Leprosy is an infectious disease characterized by skin lesions and nerve damage. Mainly affecting the peripheral nerves (those outside the brain and spinal column), skin, eyes, testicles and nose, it has a long incubation time. It is usually between three to eight years before the disease is evident. Leprosy is quite rare. It is primarily seen in tropical and subtropical Asia, Africa, South America and Central America. In the United States, most cases involve immigrants from developing countries. It may occur at any age and in any race.

There is a wide spectrum of findings in leprosy. The two major polar forms of leprosy are lepromatous leprosy and tuberculoid leprosy. Lepromatous leprosy is characterized by many skin lesions that are vague and difficult to distinguish from normal skin, as well as weakness and paralysis affecting both sides of the body equally. Tuberculoid leprosy is characterized by fewer, more prominent skin lesions and loss of feeling, weakness and paralysis affecting one side of the body more than the other. Between these two forms is borderline leprosy. Another form, indeterminate leprosy, may be mild with few or no skin lesions.

Leprosy is caused by particular bacteria (Mycobacterium leprae). The spread of the disease requires a contagious patient, a person susceptible to the disease and close or long-term contact between the two. Patients undergoing treatment are not contagious and most people are immune to the bacteria.

Skin lesions in leprosy may be reddened or hypopigmented (lighter than the surrounding skin). There is often a reduced or lack of sensitivity to temperature, touch and pain within the lesion and possibly in the hands and feet. Nerve damage can lead to deformities, such as a claw hand. In advanced cases, the nose may erode and collapse. Inflammatory reactions may also be frequent during the course of the disease and its treatment.

The diagnosis of leprosy relies upon the patient’s medical history, a physical examination and a skin biopsy from a lesion. Laboratory examination of the biopsy may detect the presence of the bacteria that causes leprosy or other characteristic changes.

Leprosy treatment relies on a multi-drug strategy employing a combination of various antibiotics. Active treatment may last from six months to two years and the patient is closely observed for up to five years after treatment ends. Patients are considered cured after the completion of the treatment regimen.