Leprosy, also known as Hansen's disease, is a bacterial infection caused by Mycobacterium leprae. The bacterium has a predilection for the skin, peripheral nerves and the upper respiratory tract. Although it is a common disease worldwide, leprosy is more common in individuals in tropical or subtropical climates. In the United States, the disease is more prevalent in California and Hawaii.
Mycobacterium leprae is a slow growing organism. Individuals that have become infected with the bacteria may not know that they are actually infected, or may not develop leprosy. In some diseased individuals, there can be a latency period of as long as 20 years before signs and symptoms of leprosy manifests.
Transmission is through close contact and respiratory droplets from affected individuals. Studies have also shown that humans can also become affected from contact with armadillos. However, the disease overall is not highly contagious, meaning that the person-to-person transmission rate is low, especially if the infected individual is being medically treated. Researchers believe that genetics play a major role in the disease's development.
The signs and symptoms of leprosy can be subtle at the initiation of the disease. The most common symptoms include, skin lesions on a body part (usually the arms, hands, legs or feet), which may be lighter than the patient’s original skin color. Some may experience muscle weakness, numbness and/or tingling in a body part, or upper respiratory problems (including a runny nose, eye, and ear problems). Combinations of the above symptoms may also occur.
Because the infection has a high level of resistance to single-drug antibiotic treatment, a multistage drug therapy (MDT) approach is used. Commonly MDT treatment uses dapsone, rifampin and clofazimine antibiotics. Treatment lasts for approximately 12 months. Single-dose treatment (rifampin, oflozacin, and minocycline) exists only for patients with a single skin lesion.
The complications of leprosy can be severe, and can lead to permanent loss of sensation in the extremities, permanent muscle weakness, and/or permanent skin disfigurement.
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