- Prevalence statistics
- Characteristics of the causative agent
- How does the infection occur?
- Development mechanism
- Classification of clinical forms
- Signs and features of intestinal amebiasis
- Endoscopic picture of the disease
- Features of the course in children
- What are the complications of amoebiasis?
- Intestinal forms
- Treatment of amebiasis
- Related videos
Amoebiasis is an infectious disease caused by a histological amoeba, a parasite that primarily affects the intestines. Synonyms: amoebic dysentery, amoebic colitis. An important epidemiological feature is the possibility of transmission from a sick person to a healthy one, as well as the formation of a carrier that creates unknown foci with a causative agent reserve.
Amoebasis of the intestine remains to this day a serious problem for countries with inadequate sanitary culture located in climatic conditions close to the tropics. Among all infectious diseases, mortality from this pathology stands in second place after malaria. She spares neither adults nor children.
Maximum prevalence is observed in Mexico and India, a high rate in South Asia and Africa. In the post-Soviet space, troubles remain in Tajikistan, Kyrgyzstan, Turkmenistan.
Mature middle-aged men are more often ill. Susceptibility to intestinal amebiasis is possessed by every tenth person who met the pathogen. According to WHO, there are about 480 million carriers of dysentery amoeba in the world. Each year, 50 million new cases are registered. At the same time, a lethal outcome occurs in 2%.
Sanitary conditions in Bangladesh represent the best option for the spread of amebiasis
The violation of sanitary well-being accompanies natural disasters, migration of people in search of work, social problems. Therefore, intestinal amebiasis remains a problem for developed countries. We will consider in detail what amoebiasis is, start with the description of the pathogen and its properties.
Characteristics of the causative agent
The causative agent of amoebic dysentery is the simplest single-celled organism from the family of amoeba. Of all the representatives of the class, dysenteric amoeba( histolytica) is considered to be pathogenic to humans, others are not dangerous.
Intestinal amoeba has characteristic structural features, by which it is distinguished by microscopy from other parasitic microorganisms:
- form is constantly changing;
- core is large, transparent;
- is the pseudopods( pseudopodia) with which the amoeba moves;
- outer shell is thin;
- intracellular fluid( cytoplasm) is colorless.
Movement is carried out by transfusion of the contents into outgrowths( pseudopods).The favorite conditions for the habitat of the parasite are created in the large intestine of a person. This sign determines the main symptoms and ways of treating the disease. Dimensions of amoebae, internal inclusions depend on the stage of development.
During the growing season, it takes 4 forms:
- tissue - the cell size is on average up to 25 μm, is found only in case of acute inflammation directly in the affected tissue, and not in feces;
- large histological - occurs when the amoeba has the ability to phagocytosis erythrocytes with the release of specific enzymes, the size reaches 40 microns, stretches to a length of 80 microns, the causative agent penetrates the mucous and submucous layers of the intestine, causes ulceration and necrosis, is found in feces analysis,is characteristic of the acute course of the disease;
- luminal - the size is up to 25 microns, the movements are sluggish, which is associated with adjustment to other microorganisms, the formation of bonds, is detected in persons who have had acute amoebiasis, suffering from recurrent chronic form, with asymptomatic flow;
- pre-cystic - provides the transition of amoeba from the luminal stage to the cyst, sizes 10-18 microns.
Lab technicians compare the look of this simplest organism with the "broken glass" of
. It is important that dysentery amoeba can not exist for a long time in the external environment in the form of a luminal and large histolytic, quickly destroyed. A cyst is a state of rest and a "waiting for a suitable event" for the manifestation of contagious properties. The microorganism is maximally protected from the external environment to maintain its viability. Characteristic:
- roundness of shape;
- dense shell;
- in the ripe condition - four cores;
- availability of "stocks" of glycogen, protein in the cytoplasm;
- localization in the sigmoid and rectum.
