Leprosy

Leprosy, also known as Hansen's Disease, is a chronic infection caused by the slow growing bacillus Mycobacterium leprae. Leprosy is a disfiguring disease [Page 1010]that commonly affects the skin, peripheral nerves, and mucous membranes, but may have a wide spectrum of clinical presentations. The mild end of the spectrum, tuberculoid leprosy, consists of a small number of well demarcated, hypopigmented skin lesions with potential associated damage to near by peripheral nerves. Lepromatous leprosy, at the severe end of the spectrum, is defined by multiple skin nodules and plaques that are full of M. leprae, dermal infiltration of the hands, feet, and face, and distal peripheral neuropathies. Borderline leprosy is considered in the middle of the severity spectrum and it may either revert to tuberculoid disease or worsen to become lepromatous.

About half of all individuals with leprosy have a history of close contact with another infected person, generally a household contact with lepromatous or borderline disease. Tuberculoid leprosy is not considered to be contagious. It is thought that the bacterium is transmitted via nasal droplets. However, a significant number of patients do not have a history of exposure to a known or suspected case, suggesting other means of transmission. It has been suggested that the organism may be transmitted via contaminated soil or insect vectors. Leprosy has a long incubation period that averages three to seven years and can be longer than 40 years.

Leprosy is generally diagnosed clinically and through biopsy of skin lesions and it may be successfully treated through multi-drug therapy. Dapson forms the foundation of any leprosy treatment. Other important components of the multi-drug therapy may include Rifampin, Clofazimine, Ethionamide, Minocycline, Clarithromycin, and Ofloxacin.

Leprosy has been a recognized human disease for millennia and was known to civilizations in ancient Egypt, India, and China. Today, the major burden of disease falls in Africa, Asia, and Latin America. In 1991, the World Health Assembly passed a motion calling for the elimination of leprosy as a major public health problem, defined as achieving a prevalence rate of less than one in 10,000, by the year 2000. On a global level, this target was achieved, however, as of 2005, the prevalence rate continues to exceed he stated goal in the countries of Brazil, India, Madagascar, Mozambique, and Nepal.