Amoebiasis - Causes, Symptoms, Diagnosis And Treatment

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Amoebiasis - Causes, Symptoms, Diagnosis And Treatment
Amoebiasis - Causes, Symptoms, Diagnosis And Treatment

Video: Amoebiasis - Causes, Symptoms, Diagnosis And Treatment

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Video: Amebiasis (Amoebic Dysentery) | Entamoeba histolytica, Pathogenesis, Signs & Symptoms, Treatment 2023, February

Amoebiasis is a protozoal infectious disease characterized by the occurrence of ulcerative lesions in the colon. Amoebiasis, the symptoms of which consist in particular in the formation of abscesses in various organs, is prone to a protracted and chronic form of the course. Note that the disease is endemic, accordingly, it is characterized by concentration in a specific area, spreading occurs in those areas that are characterized by a hot climate.

The content of the article:

  • 1 Amoebiasis
  • 2 Epidemiology
  • 3 Prevalence
  • 4 Types
  • 5 Dysentery amoeba
  • 6 Causes of infection with amebiasis
  • 7 Symptoms of amebiasis
  • 8 Intestinal amebiasis in children: symptoms
  • 9 Diagnostics

    9.1 Life cycle of dysentery amoeba

  • 10 Complications of amebiasis
  • 11 Treatment of amebiasis
  • 12 Forecast and prevention
  • 13 Prevention of amebiasis



Amoebiasis is a protozoal infection with a fecal-oral transmission mechanism, characterized by ulcerative lesions of the large intestine and extraintestinal lesions in the form of abscesses in other organs and tissues, as well as a tendency to protracted and chronic course. Only people get sick. The causative agents are the simplest parasites - amoeba. This is one of the diseases of "dirty hands".

Back in 1875, the causative agents of amoebiasis were first discovered, and in 1891 this disease was isolated into an independent nosological form, called "Amebic dysentery". The term "amebiasis" is used from 1906 to the present day.


Amebiasis is an anthroponosis of protozoal etiology. The source of infection with amoebiasis is a person who excretes E. histolytica cysts with feces. The transmission mechanism is fecal-oral. The intensity of cyst excretion per day ranges from 3 thousand to 3888 thousand per 1 g of feces and averages 580 thousand. One chronic clinically healthy carrier can excrete tens of millions of cysts daily with feces.

Vegetative forms of histolytic amoeba remain viable in feces for no more than 15 - 30 minutes. Cystic forms have significant resistance in the external environment, their survival depends on temperature and relative humidity. In feces at a temperature of + 10 … + 20 ° С they remain alive from 3 to 30 days, and at -1 … -21 ° С - from 17 to 111 days.

On the skin of the hands, cysts remain viable for up to 5 minutes. In the subungual spaces - 46 - 60 minutes, in the intestines of house flies - up to 48 hours, in milk and dairy products at room temperature - up to 15 days. At a temperature of + 2 … + 6 ° C and a relative air humidity of 80 - 100%, E. histolytica cysts survive on objects made of glass, metals, polymers and other materials for 11-25 days, and at a temperature of + 18 … + 27 ° C and relative humidity 40 - 65% - no more than 7 hours.

Considering the significant intensity of cysts secretion in amoebiasis, long periods of their survival in environmental objects and foodstuffs, the factors of transmission of amoebiasis can be soil, wastewater, water of open reservoirs, household and industrial items, fruits, vegetables, food products, hands, contaminated cysts of a dysentery amoeba.



The natural susceptibility of people to amoebiasis is high, including reinfection. About 480 million people in the world are carriers of E. histolytica, of which 48 million (10%) develop intestinal amoebiasis and its extraintestinal forms, and 40,000-100,000 patients die (JA Walsh). The disease is widespread with a predominance of morbidity in developing countries of the subtropical and tropical zones, mainly in settlements with a low level of communal and sanitary facilities.

In countries with a temperate climate, sporadic morbidity is characteristic of amebiasis, although water outbreaks of amebiasis, outbreaks in closed-type institutions (among prisoners of strict regime colonies) have been described. The worsening of the epidemiological situation for amebiasis in countries with a temperate climate is facilitated by the importation of invasions from endemic zones (migrants, tourists, refugees, businessmen and other groups of the population).

The number of asymptomatic excretors of histolic amoeba is many times greater than the number of patients and in some countries reaches 40%. Mostly people over 5 years old get sick.

In Ukraine, dysentery amoebae parasitize 3.4% of HIV-negative surveyed adults and 1.7% of children. The infection rate of E. histolytica in HIV-positive patients averaged 8%, including drug addicts - 5%, persons infected with HIV sexually - 9%, patients with primary manifestations of HIV infection - 8%, with clinical AIDS - 11% (from the number of patients in the corresponding group). The incidence is characterized by spring-summer seasonality.



