Leprosy is a chronic communicable disease which affects particularly the nerves, the skin and mucosae. Damage to, and ultimate destruction of, the nerves leads to the deformities which used to be regarded as typical of the disease. These involved the upper limb (claw-hand, wrist-drop), the lower limb (claw-toes, foot-drop), the eye (anaesthesia of the cornea, paralysis of the eyelids) and ulceration of the larynx; and resulted in neglected cases of extensive ulceration of hands and feet, with loss of digits, hoarseness of voice and severe impairment of vision or total blindness.
Leprosy is caused by a bacterium that takes up to 20 years to display symptoms. The disease is curable, only slightly contagious, and does not always cause deformities. It attacks at any age and either sex, and the effects show the widest possible variation - from complete refractoriness to high susceptibility. Hence leprosy may be a small localized patch in the skin, or a progressive generalized disease affecting the skin of the entire body, all the superficial nerve trunks of limbs and face, and the lining of the nose. In any population, a small proportion succumb to the latter form; most seem to be refractory to infection. Standard treatment requires months of antibiotic drug therapy, and at present only one patient in five is able to get effective treatment.
Because of misunderstanding, ignorance and prejudice, leprosy is often regarded as medically unique, and because of its long incubation period, inauspicious onset, slow and painless development, and slight tendency to shorten life, it is surrounded by an aura of mystery. The deformities and disfigurements, blindness and mutilations habitually associated with leprosy are mainly the result of damage sustained by tissues (muscles and skin) whose nerves have been destroyed as the result of leprosy. It is a major crippling disease, and hence is of economic importance.
The earliest written references to true leprosy are from India (600 BC), whence it was probably introduced into the West (with Alexander the Great's troops, 327-326 BC). Enormous confusion existed in the literature before leprosy was delimited (in 1847) as a specific disease and as caused by a specific micro-organism Mycobacterium leprae (1873). References to 'leprosy' in the Old Testament of the Bible (Authorized Version) are a mistranslation. Leprosy has virtually disappeared from north-west Europe, but still exists in countries of Southern Europe. Imported cases comprise a manageable problem in the industrialized West.
Leprosy occurs in most countries (hot or cold, wet or dry, low-lying or mountainous), but the bulk of the up to 6 million sufferers live in the developing countries. As of 1993, there were 121 countries where leprosy was endemic, with 1.6 billion people being at risk. 80% of all registered leprosy patients live in just five countries (in decreasing order of case numbers) India, Brazil, Nigeria, Myanmar and Indonesia. India has more than two million reported sufferers.
During the early 1990's in the 28 most severely affected countries in Latin America, Africa and Asia, rates of registered cases reached as high as 10 to 30 cases per 10,000. However, the incidence of leprosy has declined dramatically in the 1990's due to multidrug therapy, in which two or three drugs are combined to attack the leprosy bacillus, each in a different way. In 1992, WHO began trials of a cocktail of two powerful antibiotics, ofloxacin and rifampicin, which it believes could reduce treatment duration from four years to four weeks and could wipe out the disease sometime in the next century. In 1986, WHO reported 5.4 million registered patients globally. By 1996, this number had dropped to less than 1 million cases. In 1998 there were 684,000 new cases.
Although the disease is now easily curable, it is suspected that many cases of unregistered, whether for economic reasons or for fear of stigma. As a result, even though it may be "officially" eradicated, many cases may go undetected. With its 10 year incubation period, many cases could emerge long after the relevant health programmes have been terminated. It is predicted that there will be many people, especially in developing countries, suffering from leprosy-related disabilities long beyond the target eradication data of 2000.
Because leprosy does not kill (unlike smallpox or tuberculosis), or assume epidemic proportions, and is not easily preventable (by vaccination or general health measures) and because, until recently, it could not be treated rapidly or cheaply, it has tended to be neglected and to be given a low priority in official thinking. There still persists a certain shame about leprosy, and about admitting its existence. The deformed beggars, often a major social problem, represent a small and innocuous proportion of sufferers. They are not contagious for the most part and their hurt is psychological as well as physical. Hence, since leprosy does not constitute a problem of obvious urgency or outstanding importance in any country, it has tended to be neglected and ignored. However, recent recommendations concerning the use of a combination of drugs, given for only a limited period of time (in many cases as short as six months) are changing this attitude and giving new impetus to the efforts of both governments and voluntary agencies to control leprosy in the countries where it is at present a major public health problem. To succeed, these efforts involve both political will and a highly motivated health staff as well as a stable infrastructure and financial resources. The participation of the community and, where appropriate, the primary health care system are equally important. The priority is to break the chain of transmission of the infection by the treatment of the infectious cases and so in the long term to reduce the human suffering and physical disability caused by the disease. The need for custodial care for the permanently crippled and for reconstructive surgery and rehabilitation for those likely to benefit therefrom must be taken into account but at a lower priority rating.