It is found in feces of persons who have undergone amoebic dysentery, in the period of recovery and in carriers of infection. Activation of the cyst occurs after dissolution of the outer shell. It turns into an intermediate form, contains 4 cores. Each core is split in half. The process continues until 8 new amoebas are formed in luminary form, containing one nucleus each. Getting into the large intestine, they are transformed into the most pathogenic species( tissue and large vegetative).
How does the infection occur?
It was found out that with feces of a sick person or carrier, up to 400 million amoeba cysts are released per day. They are able for a long time to be in the external environment, on objects that the infected person touched with dirty hands.
The most common ways of transmission of infection are provided:
- with dirty human hands;
- in case of inadequate food processing;
- through unwashed vegetables or fruits;
- through the soil when working on garden plots, vegetable gardens;
- common utensils, household items;
- bed and underwear;
- with flies and cockroaches.
Drinking water from lakes, rivers, basin polluted with sewage sewage is one of the ways of infection
Infection with dysentery of amoeba etiology is possible only if the cysts of the causative agent enter the oral cavity. Such a transmission mechanism is called "fecal-oral".With particles of stool, cysts swallow and reach the intestine. Here they begin to multiply actively.
Infection often occurs when contact with a patient patient or carrier, handshake. It is classified as contact-household. Direct contact makes infection likely for lovers of oral-anal sex. Summer swimming in polluted water bodies promotes the spread of the disease in case of ingestion of water.
Mechanism of development of
Pancreatic enzymes that enter the small intestine of the cyst function and dissolve the envelope. The released amoeba reproduces by the process of division. Passes to the large intestine. Lumen form for a long time can not cause disease. To show symptoms of intestinal amebiasis, the pathogen should be transformed into a tissue form.
Conditions for activating the transition to tissue forms are:
- massive intestinal infection;
- different types of mucosal lesions( inflamed areas, microtrauma);
- violation of peristalsis( muscular contractions) of the intestine;
- altered balance of intestinal microflora;
- presence of other parasitic diseases( giardiasis, helminthiases);
- fasting, low-calorie diet without sufficient intake of proteins and vitamins;
- immunodeficiency state of the body;
- disturbed hormonal background( an actual condition of infection with amebiasis of women during pregnancy);
- stress and physical overload.
For sufficient reproduction of the amoeba, an incubation period of two weeks to three months is necessary. This explains the fact that the initial symptoms of amebiasis appear 3-4 months after the alleged infection. Then the pathogenic form "attacks" the intestinal mucosa.
Fixed on the intestinal wall, the microorganism secretes cytolysin, proteolytic enzymes. These substances have the ability to destroy the proteins of the cellular epithelium, disrupt the structure of their membranes. The dead cells allow the amoeba to penetrate into the deeper submucous layer of the intestinal wall. Here continues active reproduction, primary foci are formed. They open up inside, form ulcers.
Part of the mucosa is self-healing and covered with scars. The affected area looks like a combination of ulcers and healed areas. This is the pathogenesis of the disease.
On the surface, ulcers look isolated structures, but at the level of submucosal layer there is a network of "tunnels" for enhanced movement of amoebae
Classification of clinical forms
If ulceration affects the vessels, the pathogens penetrate into the blood and are carried to different organs and tissues. Thus, extraintestinal forms of the disease develop. The most sensitive to amoeba are:
- respiratory organs( lungs and pleura);
According to the area of the lesion, the clinic distinguishes:
- intestinal form( amoebic colitis);
And, depending on the severity of the symptoms, the following are distinguished:
- asymptomatic course - typical pathogens and cysts are found in the feces accidentally on the background of the patient's well-being;
- manifest forms - all kinds of disease that occurs with a bright typical symptomatology.
Asymptomatic flow is equated with carriage
Signs and features of intestinal amebiasis
Intestinal amebiasis affects the large intestine( dysentery amoebic colitis).It is the most frequent localization of specific changes. Has an acute or chronic course. A typical clinic develops gradually. Initial signs can be:
- an incomprehensible malaise;
- loss of appetite;
- Failure in abdominal pain.
