What Is Amebic Dysentery?

(A) trophic body. Large trophozoites are 20 ^ -40m in size. Relying on pseudopods to move in a certain direction, seen in patients with acute stage of stool or in the intestinal wall tissue of the throat group) red blood cells, it is also known as tissue-type trophozoites. Small trophozoites are 6-20m in size, have few pseudopods, feed on intestinal fluid, bacteria, and fungi of the host, and do not swallow red blood cells. Also known as intestinal cavity trophozoite. When the host's health status declines, it secretes histolytic enzymes, which, together with its own movement, invades the inferior layer of the intestinal cat and becomes a large trophozoite. When the conditions of the intestinal cavity change are not conducive to its activities, it becomes the pre-labor period, and then it becomes the me. The trophozoite has no significance in transmission.

Chronic amoebic dysentery

Amoebic dysentery is an intestinal infectious disease caused by amoeba protozoa. The lesions were mainly in the cecum and ascending colon. Clinically, it is characterized by abdominal pain, diarrhea, and dark red jam-like stools, which easily become chronic, and complications such as liver abscess can occur.

Chronic Amoebic Disease

Dysentery amoeba (amoeba histolytica) is the only pathogenic amoeba in the human body. There are three forms of trophozoites, small trophozoites and cysts in human tissues and feces. The trophozoites are weak in vitro. Easy to die. Baoxuan has a strong resistance to the outside world.

(B) Baopen. It is more common in the faeces of patients with cryptic infection and chronic patients. It is round, 5-20m in size, and mature cysts have 4 nuclei, which are infectious types of amoeba histolytic and infectious. Baoban has a strong resistance to the outside world. Survival in feces for at least 2 weeks. 5 weeks in water, 2 months in refrigerator. Strong resistance to chemical disinfectants, can withstand 0.2% potassium permanganate for several days, the scratch concentration of ordinary drinking water disinfection has no killing effect on it. It is sensitive to heat (50 ° C) and drying. ^[1]

Epidemiology of chronic amoebic dysentery

Chronic amoebic dysentery (a) source of infection

Mainly for chronic and convalescent patients with fecal cysts and carriers. Due to the weak resistance of trophozoites, acute patients do not have the role of source of infection. Pigs can also be used as a source of infection in China.

Chronic amoebic dysentery (two) transmission routes

Oral transmission of miba cysts is the main route of transmission. Encapsulated water pollution is the main cause of regional outbreaks and high infection rates; followed by contaminated hands, food or utensils; flies, cockroaches and other portable cyst-borne diseases; and the transmission of male homosexual sexuality in Europe The country is important.

Chronic amoebic dysentery (3) susceptible population

The crowd is generally susceptible. Both men and women suffer. Infants and children are relatively less likely to develop the disease. Those who are malnourished, immunocompromised and receive immune resistance treatment have a higher chance of developing the disease. Although the antibody titer is high after infection, it is not protective, so repeated infection is more common.

Epidemic characteristics of chronic amoebic dysentery (4)

Distributed throughout the world, with tropical and subtropical areas as the high incidence areas, the infection rate is related to health conditions and living habits.

Pathogenesis and pathology of chronic amoebic dysentery

After the amoeba cyst enters the digestive tract, it is digested by trypsin and other digestive fluids in the lower part of the small intestine. The body moves down with the feces, and becomes cystic and excreted below the sigmoid colon without causing disease. Under suitable conditions, such as reduced gastrointestinal function of the body; certain bacteria provide free gene-like factors to enhance nourishing virulence; trophozoites release lysosomal enzymes, hyaluronidases, proteolytic enzymes, etc. and rely on their pseudopods Mechanical activities invade the intestinal mucosa, destroy tissues to form small abscesses and latent (beaker-shaped) ulcers, cause extensive tissue damage to reach the muscular layer, and large trophozoites are discharged from the intestine with necrotic substances and blood, showing dysentery-like symptoms. In chronic lesions, the epithelium of the mucosa proliferates, granulation tissue forms at the bottom of the ulcer, and fibrous tissue hyperplasia and hypertrophy are seen around the ulcer, forming intestinal amoebiasis. The trophozoite can also enter the intestinal vein, portal vein or lymphatic vessels into the liver, causing intrahepatic venous embolism and surrounding inflammation, hepatic parenchymal necrosis, and the formation of intrahepatic abscesses, mostly in the right lobe. And can flow into the lungs, brain, etc. in the form of emboli, forming a migrating abscess. Intestinal trophozoites can also spread directly to surrounding tissues, forming various lesions such as rectal vaginal fistula or skin and mucosal ulcers. Individual cases can cause intestinal bleeding, intestinal perforation, or complications of peritonitis and appendicitis.

