Colon Amoeba

Introduction to colonic amoeba Colonic amebic disease (amoebacoli) is an acute or chronic inflammatory disease caused by the invasion of the lytic amoeba into the intestinal wall of the colon. The main lesion is the colon, which occurs in the cecum, followed by the ascending colon, rectum, sigmoid colon, and appendix. The intestine of the ileum or other parts. In severe cases, the large intestine and the lower part of the small intestine can be affected. 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. basic knowledge The proportion of illness: more common in rural areas or polluted areas, the overall incidence rate is about 0.03% - 0.05% Susceptible people: no special people Mode of transmission: oral transmission Complications: peritonitis abscess bladder spasm intestinal fistula edema fecal fistula abdominal pain diarrhea intestinal obstruction intussusception colon cancer rectal cancer gastrointestinal bleeding

Colonic amoebic cause

(1) Causes of the disease

(1) Source of infection

The main source of infection is those who continue to receive cysts in the feces, including chronic patients, recovery periods, 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.

(2) Route of infection

It is generally believed that amoeba cysts contaminate things and water, and oral infection is the main route of transmission. Water pollution causes endemic epidemics. 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.

(3) Susceptibility to the population

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.

(4) Popular features

It is distributed all over the world and is highly prevalent in tropical and subtropical areas. The infection rate is related to health conditions 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.

(two) pathogenesis

In the tissue, the amoeba trophozoite invades the intestinal wall and causes amebiasis. The common site is in the cecum, followed by the rectum, sigmoid colon and appendix. The transverse colon and descending colon are rare. Sometimes it can involve all or part of the large intestine, under the microscope. The main lesion is tissue necrosis, visible lymphocytes and a small amount of neutrophil infiltration, if the bacterial infection is serious, it may be acute diffuse inflammatory changes, a large number of inflammatory cell infiltration, mucosal edema, necrosis, multiple Ami visible lesions Balinese trophozoites, mostly gathered at the edge of the ulcer.

1. In the acute phase, the intestinal mucosa is destroyed, resulting in erosion and superficial ulcers. If the lesion continues to progress, involving the submucosal layer, a typical bottle-like ulcer with a large mouth and small bottom is formed. The cavity is filled with brown-yellow necrotic material and contains dissolved The cell debris, mucus and trophozoites produce clinical dysentery-like stools when discharged from the contents. Unlike the bacterial dysentery lesions, the mucosa between the ulcers is mostly intact. Because the intestinal wall tissue is loose, the amoeba continues to The submucosal layer progresses, and the protozoa expands on both sides of the long axis of the intestine, so that a large amount of tissue is dissolved to form a honeycomb-like region in which many fistulas communicate with each other. There are many inflammatory reactions around the lesion, and generally only lymphocytes and a little plasma cells are infiltrated. Secondary bacterial infection can have a large number of neutrophil infiltration, capillary lesions are prone to capillary thrombosis, blepharospasm and necrosis, due to the destruction of small blood vessels, the discharge contains more red blood cells, severe cases of lesions can be Deep, even through the serosa layer, due to the progressive development of the lesion, the serosa layer is easy to adhere to adjacent tissues, so there is not much acute intestinal perforation , Amoebic generally deeper ulcers, vascular corrosive, can cause a large number of intestinal bleeding, lesions in the healing process, can be seen tissue reaction subsided, the disappearance of lymphocyte infiltration substituting connective tissue.

2. Chronic phase This period is characterized by intestinal mucosal epithelial hyperplasia, granulation tissue at the bottom of the ulcer, fibrous tissue hyperplasia around the ulcer, tissue destruction and healing often occur simultaneously, the intestinal wall is thickened, the intestinal lumen is narrow, and the connective tissue is a tumor. Proliferation, become amoebic tumor, more common in the anus, anorectal junction, transverse colon and cecum, amoebic tumor sometimes large, hard, difficult to distinguish with colorectal cancer.

Colonic amoeba prevention

Pay attention to food hygiene. Patients with chronic diarrhea should be promptly examined, such as patients with intestinal amebiasis or those with cysts who must be thoroughly treated and isolated from the intestine. For the catering industry, personnel should be temporarily transferred from work. It is also important to vigorously eliminate flies and cockroaches and strengthen manure management.

Colonic amoebic complications Complications Peritonitis abscess Bladder sputum edema edema fecal abdominal pain diarrhea intestinal obstruction intussusception colon cancer rectal cancer gastrointestinal bleeding

Amoebic perforation

The incidence rate is 1% to 4%. The intestinal perforation rate of patients with amoeba autopsy is 3% to 20%. Acute perforation occurs mostly in the cecum, appendix, ascending colon, followed by the rectum and sigmoid junction, which occurs mostly in acute Patients with symptoms of amoebic dysentery, diffuse peritonitis after perforation, the condition is dangerous, should be treated early.

Chronic perforation is caused by adhesion first, and the infection is limited after perforation to form a local abscess, or penetrate into nearby organs to form internal hemorrhoids, such as rectal bladder spasm, colonic jejunum fistula, and the like.

