Amebic Colitis

Amebic dysentery is an infectious disease caused by Entamoeba histolytica, the only pathogenic amoeba in humans, belonging to Protozoa, Sarcodina, Rhizopoda. Its body consists of a single cell with no fixed shape and can change form arbitrarily. It extends pseudopodia throughout the body mainly for movement and feeding. In human tissues and feces there are three forms: large trophozoite, small trophozoite, and cyst. When bodily resistance decreases, E. histolytica damages the intestinal wall or invades other organs. Trophozoites have weak resistance outside the body and die easily.

Common Symptoms

Loose stool; diarrhea; chocolate-colored pus...; mucoid stool; abdominal pain; mucoid stool

Causes and Pathogenesis

(1) Etiology: It has been reported that some strains of E. histolytica are non-pathogenic and can survive long-term in the intestines of certain people without causing symptoms. Non-pathogenic strains have different surface antigen components, do not produce proteolytic enzymes, and do not elicit corresponding antibodies in host blood. (2) Pathogenesis: E. histolytica has trophozoite and cyst stages in its life cycle. After cysts are ingested, they pass intact through the stomach and upper small intestine; in the lower small intestine, trypsin digestion releases the mature 4-nucleated cyst into small trophozoites (7 to 20 μm in diameter), which live in the intestinal lumen, feed on bacteria, and do not damage the intestinal wall, reproducing by binary fission and growing well in the hypoxic ileocecal region. When bodily resistance is insufficient or the local mucosa is damaged, small trophozoites become large trophozoites (20 to 40 μm in diameter), which secrete histolytic enzymes to destroy intestinal wall tissue, invade the mucosa and submucosa, multiply abundantly, and form localized submucosal abscesses containing mainly necrotic material; abscess rupture forms flask-shaped ulcers, with the mucosa between ulcers basically normal, which clearly differs from bacillary dysentery. When resistance increases, large trophozoites revert to small trophozoites and further become cysts (about 10 μm in diameter) excreted in feces. Cysts survive 2 to 4 weeks in cool, moist environments and 6 to 7 weeks in the refrigerator, but are heat-sensitive, dying within 5 min at 50°C. Only mature 4-nucleated cysts are infective; immature 1 to 2 nucleated cysts are not infective but can develop into 4-nucleated cysts under suitable external conditions. Trophozoites excreted in stool die quickly. In prolonged cases, simultaneous destruction of intestinal wall tissue and connective tissue hyperplasia can cause bowel wall thickening and luminal narrowing, and occasionally excessive connective tissue hyperplasia forms an ameboma.

Treatment

Drug therapy, rehabilitation therapy

Preventive Measures

Drinking water must be boiled; do not eat raw vegetables; prevent food contamination; prevent fly breeding and eliminate flies; examine and treat cyst passers and chronic patients in the food industry.

Department to Visit

It is recommended to visit the Gastroenterology department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.