Classification of amebiasis according to the WHO recommendation, 1970:

  • Intestinal amebiasis;
  • Extraintestinal amebiasis;
  • Cutaneous amoebiasis.

In domestic practice, extraintestinal and cutaneous amebiasis is regarded as a complication of the intestinal form.

Intestinal amebiasis can occur in the form of acute, chronic recurrent and chronic continuous variants in various forms of severity.

The causative agent is an amoeba. The life cycle consists of two stages - vegetative and dormant stages (cysts), replacing each other depending on the environmental conditions. There are two forms of amoeba existence - tissue and luminal. The main role in human infection and the spread of amoebiasis belongs to amoeba cysts. Often, amebiasis is recorded as a mixed infection (together with other intestinal infectious diseases).

The source of infection is a cyst carrier or a patient with a chronic form in remission. Patients with an acute form or patients with chronic amoebiasis during the period of relapse release into the external environment unstable vegetative forms of the pathogen that do not pose an epidemic danger.

The carriage of luminal forms and cysts of amoeba is a widespread natural phenomenon, recorded everywhere and forming the level of infection of the population.

The mechanism of infection with amebiasis is the ingestion of feces into the mouth. Ways of transmission of amoebiasis - food, water, contact. The highest incidence of amebiasis is recorded in tropical and subtropical climates.

Dysentery amoeba


It is known that in humans, 6 species of amoebas can parasitize, 5 of them are not pathogenic and feed on intestinal bacteria, and 1 - Entamoeba histolytica - is pathogenic, causing severe intestinal symptoms.

Like any parasite, the dysentery amoeba has 2 life forms - trophozoite (vegetative stage) and cyst (resting stage). Trophozoite also goes through several stages and can stay in one of them for a long time:

  • tissue form (found only in acute amebiasis in the affected organs and rarely in feces);
  • a large vegetative form (this form already lives in the intestines and is found in the coprogram, it absorbs red blood cells);
  • the luminal form (found in chronic amoebiasis or in the stage of reconstructiveness after taking a laxative);
  • precystic form (found under the same conditions as luminal).

All this is important for determining the source and methods of fighting against its parasites.

Cysts are found in patients with chronic recurrent amoebiasis in remission and in carriers of amoebas.

The stability of trophozoite and all its varieties is very low, in the external environment it dies within 30 minutes. Cysts are the most resistant, for example:

  • at 17-20 ° C they are stored for a month, in darkened and moist soil - up to 8 days;
  • in chilled food products, fruits, vegetables and household items - up to 5 days on average;
  • at subzero temperatures they are stored for several months.

Drying and heat kills the amoeba almost instantly. Of the disinfectants, only cresol and emitin have a detrimental effect on them, and even chloramine does not have a negative effect on them.

Causes of infection with amebiasis


Age groups of both sexes suffer from amebiasis, but mainly pregnant women due to the physiological suppression of the immune system, namely, cellular immunity. Persons who received immunosuppressive therapy (GCS, cytostatics, etc.) can also be classified as a high risk of infection. The incidence is recorded year-round, with a maximum rise in the hot months. This disease is especially common in countries with hot climates, including in the countries of Central Asia, in the Caucasus. Carriage is quite common when there are no symptoms, but there is an amoeba in the body.

The source is a person who secretes cysts, it can be with or without symptoms. Isolation of the pathogen continues for many years, 300 million cysts or more are released per day. With vivid symptoms, patients are not dangerous, because they emit vegetative forms that are not stable in the external environment.

Factors that reduce the body's resistance to the pathogen: dysbiosis, protein deficiency, concomitant helminthic invasions, pregnancy and other conditions, accompanied by a decrease in immunity.

Symptoms of amebiasis

The incubation period lasts from 1–2 weeks to several months.

Manifestations of the intestinal form of amebiasis


Intestinal amoebiasis is manifested by gradually increasing cramping abdominal pains (mainly in the left lower abdomen) and frequent loose stools with a significant admixture of mucus and blood (raspberry jelly).

Fever is also characteristic, manifestations in the form of decreased performance, weakness, heart palpitations, lowering blood pressure. Acute symptoms of intestinal amebiasis decrease within 4-6 weeks, however, spontaneous recovery and cleansing of the body from the pathogen are rare.

In most cases, after remission, an exacerbation of the disease is recorded in a few weeks or months. In these cases, the total duration of the disease (chronic form of amebiasis) without adequate treatment is decades. This form is characterized by disorders of all types of metabolism (exhaustion, hypovitaminosis, hormonal metabolism disorders, anemia, etc.)

