many skin lesions with macules (flat lesions) papules (raised bumps), plaques, and nodules, sometimes with or without anesthesia; the form may persist, regress or progress to lepromatous leprosy
• Lepromatous leprosy: Early lesions are pale macules (flat areas) that are diffuse and symmetric; later many M. leprae organisms can be found in them. Alopecia (hair loss) occurs; often patients have no eyebrows or eyelashes. As the disease progresses, nerve involvement leads to anesthetic areas and limb weakness; progression leads to aseptic necrosis (tissue death from lack of blood to area), lepromas (skin nodules), and disfigurement of many areas, including the face. The lepromatous form does not regress to the other less severe forms. Histoid leprosy is a clinical variant of lepromatous leprosy that presents with clusters of histiocytes (a type of cell involved in the inflammatory response) and a grenz zone (an area of collagen separating the lesion from normal tissue) seen in microscopic tissue sections.

The Ridley-Jopling classification is used globally in evaluating patients in clinical studies. However, the WHO classification system is more widely used; it has only two forms or classifications of leprosy. The 2009 WHO classifications are simply based on the number of skin lesions as follows:

• Paucibacillary leprosy: skin lesions with no bacilli (M. leprae) seen in a skin smear
• Multibacillary leprosy: skin lesions with bacilli (M. leprae) seen in a skin smear

However, the WHO further modifies these two classifications with clinical criteria because "of the non-availability or non-dependability of the skin-smear services. The clinical system of classification for the purpose of treatment includes the use of number of skin lesions and nerves involved as the basis for grouping leprosy patients into multibacillary (MB) and paucibacillary (PB) leprosy." Investigators state that up to about four to five skin lesions constitutes paucibacillary leprosy, while about five or more constitutes multibacillary leprosy.

Multidrug therapy (MDT) with three antibiotics (dapsone, rifampicin, and clofazimine) is used for multibacillary leprosy, while a modified MDT with two antibiotics (dapsone and rifampicin) is recommended for paucibacillary leprosy and composes most current treatments today (see treatment section below). Paucibacillary leprosy usually includes indeterminate, tuberculoid, and borderline tuberculoid leprosy from the Ridley-Jopling classification, while multibacillary leprosy usually includes the double (mid-) borderline, borderline lepromatous, and lepromatous leprosy.