2. Amoebic appendicitis and appendix abscess

Because amoebic bowel disease occurs in the cecum, it has more chances of involving the appendix. Among the autopsy cases of colonic amebiasis, 4.0% to 6.2% have amoebic appendicitis, and some form abscesses or perforations. Miba appendicitis is rare, and its symptoms are similar to bacterial appendicitis. It is often found in surgery that the lesion is not limited to the appendix. The intestinal wall of the cecum is thickened and edematous. In this case, it is difficult to treat the appendix stump. It is also easy to form the appendix stump.

Chronic amoebic appendicitis is more common, manifested as recurrent episodes of right lower abdomen and lower right abdomen, or persistent discomfort in the right axilla. There may be an acute attack with a septic infection.

For patients with suspected amoebic appendicitis, anti-amebic drugs should be given first, and then surgery. If surgical treatment is used, the lesions can spread, causing feces and even death.

3. Amoebic granuloma

Lesions are more common in the cecum, followed by the sigmoid colon, descending colon and rectum, 5% to 10% are multiple, early can be asymptomatic, after the disease develops, there are localized abdominal pain, diarrhea and fever, hyperplastic granuloma to the intestine Strangulation, can cause intestinal obstruction, intussusception, massive hemorrhage, perforation of the intestinal wall or through the abdominal wall, external hemorrhoids, etc., in addition to local tenderness, percussion can be compared with a hard mass, X-ray barium enema examination can be seen filling defects And the intestinal lumen is narrowed, the amoebic abscess and granuloma of the intestinal wall enter the intestine, forming a jagged shadow. The sigmoid colonoscopy shows mucosal thickening, the tumor is grape-like into the intestine, and there are often scattered granulation tissue nearby. And ulcers, specimen biopsy taken from the bottom of the ulcer, ampicillary trophoblast detection rate is higher, amoebic granuloma is easily misdiagnosed as intestinal tumor, after pathological examination found that amoeba can confirm the diagnosis, Amoebic disease after drug treatment, scarred scarring or internal and external hemorrhoids should be treated surgically.

4. Colon or rectal cancer

Chronic amoebic bowel disease may be associated with colon cancer and rectal cancer. Some people think that chronic inflammation may be caused by intestinal irritation, and inflammatory polyps are also beneficial for cancer.

5. Gastrointestinal bleeding

The amoeba protozoa spreads on both sides of the long axis of the intestine, causing a large amount of tissue to dissolve in the intestinal wall. The lesion can reach the serosa layer deeply. When the blood vessels are corroded, a large amount of intestinal bleeding can be caused. The patient can show an increase in the number of bowel movements and blood. Severe fatigue, pulse rate, blood pressure drop.

Symptoms of colonic amoeba Common symptoms Abdominal discomfort, thin stools, diarrhea, urgency, heavy constipation, high heat, intestinal bleeding, fatigue, dysentery, intestinal perforation

Colonic amebiasis lacks specific clinical manifestations, generally slow onset, mild symptoms of poisoning, recurrent episodes, intestinal symptoms or diarrhea-like diarrhea.

Acute amebic enteropathy

(1) Asymptomatic type: Most amoebic patients have this type of cyst. The cyst can be found in the feces, but it is asymptomatic, and can even invade the intestinal mucosa and cause lesions.

(2) Ordinary type: the incidence is slower, the general symptoms of poisoning are lighter, diarrhea is 1 to 4 times a day, the stool is foul-smelling, showing a loose stool or dark red jam, with mucus and pus and blood, and those with severe illness have dozens of stools every day. And there is a sense of urgency, often accompanied by flatulence and abdominal cramps, physical examination can be found in this type of patients with hepatomegaly and abdominal tenderness.

(3) fulminant: seen in the violent epidemics caused by sexual transmission of water, this type is mostly caused by weak or immune function, sudden onset, high fever up to 40 ~ 41 ° C, obvious symptoms of poisoning, extreme exhaustion, abdominal pain, a large number of solutions Bloody loose stools can be accompanied by a sense of urgency, easy to have intestinal bleeding, intestinal perforation, and a large number of amoebic trophozoites can be seen in stool microscopy.

2. Chronic amoebic bowel disease :

This type is often caused by the incomplete continuation of common type of treatment. Patients may have diarrhea and constipation alternating with abdominal discomfort. The symptoms may be intermittent or intermittent. The interval may be several weeks, months or years, fatigue, cold and improper diet. Can be induced, repeated attacks may cause ulcerative colitis.

Repeated bowel disorder or diarrhea-like diarrhea, the cause is not clear, or the sulfa drug, antibiotic treatment should be considered when the disease is considered, the pathogen examination is an important diagnostic basis, the amoeba pathogen can be diagnosed in the stool, usually In order to find the large trophozoites as the current patients, and to find small trophozoites or cysts only as infected.

