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Hansen's Disease (Leprosy)

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  1. General Information
  2. Technical Information
  3. Additional Information

Clinical Features

This chronic infectious disease usually affects the skin and peripheral nerves but has a wide range of possible clinical manifestations. Patients are classified as having paucibacillary or multibacillary Hansen's disease. Paucibacillary Hansen's disease is milder and characterized by one or more hypopigmented skin macules. Multibacillary Hansen's disease is associated with symmetric skin lesions, nodules, plaques, thickened dermis, and frequent involvement of the nasal mucosa resulting in nasal congestion and epistaxis.

Etiologic Agent

A bacillus, Mycobacterium leprae, that multiplies very slowly and mainly affects the skin, nerves, and mucous membranes. The organism has never been grown in bacteriologic media or cell culture, but has been grown in mouse foot pads.


In 2002, the number of new cases detected worldwide was 763,917. In 2002, 96 cases occurring in the United States were reported to CDC. In 2002, WHO listed Brazil, Madagascar, Mozambique, Tanzania, and Nepal as having 90% of cases.


Worldwide, 1-2 million persons are permanently disabled as a result of Hansen's disease. However, persons receiving antibiotic treatment or having completed treatment are considered free of active infection.


Although the mode of transmission of Hansen's disease remains uncertain, most investigators think that M. leprae is usually spread from person to person in respiratory droplets.

Risk Groups

Close contacts with patients with untreated, active, predominantly multibacillary disease, and persons living in countries with highly endemic disease.


Hansen's disease is nationally notifiable in the United States.


Prevalence has remained relatively stable in the United States. Decreasing numbers of cases worldwide with pockets of high prevalence in certain countries.


Multi-drug therapy has not been implemented in many endemic areas. Nerve damage must be recognized and managed. Relapse rate after completion of short course multi-drug therapy may rise.


Opportunities exist for participation in Hansen's disease elimination activities in endemic-disease countries, and for Mycobacterium research in the Laboratory Research Branch of the National Hansen's Disease Program.

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