Amoebic colitis

　　The pathogen of amebic colitis is the invasive ameba. In recent years, some reports have shown that some invasive amebas are non-pathogenic and can survive in the intestines of some people for a long time without causing symptoms. Non-pathogenic strains have different surface antigen components from pathogenic strains and do not produce proteolytic enzymes, and no corresponding antibodies are produced in the host blood. The invasive ameba appears in two different morphological stages in its life cycle: trophozoite and cyst stage. After the cyst is ingested by humans, it can pass through the stomach and the upper part of the small intestine without damage, and after being digested by trypsin in the lower part of the small intestine, the mature cyst with 4 nuclei can shed and become a small trophozoite (diameter 7-20μm), parasitizing in the intestinal lumen, feeding on bacteria, not damaging the intestinal wall tissue, and undergoing binary fission reproduction. It grows well in the ileocecal region with insufficient body resistance or local intestinal mucosal injury. The small trophozoite can become a large trophozoite (diameter 20-40μm), which can secrete lysosomal enzymes to destroy the intestinal wall tissue, invade the intestinal mucosa and submucosa, multiply extensively, and form localized submucosal abscesses, mainly containing necrotic material. When the abscess bursts, it forms flask-shaped ulcers.

　　The mucosa between ulcers is basically normal, which is obviously different from bacterial dysentery. When the body's resistance is enhanced, the large trophozoite can become a small trophozoite and can further become a cyst (about 10μm in diameter), excreted out of the body with feces. In a cool and humid environment, it can survive for 2-4 weeks, and can live for 6-7 weeks in the refrigerator, but it is not heat-resistant, and it will die after 5 minutes at 50℃. Only the mature cysts with 4 nuclei have infectivity, and the immature cysts with 1-2 nuclei are not infectious, but they can develop into 4-nucleus cysts in a suitable external environment. Both large and small trophozoites will die quickly if excreted out of the body. If the course of the disease is prolonged, the destruction of the intestinal wall tissue and the proliferation of connective tissue occur simultaneously, leading to thickening of the intestinal wall and narrowing of the intestinal lumen. Occasionally, excessive proliferation of connective tissue can form 'amebic tumor'.

　　Chronic patients with amebic colitis may present with anemia and malnutrition. In addition, the intestinal wall tissue is damaged differently in acute and chronic stages, which can cause the following complications.

　　1. Intestinal perforation leads to peritonitis

　　Zeng's report involved 254 cases of amebic dysentery patients, among whom 19 had intestinal perforation confirmed by surgery and autopsy, accounting for 7.48%. Adams reported that in 3013 cases, 97 developed peritonitis (3.2%), the incidence rate was not very high, but the prognosis was poor.

　　2. Amebic Appendicitis

　　In the autopsies of 186 amebic patients reported by Clark, 40% had appendicitis. Criag reported that 26.67% of 60 patients had concomitant appendicitis. The incidence rate is indeed high. Therefore, in areas with a high incidence of amebic disease, many acute abdominal emergencies are caused by amebic appendicitis or amebic appendiceal perforation.

　　3. Intestinal Stenosis

　　In chronic amebic colitis, the intestinal wall tissue becomes hyperplastic and thickened, and amebic granulomas form, leading to stenosis. A few patients even develop intestinal obstruction requiring surgical treatment.

　　4. Ameboma

　　Among the 3013 patients reported by Adams, 15 developed ameboma (0.5%).

　　5. Non-specific Ulcerative Colitis

　　The amebae have been completely eliminated and have transformed into non-specific ulcerative colitis. Adams' statistics show that there were 21 cases (0.7%).

　　In addition, less common conditions include intestinal hemorrhage, intestinal polyps, and intussusception, etc.

　　Amebic colitis has a certain latent period, which varies in length, from 1 to 2 weeks or more than a few months. Different clinical manifestations may occur due to different numbers of ingested cysts, pathogenicity, and the strength of the body's resistance.

　　1. Symptoms and Signs

　　1. Asymptomatic type mainly refers to those carriers of amebic cysts, often discovered through mass screening. These people are often ignored by patients because of their mild symptoms. These patients are an important source of infection for this disease.

　　2. Amebic enteritis is similar to common enteritis, with symptoms such as abdominal pain and diarrhea, loose or watery stools, mixed with mucus and undigested food, with a strong odor.

　　3. The symptoms of amebic dysentery are similar to those of bacterial dysentery, but the toxic symptoms are milder. The patient may have a fever of about 38℃, abdominal pain, diarrhea, several to more than 10 times a day. Stool is bloody mucous, or stool and blood are separated, sometimes completely bloody. If the frequency is not high, the stool is dark red or jam-like, with a strong odor.

　　Carefully search for amebae in the fresh feces of the patient, especially in the bloody mucus area. Once an active, phagocytic trophozoite with red blood cells is found, the diagnosis can be confirmed. If not found in one instance, repeat multiple checks and strive for bacterial and amebic cultures. When doing microscopic examination, attention should be paid to maintaining warmth, otherwise the amebic trophozoites are inactive and are not easily distinguished from macrophages. Sigmoidoscopy is very helpful for diagnosis, especially for differential diagnosis. In the acute phase, bottle-shaped ulcers can be seen, with normal mucosa between the ulcers. In the chronic phase, intestinal mucosal hyperplasia, granulomas, and polyps can be seen, and viable tissue can be taken from the lesion for pathological examination to further determine its nature.

