HANSEN'S DISEASE (LEPROSY)
	An impressive body of scientific data on leprosy has been acquired during the past thirty years. It is known with certainty that: A bacterium, Mycobacterium leprae, related to the organism causing tuberculosis, is the causative agent of leprosy. Although humans appear to be the primary source of M. leprae, naturally-acquired leprosy has been found in nine-banded armadillos and several species of nonhuman primates. A leprosy zoonosis has the potential for perpetuating the infection in areas where leprosy in humans is no longer endemic. Drugs are used to control the disease, but treatment requires 2 years. Newer drugs and drug regimens are needed to shorten this period. Many of the disabilities are the result of late diagnosis. Some of these can be corrected surgically, and the patient can continue to lead a normal, useful and productive life. Despite our increased knowledge about leprosy - its diagnosis, clinical manifestations and treatment - many obstacles hinder further progress. For example: Mycobacterium leprae has yet to be cultivated successfully in the laboratory. Until this is accomplished there will be considerable difficulty in developing vaccines, conducting research on immunological problems, studying the physiology and metabolism of the organism, or efficiently exploring the possibility of more effective chemotherapy. Leprosy is generally considered to be a scourge of past centuries. However, it is very much with us today. Of immediate concern is the fact that there are approximately 6,000 known cases of leprosy in the United States. The actual number of cases is undoubtedly higher. On a global basis, there are an estimated 2 - 3 million people with the disease, with about 600,000 new cases being detected annually. Even today, it is very difficult to obtain accurate data on the prevalence and incidence of this disease. Although regarded as primarily a disease of the tropics and sub-tropics, leprosy is by no means confined to those zones. In the past, it was endemic in northern Japan, Korea, Australia, some areas of Europe, and the Soviet Union. It persists today in developing regions such as Southeast Asia, India and South America, many of which are in tropical areas of the world. Our inability to culture the organism in the laboratory requires us to rely heavily on experimental animal models. However, the only species readily susceptible are the nine-banded armadillo and the mangabey monkey, both of which require special housing and handling. Naturally-acquired leprosy has also been diagnosed in these species. Few diseases have been so misunderstood. Since pre-Biblical times, the leprosy patient has been surrounded by myth, superstition, fear, apathy and rejection. In most instances the unfortunate individual was faced not only with a totally debilitating and deforming disease, but also with dire social and psychological consequences as well. He or she suffered social ostracism, inability to work, forced separation from family, and had virtually no hope of cure or return to normalcy. As a result, many of them simply disappeared. The victims, often believing they "were being punished for their sins" became despondent, apathetic and resigned to fate. Unfortunately, even today tolerance by society has been the exception rather than the rule. It is encouraging that considerable progress has been made in recent years toward changing these attitudes through education. Visible evidence of successful therapy has contributed greatly to this process. There should be no room for past stigmas, but they do still exist. Every effort must be made to eliminate these prejudices. Leprosy is, of course, a precisely-defined medical and scientific entity offering unusual intellectual challenges to physicians, research scientists, psychologists, sociologists and others. In spite of well designed and informative studies, the epidemiology of leprosy remains obscure. Insofar as we know, infection is acquired via the naso-respiratory route. Insects and other transmission vectors have not been definitely incriminated nor confirmed. The incubation period following exposure is usually 2 to 5 years, but can range from a few months to as long as 20 years. Analysis of the usual factors influencing the epidemiology of a disease such as age, sex, race, climate, nutrition, social behavior, geographic environment, genetic susceptibility, etc., have led to inconclusive evidence about the role of any specific factor. Unanswered questions remain as to why Mycobacterium leprae produces the tuberculoid type (mild) of disease in some people, and the lepromatous type (serious) in others. Although the immunity of individuals plays a major role in determining the type of disease one develops, we do not know what determines this response to M. leprae. The Memorial, now celebrating over 72 years of successful operation, has played a major role in scientific studies. It is foremost among American agencies in this field. We are proud of the achievements our staff has made to leprosy research and we will continue to make every effort to eventually eradicate this tragic disease that has plagued mankind for so many centuries.

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