Examination of colonic amoeba

Fecal examination

(1) Live trophozoite examination method: the trophozoite is used to check the active trophozoite by the direct smear method of normal saline. The typical amoebic dysentery stool is a red mucus-like sauce, which has a special odor and is a pus and bloody stool for patients with acute dysentery. Microscopic examination of the stool of Miba patients shows that the mucus contains more red blood cells and fewer white blood cells, and sometimes visible active trophozoites. These characteristics can be distinguished from the stool of bacterial dysentery. When collecting specimens, The container is required to be clean and the fecal sample is fresh. The quicker the inspection, the better. In the cold season, pay attention to the insulation during transportation and inspection.

(2) Encapsulation examination method: The iodine liquid smear method is commonly used in clinical practice. This 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. The solution was flaky and covered with a cover glass and then examined under a microscope to identify the characteristics and number of nuclei.

2. Amoebic culture

There are a variety of improved artificial media, commonly used such as Lock's solution, egg white, serum medium, nutrient agar serum saline medium, agar protein biphasic medium, etc., but the technical operation is complex, requires certain equipment, and The positive rate of Miba artificial culture in most subacute or chronic cases is not high, and it is generally not suitable for routine examination of amoeba diagnosis.

3. 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 sensitivity to various cases Different, IHA is more sensitive, the positive rate of intestinal amebiasis is 98%, the positive rate of parenteral amebiasis is 95%, and the asymptomatic worm is only 10% to 40%, IFAT sensitive. Less than IHA, EALSA has strong sensitivity, high specificity, and promising future. Others such as gelatin-dispersed precipitin test and intradermal test have the value of auxiliary diagnosis. In recent years, sensitive immunological techniques have been reported. The successful detection of amoeba-specific antigens in feces and pus, especially the application of anti-amebic monoclonal antibodies, provides a reliable, sensitive and anti-interference method for immunological detection of pathogenic substances in host excreta.

4. Blood test :

The total number and classification of peripheral white blood cells are normal. When there is a violent or secondary bacterial infection, the total number of white blood cells and the proportion of neutrophils can be increased. Chronic patients may have mild anemia.

5. Colonoscopy

In most cases, there are scattered ulcers of different sizes. The center has exudation, the edges are neat, and there is sometimes a circle of blush around the ulcer. The mucosa is normal between the ulcers. The smear of the edge of the ulcer and the biopsy can be seen through the sigmoidoscopy or electronic colonoscopy. Direct observation of mucosal ulcers, and tissue biopsy or scraping smear, the highest detection rate, reported that the rectum, sigmoid colon lesions accounted for about 2 / 3 of the symptoms of patients, therefore, all suspected patients should be allowed Try to make a colonoscopy, scraping smear or biopsy. The trophozoites must be taken at the edge of the ulcer. It is advisable to have a slight local bleeding after clamping. The puncture fluid should be taken from the wall of the abscess. It is easier to find trophozoites.

6. Barium enema angiography

It can be seen that the filling defect and the intestinal lumen are narrow, and the amoebic abscess and granuloma of the intestinal wall are swollen into the intestine, forming a jagged shadow.

Diagnosis and identification of colonic amoeba

Differential diagnosis

1. Colonic schistosomiasis has a history of contact with schistosomiasis, slow onset, intermittent diarrhea, hepatosplenomegaly, marked increase in eosinophils in the blood, fecal or intestinal mucosal biopsy can find eggs, positive stool incubation test, Serological tests detect specific antibodies to the eggs.

2. Bacterial dysentery occurs in summer and autumn, abdominal pain, diarrhea and pus and bloody stools. Patients in the acute phase have more fever, peripheral blood leukocytes and neutrophils, and often appear before the gastrointestinal symptoms, feces in the feces The quality is small, it is reddish and sticky, and has no odor. The frequency of stool is more than that of amoebic bowel disease. It is heavier and heavier after urgency. Symptoms of toxemia can occur. A large number of pus cells and red blood cells can be seen under the microscope, and there are macrophages. Cells, feces culture can detect dysentery bacilli.

3. Intestinal tuberculosis Most patients have primary tuberculosis lesions, there are symptoms of tuberculosis poisoning in the afternoon, such as low fever, night sweats, weight loss, stools are mostly yellow loose stools, with mucus and less pus, diarrhea and constipation often appear alternately, OT test Positive, colonoscopy and X-ray barium enema examination are helpful for diagnosis.

4. Patients with colon cancer are often older. Cancer patients with left colon are often have bowel habit changes, stools become thinner, contain blood, and have progressive bloating. Cancers in the right colon are often showing progressive anemia. Irregular fever, irregular bowel movements, stools are mostly mushy, fecal occult blood positive, late sputum and abdominal mass, barium enema and colonoscopy help to identify.

5. Ulcerative colitis The clinical manifestations of this disease are similar to those of chronic amebic enteropathy, sometimes difficult to identify, but multiple pathogen tests, serum amoebic specific antibody tests, colonoscopy or diagnostic treatment can help identify diagnosis.

The material in this site is intended to be of general informational use and is not intended to constitute medical advice, probable diagnosis, or recommended treatments.