Leprosy is caused by the bacterium Mycobacterium leprae. It is not very contagious and it has a long incubation period (time before symptoms appear), which makes it hard to know where or when someone caught the disease. Children are more likely than adults to get the disease.
Leprosy has two common forms: tuberculoid and lepromatous. Both forms produce sores on the skin. However, the lepromatous form is most severe. It causes large lumps and bumps (nodules).
Leprosy is common in many countries worldwide, and in temperate, tropical, and subtropical climates. About 100 cases per year are diagnosed in the United States. Most cases are in the South, California, Hawaii, and U.S. islands.
Effective medications exist. Isolating people with this disease in "leper colonies" is not needed.
Drug-resistant Mycobacterium leprae and an increased numbers of cases worldwide have led to global concern about this disease.