1. Acute infectious enteritis: caused by various bacterial infections. There are often epidemiological features (such as a history of unclean food or contact with infected areas), acute onset is often accompanied by fever and abdominal pain, self-limiting (usually a few days to 1 week, not more than 6 weeks); anti-inflammatory drug therapy is effective; fecal detection of pathogens can confirm the diagnosis. 2. Amoebic enteropathy: epidemiological features, jam-like stools, deep colonoscopic ulcers with subterranean margins, interspersed with normal-appearing mucosa; confirmation depends on finding the pathogen in stool or tissue; positive serum anti-amoebic antibodies in patients from non-endemic areas can help in the diagnosis. Anti-amoebic treatment is effective in highly suspected cases. 3. Intestinal schistosomiasis: history of exposure, often with hepatomegaly and splenomegaly. Confirmation of diagnosis depends on positive fecal examination for schistosome eggs or hatching trichurias; acute stage of proctoscopy for rectosigmoid colon with yellow-brown granules in the mucosa, biopsy for mucosal compression or histopathology for schistosome eggs. Immunological examination can help to differentiate. 4, other: intestinal tuberculosis, fungal enteritis, antibiotic-associated enteritis (including pseudomembranous enteritis), ischemic colitis, radiation enteritis, eosinophilic enteritis, allergic purpura, collagenous colitis, leukoaraiosis, colonic polyposis, colonic diverticulitis and human immunodeficiency virus (HIV) infection combined with colonic lesions should be distinguished from this disease. It should also be noted that mild inflammatory changes in the rectum detected by colonoscopy that do not meet other diagnostic points of UC are often nonspecific and should be carefully investigated for etiology and observed for changes in the condition.