Amebic colitis in asymptomatic subjects with positive fecal occult blood test results: clinical features different from symptomatic cases.

Amebiasis is a common parasitic infectious disease in developing countries. In developed countries, it is occasionally encountered in travelers to the tropics and in homosexual males. During the past eight years, we detected four cases of amebic colitis among 5,193 subjects who underwent colonoscopy because of positive fecal occult blood test results in a mass screening. All four cases did not have any abdominal symptoms. Ulcerative lesions were observed only in the cecum and ascending colon; another portion of the colon and rectum appeared normal. We may encounter amebic colitis during colonoscopic examination even in subjects who are asymptomatic.