Amebic dysentery

　　Amoebic dysentery is an intestinal infectious disease caused by Entamoeba histolytica, with the main lesions in the cecum and ascending colon. Clinically, it is characterized by abdominal pain, diarrhea, and the excretion of dark red jam-like stools. The disease is prone to become chronic and can cause complications such as liver abscesses.

　　The main amebae in the human colon are mainly four species, among which only Entamoeba histolytica is related to human diseases. Entamoeba histolytica has two species: one is the pathogenic Entamoeba histolytica (entamoeba histolytica), and the other is the symbiotic Dispar ameba (entamoeba dispar). Although their morphology is the same, their antigenicity, genetic structure, and pathogenicity are completely different. The latter is a non-invasive ameba, non-pathogenic, asymptomatic after infection; the former can cause invasive lesions, and human amebiasis is caused by the pathogenic Entamoeba histolytica.

　　Entamoeba histolytica has two forms, trophozoite and cyst, but only the cyst can transmit the disease, which is the infective form of the protozoan. Chronic patients and asymptomatic carriers of cysts excrete cysts through feces, contaminating food and water. People who eat contaminated food and drink contaminated water can become ill.

　　According to traditional Chinese medicine, unclean diet, internal invasion of worm toxins,潜伏 in the large intestine, accumulated and produced damp-heat, obstructing the intestinal qi, disturbing the intestinal blood circulation, leading to disharmony of Qi and blood, damage to the intestinal collaterals, worm toxins and damp-heat corrupting Qi and blood, turning into pus and blood, mixing together and descending, resulting in strange and constant dysentery. Damp-heat and worm toxins damage the intestinal collaterals, causing external steaming of the muscles, symptoms such as fever, purulent stools, urgent need to defecate, etc.; if the spleen and stomach are not healthy, the body is weak and the evil is strong, it often occurs intermittently and is difficult to heal. A few patients may develop liver abscess due to damage to the spleen and stomach, delayed transformation, leading to liver failure of excretion, worm toxins stagnating in the liver, causing corruption of blood and flesh, and developing into liver abscess.

　　1. Intestinal hemorrhage:Ulceration of the intestinal wall involving blood vessels can cause intestinal bleeding. The amount of bleeding varies, and in cases of massive bleeding, patients often show symptoms of hemorrhagic shock, such as pale complexion, rapid pulse, and decreased blood pressure.

　　2. Intestinal perforation:It is more common in fulminant cases. The perforation site is most common in the cecum, appendix, and ascending colon. Acute perforation can cause diffuse peritonitis, with severe condition. Chronic perforation causes adhesion of surrounding tissues, forming local abscesses.

　　3. Appendicitis:The symptoms of amebic appendicitis are similar to those of common appendicitis, and it is prone to form abscesses. If there is a history of chronic diarrhea or amebic dysentery, and amebic trophozoites or cysts are found in the feces, it can help in the differential diagnosis of the two.

　　4. Non-dysenteric colonic lesions:It is caused by proliferative lesions, including ameboma, intestinal amebic granuloma, and fibrous stricture. Ameboma is an inflammatory pseudotumor of the colon wall, with abdominal pain and changes in defecation habits being the most common, some accompanied by intermittent dysentery, which can induce intussusception and intestinal obstruction. The main signs are: palpable, movable, smooth, egg-shaped or intestinal loop-like masses in the right iliac region, with locoregional lesions seen on X-ray, and good response to antiamoebic treatment.

　　The extraintestinal complications of amebic dysentery include: The most common extraintestinal complication is liver abscess, which can perforate and extend to nearby tissues and organs. The blood vessels can directly affect the brain, lungs, testicles, prostate, ovaries, and so on. Amebic liver abscess can occur throughout the course of the disease or several weeks to several years after the disease. It usually starts with a long-term irregular fever, with body temperature reaching above 39℃, with remittent fever type being more common, often accompanied by pain in the upper right abdomen or lower right chest, progressive enlargement of the liver, and significant tenderness as the main clinical manifestations. Most abscesses are solitary and mostly located in the right lobe of the liver, the reason being that the right lobe is large, accounting for 4/5 of the total liver volume, and the intestinal lesions are mostly located in the ileocecal region, where most of the blood circulation passes through the superior mesenteric vein into the right lobe of the liver. If the abscess is located in the left lobe, it can appear with obvious local symptoms and signs in a shorter time, but diagnosis is difficult. Superficial abscesses may have local tenderness or fluctuation, at which time liver puncture shows pork liver-colored pus with a foul smell, containing dissolved necrotic liver cells, red blood cells, fat, and Schmorl's crystals, etc. Trophozoites are not commonly found, but they can be found in the wall of the abscess cavity, and no cysts have been found. If there is a bacterial infection, the pus in the abscess cavity is yellow-green or yellowish-white.