　　2. Typical Clinical Manifestations

　　1. The main symptoms of acute amebic dysentery or enteritis are abdominal pain, diarrhea, bloody mucous stools, and manifestations of colitis, accompanied by a fever of over 38℃. The frequency of defecation is usually less than 10 times a day. The cecum and ascending colon are the most commonly affected areas. The rectum and sigmoid colon are next, so abdominal tenderness is often more pronounced on the right side than on the left. Mild cases may have mucus in the stool but no obvious blood changes.

　　2. Acute fulminant colonic mucosal necrosis in large areas, followed by secondary bacterial infection, causing marked and severe toxicemia symptoms, with the patient having high fever, abdominal pain, diarrhea, more than ten or more stools, and watery stools with blood. Nausea and vomiting may occur. The risk of intestinal hemorrhage and perforation is high. Fortunately, it is rare in recent years.

　　3. Chronic amebic colitis often manifests as chronic enteritis. Abdominal pain and diarrhea are not severe, but they are persistent and can be good or bad at times. When symptoms are obvious, there may be 3-5 loose stools a day, with mucus, and amebic trophozoites can be found in fecal examination. Amebic cysts can be found in feces when there is no obvious diarrhea. During a marked acute attack, dysenteric-like stools can be excreted.

　　This disease is mainly transmitted through the fecal-oral route, and in prevention, attention should be paid to the cleanliness of food and drinking water. Drinking water should be boiled, raw vegetables should not be eaten to prevent contamination of food. Prevent the breeding of flies and kill flies. Check and treat carriers of cysts and chronic patients engaged in the catering industry, and change jobs during treatment. Pay attention to personal hygiene such as washing hands before and after meals.

　　In addition, from the perspective of the transmission process, preventive measures should be taken from the following three aspects:

　　(1) Sources of infection

　　Chronic patients, convalescent patients, and healthy carriers are the sources of infection for this disease, and the resistance of cysts is very strong, they can survive for more than 12 days in a humid and low-temperature environment, and can live for 9-30 days in water. However, the resistance of cysts to dryness, high temperature, and chemical drugs is weak, such as at 50°C, they will die shortly, and their survival time in a dry environment is only a few minutes. They cannot survive for a long time in 0.2% hydrochloric acid, 10%-20% salt water, and soy sauce, vinegar, and other condiments. 50% alcohol can kill them quickly.

　　(2) Transmission routes

　　The transmission modes of Entamoeba histolytica include the following several kinds:

　　① Cysts can cause outbreaks in a region by contaminating water sources;

　　② In the case of using feces as fertilizer, unwashed and uncooked vegetables are also important factors for transmission;

　　③ Cysts can be transmitted by contaminating fingers, food, or utensils;

　　④ Flies and cockroaches can contact feces, carry feces on their bodies, and vomit feces, polluting food with cysts and becoming important transmission media.

　　(3) Characteristics of the epidemic

　　The disease caused by Entamoeba histolytica is widespread, in temperate regions, the disease can occur sporadically, and in tropical and subtropical regions, its prevalence is particularly serious.

　　For amebic colitis, fecal examination is an important basis for diagnosis. In the fresh feces of patients, especially at the site of bloody mucus, carefully search for amebae, and once an active tissue ameba trophozoite that engulfs red blood cells is found, it can be diagnosed. If not found once, repeat multiple checks and strive to do bacterial and amebic cultures. Pay attention to heat preservation during microscopic examination, otherwise the tissue ameba trophozoite is inactive and is not easy to distinguish from macrophages. Sigmoidoscopy is very helpful for diagnosis, especially for differential diagnosis. In the acute stage, flask-shaped ulcers can be seen, and the mucosa between ulcers is normal. In the chronic stage, the intestinal mucosa can be seen to be hyperplastic and thickened, granulomas, and polyps, and viable tissue can be taken from the lesion site for pathological examination to further determine its nature.

　　Laboratory examination

　　Stool examination is an important basis for diagnosis. After identifying the pathogen, it is necessary to differentiate non-pathogenic amoebae. Currently, serological tests are developing rapidly and are a key experiment for the diagnosis of amoebiasis, with about 90% of patients' sera detectable by ELISA, indirect hemagglutination, and indirect immunofluorescence for different titers of antibodies. PCR diagnostic technology is a highly effective, sensitive, and specific method. The WHO Special Committee recommends that if tetranucleate cysts are found under the microscope, they should be identified as Entamoeba histolytica or Entamoeba dispar; if erythrocytic trophozoites are detected in the stool, it should be highly suspected as Entamoeba histolytica; if a high titer of positive serological tests is found, it should be highly suspected as an infection with Entamoeba histolytica. Amoebiasis is caused only by Entamoeba histolytica.