Symptoms of "acute" intestinal amebiasis (the onset is subacute - that is, the symptoms are noticeable not on the first day, but with an increase in 2-3 days):

  • loose stools 4-6 times a day, with transparent mucus and a pungent odor;
  • the frequency of bowel movements gradually increases up to 10-20 times a day and the stool is no longer fecal, but in the form of vitreous mucus;
  • after a few days or immediately, an admixture of blood appears in the stool in the form of "raspberry jelly";
  • persistent or cramping pains of varying intensity, aggravated by bowel movements;
  • the appearance of tenesmus - false urge to defecate, they are painful, long-lasting and do not lead to results;
  • subfebrile temperature 37-38 ° C, lasts for several days;
  • bloating and soreness of the abdomen.

The appearance of blood in the feces suggests that the wall has already been destroyed by the invading parasites, and the appearance of tenesmus is due to damage to the nerve endings of the intestinal walls. This symptomatology lasts for 4-6 weeks with the timely start of specific treatment. If left untreated, then remission occurs and the disease takes on a chronic course, which leads to more extensive damage to the intestinal walls, and subsequently to impaired digestion and absorption.

Chronic course (as a result of late started treatment):

  • Amebiasis

    With amoebiasis, the tongue is coated with a white coating

    unpleasant taste in the mouth, difficult to characterize;

  • the tongue is coated with a white coating;
  • the stomach at this stage is retracted, despite possible flatulence, on palpation - pain;
  • asthenic syndrome (weight loss), with a deficiency of proteins and vitamins (pallor of the skin, brittle nails, dull hair, etc., there are a lot of options and they will depend on a certain vitamin deficiency);
  • decreased appetite / absent;
  • decompensation is observed on the part of other organs and systems (but these symptoms are unstable and may be absent altogether), especially for the cardiovascular system and hepatic function: on the part of the heart - tachycardia and muffled heart sounds, and on the part of the liver - it may increase slightly and soreness.

With immunodeficiency, as well as in young children, a lightning-fast course of amebiasis is possible: the disease develops within the first two days, manifests itself in high fever, severe intoxication, severe pain, frequent bowel movements, dehydration.

Rapidly, extensive damage to the intestinal wall occurs, which leads first to the formation of ulcers, then to paresis, and there is a high risk of perforation of the intestinal wall and the development of peritonitis. With such forms, a very high mortality rate.

There are also other clinical forms of amebiasis, but it is better to attribute them to complications, because they occur more often due to untimely treatment.

Intestinal amebiasis in children: symptoms

Most often, this form of the disease in children manifests itself in the form of severe symptoms characteristic of intoxication. In particular, these are:

  • Temperature rise (up to 39 ° C);
  • Drowsiness;
  • Nausea, vomiting.

Additionally noted:

  • Loose or mushy stools;
  • Impurities of mucus in stool;
  • Increased stool (up to 15 times a day);
  • Dehydration becomes a possible phenomenon.


  • Amebiasis

    The study of blood serum is one of the methods for detecting amebiasis

    Identification of tissue and large vegetative forms of the pathogen in the patient's feces, sputum, contents of abscesses, separated from the bottom of ulcers. Study of smears;

  • Serum research;
  • Colon and sigmoidoscopy;
  • Plain radiography;
  • General blood analysis;
  • Ultrasound of the liver to detect amoebic abscess.

The life cycle of a dysentery amoeba

The entire life cycle of a dysentery amoeba consists of two stages, which are constantly alternating.

The stages of the life cycle of an amoeba are:

  • resting stage (cyst form);
  • active stage (vegetative, tissue and luminal form).

During the dormant period, a mature cyst, covered with a dense membrane, remains dormant. All vital processes during this period are suspended. Dysentery amoeba can be in the environment for a long time in this form.

The active stage of the amoeba life cycle begins with the ingress of a cyst into the human body. In the lower part of the small intestine, enzymes dissolve the outer membrane of the cyst. Further, there is a reproduction and a gradual transformation of the amoeba.

The stages of the active stage of development of dysentery amoeba are:

  • the formation of primary amoebas;
  • reproduction of luminal forms;
  • transition to tissue form;
  • an increase in cells with transformation into a large vegetative form;
  • gradual reduction of amoebas and covering with a dense shell;
  • excretion of amoebas from the body.

After dissolution of the outer shell, the cyst turns into an intermediate form of amoeba with four nuclei. Inside the cell, each nucleus is divided into two. The eight-core cell lengthens and divides into two new cells, each containing four nuclei. Cell division continues until eight young amoebas are formed, each containing one nucleus. They are a luminal form that enters the large intestine. Further reproduction of the luminal forms also occurs due to simple division.