　　The incubation period of invasive amebiasis is on average 1 to 2 weeks (4 days to several months), with different clinical presentations.

　　(One) Asymptomatic type (carrier of cysts): This type often does not present with symptoms clinically, and amebic cysts are found during multiple fecal examinations.

　　(Two) The common type usually has a slow onset, with mild systemic symptoms of poisoning, often without fever, mild abdominal pain, diarrhea, with more than 10 bowel movements a day, moderate in amount, with blood and mucus, blood and necrotic tissue mixed evenly like jam, with a foul smell, containing dysentery amebic trophozoites and a large number of red blood cells in clumps, which is one of its characteristics. The lesion site may be low with a feeling of urgency and tenesmus. Abdominal tenderness is mainly on the right side. These symptoms can resolve spontaneously. They can also recur due to incomplete treatment.

　　(Three) The mild type is seen in individuals with strong constitution, with mild symptoms, usually 3 to 5 loose or watery stools per day, or alternating diarrhea and constipation, or no diarrhea, just feeling discomfort or pain in the lower abdomen, stool occasionally contains mucus or a small amount of blood, and the amebic cysts and trophozoites can be detected. There are no complications, and the prognosis is good.

　　(Four) The fulminant type is very rare and can occur due to severe infection with this pathogen, or concurrent intestinal bacterial infection, or weakened constitution, presenting as fulminant. It has a sudden onset with marked symptoms of poisoning, such as chills, high fever, delirium, and toxic intestinal paralysis. Severe abdominal pain and tenesmus, frequent diarrhea, up to dozens of times a day, even incontinence, feces may appear as bloody water, meat water, or thin water, resembling acute bacillary dysentery, but with a very strong smell and containing a large number of active amebic trophozoites, which is its unique feature. Abdominal tenderness is marked. It often leads to peripheral circulation disorders due to dehydration, or accompanied by consciousness disorders, even intestinal hemorrhage, intestinal perforation, peritonitis, and other complications, with poor prognosis.

　　(Five) Chronic type often causes alternating diarrhea and constipation due to improper treatment during the acute phase, causing recurrent clinical symptoms and lasting for more than 2 months or even several years. It often recurs due to catching a cold, fatigue, or improper diet. Patients often feel bloating and pain in the lower abdomen, and over time, they may become weak, anemic, and malnourished. The right lower abdomen may have thickened colon that is slightly tender; the liver may swell with tenderness. Stool may contain pus and blood, trophozoites, and sometimes cysts.

　　(Six) Other types of amebiasis can occur in infections of the urinary tract, reproductive system, skin, and other places, but they are very rare. They can also onset as complications, making misdiagnosis easy.

　　For the prevention of amebic dysentery, in daily life, we should do the following:

　　1. Protect public water sources, strictly prevent fecal contamination. Drinking water should be boiled.

　　2. Vigorously eliminate flies and cockroaches, use fly-proof covers or other measures to prevent food from being contaminated.

　　3. Strengthen the sanitation management of canteens. There should be health supervision measures in the process of food preparation and staff operations.

　　4. Strengthen the management of feces, the sanitation of animal pens, and do a good job of harmless treatment of feces according to local conditions to improve the environmental hygiene.

　　5. Pay attention to dietary hygiene, personal hygiene, and a civilized lifestyle. Do not drink unboiled water, do not eat unclean fruits and vegetables, and develop the habit of washing hands before meals or after defecation, or before preparing food.

　　8. Patients should be treated promptly, and measures such as epidemic reporting, disinfection, and isolation should be implemented according to the management of infectious diseases. Family members or contacts should be examined.

　　If amebic dysentery is suspected, some laboratory tests are required, among which fecal examination is an important basis for diagnosis.