Under the microscope, tissue necrosis is the main lesion, and lymphocytes and a small amount of neutrophil infiltration. If the bacterial infection is serious, it can show acute diffuse inflammation changes, more infiltration of inflammatory cells and changes in edema and necrosis. Multiple amoeba trophozoites can be seen at the lesion, and most of them accumulate at the edge of the ulcer. ^[2]

Clinical manifestations of chronic amoebic dysentery

The incubation period varies in length, ranging from a few days to a few weeks, mostly over 3 weeks.

1. Asymptomatic: After infection with amoeba, the cysts are excreted in the stool, but there are no clinical symptoms. Among them, 80% were infected with non-pathogenic strains, and the protozoa grew in the intestinal cavity without antibody formation, and were in a carrier state. A few patients were infected with pathogenic worm strains, but the intestinal lesions were limited and superficial, with antibody formation, and were insidious. Infection can be transformed into amoebic dysentery or liver abscess under the influence of certain factors.

2, common type: symptoms are not specific. Typical manifestations are amoebic dysentery, with slow onset, generally no fever, intermittent diarrhea, abdominal distension, mild to moderate abdominal cramps during onset, and stools several to 10 times a day. Typical amoebic dysentery has a moderate stool volume, more feces, a foul odor, and a bloody mucus-like jam. Intermittent stool is basically normal. The signs are only mild tenderness in the cecum and ascending colon, and occasionally hepatomegaly with tenderness. Symptoms can last months to years.

3, violent hair: serious condition. Often due to severe infection, poor body resistance or combined bacterial infection. Sudden onset of more than half, high fever, bowel movements more than a dozen times a day, severe intestinal colic for a long time before defecation, accompanied by heavy rush, heavy feces, mucus bloody or bloody water, and vomiting, dehydration, Prolapse occurs quickly, and intestinal bleeding and intestinal perforation may occur in the later stage. Physical examination shows obvious abdominal distension, diffuse abdominal tenderness, sometimes quite significant, and even suspected peritonitis, and liver enlargement is common. If not rescued in time, they can die within 1 to 2 weeks. ^[3]

Complications of chronic amoebic dysentery

Intestinal complications of chronic amoebic dysentery

intestinal bleeding: extensive intestinal lesions, or invasion of blood vessels in the intestinal wall can cause blood in the stool. Major bleeding caused by corrosion of large blood vessels is rare, and the condition is critical, often leading to shock.

Intestinal perforation: Severe deep and serous amebic ulcers can cause perforation, which are more common in the cecum, appendix, and ascending colon, and often have multiple perforations. Most of them occur slowly, without severe abdominal pain, and the specific time of perforation is difficult to determine. The patient had progressive bloating, vomiting, and dehydration, and his condition deteriorated rapidly. Bowel sounds disappeared with local peritoneal irritation. On the plain film of the abdomen, there is free gas under the diaphragm. When there is intestinal adhesion, a local abscess or internal fistula is formed.

Appendicitis: Amoebic appendicitis is similar to ordinary appendicitis. Easy to form abscesses. A history of chronic diarrhea or amoebic bowel disease, and amoeba found in stool can help differentiate.

Non-dysentery colonic lesions: caused by proliferative lesions, including amoebic tumors, intestinal amoebic granulomas, and fibrous stenosis. Amoebiaoma is an inflammatory pseudotumor of the large intestine wall. It has the most changes in abdominal pain and bowel habits. Some are accompanied by intermittent dysentery, which can induce intussusception and intestinal obstruction. The main signs are that the right popliteal fossa touches the movable, tender, Smooth goose oval or bowel-like masses, with space-occupying lesions on the X-ray, have a good effect on anti-amoeba treatment.

