Leprosy (Mycobacterium leprae)

Clinical criteria
Any person with the following clinical picture: leprosy is a chronic bacterial disease characterised by the involvement primarily of skin as well as peripheral nerves and the mucosa of the upper airways. Clinical forms of leprosy represent a spectrum reflecting the cellular immune response to Mycobacterium leprae. The clinical manifestations of the disease vary in a continuous spectrum between the two polar forms, lepromatous and tuberculoid leprosy:

  • In lepromatous (multibacillary) leprosy, nodules, papules, macules and diffuse infiltrations are bilateral symmetrical and usually numerous and extensive; involvement of the nasal mucosa may lead to crusting, obstructed breathing and epistaxis; ocular involvement leads to iritis and keratiti
  • In tuberculoid (paucibacillary) leprosy, skin lesions are single or few, sharply demarcated, anaesthesic or hypoaesthesic, and bilateral asymmetrical; involvement of peripheral nerves tends to be severe
  • Borderline leprosy has features of both polar forms and is more labile
  • Indeterminate leprosy is characterised by hypopigmented macules with ill- defined borders; if untreated, it may progress to tuberculoid, borderline or lepromatous disease

Laboratory criteria

At least one of the following two:

  • Demonstration of characteristic acid-fast bacilli in skin or dermal nerve, obtained from either a punch biopsy or a slit skin biopsy of a lepromatous lesion (depending on the clinical presentation). The identity of Mycobacterium leprae can be confirmed by nucleic acid amplification tests.
  • Histopathological report from skin or nerve biopsy compatible with leprosy (Hansen’s disease) examined by a consultant pathologist experienced in leprosy diagnosis.

Epidemiological criteria

Case classification
A. Possible case
B. Probable case
C. Confirmed case
Any person meeting the clinical and the laboratory criteria 

Current as of: 28 May 2018