Under certain conditions, the luminal forms of amoebas penetrate into the mucous layer of the large intestine, transforming into tissue forms. Here they destroy the cells of the mucous layer, causing a disease - amoebic colitis.

Some of the tissue amoebas are secreted back into the intestinal lumen. They begin to absorb red blood cells and gradually increase in size. Hence their name - large vegetative form. When a vessel is damaged, amoebas enter the bloodstream and spread throughout the body.

Some of the vegetative forms are excreted from the body with feces and quickly die in the environment. The other part is retained in the lower segment of the intestine (sigmoid and rectum), where it gradually decreases in size and becomes covered with a dense capsule. As a result, cysts are formed, which are also excreted from the body in the feces. From the environment, the cyst again enters the human digestive system, and the life cycle of the amoeba begins anew.

Complications of amebiasis

  • The occurrence of extraintestinal amebiasis (liver abscess, pleuropulmonary amoebiasis, brain abscess, skin lesions);
  • Intestinal perforation leading to peritonitis and high mortality;
  • Strictures (narrowing of areas) of the intestine;
  • Intestinal bleeding;
  • Breakthrough abscesses.

Treatment of amebiasis

There are several groups of drugs that act at different stages of the disease:

  1. Preparations of direct contact action (direct amoebicides), which have a detrimental effect on the luminal forms of the pathogen.
  2. It is used to sanitize carriers of amoebae and treat chronic amoebiasis in remission. This is Hiniophone, Diyodohin. Hiniofon can be used as enemas.
  3. Drugs acting on tissue amoebocytes, i.e. against tissue and luminal forms in the stage of acute intestinal (possibly extraintestinal) amoebiasis: Emetin, Dihydroemitin, Ambilgar, Quinamin (with amoebic liver abscesses).
  4. Preparations of universal / combined action, applicable for all forms of amebiasis: Metronidazole (Trichopolum), Furamid.
  5. Antibiotics are used to change the microbial biocenosis in the intestine.
  6. Preparations that restore normal intestinal microflora: prebiotics, probiotics, symbiotics, a complex immunoglobulin preparation (CIP) is possible.
  7. Enzyme preparations (digestal, panzinorm) for relief of colitis syndrome.

Dosages of drugs are not given purposefully, since a number of drugs are toxic, are often used in combination with each other or other groups of drugs (with antibiotics), and are prescribed under the supervision of laboratory diagnostics.

In parallel with drug treatment, a protein mechanically-chemically sparing diet is used. Vitamin therapy with oral access, bypassing the intestines, because absorption is impaired there. In the presence of abscesses in certain organs, surgical tactics are used against the background of complex treatment.

Forecast and prevention


Untreated, amoebiasis can lead to death. With treatment, improvement usually occurs within a few days. In some patients, signs of colon irritation (diarrhea, cramping pain in the left lower abdomen) persist for several weeks after successful treatment of the disease. Relapses are possible.

Discharge from the hospital with complete cleansing of the intestine from the pathogen, which is established by 6-fold examination of feces taken at intervals of 1-2 days.

For persons staying in an epidemiologically unfavorable region, individual chemoprophylaxis with drugs of universal amoebicidal action (quiniofon, metronidazole) is provided.

Surrounded by the patient, the current disinfection is carried out with a 3% lysol solution or a 2% cresol solution.

Prevention of amebiasis

Measures for the prevention of amoebiasis are aimed at identifying those infected with histolytic amoeba among risk groups, their sanitation or treatment, and also at breaking the transmission mechanism.

Risk groups for infection with amebiasis are patients with gastrointestinal tract pathology, residents of non-canalized settlements, employees of food enterprises and food trade, greenhouses, greenhouses, treatment and sewage facilities, persons returning from countries endemic for amebiasis, homosexuals.

Persons applying to work at food and similar enterprises (children's institutions, sanatoriums, waterworks, etc.) are subject to scatological (for helminth eggs and intestinal protozoa) examination. When a dysentery amoeba is detected, they are subjected to sanitation.

Dispensary observation of those who have recovered is carried out for 12 months. Medical observation and laboratory examination are carried out once a quarter, as well as when intestinal dysfunctions appear.

Measures aimed at breaking the transmission mechanism include the protection of environmental objects from contamination with invasive material by sewerage of populated areas, provision of the population with good-quality drinking water and food, disinfection of objects contaminated with patient's secretions in treatment-and-prophylactic and other institutions using chemical means and boiling.

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