Differential Diagnosis of Leprosy and Black Foot Disease

Abstract

By the end of World War II, a specific disease, which might have existed in the past, yet was not known to the public, was found in the down-stream basin of the Pa-Chang River on the south west coast of Taiwan. The disease was found to cause gangrene of the extremities, especially the foot, and mutila-tion, and was called the "black-foot" disease by the local people, though it could probably be arsenical gangrene by nature. This disease has been feared by the people for, once infected, patients suffer as much as the lepers. In fact, several clinical symptoms of this specific disease, such as red swelling of toes and fingers, the initial stage of paresthesia, breaking of fingers and toes, the later stage of mutilation, resemble some symptoms of leprosy. Therefore, the dif-ferential diagnosis of this "black-foot" disease in the course of the diagnosis of leprosy has become quite necessary in this country. Since few health workers in the field of leprosy control in this country have encountered this disease, it is helpful to describe the similarity and differences of these two diseases for reference.
1. Paralysis and gangrene found in black-foot disease patients are caused by long-term intake of arsene with a result in changes primarily in the blood system, such as intimal arteritis, particularly capillar sclerosis, obliterans, and even thrombosis. Peripheral nerves are injured to cause peripheral multiple neuritis, and therefore paralysis. The trophic nerves are then injured, and the deep tissue therefore becomes necrotic, resulting in gangrene and mutilation
2. Leprosy is the only bacillary infection which attacks the peripheral nerves. Paresthesia occurs naturally. The Mycobacterium leprae parasitizes and multiplies in the small arteria, the round cells are then infiltrated, and the con-nective tissue becomes thicker. As a result, the arterial lumen becomes nar-rower, and macula circumscripta and paralysis occur. The severity and the frequency of the red-swelling of fingers and toes in leprosy are less than seen in Black foot disease.
3. Although these two diseases are caused by different agents, their local symptoms, such as the red-swelling of fingers and toes, numbness, cold feeling, contraction of fingers and toes, dwindle and remnant of nails, are similar.
4. While anhidrosis is found in the leprosy patients, hyperidrosis is found in the black-foot disease patients,
5. Other symptomatological, and bacteriological findings mentioned in this article can be of reference to the differential diagnosis of these two diseases. In one word, there is neither superficial nerve hypertrophy, nor leprotic erup-tion in the black-foot disease. At the ulcerous lesions, hyperesthesia instead of anesthesia occurs. Since the black-foot disease is a nonbacillary disease, no acid-fast bacilli can be found.
6. It was found in this study that the increase of arsenical content in water in these areas might probably have something to do with earthquakes.
Acknowledgement: This work was aided by grants from the Natioual Council on Science Development of the Republic of China.