(redirected from buffalo leprosy)
Also found in: Dictionary, Thesaurus, Medical.


leprosy or Hansen's disease (hănˈsənz), chronic, mildly infectious malady capable of producing, when untreated, various deformities and disfigurements. It is caused by the rod-shaped bacterium Mycobacterium leprae, first described by G. Armauer Hansen, a Norwegian physician, in 1874. The mode of transmission is not fully understood. It is thought to be transmitted by nasal discharges and skin sores, and possibly also by contaminated objects and arthropods and by infected armadillos (which are also susceptible to the disease). Only 5% of those exposed acquire the disease. The onset is intermittent and gradual; symptoms may not appear until years after exposure. It is seldom fatal, but its involvement of the peripheral nerves destroys sensation and makes the patient prone to inadvertent injury.

Types of Leprosy

There are two forms of leprosy. In the tuberculoid form of the disease the skin lesions appear as light red or purplish spots. Tuberculoid leprosy is the more benign type, even though it is accompanied by nerve involvement, which leads to numbness (usually of the extremities), contractures, and ulceration. In lepromatous leprosy the skin lesions appear as yellow or brown infiltrated nodules (protuberances) that affect the mucous membranes of the eyes, nose, and throat. There is a general thickening of the skin, especially the face and ears. Lepromatous leprosy is the more easily spread of the two.

Diagnosis and Treatment

Since Hansen identified the bacterium that causes leprosy, diagnosis has been established by isolating the bacterium from the skin lesions or the mucous membranes of the nose and identifying it under the microscope. In 2013 a simple rapid test, using a drop of a patient's blood and some reagent, was released; developed at the Infectious Disease Research Institute, Seattle, it can detect the bacterium before symptoms develop. Duration and treatment of the disease depend upon its extent and character. Patients with nodular lesions are more difficult to treat and may succumb sooner; those with the neural type of lesion, despite possible mutilation and deformity, usually live longer and even experience spontaneous periods of subsidence of the malady. Dapsone was the drug of choice for leprosy from the 1940s until 1980, but due to drug resistance and the necessity for long-term (sometimes lifelong) treatment, it has been replaced by a combination of drugs. This combination, referred to as multiple drug therapy, has been highly effective and requires a shorter treatment period. The drug thalidomide has been approved for use against a complication of leprosy called erythema nodosum leprosum, which causes fever, skin lesions, and other symptoms.

History and Incidence

Diseases that probably included the malady now known as Hansen's disease are described as leprosy in the Bible; segregation and disinfection were advocated as methods of control (Lev. 13.14). Leprosy, which may have originated in Africa or S Asia, is believed to have existed in India and Egypt earlier than 1000 B.C.; a skeleton that dates to c.2000 B.C. and that shows possible evidence of leprosy has been found in NW India. The first clearly identifiable written reference to the disease is from an Indian source c.600 B.C. Infectious diseases from the East—all called leprosy—later spread over most of Europe and the British Isles, and the Crusades were a factor in disseminating them still farther, so that by the 13th cent. they had reached epidemic proportions. Leprosariums were eventually established in most countries for the care of those actually afflicted with leprosy.

The disease still occurs in tropical and subtropical countries of Asia, Africa, and Latin America—mainly Brazil, S central Africa, and India—especially where crowded and unsanitary conditions contribute to its spread. Even in the more developed countries it crops up from time to time. In the United States, the disease is found mostly in Louisiana, Texas, Florida, Hawaii, as well as in California, the Northeast, and other areas where immigrants from endemic areas have settled. Although modern treatment is effective against the disease, the number of cases in the United States has increased significantly since the 1960s. The World Health Organization is working to eradicate the disease worldwide, but progress has been more slow than was anticipated.

The Columbia Electronic Encyclopedia™ Copyright © 2022, Columbia University Press. Licensed from Columbia University Press. All rights reserved.


A chronic infectious disease caused by Mycobacterium leprae that primarily affects the skin and peripheral nerves and, to a lesser extent, the eyes and mucous membranes. Leprosy, or Hansen's disease, has been known for more than 2000 years. It afflicts at least 3 million people worldwide and is most common in developing countries. There are about 200 new cases yearly in the United States. Its epidemiology is not fully understood, but transmission probably takes place by the respiratory route. The bacillus is very slow-growing, and the incubation period is usually 3–5 years. Less than 5% of any population is susceptible, and these individuals have a deficient cell-mediated immune response specifically to M. leprae, which may be genetic in origin. Epidemics have occurred, but are rare. See Mycobacterial diseases

