Leprosy Health Dictionary

See: HANSEN’S DISEASE. 

See Hansen’s disease.

Also known as Hansen’s disease, this is a chronic bacterial infection caused by Mycobacterium leprae affecting the skin, mucous membranes, and nerves. Infection is now almost con?ned to tropical and subtropical countries – mostly in Africa and India. There are two distinct (polarised) clinical forms: tuberculoid and lepromatous. The former usually takes a benign course and frequently burns out, whereas the latter is relentlessly progressive; between these two polar forms lies an intermediate/dimorphous group. Susceptibility may be increased by malnutrition. Nasal secretions (especially in lepromatous disease) are teeming with M. leprae and constitute the main source of infection; however, living in close proximity to an infected individual seems necessary for someone to contract the disease. M. leprae can also be transmitted in breast milk from an infected mother.

Only a small minority of those exposed to M. leprae develop the disease. The incubation period is 3–5 years or longer. The major clinical manifestations involve skin and nerves: the former range from depigmented, often anaesthetic areas, to massive nodules; nerve involvement ranges from localised nerve swelling(s) to extensive areas of anaesthesia. Advanced nerve destruction gives rise to severe deformities: foot-drop, wrist-drop, claw-foot, extensive ulceration of the extremities with loss of ?ngers and toes, and bone changes. Eye involvement can produce blindness. Laryngeal lesions produce hoarseness and more serious sequelae. The diagnosis is essentially a clinical one; however, skin-smears, histological features and the lepromin skin-test help to con?rm the diagnosis and enable the form of disease to be graded.

Although the World Health Organisation had originally hoped to eliminate leprosy worldwide by 2000, that has proved an unrealistic target. The reason is an absence of basic information. Doctors are unable to diagnose the disorder before a patient starts to show symptoms; meanwhile he or she may have already passed on the infection. Doctors do not know exactly how transmission occurs or how it infects humans – nor do they know at what point a carrier of the bacterium may infect others. The incidence of new infections is still more than 650,000 cases a year or about 4.5 cases per 10,000 people in those countries worst affected by the disease.

Treatment Introduction of the sulphone compound, dapsone, revolutionised management of the disease. More recently, rifampicin and clofazimine have been added as ?rst-line drugs for treatment. Second-line drugs include minocycline, o?oxacin and clarithromycin; a number of regimens incorporating several of these compounds (multi-drug regimens – introduced in 1982) are now widely used. A three-drug regime is recommended for multi-bacillary leprosy and a two-drug one for parcibacillary leprosy. Dapsone resistance is a major problem worldwide, but occurs less commonly when multi-drug regimens are used. Older compounds – ethionamide and prothionamide

– are no longer used because they are severely toxic to the liver. Corticosteroids are sometimes required in patients with ‘reversal reaction’. Supportive therapy includes physiotherapy; both plastic and orthopaedic surgery may be necessary in advanced stages of the disease. Improvement in socio-economic conditions, and widespread use of BCG vaccination are of value as preventive strategies. Early diagnosis and prompt institution of chemotherapy should prevent long-term complications.

(Hansen’s disease) n. a chronic disease, caused by the bacterium Mycobacterium leprae, that affects the skin, mucous membranes, and nerves. It is confined mainly to the tropics and is transmitted by direct contact. After an incubation period of 1–30 years, symptoms develop gradually and mainly involve the skin and nerves. Lepromatous (multibacillary) leprosy is a contagious steadily progressive form of the disease characterized by the development of widely distributed lumps on the skin, thickening of the skin and nerves, and in serious cases by severe numbness of the skin, muscle weakness, and paralysis, which leads to disfigurement and deformity. Tuberculosis is a common complication. Tuberculoid leprosy is a benign, often self-limiting, form of leprosy causing discoloration and disfiguration of patches of skin (sparsely distributed) associated with localized numbness. Indeterminate leprosy is a form of the disease in which skin manifestations represent a combination of the two main types; tuberculoid and indeterminate leprosy are known as paucibacillary leprosy.

Like tuberculosis, leprosy should be treated with a combination of antibacterial drugs, to overcome the problem of resistance developing to a single drug; the WHO advocates a combination of rifampicin and dapsone for six months to treat paucibacillary leprosy and these drugs with the addition of clofazimine for multibacillary leprosy, this multidrug therapy (MDT) to be continued for two years. Reconstructive surgery can repair some of the damage caused by the disease. A vaccine is being developed and tested.