Schistosomiasis as a Mimicker of Inflammatory Bowel Disease

Abstract

A 36 year old Brazilian-born male without family history of colon cancer or significant travel history presented to the GI clinic for abdominal bloating and several years of chronic diarrhea which had recently become bloody. His physical exam was without abnormalities. Labs were notable for 7% eosinophils and elevated transaminases, AST 191 u/l and ALT 158 u/l. The patient underwent a colonoscopy which was notable for diffuse erythema of the rectum concerning for Inflammatory Bowel Disease. Biopsies of the right colon and rectum demonstrated “submucosal granulomas with structures suggestive of schistosomal eggs”. He later underwent a liver biopsy which showed “schistosomal organisms in granulomas with inflammation” and hypereosiniphilia as well as non-alcoholic steatohepatitis. The patient was given one day of Praziquantel and on outpatient follow-up had improvement in his diarrhea and normalization of his liver function tests. He was able to gain 20 pounds and did not require further medical care for his diarrhea. We can infer based on his Brazilian heritage that he was likely infected with Schistosoma Mansoni. Chronic schistosomiasis refers to colonization by one of the schistosoma trematodes. Patients with gastrointestinal manifestations can present with abdominal pain, tenesmus, diarrhea, rectal pain and hematochezia. Hepatic presence of the egg antigen induces a host-immune response leading to granuloma formation and neo-angiogenesis. This causes inflammation of the portal tracts which can lead to hepatomegaly and, if left untreated, irreversible hepatic fibrosis and portal hypertension. Patients with severe liver involvement manifest with complications of portal hypertension sooner than complications of hepatic dysfunction. With intestinal involvement, schistomsoma tend to reside in areas drained by the inferior mesenteric venous plexus and induce localized inflammation and fibrosis of the submucosa and hyperplasia of the mucosa. Endoscopic findings show edematous and congested mucosa with petechial hemorrages similar in appearance to inflammatory colitis. Left untreated, nodules and polyps with ulcerations can form. Nodules tend to have a gray-yellow appearance similar to those seen with pseudomembranous colitis. Although there is little to no risk of malignancy, polyps need to be endoscopically removed as they do not resolve with medical therapy alone. In non-endemic areas, post-treatment studies to confirm eradication are not necessary.