Parenteral complications of chronic amoebic dysentery

Pulmonary and pleural amebiasis: The pathogen can come from the liver or intestine, most of which are secondary to liver amebiasis. Through the direct spread or lymphatic pathway, individual circulation to the lungs is common on the right side. Liver abscesses are complicated by pleura and pulmonary amoebiasis, accounting for 10% to 20%. When bronchohepatic fistula is complicated, a large amount of brown pus can be coughed, which is equivalent to drainage, and the condition can be improved rapidly. There is a large amount of pleural exudate during pleurisy, and the pleural fluid is chocolate-colored to help diagnose.

Pericardial amoebiasis: Mostly caused by left amebia liver abscess penetrating into the pericardium, it is the most dangerous complication of this disease. It has the symptoms and signs of pericarditis, such as anterior cardiac pain, shortness of breath, palpitations, pericardial friction sounds, and various manifestations of liver abscess. Sometimes puncture of liver abscess causes acute pericardial tamponade, resulting in shock and sudden death.

cerebral amoebiasis: rare. Most are secondary to intestinal, liver, and pulmonary amoebiasis.

Amoeba peritonitis: It can be caused by liver abscess or intestinal ulcer puncture or direct spread. When amoebic liver abscess is complicated by peritonitis, the chance of jaundice is more than that of simple liver abscess, which is easy to be misdiagnosed as cholecystitis.

Amebiasis of the urinary tract: symptoms include low back pain, urine-like rice soup and so on. Urinary pain, urgency, and turbid urine were bloody when the bladder was involved. Urine tests showed protein, red blood cells, white blood cells, and amoeba trophozoites.

Reproductive system amoebiasis: such as amoebic cervicitis and vaginitis, there are many pain with bloody or purulent secretions, which can form fistulas. The cervix is significantly damaged and deformed and ulcers are formed, which is easy to bleed on palpation. The vaginal mucosa is rough, with granular protrusions, granulation tissue or ulcers formed, and it is easy to be mistaken for cancer. Cervical and vaginal discharge smears or biopsies show trophozoites.

skin amoebiasis: rare in even severe endemic areas. It is common in perineal and perianal skin, and is caused by chronic dysentery infection or visceral amoebic puncture, or local infection after surgical drainage, forming ulcers and granulomas.

Diagnosis of chronic amoebic dysentery

1. Epidemiology: There are many cases in autumn, and most of them are sporadic. Patients often have unclean eating habits or a history of close contact with chronic patients.

2. Clinical characteristics: The disease usually starts slowly, has a long course, and has a tendency to recur.

Acute amoebic dysentery:

Typical: mild systemic symptoms, no fever or low fever, diarrhea less than 10 times a day, moderate amount of feces, often with mucus and blood, typically with a tan-colored jam-like appearance and a foul odor. Have tenderness in the right lower quadrant. After anxiety, heavier or lighter.

Mild: Only mild abdominal pain and loose stools.

Fulfilled hair: Rushing fever, obvious toxemia. The stools are more than 20 times a day, mostly bloody or gravy-like, with severe aftermath and obvious abdominal tenderness, and are prone to intestinal bleeding or bowel perforation.

Chronic amoebic dysentery: the symptoms of dysentery become heavier, lighter and heavier, or abdominal pain, bloating, alternating constipation and diarrhea that last for months or years. The chronic diseases include malnutrition and anemia.

3.Laboratory inspection

Stool microscopy: clusters of red blood cells and a few white blood cells can be seen. Finding a histolytic amoeba trophozoite can confirm the diagnosis. The detection of amoebic cysts in the chronic phase is helpful for diagnosis.

Amoeba culture or serological examination: If possible, amoeba culture or serological examination can be done, such as: complement binding test, indirect hemagglutination, indirect immunofluorescence, ELISA, etc.

Colonoscopy: There are scattered buttonhole-like ulcers on the normal mucosa, and the contents are scraped to check the dissolved amoeba trophozoite. The positive rate is high. In addition to ulcers in chronic patients, thickening of the mucosa and formation of polyps can be seen.

Identification of chronic amoebic dysentery

The main symptoms of chronic diarrhea should be distinguished from invasive intestinal bacterial infections such as bacterial dysentery, schistosomiasis, pouchiasis, trichinellosis, and chronic non-specific ulcerative colitis. Attention should be paid to the identification of intestinal tuberculosis, colon cancer and clonal disease.

