Amebic enteropathy

Introduction to amoebic bowel disease Entamoeba Hertolytica Schmidnn (1930), mainly parasitic in the colon, causing amoebic dysentery or amoebic colitis. Amoeba is also the most important pathogenic species in the root-footed worm family. Under certain conditions, it can be extended to the liver, lung, brain, genitourinary and other parts to form ulcers and abscesses. basic knowledge The proportion of sickness: 0.0052% Susceptible people: no specific population Mode of infection: digestive tract spread Complications: intestinal obstruction, abdominal distension, anal fissure, liver abscess

Etiology of amoebic bowel disease

Water pollution (40%)

The main source of infection is the population of people who continue to receive cysts in the feces, including chronic patients, recovery period and asymptomatic carriers. Because the capsule is resistant to the external environment, it can survive for 5 weeks in the feces, such as contaminated water and food, which can spread the disease. Patients in the acute phase often discharge a large number of trophozoites, but die rapidly in the external environment, so patients in the acute phase are not included in the main source of infection. Human is the main host and storage host for the tissue amoeba. Although mites, pigs, dogs, rats, etc. can naturally infect E. histolytica, the source of infection is of little significance. Oral infection is the main route of transmission. Water pollution causes endemic epidemics.

Raw food pollution (35%)

Raw and contaminated fruits and vegetables can also cause disease. Fly and cockroaches can also play a role in transmission. Male homosexuals can be infected by mouth-to-pubic contact.

Other factors (20%)

The population is generally susceptible. There is no difference in gender, and there are relatively few chances of babies and children. Malnutrition, low immunity and treatment with immunosuppressive agents have many chances of developing diseases. Although the antibody titer is high after infection in the population, it has no protective effect, so repeated infection is more common.

Popular characteristics: The distribution is spread all over the world, with high incidence in tropical and subtropical regions. The infection rate is related to health and living habits. In a few indeveloped countries, the infection rate is estimated to be 50%. In the world, the average infection rate is about 10%. In recent years, cases of acute amoebic dysentery and liver abscess in China are rare, and only some areas are still distributed.

Pathophysiology

(1) Pathogenesis: Humans ingested foods and drinking water contaminated by cysts, and the cysts that have not been killed after the stomach are advanced to the lower part of the small intestine with food and bowel movements, and are decapulated by trypsin to escape small trophozoites. , parasitic in the intestinal lumen of the colon, when the host becomes an asymptomatic carrier. If the infected insect is invasive, the small trophozoite invades the intestinal wall tissue and transforms the large trophozoite when the body's immunity declines, phagocytizing red blood cells and tissue cells, damaging the intestinal wall and forming lesions. The invasiveness of E. histolytica to the host is through a contact (contact killing) mechanism, which includes continuous processes such as adhesion, enzymatic lysis, cytotoxicity, and phagocytosis. Adhesion refers to galactose-specific adhesin, which has ligand-receptor binding to acetylglucosamine and acetylgalactosamine on the target cell membrane, and trophoblast target cells are made within a few seconds after adhesion. Lethal effect, the target cells die after 2 minutes. The adhesion of trophozoites causes a significant increase in the concentration of Ca2+ in the target cells, which is part of the cause of target cell death. The dissolved tissue contains a large amount of proteolytic enzyme, and the protease dissolves the extracellular matrix to fix the nuclear structure. Cysteine proteolytic enzymes degrade the human secretory IgA molecule to evade immunity. The amoebic trophozoites in the lysate also have enterotoxin-like activity, and the secreted components can cause diarrhea. Serum IgG can persist for several years after healing, but the titer is decreasing. The IgG and IgM antibodies of amoebic patients are only important for immunodiagnosis. But no protection. Specific cellular immunity was inhibited, and the ratio of CD4+/CD8+ in blood decreased. It was speculated that TH2 was activated in the CD2+ subpopulation, promoting IL-10 secretion, negatively regulating cellular immunity, and allowing the worm to escape host immune effector cells.

(2) Pathological anatomy: The lesion is in the colon, which is more common in the cecum, ascending colon, rectum, sigmoid colon, appendix and ileum. The typical initial lesions are small, scattered superficial erosions, which form more isolated and lighter small abscesses. After rupture, they form marginal irregularities, mucus and trophozoites. The ulcer is from the size of the needle cap to 3-4 cm, which is round or irregular, and the mucosa between the ulcers is normal. When secondary bacterial infection occurs, the mucosa is extensively congested and edematous. If the ulcer continues to deepen, the condition may destroy the submucosal layer to cause large mucosal necrosis and shedding, and if it is deeper and involves the muscular layer and the serosa layer, it may be accompanied by intestinal bleeding and intestinal perforation. Chronic stage lesions, tissue persecution and repair coexist, intestinal wall hypertrophy or occasionally scarring stenosis, intestinal polyps, meat edema.