　　Other auxiliary examinations

　　1. Colonoscopy can be performed for cases that have not yielded positive results from microscopic examination, serological tests, and PCR tests, but are highly suspected clinically. In about 2/3 of symptomatic cases, scattered ulcers of varying sizes can be seen on the mucosa of the rectum and sigmoid colon, covered with yellow pus, with slightly protruding edges and slight congestion. The mucosa between the ulcers is normal. Materials from the ulcer surface can be scraped for microscopic examination, and trophozoites can be found more often.

　　2. X-ray barium enema examination shows signs of filling defects, spasm, and obstruction in the lesion area. Although this finding is not specific, it is helpful in distinguishing between amoebic tumors and colorectal cancer.

　　Amoebic colitis and common enteritis are similar, patients may have abdominal pain and diarrhea, the stool is not formed or loose, mixed with mucus and undigested food. While receiving timely treatment, attention should be paid to dietary adjustment, which is helpful for early recovery.

　　1. Water must be boiled, raw vegetables should not be eaten to prevent food contamination. Prevent the breeding of flies and the extermination of flies. Check and treat carriers and chronic patients engaged in the catering industry, and change their work during treatment. Pay attention to personal hygiene such as washing hands before and after meals.

　　2. High energy and high protein to compensate for the nutritional consumption caused by long-term diarrhea, the supply amount can be gradually increased according to the patient's tolerance of digestion and absorption.

　　3. Ensure an adequate intake of vitamins and inorganic salts to compensate for the nutritional loss caused by diarrhea.

　　4. Limit dietary fat and fiber: Diarrhea often accompanies malabsorption of fat, and severe cases may have steatorrhea. Therefore, the intake of dietary fat should be limited, and low-fat foods and cooking methods should be used. For those with steatorrhea, medium-chain triglyceride oils can be used. Avoid eating foods that are high in irritants and fiber, such as spicy foods, sweet potatoes, radishes, celery, raw vegetables, fruits, and刺激性 onions, ginger, garlic, and coarse grains, dried beans, etc.

　　5. Eat less and more often: To reduce the burden on the intestines, increase the intake of nutrients by eating less and more often.

　　Amoebic colitis belongs to the category of 'resting dysentery' in traditional Chinese medicine, and its onset is often due to unclean diet and weak spleen and stomach, so traditional Chinese medicine treatment must invigorate the body and expel pathogenic factors, warm the middle and clear the intestines. Treatment methods include the following:

　　(1) Formula One

　　Prescription: Scutellaria baicalensis 30 grams, Phellodendron amurense 15 grams, Coptis 10 grams, Cortex moutan 15 grams, raw ulmus 30 grams, apocynum 15 grams.

　　Usage: Decocted for oral administration, 1 dose per day, divided into 2 servings.

　　Effects: Clearing heat, removing dampness, and detoxifying.

　　(2) Formula Two

　　Prescription: 300 grams of Huaishan, 25-30 grams of notoginseng, 100-120 seeds of Brucea javanica.

　　Usage: First grind Huaishan and notoginseng into fine powder. Mix 30 grams of Huaishan powder with cold water, cook it into porridge in a pot (stir continuously with chopsticks to prevent it from sticking together), add 1.25 grams of notoginseng powder, and swallow 10 seeds of Brucea javanica with this porridge, twice a day.

　　Effects: Benefiting the spleen and kidney, transforming decay and promoting muscle growth.

　　(3) Formula Three

　　Prescription: Coptis 6 grams, licorice 6 grams, dried ginger 9 grams, angelica sinensis 9 grams, black plum 9 grams, costus 9 grams, 12 grams of donkey hide glue, 18 grams of white peony, 30 grams of carbonized ulmus, 24 grams of yam, 30 seeds of Brucea javanica.

　　Usage: Decocted for oral administration, 1 dose per day. Take Brucea javanica seeds wrapped in bun skin.

　　Effects: Nourishing yin and blood, clearing heat and removing dampness.

　　(4) Formula Four

　　Prescription: Scutellaria baicalensis 30 grams, codonopsis 30 grams, coix seed 30 grams, poria 30 grams, Coptis 3 grams, Phellodendron amurense 15 grams, Cortex moutan 15 grams, peony 15 grams, atractylodes 12 grams, licorice 10 grams, amomum 6 grams.

　　Usage: 1 dose per day, decocted for oral administration.

　　Effects: Benefiting the spleen and stomach, removing dampness and clearing heat, cooling blood and stopping diarrhea.

　　(5) Formula Five

　　Prescription: Cinnamon 6 grams, dried ginger 6 grams, atractylodes 15 grams, atractylodes macrocephala 15 grams, codonopsis 20 grams, poria 20 grams, tangerine peel 10 grams, amomum 10 grams (added later), prepared aconite 8 grams, costus 8 grams, baked magnolia bud 3 pieces, baked licorice 3 grams.

　　Usage: Decocted for oral administration, 1 dose per day.

　　Effects: Warming and tonifying the spleen and stomach, resolving food accumulation and stagnation.