A skin rash and loss of feeling due to nerve damage by M. leprae are the hallmarks of leprosy. Usually the nerve damage is mild, but when severe the inability to feel, particularly in the hands and feet, predisposes the individuals to frequent injuries. Nerve involvement may also lead to a loss of muscle function that produces clawing of the fingers and toes as well as other neuromuscular dysfunctions. Manifestations of the disease depend upon the degree of the immune defect. Initially, most patients develop one or several depigmented areas of skin that may have decreased sensation, a stage referred to as indeterminate disease. The condition may self-heal. If treatment or self-healing does not halt the disease, it may progress to one of three advanced types. The mildest of these, tuberculoid disease, is usually manifested as a single large depigmented, scaly, numb area. The most severe type, lepromatous leprosy, usually involves most of the skin to varying degrees, with variously sized nodules or other changes. Between the two extremes immunologically is borderline disease, with skin changes of both types. The World Health Organization's simplified classification labels indeterminate and tuberculoid patients paucibacillary (few bacilli) and borderline and lepromatous patients multibacillary.

Paucibacillary disease is treated with dapsone plus rifampin for 6–12 months. Clofazimine is added for multibacillary individuals and the treatment continued for 2 or more years. Isolation is unnecessary, since patients become noninfectious within days of starting treatment. See Infectious disease

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



a chronic infectious disease of man caused by Hansen’s bacillus, Mycobacterium leprae, discovered by the Norwegian physician G. Hansen in 1871. Attempts to infect animals have been unsuccessful.

Leprosy was widespread in ancient Egypt, the Near East, China, Japan, and India well before the Common Era. About 10 million persons are estimated to have the disease (1974). It occurs on all the continents and is most prevalent in Africa, Asia, and Central and South America. Factors leading to infection are malnutrition, vitamin deficiency, unsanitary conditions, and population density; the possibility of infection increases in proportion to the length of contact with an infected person. The causative agent is believed to penetrate into the body through injured skin and the mucous membranes of the upper respiratory tract. The incubation period is generally four to six years (ten to 20 years or more are possible).

Three types of leprosy are distinguished according to the symptoms and course. The lepromatous type is the most serious and most contagious. This type of leprosy may affect the skin, mucous membranes, lymph nodes, nerve trunks, and internal organs. Multiple intracutaneous or subcutaneous hemispherical circumscribed nodes, or lepromas, generally appear on the face and less commonly on the forearms, legs, and other parts of the body. They are firm and elastic to the touch, bluish purple and brown in color, and the size of a hazelnut. Their surface is shiny, oily, hairless, and insensitive to temperature, pain, and touch. When these nodes appear on the face, they give it a leonine appearance.

Lepromas may exist for many months and even years before undergoing fibrosis or atrophy into cicatrices, with pigmentation or disintegration and ulceration. Erythematous pigment spots may form on the skin, and sensitivity in these places may be impaired. The formation of lepromas on the mucous membranes may result in nasal bleeding, deformity of the nose, hoarseness or total loss of the voice, episcleritis, keratitis, or iridocyclitis. Neuritis nodosa often develops and is manifested by the formation of painful nodes on the nerves and by loss of sensation in the affected areas.

The tuberculoid type of leprosy is milder and involves principally the skin and the nerve trunks. Ring-shaped lesions with a raised red-brown peripheral ridge usually form on the legs, thighs, and face. Perspiration and sensitivity to pain, temperature, and touch are usually absent in the region of these lesions.

The borderline type of leprosy is characterized chiefly by neurological symptoms with symmetrical involvement of the ulnar, great auricular, fibular, and other nerves, which become compact and painful and form beadlike nodes. Sensitivity to temperature, pain, and touch is impaired along the nerve pathways. Motor and trophic disturbances (bald spots and atrophy of the nails) may also occur. This type of leprosy may evolve into the lepromatous or tuberculoid type.

The diagnosis of leprosy is confirmed by the presence of mycobacteria in scrapings from the nasal mucosa in the leproma fluid, in material from the lymph nodes, or in histological preparations, as well as by the results of special functional tests. The disease is treated with drugs of the sulfone series, long-acting sulfanilamides, and thiourea and phenothiazine derivatives combined with general roborants. Patients are sent to a leprosarium for treatment. Individuals who come in close contact with leprosy patients should be examined from time to time.


Torsuev, N. A. Lepra. Moscow, 1952.
Baroian, O. V. Ocherkipo mirovomu rasprostraneniiu vazhneishikh zaraz-nykh boleznei cheloveka, 2nd ed. Moscow, 1967.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


Pathol a chronic infectious disease occurring mainly in tropical and subtropical regions, characterized by the formation of painful inflamed nodules beneath the skin and disfigurement and wasting of affected parts, caused by the bacillus Mycobacterium leprae
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
Full browser ?