Amoebic bowel disease prevention

For patients and those who carry the capsules, the drinking water must be boiled, do not eat lettuce, and prevent the diet from being contaminated. Prevent flies from breeding and killing flies.

Amoebic intestinal complications Complications, intestinal obstruction, abdominal distension, anal fissure, liver abscess

(1) Intestinal complications:

1, intestinal perforation: acute intestinal perforation occurs in patients with severe amebic bowel disease, this is the most serious complication of intestinal amebiasis, perforation can cause intestinal contents into the abdominal cavity due to intestinal wall lesions Localized or diffuse peritonitis, the perforation site is more common in the cecum, appendix and ascending colon. Chronic perforation first forms intestinal adhesion, and then often forms a local abscess or penetrates into nearby organs to form internal hemorrhoids.

2, intestinal bleeding: the incidence of less than 1%, can generally occur in patients with amoebic dysentery or granulomatosis, due to ulcer invasion of the intestinal wall blood vessels, a large number of bleeding per ulcer caused by the submucosal layer, invading large blood vessels, or Caused by the destruction of granuloma, a large number of bleeding is rare, but once it occurs, the condition is critical, often caused by shock, and a small amount of bleeding is caused by superficial ulcer bleeding.

3, appendicitis: because the amoebic bowel disease is better than the cecal part, so there are more opportunities involving the appendix, 6.2% ~ 40.9% of the colon amebia disease autopsy found appendicitis, domestic reports, only 0.9% involving the appendix, its Symptoms are similar to bacterial appendicitis. There are also acute and chronic manifestations. However, if there is a history of amoebic disease and there is obvious right lower quadrant tenderness, the disease should be considered.

4, amoebic tumor: the intestinal wall produces a large number of granulation tissue, forming a palpable mass, mostly in the cecum, also seen in the transverse colon, rectum and anus, often accompanied by pain, very similar to tumor, not easy to distinguish from intestinal cancer, tumor growth When it is large, it can cause intestinal obstruction.

5, intestinal stenosis: chronic patients, fibrous tissue repair of intestinal ulcers, can form scarring stenosis, and abdominal cramps, vomiting, abdominal distension and obstruction symptoms.

6, eschar disease around the anus: the disease is less common, often misdiagnosed in the clinic, when there are skin damage or anal fissure, anal canal and cryptitis, the amoebic trophozoite can directly invade the skin Internally, it causes amebic disease around the anus. Sometimes the lesion can be secondary to the treatment of sputum. The amoebic trophozoite can infect the surrounding tissues of the anus through the blood, and the brown rash of the miliary size appears. The edge is unclear, and finally ulcers or abscesses are formed. After rupture, pus and secretions are discharged, which is easily misdiagnosed as rectal anal canal cancer, basal cell carcinoma or skin tuberculosis.

(B) extraintestinal complications: amoebic trophozoites can spread from the intestine through the bloodstream a lymphatic spread of distant organs and cause various extraintestinal complications, of which liver abscess is common, followed by lung, pleura, pericardium , brain, peritoneum, stomach, gallbladder, skin, urinary system, female reproductive system, etc. can be invaded.

Symptoms of amoebic bowel disease Common symptoms Pus are chocolate color... Diarrhea toxemia is foamy, stinking, loose, cold, hot, abdominal pain, intestinal bleeding

The latency of amoebic bowel disease varies from 1 to 2 weeks to several months, although patients have long been infected with E. histolytica in the lysate, only living in commensal, when the host resistance is weakened and intestinal infections, etc. Symptoms appear clinically and are classified into the following types according to clinical manifestations:

1. Asymptomatic worms: Although the patient is infected with E. histolytica, and the amoeba is only commensal, more than 90% of the people do not develop symptoms and become carriers. Under the condition, the tissue can be invaded, causing lesions and symptoms. Therefore, from the viewpoint of controlling the source of infection and preventing the cause of the disease, the carrier should be given sufficient attention and must be treated.

2, acute atypical oeba disease: the incidence is slow, no obvious systemic symptoms, may have abdomen unknown, only loose stools, sometimes diarrhea, several times a day, but lack of typical dysentery-like feces, and similar to general enteritis The stool can be found to detect trophozoites.

3, acute typical amoebic bowel disease: the onset is often slow, starting with abdominal pain and diarrhea, the frequency of stool gradually increased, up to 10 to 15 times a day, when there are different degrees of abdominal pain and urgency, the latter represents lesions Has spread to the rectum, the stool with blood and mucus, mostly dark red or purple red, paste-like, with a stench smell, the condition can be bloody stool, or white mucus covered with a little bright red blood, the patient's systemic symptoms are generally lighter. Early body temperature and white blood cell counts can be elevated, and trophozoites can be found in feces.