　　1. Fecal examination

　　This is an important basis for diagnosis. The feces of typical amebic dysentery are dark red jam-like, with a special smell of fishiness, abundant fecal matter, containing blood and mucus. Microscopic examination shows a large number of clumps of mucus-bound red blood cells and a small number of white blood cells, and sometimes active trophozoites that engulf red blood cells and Charcot-Leyden crystals can be seen. In chronic patients, only cysts can generally be detected in formed feces. After concentrating by methods such as zinc sulfate centrifugal flotation, mercury iodide precipitation, or silicon gel colloidal suspension (trade name percoll) gradient separation, the cysts can be stained with iodine to improve the positive detection rate.

　　Isolation and culture of protozoa from fecal specimens is commonly done using Robinson medium, which has a higher detection rate for subacute or chronic cases. However, due to its high requirements, it is currently not yet used as a routine examination for hospital diagnosis. When examining amebae, one should differentiate them from other non-pathogenic intestinal protozoa, such as Entamoeba coli and Entamoeba hartmanni, based on aspects such as the size of the body, the number of nuclei, the shape of pseudopodia, and the mode of movement. In necessary cases, the cyst or trophozoite can be stained, and differentiation can be made based on the structure of the nucleus, the chromatin, glycogen vacuoles, and other characteristics.

　　Currently, there are several methods to distinguish between Entamoeba histolytica and Entamoeba dispar, including isoenzyme analysis, enzyme-linked immunosorbent assay, and PCR analysis. Using the surface molecule of Entamoeba histolytica with a molecular weight of 260103 Gal/GalNAC lectin as the target antigen, detection by monoclonal antibody achieves sensitivity and specificity of 88% and 99% in blood and feces, and this method has kits available in Europe and America. PCR can directly identify the two endoamebas at the DNA level, with the detection of the gene encoding the 29103/30103 cystine antigen being the most specific and feasible. It is said that the two endoamebas can be directly identified by PCR in feces.

　　2. Serological examination

　　A variety of immunoserological diagnostic tests can be performed using pure amebic antigens. Antibody detection is negative in asymptomatic carriers of cysts, and antibodies are only formed when there are invasive lesions in the body. Detection methods include indirect hemagglutination (IHA), indirect immunofluorescence antibody (IFA), agar diffusion (AGD), and enzyme-linked immunosorbent assay (ELISA). The positive rate of amoebic dysentery can reach 60% to 80%, and these antibodies can persist for 2 to 10 years after treatment. The ELISA antibody titer can turn negative within a few months after the onset of the disease, indicating that a positive antibody indicates an acute infection. In addition, the IFA method generally detects antibodies 6 to 12 months after recovery, and the antibody titer can significantly decrease or turn negative, which can also be used as a diagnostic method. Recombinant antigens have been used to detect antibodies, and it has been reported that their sensitivity and specificity are both over 90%.

　　3. Nucleic acid testing

　　The main targets for detection are pus or stool culture, biopsy of intestinal tissue, and DNA from脓血便, which are amplified using appropriate primers. It is currently considered that primers designed based on the molecular weight of 29103/30103 dicysteine antigen (also known as peroxiredoxin) of intracellular amebae are the most suitable for specificity and sensitivity.

　　4. Barium enema X-ray examination

　　Barium enema X-ray examination can show filling defects, spasm, and obstruction in the lesion area.

　　Amoebic dysentery, also known as intestinal amoebiasis, is an intestinal infectious disease characterized by dysentery symptoms caused by pathogenic tissue-invasive amebae invading the colonic wall. The lesions are mostly located in the ileocecal colon and are prone to recurrence and chronicity. The protozoa can also migrate from the intestinal wall to the liver, lungs, brain, and other organs through blood flow-lymph or directly, becoming extraintestinal amebiasis, with amoebic liver abscess being the most common. Special attention should be paid to diet for patients with amoebic dysentery, as improper diet can exacerbate the condition.