Expressed symptoms of amebiasis are manifested:
- diarrhea - the frequency of diarrhea in the first day of 5-6 times, then comes up to 20 times, the feces have a lot of mucus, blood clots, impurities of pus;
- strong thirst - indicates an intoxication of the body;
- weakness and drowsiness;
- with cramping pains in the left or right abdomen;
- by tenesms( false urges) to defecation - are caused by a local lesion of the sigmoid and rectum.
In case of severe course, the symptoms of intoxication are typical:
- high temperature;
- aches all over the body.
With the amoeba process in the cecum and vermiform appendage, the symptoms are very similar to acute appendicitis. Palpation of the abdomen is accompanied by local muscle tension.
The acute form of the disease lasts 4-6 weeks, self-healing and well-being are not ruled out, but there is no guarantee that a person does not become an infection carrier. In the absence of timely therapy, the acute process passes into a chronic form with alternations of periods of exacerbation and remission( remission).
Chronic amoebic dysentery occurs in the form of a recurring form or is accompanied by a continuous, non-stopping process. For chronic amoebiasis are characterized:
- complaints of the patient for a constant unpleasant aftertaste in the mouth;
- lack of appetite;
- dehydration( fluid loss), so facial features look pointed;
- pain along the bowel;
- burning or pain in the area of the tongue;
- lagging of the tongue in a dense grayish bloom;
- prolonged upset of the stool( diarrhea alternates with constipation, unstable blood clots and mucus in the stool);
- low working capacity;
- a constant feeling of fatigue;
- heartbeat, arrhythmia.
During the period of remission, pains become rare, disturbed by rumbling in the abdomen, swelling. Against the background of continuous flow, the condition does not improve, but new symptoms are added:
- significant weight loss;
- disorders of the psyche( irritability or apathy, tearfulness;
- memory loss;
- stitching pain and a feeling of arrhythmia in the heart;
- unstable blood pressure.
Endoscopic picture of the disease
Modern endoscopic technique allows not only to use the sigmoidoscopy that provides access to the mucosa of the large intestineto the lower divisions, but also to apply fibrocolonoscopy in the diagnosis of upper pathology. In 40% of patients with intestinal amoebiasis already in the initial period byinflammation in the area of the rectum and sigmoid colon is fixed:
- on the 2-3 day there are foci of hyperemia,
- for 4-5 - small ulcers 5 mm in size
- by 6-10 days the size of ulcers reach 2 cm, visible undercut edges and necrosis in the center
In chronic course,
- large ulcers are formed on the mucosa,
- polyposis proliferation,
- amebodies( in 2% of patients).
Intestinal lumen narrowed by protrusion of ameba
Amoeboma is a tumor-like formation consisting of a large inflammatory infiltrate with proliferation of granulations, cells from fibrous tissue. It is more often located in the blind and ascending gut. It has clear boundaries, it can reach considerable dimensions. It protrudes into the lumen of the intestine in the form of a tumor.
Features of the course in children
Symptoms of amoebic dysentery in childhood most often develop in the intestinal scenario, but differ in severe intoxication. The child has:
- high fever;
- retardation, drowsiness;
- nausea, frequent vomiting;
- liquid or mushy feces 10-15 times a day;
- an admixture of mucus and blood in the stool.
Children are more than adults sensitive to dehydration( loss of fluid).Reduced blood pressure, there is rapid heartbeat, arrhythmias. In the treatment of amoebiasis in children, it is necessary to restore the balance of water in the body as a matter of priority.
What are the complications of amebiasis?
Intestinal form of amoebic dysentery in the absence or inappropriate treatment can cause:
- gangrene and rupture( perforation) of the wall of the large intestine with the development of severe peritonitis and shock( almost 100% of cases are fatal);
- acute bleeding;
- attack of appendicitis;
- narrowing of the intestine by cicatricial tissue.
