Amoebic colitis (AC) and inflammatory bowel disease (IBD) share common clinical and histopathological features; however in developed countries AC is primarily considered in the context of travel to endemic areas or other specific risk factors. Differentiating the two and excluding AC in suspected cases of IBD is vitally important, as administration of immunosuppressive therapy, particularly corticosteroids, may precipitate fulminate AC with toxic megacolon or perforation.
We present 2 cases of AC masquerading as IBD, and investigated and treated as such for 2-6 months including with infliximab and/or prednisolone. Neither had any relevant travel history. Initial faecal microscopy was negative or indeterminate for Entamoeba histolytica detection and recognition of AC was facilitated by a recently introduced PCR assay. Two additional cases in patients with minor gastrointestinal symptoms had caecal or colonic ulcerations on endoscopy and a histological diagnosis of AC. One of these patients, with a history of travel to Vietnam 5 years earlier, had testing by PCR and was positive for E. histolytica.
These cases highlight the importance to clinicians of considering infective etiologies, especially E. histolytica, in the differential diagnosis of colitis, even when there is no history of travel to developing regions and no other traditional risk factors. Molecular diagnostic methods facilitate the accurate diagnosis of E. histolytica infection and we recommend that PCR-based assays be included in the work-up of all patients presenting with colitis. Improved diagnostic assays for E. histolytica should result in further insights into the epidemiology and clinical presentations of infection in developed countries.