Image: DFB

Leprosy is essentially a clinical diagnosis, although a laboratory test (the slit skin smear) is important in some cases. Normally, the diagnosis rests on finding any one of three cardinal signs, which are fully explained in ILEP's Learning Guide One (526KB):

  • one or more hypopigmented, anaesthetic skin patches, typical of leprosy;
  • one or more thickened peripheral nerves; or
  • a positive skin smear.

 

 

WHO emphasizes the first of these signs for use by junior health workers in endemic areas and gives a clear description of how to examine the skin. Photographs of early skin lesions are available. The place of slit skin smears in the diagnosis of leprosy and technical guidelines for doing the test are contained in ILEP's Learning Guides Three (440KB):

As with many diseases, the most accurate diagnostic test is a biopsy, with subsequent staining and histopathological examination of the tissues.

One major topic for research at present, is the development of new diagnostic tests, which may allow leprosy to be diagnosed with confidence at a much earlier stage; this would mean that treatment could begin early, resulting in less disability and probably also in less transmission of the disease to contacts.