Extraintestinal forms of
Some authors consider the appearance of extraintestinal forms as a sign of a complicated course of intestinal amebiasis. Others - represent how certain types of organ damage. The hepatic variant of pathology is most often observed. Activated cysts are entered into the liver tissue through the venous blood flow. Changes in the organ develop as follows:
- amoebic hepatitis;
- liver abscess.
The clinical course is acute, subacute or chronic. Symptoms can appear both concomitantly with acute colitis, and after several months and years after it. Symptoms are:
- pain in the right hypochondrium;
- moderate temperature increase;
- enlargement of the liver( sometimes up to large sizes), dense edge on palpation;
- jaundice of the skin and mucous membranes.
With amoebic abscess:
- pain intense;
- the temperature is constantly high or with a sharp drop, chills;
- marked sweating at night.
In 1/5 patients, an atypical abscess flow is detected. Among the symptoms are:
- signs of cholecystitis;
- only a small temperature;
- not clear jaundice.
Pleural empyema, abscess of lung tissue, suppuration of hepatic-bronchial stroke( fistula) develop. Patients appear:
- chest pain when breathing;
- shortness of breath;
- in the sputum, blood is found with an admixture of pus;
- temperature rises to high figures, accompanied by chills.
The cerebral form is caused by the infection of the infection with blood in the brain. In the brain tissue, single or multiple abscesses are formed. The left hemisphere is more often affected. Usually, the course of the disease is lightning fast and is rarely diagnosed during life.
Pericarditis is one of the possible complications of
Amoebic pericarditis accompanies a breakthrough in the abscess of the left lobe of the liver through the diaphragm. An inflammatory fluid accumulates in the heart bag, which can lead to tamponade and death.
There are cases of urogenital amoebiasis. Pathology is associated with the ingestion of the pathogen from rectum ulcers directly to the genitals. For women, there is a risk of subsequent development of cervical cancer. For homosexual relationships, ulcers in the anus and external genitalia are characteristic.
During preliminary diagnosis, the possible source of infection, patient complaints, inspection results are taken into account. For confirmation, laboratory diagnostics is carried out. The tests include examination of feces for coprogram, latent blood, preparation of a smear and its microscopy.
In a smear under a microscope, you can see live forms of amoeba or cyst. The research rule includes mandatory viewing of at least four unpainted strokes. The mobile luminal and tissue forms are revealed. The study can be effective with microscopy within 30 minutes after defecation. With long-term storage, amoeba die.
Iodine staining promotes good visibility of the nuclei of unicellular organisms. The diagnosis is confirmed when identifying the vegetative large forms of the pathogen. The study includes differential diagnosis with dysentery caused by shigellosis.
Microorganisms differ in structure, this dysentery shigella
For the diagnosis of liver abscess, the following is used:
- computer and magnetic resonance imaging;
- radioisotope scans of the liver.
Treatment of amebiasis
To treat amoebic dysentery, drugs that destroy the pathogen in various forms, including cysts, are needed. In practice, three groups are used for their effect on amoebae:
- on those pathogens that are located in the lumen of the intestine( Yatren, Diiodohin, tetracycline antibiotics);
- located in the mucosa of the intestinal wall and in other organs( Emetin, Hingamin, Chlorokhin);
- of all possible forms( Metronidazole, Tinidazole, Ornidazole).
In the recovery phase, patients are assigned:
- pro- and prebiotics to restore intestinal flora;
- vitamins( especially A, E, D, B and K);
Preventing infection requires that a person comply with hygiene in all conditions. In the territories with a significant incidence of the disease, "memos" are distributed to the population, they talk about when to wash their hands, how to handle food, and how to drink water. Communal services are involved in solving the problem. They are obliged to provide people with normal toilets, dry closets, special hand towels.
The control over drinking water and the state of natural sources is carried out by epidemiological institutions. When detecting contamination, a sign that prohibits use is displayed. Treatment of acute amebiasis must necessarily be conducted under the guidance of an infectious disease doctor. A full course of therapy will avoid complications and transition to a chronic course.