　　The purpose of dietary treatment is to reduce intestinal irritation, alleviate the symptoms of diarrhea in patients, and prevent and correct electrolyte and water balance. When fever, abdominal pain, and diarrhea are severe, fasting should be practiced. When symptoms slightly improve, light, nutritious, easily digestible, and low-fat liquid foods can be consumed, such as lotus root starch, rice porridge, fruit juice, vegetable juice. Milk, soy milk, and foods that produce gas should be avoided to ensure the full rest of the intestines, and water and electrolytes should be supplemented. After fever and diarrhea symptoms improve, low-residue, non-irritating foods can be consumed, transitioning from low-residue, low-oil semi-liquid to semi-liquid, soft food, or regular food. Foods such as congee, noodles, noodles, small wontons, tofu, steamed egg custard, small meatballs, fish balls, fried fish, and mashed vegetables can be consumed. Three or five meals a day can be taken, but the amount should not be excessive. It is advisable to drink more water to improve dehydration and toxicemia, which is conducive to the excretion of toxins. Oily or fried foods, celery, chives, radishes, coffee, strong tea, alcohol,刺激性调味品, and cold foods should be avoided until the intestinal lesions recover, and then normal diet can be resumed.

　　For amebic dysentery, the treatment principle in traditional Chinese medicine is to guide stagnation, promote qi, and harmonize blood. In the early stage, it belongs to damp-heat syndrome, so 'the method of benefit is to stop it'. In the later stage, it belongs to deficiency or deficiency with excess, so it is applied to both attack and supplement, or warm tonification and astringent are mainly used, and it should not be too bitter and cold, damaging the spleen and stomach. If the condition is severe, it belongs to internal closure and external leakage, and it is urgent to rescue Yang and prevent loss, and actively rescue.

　　(1)Damp-heat Obstruction

　　Symptoms: Abdominal pain, diarrhea, purulent diarrhea, mucus dark red like jam, decayed and foul smell, anal heat, short and red urine, yellow greasy fur, slippery and rapid pulse.

　　Treatment Method: Clear heat and remove dampness, promote qi and activate blood.

　　Prescription: Radix Paeoniae Alba 12 grams, Angelica Sinensis 10 grams, Sandalwood 10 grams, Averrhoa carambola 10 grams, Forsythia 10 grams, Coptis 10 grams, Rhei Cortex 8 grams, Cinnamon 3 grams, Licorice 6 grams, Strychnos nux-vomica 5 grams.

　　(2)Epidemic Toxin Retained in the Intestine

　　Symptoms: Fresh purple pus or blood in diarrhea, severe abdominal pain, or severe heat and thirst, headache and irritability, red and绛 red tongue fur, yellow and dry fur, slippery and rapid pulse.

　　Treatment Method: Clear heat and cool blood, detoxify and purify turbidity.

　　Prescription: Herba Pulsatillae 10 grams, Coptis 10 grams, Phellodendron 10 grams, Cortex Phellodendri 10 grams, Strychnos nux-vomica 5 grams, Scutellaria 10 grams, Lonicera 12 grams, Sanguisorba 10 grams, Moutan Cortex 10 grams, Frankincense 3 grams.

　　(3)Severe Heat-toxin

　　Symptoms: Bloody stools with foul smell, abdominal pain, abdominal mass, pain that resists pressure, chills and high fever, red tongue with yellow greasy fur, slippery and rapid or wiry pulse.

　　Treatment Method: Clear heat and detoxify, activate blood and drain pus.

　　Prescription: Lonicera 10 grams, Radix Paeoniae Rubra 10 grams, Angelica Sinensis 10 grams, Coptis 10 grams, Scutellaria 10 grams, Sandalwood 10 grams, Gardenia 10 grams, Licorice 6 grams, Rhizoma Anemarrhenae 10 grams, Patrinia 12 grams, Coix Seed 10 grams.

　　(4)Deficient Cold Diarrhea

　　Symptoms: Chronic diarrhea that does not heal, diarrhea with thin stools, white jelly, sticky and smelly mucus, or slippery and uncontrollable, or abdominal hidden pain, decreased appetite, fatigue, weakness, pale tongue with thin white fur, deep and thin pulse.

　　Treatment Method: Warm and tonify the spleen and kidneys, contract and fix.

　　Prescription: Ginseng 6 grams, Atractylodes 10 grams, Myrobalan 6 grams, Opium Poppy Shell 6 grams, Cinnamon 3 grams, Angelica Sinensis 10 grams, White Peony 10 grams, Sandalwood 10 grams, Nutmeg 10 grams, Prickly Ash 6 grams, Fructus Evodia 10 grams, Bitter Melon 10 grams.