4, acute fulminant amoebic bowel disease: acute onset, poor nutritional status, severe illness, significant symptoms of poisoning, high fever, chills, phlegm, abdominal pain, heavy after the emergency, stool is pus and blood, there is stench, can also be water Sample or car water-like stool, up to 20 times a day, accompanied by vomiting, collapse, varying degrees of dehydration and electrolyte imbalance, blood tests for neutrophils, easy to have intestinal bleeding or perforation, if not treated in time He died of toxemia within 1 to 2 weeks.

5, chronic prolonged amebic enteropathy: usually a continuation of acute infection, diarrhea and constipation alternately, the course of disease lasts for months or even years, unhealed, during the interval, can be healthy as usual, recurrence often improper diet, binge drinking Overeating, drinking, cold, fatigue and other incentives, daily diarrhea 3 to 5 times, stool is yellow paste, can be found trophozoites or cysts, patients often accompanied by umbilical or lower abdominal dull pain, varying degrees Anemia, weight loss, malnutrition, etc.

Amoebic examination

First, the pathogen examination:

1. Fecal examination:

(1) Live trophozoite examination method: commonly used physiological saline direct smear method to check the activity of trophozoites, pus and bloody stools of patients with acute dysentery or loose stools of amebic patients, requiring containers to be clean, fresh feces, the faster the examination, the more Well, during the cold season, pay attention to the heat preservation during transportation and inspection. Take a clean glass slide, add 1 drop of normal saline, and then take a small amount of feces with bamboo sticks, apply it in physiological saline, and cover the glass. The tablets are then placed under a microscope. The typical amoebic dysentery stool is a red mucus-like sauce with a special odor. The microscopic examination reveals more red blood cells and less white blood cells in the mucus, sometimes visible in summer. Charcot-Leyden crystals and active trophozoites are distinguished from fecal dysentery.

(2) Encapsulation examination method: The iodine liquid smear method is commonly used in clinical practice. The method is simple and convenient. Take a clean glass slide, add 1 drop of iodine solution, and then take a small amount of fecal sample with bamboo stick in the iodine solution. The slides were coated and covered with a microscope and examined under a microscope to identify the characteristics and number of nuclei.

2. Amoeba culture: There are a variety of improved artificial media, such as Rockwell's solution, eggs, serum medium, nutrient agar serum saline medium, agar protein biphasic medium, etc., but the technical operation is complicated. Certain equipment is required, and the positive rate of amoebic artificial culture in most subacute or chronic cases is not high, and it seems that it is not suitable for routine examination of amoeba diagnosis.

3. Tissue examination: Mucosal ulcers were directly observed by sigmoidoscopy or fiberoptic colonoscopy, and the biopsy or scraping smear was performed. The detection rate was the highest. It was reported that the sigmoid colon and rectal lesions accounted for about 2/ of patients with symptoms. 3, therefore, all suspected patients allowed by the situation should strive for colonoscopy, scraping smear or biopsy, trophozoites must be on the edge of the ulcer, after the clamp is appropriate to local bleeding. In addition to the attentional features of the puncture fluid examination, it should be taken from the wall of the abscess, which is easier to manage.

Second, immunodiagnosis:

In recent years, a variety of serological diagnostic methods have been reported at home and abroad, including indirect hemagglutination (IHA), indirect fluorescent antibody (IFAT) and enzyme-linked immunosorbent assay (ELISA), but the sensitivity is different for each case. IHA is more sensitive, with a positive rate of 98% for intestinal amebiasis, 95% for intestinal amebiasis, and only 10% to 40% for asymptomatic carriers. IFA sensitivity Slightly inferior to IHA, EALSA has strong sensitivity, high specificity, and promising future. The complement fixation test also has a trapping significance for the diagnosis of exo amoeba, and its positive rate can reach more than 80%. Others such as gelatin dispersion precipitin test, skin Internal testing has the value of assisted diagnosis. In recent years, it has been reported that the application of sensitive immunological techniques to detect amoeba-specific antigens in feces and pus is successful, especially the application of monoclonal antibodies against amebic murmur tumors. A reliable, sensitive and anti-interference tracer for the detection of pathogens in host excreta for immunological techniques,

(D) Diagnostic treatment: If clinically highly suspected and can not be diagnosed by the above-mentioned examination, a sufficient amount of vomiting root injection or oral administration of Anqiping and metronidazole may be given. If the effect is obvious, a preliminary diagnosis may be made.

Diagnosis and diagnosis of amoebic bowel disease

In the diagnosis of amebiasis, in addition to the patient's complaint, medical history and clinical manifestations as the basis for diagnosis, it is important to diagnose the pathogen, and the amebic pathogen is the only reliable diagnosis basis. Usually, people with large trophozoites are found to be present in the disease, and small trophozoites or cysts are found only as infected people.

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