Amebiasis and Ulcerative Colitis

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EPIDEMIOLOGICALLY, there seems to be no relation between amebiasis or amebic colitis and idiopathic ulcerative colitis. In geographic regions in which there is a high incidence of ulcerative colitis, such as in the United States and England, there is a low incidence of amebic dysentery, and vice versa. [Conversely, in those regions in which there is a high incidence of amebic dysentery (such as in some countries in South America and southwestern Asia), there is a low incidence of ulcerative colitis.] However, the apparent precipitation of typical ulcerative colitis by amebiasis in veterans returning from endemic amebic areas overseas suggests that the relationship between the two conditions may be closer than previously believed.

The diagnosis of ulcerative colitis is based upon typical proctosigmoidoscopic and roentgenographic features and the absence of pathogenic bacteria and parasites in the feces. Although it is generally accepted that the proctosigmoidoscopic findings in amebic colitis are specific, identification of the parasite Endamoeba histolytica is necessary for a definite diagnosis.

In amebiasis, large discrete ulcers with an overhanging edge are scattered throughout the rectosigmoid area with normal mucosa between the ulcers. In contrast, the mucosa of chronic ulcerative colitis is inflamed, edematous, and friable with many petechial ulcers. The roentgenographic changes in regard to ulcerative colitis may reveal an altered mucosal pattern, absence of haustral markings, or narrowing and shortening of the colon. These changes are dependent upon the severity and extent of the disease. They are diffuse and occur mostly in the sigmoid and descending colon; . . .



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