Leprosy is a disease caused by the bacteria Mycobacterium leprae that causes damage to the skin and the peripheral nervous system. The disease develops slowly (from six months to 40 years!) and results in skin lesions and deformities, most often affecting the cooler places on the body (for example, eyes, nose, earlobes, hands, feet, and testicles). The skin lesions and deformities can be very disfiguring and are the reason that infected individuals were considered outcasts in many cultures. Although human-to-human transmission is the primary source of infection, three other species can carry and (rarely) transfer M. leprae to humans; chimpanzees, mangabey monkeys, and nine-banded armadillos. The disease is termed a chronic granulomatous disease because it produces inflammatory nodules (granulomas) in the skin and nerves over time.

What is the history of leprosy (Hansen's disease)?

Unfortunately, the history of leprosy and its interaction with man is one of suffering and misunderstanding. The newest research suggests that at least as early as 4000 B.C. individuals had been infected with M. leprae (studies are ongoing to prove this by genetic analysis), while the first known written reference to the disease was found on Egyptian papyrus in about 1550 B.C. The disease was well recognized in ancient China, Egypt, and India. Because the disease was poorly understood, very disfiguring, slow to show symptoms, and had no known treatment, many cultures thought the disease was a curse or punishment from the gods. Consequently, leprosy was left to be "treated" by priests or holy men, not physicians.

Since the disease often appeared in family members, some people thought it was hereditary; other people noted that if there was little or no contact with infected individuals, the disease did not infect others. Consequently, some cultures considered infected people (and occasionally their close relatives) as "unclean" or as " lepers" and ruled they could not associate with uninfected people. Often infected people had to wear special clothing and ring bells so uninfected people could avoid them.

The Romans and the Crusaders brought the disease to Europe, and the Europeans brought it to the Americas. In 1873, Dr. Hansen discovered bacteria in leprosy lesions, suggesting leprosy was an infectious disease, not hereditary or a punishment from the gods. However, patients with the disease were still ostracized by many societies and cared for only at missions by religious personnel. Patients with leprosy were encouraged or forced to live in seclusion up to the 1940s, even in the U.S. (for example, the leper colony on Molokai, Hawaii, and at Carville, La.), often because no effective treatments were available. Because of Hansen's discovery of M. leprae, efforts were made to find treatments that would stop or eliminate M. leprae; in the early 1900s to about 1940, oil from Chaulmoogra nuts was used with questionable efficacy by injecting it into patients' skin. At Carville in 1941, Promin, a sulfone drug, showed efficacy but needed many painful injections. Dapsone pills were found to be effective in the 1950s, but soon (1960s-70s), M. leprae developed resistance to dapsone. Fortunately, drug trials on the island of Malta in the 1970s showed that a three-drug combination (dapsone, rifampicin, and clofazimine [Lamprene]) was very effective in killing M. leprae. This multi-drug treatment (MDT) was recommended by the WHO in 1981 and remains, with minor changes, the therapy of choice. MDT, however, does not alter the damage done to an individual by M. leprae before MDT is started.

Leprosy is often termed "Hansen's disease" by many clinicians in an attempt to have patients forgo the stigmas attached to being diagnosed with leprosy. » Read more