1. Schistosomiasis: history of contact with epidemic water, slow onset, intermittent diarrhea, hepatosplenomegaly, increased blood eosinophils, worm eggs or intestinal mucosal biopsy found worm eggs, positive stool incubation, worm eggs found in blood Soluble antigens can be diagnosed.

2. Intestinal tuberculosis: Most of the primary tuberculosis lesions are present. Patients have wasting fever, night sweats, and nutritional disorders. The stool is mostly yellow and congee-like, with mucus and less pus and blood, and diarrhea and constipation alternate. Gastrointestinal X-rays can help diagnose.

3. Colon cancer: Patients are often older. Every person with colon cancer on the left has a bowel habit change, the stool becomes thinner and contains blood, and there is progressive abdominal distension. The right colon cancer often manifests as progressive anemia, weight loss, irregular fever, etc., has a sense of poor bowel movements, stools are mostly mushy, except for positive occult blood tests, occasionally containing a small amount of mucus, there is rarely blood. Most of the late can touch the abdominal mass. Barium enema and fiber enteroscopy can help distinguish.

4. Chronic non-specific ulcerative colitis: It is difficult to distinguish clinically from chronic amoebic bowel disease, multiple pathogen tests are negative, serum amoeba antibodies are negative, and the diagnosis of the disease is supported when the specific treatment fails.

5. Sudden onset, symptoms of systemic poisoning such as chills, high fever, and malaise. The number of pus and bloody stools is large and the amount is small, no fishy odor. Fecal examination revealed a large number of pus cells and a small number of macrophages. ^[4]

Treatment of chronic amoebic dysentery

1. General treatment: Patients in the acute stage should rest in bed, be isolated from the intestines, and be given a liquid or less residue diet according to the condition. Chronic patients should avoid irritating food, pay attention to maintaining nutrition, and correct a large number of diarrhea patients with water and electrolyte disorders. In the event of shock, blood transfusions were performed in time, and vasoactive drugs were added.

2. Anti-pathogen treatment: non-pathogenic amoeba infection and serum antibody-negative patients do not need treatment. All patients with pathogenic strains should be treated, even if they are asymptomatic.

Most anti-amoeba drugs cannot kill pathogens in all parts. Those who have a killing effect on ameba that invade the tissue are said to kill ameba drugs in the tissue, such as tugenin, dehydrotoxane, chloroquine, tetracycline, etc .; those who have an effect on ameba in the intestinal cavity are called intestines Anti-amoeba drugs, such as diiodoquinoline, ambipin, paromomycin, and amide. Nitroimidazoles represented by metronidazole have effects on intestinal and external lesions. For best results, medication can be used in combination.

3. Treatment of complications: Add appropriate antibiotics when there is mixed bacterial infection, timely blood transfusion when intestinal bleeding, timely surgical treatment when intestinal perforation, and apply metronidazole and broad-spectrum antibiotics.

4. Cure criteria:

Symptoms disappeared, stool characteristics returned to normal, and the number of daily stools did not exceed 2 times.

After discontinuation of the drug, fecal microscopy and amoeba culture were performed once every other day and negative for two consecutive times. Chronic patients' fecal concentration method was used to find at least two amoeba cysts in the dissolved tissue; sigmoidoscopy showed normal mucosa.

Follow-up once a month after discharge (including symptoms, signs, stool examination, and amoeba culture), a total of 6 times, each of which is negative. ^[5]

Prevention and prognosis of chronic amoebic dysentery

The prevention of this disease is basically the same as that of bacterial dysentery. Thoroughly treat patients and carriers. Vigorously eliminate flies and cockroaches. Pay attention to drinking water and diet hygiene, strengthen the management of feces, and prevent feces from contaminating food and water.

The prognosis is generally good. It is related to the duration of the disease, whether there are complications, whether it is diagnosed early and treated in a timely and effective manner. The uncomplicated amoebic liver abscess has a mortality rate of less than 1% in early diagnosis and treatment. In patients with fulminant style, patients with brain migratory abscess, intestinal perforation, and diffuse peritonitis have a poor prognosis. ^[6]