5th June 2025

Leprosy

Leprosy is a chronic infectious disease caused by Mycobacterium leprae that affects the skin and peripheral nerves. It is one of the most common causes of peripheral neuropathy worldwide but is rare in the UK.

Diagnosis 

Symptoms can develop insidiously, and three features are required to make the leprosy diagnosis. This includes thickened peripheral nerves, presence of acid-fast bacilli in skin smears/ biopsies and hypopigmented or erythematous skin lesions with loss of sensation.

The initial skin lesion may resolve spontaneously, and this is referred to as indeterminate leprosy.

Lepromatous leprosy is a severe form with high bacterial load where there is systemic involvement including respiratory tract, testes, kidneys, bones, eye, and lymph glands.

Image Source: Wikimedia Commons (2019). Multibacillary Leprosy Lesion, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/w/index.php?search=Multibacillary_leprosy_lesion.jpg&title=Special:MediaSearch&type=image (Accessed 20 May 2025).

Investigation

Skin smear can be done which will be positive for acid-fast bacilli.

Skin and nerve biopsies can also be done to determine classification of the disease and presence of acid-fast bacilli. 

Polymerase chain reaction to detect Mycobacterium leprae DNA in tissue.

Management

Multidrug therapy is needed for leprosy and the medications include rifampicin, dapsone and clofazimine. For the treatment of leprosy reactions corticosteroids are used.