What It Is
Leprosy is a chronic infectious disease of humans caused by the bacteria Mycobacterium leprae. Leprosy is also known as hansen’s disease.
Greek: lepid = scales on a fish.
The disease can affect the skin, mucous membranes, and eyes and some of the nerves that are located outside the central nervous system (peripheral nerves). These are primarily the nerves of the hands, feet, and eyes, and some of the nerves in the skin. In severe, untreated cases, loss of sensation, muscle paralysis of hands and feet, disfigurement, and blindness may occur.
Leprosy has traditionally been classified into two major types, tuberculoid and lepromatous. Patients with tuberculoid leprosy have limited disease and relatively few bacteria in the skin and nerves, while lepromatous patients have widespread disease and large numbers of bacteria. Tuberculoid leprosy is characterized by a few flat or slightly raised skin lesions of various sizes that are typically pale or slightly red, dry, hairless, and numb to touch (anesthetic). Lepromatous leprosy is at the other end of the spectrum, with a much more generalized disease, diffuse involvement of the skin, thickening of many peripheral nerves, and at times involvement of other organs, such as eyes, nose, testicles, and bone. There are also intermediate subtypes between these two extremes that are commonly known as borderline leprosy. The intermediate subtypes are borderline tuberculoid, midborderline, and borderline lepromatous leprosy. Borderline leprosy and the subtypes are characterized by more extensive disease than polar tuberculoid, with more numerous skin lesions and more nerve involvement, but not as widespread disease as in lepromatous leprosy. Indeterminate leprosy refers to a very early form of leprosy that consists of a single skin lesion with slightly diminished sensation to touch. It will usually progress to one of the major types of leprosy.
Spread of Leprosy
It is not clear how leprosy is spread. However, one way the disease is likely passed from person to person is through droplets expelled from the nose and mouth of an infected person and breathed in or touched by an uninfected person. But even with the bacteria in the air, most people do not contract leprosy. About half of the people with leprosy probably contracted it through close, long-term contact with an infected person. Casual and short-term contact do not seem to spread the disease. Leprosy cannot be contracted by simply touching someone with the disease, as is commonly believed. Health care workers often work for many years with people who have leprosy without contracting the disease. Other potential sources of Mycobacterium leprae are soil, armadillos, and possibly bedbugs and mosquitoes.
About 95% of people who are exposed to Mycobacterium leprae do not develop leprosy because their immune system fights off the infection. In people who do develop the disease, the infection can range from mild (tuberculoid leprosy) to severe (lepromatous leprosy). The tuberculoid form of leprosy is not contagious.
Treatment of Leprosy
For many years, it was considered a mysterious disorder associated with some type of curse, and persons with the disease were isolated and ostracized. Today, there is effective treatment and the disease can be cured. There is no longer any justification for isolating persons with leprosy. Antibiotic treatment can stop the progression of leprosy but does not reverse any nerve damage or deformity. Thus, early detection and treatment are vitally important. Because some leprosy bacteria may be resistant to certain antibiotics, doctors prescribe more than one drug. The standard combination is dapsone and rifampin