Two cases of amoebic colitis in which serological tests were useful for the differential diagnosis

We presented 2 patients with amoebic colitis, whose endoscopic findings were similar to those of ulcerative colitis. They came to the hospital for bloody diarrhea. Barium enema showed slight mucosal granularity and irregularity of bowel margins with erosions. On endoscopic examination, there were so-called varioform and aphthoid lesions with the redness and edema in intervening mucosa in both patients. These findings suggested amoebic colitis, but ulcerative colitis and the other infectious colitis could not be ruled out. The initial fecal and pahological tests for amoeba were negative. However, both of the patients showed positive serological tests for amoeba. One showed positive in gel diffusion precipitin test (GDP) and enzyme-linked immunosorbent assay (ELISA), and the other in GDP, counterimmunoelectrophoresis (CIE), immunofluorescent antibody test (IFA), and indirect hemagglutination test (IHA). Fecal and pathological tests were repeated and then trophozoites of amoeba were demonstrated in the specimens. We concluded that serological tests for amoeba were simple and useful for the differential diagnosis and early treatment.