Amebic colitis results from an invasive infection of the colonic mucosa by Entamoeba histolytica (E histolytica). Losch first reported disease due to E histolytica in 1875; he found amoebas in colonic ulcers at autopsy and showed that the disease could be experimentally induced in vivo by rectal inoculation with human feces (see Image. Amebic Colitis). Other scientists have shown that amoeba is the cause of the disease. E histolytica has a worldwide distribution but is uncommon in the United States. However, it occurs with increased frequencies in patients with AIDS and men who engage in sex with other men. Symptoms vary widely and include the following: Dysentery with diarrhea and rectal bleeding mimicking irritable bowel disease (IBD). Liver abscesses. Colonic granulomatous masses that can mimic carcinoma. Complications include colonic perforation and fistulas or liver abscesses . E histolytica can spread by the ingestion of the amoeba cyst. The infective cysts can occur in contaminated food and water. Transmission by fecal-oral self-inoculation can also happen in oral-anal sexual contact.