Also known as: Leprosy
Hospital: Report by IDSS, facsimile, mail or phone
Lab: Report by IDSS, facsimile, mail or phone. Send isolates to the State Hygienic Laboratory (SHL) for testing
Physician: Report by facsimile, mail or phone
Local Public Health Agency (LPHA): Report by facsimile, mail or phone. Follow Up Required
Iowa Department of Public Health
Disease Reporting Hotline: (800)-362-2736
Secure Fax: (515) 281-5698
Hansen’s disease (also called leprosy) is a chronic infectious disease caused by the bacterium Mycobacterium leprae. Even though the medical community is moving away from using diseases named after people, this is one that will retain the moniker “Hansen’s” disease because of the stigma of the name leprosy.
B. Clinical Description
A chronic bacterial disease characterized primarily by the involvement of skin, which can also involve peripheral nerves, testicles, and the mucosa of the upper airway. Clinical forms of Hansen’s disease represent a spectrum reflecting the degree of cellular immune response to Mycobacterium leprae. The following characteristics are typical of the major forms of the disease.
- Tuberculoid: One or a few well-demarcated, hypopigmented, and anesthetic skin lesions, frequently with active, spreading edges and a clearing center; peripheral nerve swelling or thickening also may occur.
- Lepromatous: A number of erythematous papules and nodules or an infiltration of the face, hands, and feet with lesions in a bilateral and symmetrical distribution that progress to thickening of the skin.
- Borderline (dimorphous): Skin lesions characteristic of both the tuberculoid and lepromatous forms.
- Indeterminate: Early lesions, usually hypopigmented macules, without developed tuberculoid or lepromatous features.
Its main targets are the skin and nerves, though other organs can be involved. If not treated, the nerves are damaged and patients may be unable to feel, which can result in injuries or burns. Such wounds may result in ulcers. The patient may suffer muscle weakness and paralysis. Serious disabilities and deformities may occur. Prompt and appropriate treatment prevents most of these complications.
Humans are the only reservoir of proven significance for leprosy. There have been reports suggesting that leprosy in armadillos may be naturally transmitted to humans.
D. Modes of Transmission
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 after prolonged close contact. Most humans probably are not susceptible.
E. Incubation period
The incubation period probably ranges from 9 months to 20 years.
F. Period of Communicability or Infectious Period
Evidence suggests that infectiousness is lost in most instances within a day of beginning treatment with multidrug therapy.
While worldwide prevalence of leprosy decreased to less than 1 million registered cases in 1998, incidence has changed little since 1985. The majority of cases occur in developing countries, with 92% in just 16 countries, led by India and Brazil. In the United States, cases usually occur in immigrants or refugees. Although leprosy affects people of all ages and gender, cases in children under 3 years of age are rare.
H. Bioterrorism Potential
I. Additional Information
The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions for Hansen’s Disease can be found at: www.cdc.gov/osels/ph_surveillance/nndss/phs/infdis.htm#top
CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)
American Academy of Pediatrics. 2006 Red Book: Report of the Committee on Infectious Diseases, 27th Edition. Illinois, American Academy of Pediatrics, 2006.
CDC website. Hansen’s Disease, available at: www.cdc.gov/leprosy/
Heymann, D.L., ed. Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.
Jacobson, R., Krahenbuhl, J., Leprosy, The Lancet, 1999; 353: 655-60.