Leprosy, also known as Hansen’s disease, is a chronic infectious disease caused by Mycobacterium leprae. The disease mainly affects the skin, the peripheral nerves, mucosal surfaces of the upper respiratory tract and the eyes. Leprosy is known to occur at all ages ranging from early infancy to very old age. Leprosy is curable and treatment in the early stages can prevent disability.
Leprosy is likely transmitted via droplets, from the nose and mouth, during close and frequent contact with untreated cases.
Symptoms may occur within 1 year but can also take as long as 20 years or even more to occur.
Clinical signs are easy to observe. Skin lesion has usually a different pigmentation than the surrounding normal skin (less pigmented, reddish or copper-coloured) and may have various aspects (flat, raised or nodules). Skin lesion can be single or multiple and may show a loss of sensation in the skin.
Skin smears are also used to diagnose leprosy.
Leprosy can be classified on the basis of clinical manifestations and skin smear results. In the classification based on skin smears, patients showing negative smears at all sites are said to have paucibacillary leprosy (PB), while those showing positive smears at any site are said to have multibacillary leprosy (MB).
Leprosy is curable with a combination of drugs known as multidrug therapy, as the treatment of leprosy with only one antileprosy drug (monotherapy) will result in development of drug resistance to that drug. The combination of drugs used in the MDT depends on the classification of the disease (paucibacillary or multibacillary leprosy).