Leprosy, also known as Hansen's disease (HD), is a chronic infection caused by the bacteria Mycobacterium leprae and Mycobacterium lepromatosis. Initially infections are without symptoms and typically remain this way for 5 to as long as 20 years. Symptoms that develop include granulomas of the nerves, respiratory tract, skin, and eyes. This may result in a lack of ability to feel pain and thus loss of parts of extremities due to repeated injuries. Weakness and poor eyesight may also be present.
There are two main types of disease based on the number of bacteria present: paucibacillary and multibacillary. The two types are differentiated by the number of poorly pigmented numb skin patches present, with paucibacillary having five or less and multibacillary having more than five. The diagnosis is confirmed by finding acid-fast bacilli in a biopsy of the skin or via detecting the DNA by polymerase chain reaction. It occurs more commonly among those living in poverty and is believed to be transmitted by respiratory droplets. It is not very contagious.
Leprosy is curable with treatment. Treatment for paucibacillary leprosy is with the medications dapsone and rifampicin for 6 months. Treatment for multibacillary leprosy consists of dapsone and rifampicin and clofazimine for 12 months. These treatments are provided for free by the World Health Organization. A number of other antibiotics may also be used. Globally in 2012 the number of cases of leprosy was 180,000, having decreased a great deal since the 1960s. Most new cases occur in 16 countries, with India accounting for more than half. In the past 20 years, 16 million people worldwide have been cured of leprosy.
Leprosy has affected humanity for thousands of years. The disease takes its name from the Latin word Lepra, which means "scaly", while the term "Hansen's disease" is named after the physician Gerhard Armauer Hansen. Separating people in leper colonies still occurs in countries like India where there are more than a thousand; China, where there are hundreds, and in the continent of Africa. However, most colonies have closed. Leprosy has been associated with social stigma for much of history, which remains a barrier to self-reporting and early treatment. World Leprosy Day was started in 1954 to draw awareness to those affected by leprosy.
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, 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, and there are several references to the disease in the Bible. 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.
Leprosy is primarily a granulomatous disease of the peripheral nerves and mucosa of the upper respiratory tract, skin lesions are the primary external sign. Left untreated, leprosy can be progressive, causing permanent damage to the skin, nerves, limbs and eyes. Contrary to folklore, leprosy does not cause body parts to fall off, although they can become numb or diseased as a result of secondary infections; these occur as a result of the body's defenses being compromised by the primary disease. Secondary infections, in turn, can result in tissue loss causing fingers and toes to become shortened and deformed, as cartilage is absorbed into the body.
At highest risk are those living in endemic areas with poor conditions such as inadequate bedding, contaminated water, and insufficient diet, or other diseases that compromise immune function. There appears to be little interaction between HIV and the risk of leprosy..
Although the mode of transmission of leprosy remains uncertain, many think that M. leprae is usually spread from person to person in nasal droplets. Studies have shown that leprosy can be transmitted to humans by armadillos. Leprosy is not known to be either sexually transmitted or highly infectious after treatment. Approximately 95% of people are naturally immune and sufferers are no longer infectious after as little as two weeks of treatment.
It is estimated that due to genetic factors, only 5% of the population is susceptible to leprosy. This is mostly because the body is naturally immune to the bacteria, and those persons that do become infected experience severe allergic reactions to the disease. However, the role of genetic factors is not entirely clear in determining this clinical expression. In addition, malnutrition and prolonged exposure to infected persons may play a role in development of the overt disease. <
The most widely held belief is that the disease is transmitted by contact between infected persons and healthy persons. In general, closeness of contact is related to the dose of infection, which in turn is related to the occurrence of disease. Of the various situations that promote close contact, contact within the household is the only one that is easily identified, although the incidence among contacts and the relative risk for them appear to vary considerably in different studies.
Two exit routes of M. leprae from the human body often described are the skin and the nasal mucosa, although their relative importance is not clear. Lepromatous cases show large numbers of organisms deep in the dermis but whether they reach the skin surface in sufficient numbers is doubtful.
The importance of the nasal mucosa was recognized as early as 1898 by Schäffer, in particular that of the ulcerated mucosa. The quantity of bacilli from nasal mucosal lesions in lepromatous leprosy was demonstrated by Shepard as large, with counts ranging from 10,000 to 10,000,000. Pedley reported that the majority of lepromatous patients showed leprosy bacilli in their nasal secretions as collected through blowing the nose. Davey and Rees indicated that nasal secretions from lepromatous patients could yield as much as 10 million viable organisms per day.
The entry route of M. leprae into the human body is also not definitively known: The skin and the upper respiratory tract are most likely. While older research dealt with the skin route, recent research has increasingly favored the respiratory route. Rees and McDougall succeeded in the experimental transmission of leprosy through aerosols containing M. leprae in immune-suppressed mice, suggesting a similar possibility in humans. <
In leprosy, both the reference points for measuring the incubation period and the times of infection and onset of disease are difficult to define, the former because of the lack of adequate immunological tools and the latter because of the disease's slow onset. Even so, several investigators have attempted to measure the incubation period for leprosy. The minimum incubation period reported is as short as a few weeks and this is based on the very occasional occurrence of leprosy among young infants. The maximum incubation period reported is as long as 30 years, or over, as observed among war veterans known to have been exposed for short periods in endemic areas but otherwise living in non-endemic areas. It is generally agreed that the average incubation period is between three and five years.
The first symptom of leprosy which is most obvious is excess eye fluid. Medications can decrease the risk of those living with people with leprosy from acquiring the disease and likely those with whom people with leprosy come into contact outside the home. There are however concerns of resistance, cost, and disclosure of a person's infection status when doing follow up of contacts, thus the WHO however recommends that people who live in the same household be examined for leprosy and only be treated if symptoms are present.
World distribution of leprosy, 2003.
Globally in 2012 the number of cases of leprosy was 180,000. In 2011 the approximate number of new cases diagnosed was 220,000. The number of cases has decreased significantly from the 1960s to the 2010s.
In 1995 two to three million people were estimated to be permanently disabled because of leprosy. India has the greatest number of cases, with Brazil second and Myanmr third.
Leprosy was once believed to be highly contagious and was treated with mercury—all of which applied to syphilis, which was first described in 1530. It is possible that many early cases thought to be leprosy could actually have been syphilis. Effective treatment first appeared in the late 1940s. Resistance has developed to initial treatment. It was not until the introduction of MDT in the early 1980s that the disease could be diagnosed and treated successfully within the community.
Stigma in India
Leprosy patients in India, like many parts of the world, suffer under some of the worst conditions and stereotypes about their disease. Depending on the level of disfigurement, a leper could receive harsher stigma and ostracism. Leprosy sufferers are markedly disadvantaged with respect to income, with 16-44% of victims reporting a decrease in pay as a result of having leprosy. Women suffer greater restrictions and social stigma than men. Leprosy prevents mothers from getting too close to their children out of fear that they could infect them. In a report, 49% of women stopped breast-feeding their babies as a result of having leprosy. Doctors and other health care providers and NGOs are working hard to educate people about the disease. In one study when leprosy treatment and education were mixed in with the local healthcare program, the attitudes towards the disease were somewhat alleviated as people had a better understanding of it. Now the disease prevalence has been reduced to less than 1 per million population in most parts of the country.