Amoebiasis

Amebiasis - protozoal illness characterised by moderately expressed intoxication, a canker of an intestine and becoming complicated in some cases abscesses of a liver, a brain, easy and other organs.

Aetiology. The originator (Entamoeba histolytica) can exist in three forms. The big vegetative form (the histic form, erythrophage, an erythrophage) has 20-30 microns in diameter, and at active locomotion is extended and reaches length till 60-80 a micron. This form is capable to englobe erythrocytes. Their number reaches to 20 and more in one ameba. Meets only at sick humans. The luminal form (the fine vegetative form, free, not histic, precystic) has diameter 15-20 microns. Erythrocytes does not englobe. It is found in carriers of amebas. The cyst stage represents formation in diameter 7-18 microns, has from 1 to 4 nuclei, is steady in an external environment. The mature cyst, capable to cause a becoming infected, has 4 nuclei.

Epidemiology. An infestation source is the human sick of an amebiasis, or the carrier of dysenteric amebas. In 1 gramme of excrements can contain to 6 million cysts of amebas. It is characteristic fecal - an oral path of a transmission of infection (ingestion of cysts with the polluted water, food stuffs). An amebiasis eurysynusic in many countries (prevalence population dysenteric amebas on the average about 10 %). The case rate is especially great in tropical and subtropical regions (the countries of Africa, Southern Asia, Central and the South America). In these countries the amebiasis causes to 20 % of all illnesses proceeding with intestinal disorders. It is characterised expressed summer - autumn seasonal prevalence. Humans of middle age is more often are ill.

Pathogenesis. Infestation descends at hit of cysts of a dysenteric ameba in a digestive tube of the human. In the inferior department thin or in initial department of a colon the cyst cover is blasted, and the cyst turns to the luminal form of a dysenteric ameba. Last dwells and propagates in a lumen of proximal department of a colon. It is not accompanied by any clinical implications (a healthy carriage). In some cases the luminal form takes root into a mucosa, inpours into a submucosa of an intestine and turns to the pathogenic histic form (erythrophage).

Mechanism of metamorphosis of the luminal form in the histic is studied insufficiently. Penetration into tissues and their fusion are bound to presence at an ameba of the special materials - cytolysins and proteolytic enzymes. The great value in an amebiasis pathogenesis belongs to an intestine dysbacteriosis. Character of a food and a state of the macroorganism matters. Propagating in a tissue of a side of an intestine, the histolytic ameba causes occurrence of small abscesses in a submucosa which then break in a lumen of an intestine with formation of ulcers of a mucosa. With disease the number of amebic ulcers is enlarged. Lesions become perceptible on all extent of a colon, but are mainly localised in the field of blind and ascending. Hematogenous by the dysenteric ameba from an intestine can inpour into a liver and other organs and cause formation there abscesses.

Dimensions of abscesses vary over a wide range and can reach 20 sm and more in diameter. Liver microabscesses are quite often treated as implication of a so-called amebic hepatitis. In such cases speak about abenteric complications of an amebiasis. The process beginning always is bound to an intestine lesion. At punching of intestinal ulcers the circumscribed (encysted) peritonitis is observed. At healing of ulcers the cicatrical tissue which can lead to intestine narrowing educes.

Symptoms and flow. The incubation interval proceeds from 1 week till 3 months (more often 3-6 weeks). More half are ill during the first half of the year of stay in precinctive district on an amebiasis. The amebiasis is characterised by variety of clinical implications. Excrete following clinical forms: an intestinal amebiasis (acute, chronic, latent); abenteric complications of an amebiasis (amebic abscesses of a liver, amebic hepatitises, lesions of a skin, etc.); an amebiasis in a combination to other illnesses (a dysentery, helminthiases, etc.).

Illness begins rather acutely. There is the general delicacy, moderately expressed headache, abdominal pains. A body temperature subfebrile. One of precursory symptoms is the diarrhoeia. At the majority of patients in an initial stage the chair liquid without pathological admixings from 2 to 15 times a day, only at some becomes perceptible an insignificant admixing of slime. Later 2-5 days from the illness beginning in fecal masses can show slime and blood. Abdominal pains in the first days, as a rule, are absent or happen very weak, at some patients they appear only for 5-7th day of illness. Expression of a painful syndrome gradually accrues. Pains are localised mainly in the inferior departments of a gaste. Tenesmuses are observed seldom (at 10 % of patients).

Disharmony between expression of intestinal disorders (a frequent chair, an admixing of slime and blood in excrements) and rather satisfactory state of health, absence of the fever kept by working capacity of the patient is characteristic. At survey the skin of a normal coloration, an eruption is not present. At the majority of patients become perceptible a moderate abdominal distention, at a palpation - morbidity and a spastic stricture of various departments of a colon. At separate patients small bowel changes, and also small augmentation of a liver are taped. From other organs of essential disturbances it does not become perceptible.

Intestinal amebiasis proceeds in the form of slowly progressing disease at 2/3 patients is more often, is more rare - at 1/3 - in the form of quickly progressing process. In the first case the initial stage is characterised oligosymptomatic, even imperceptible for sick of flow. The chair liquid, to 5 times a day, sometimes with a slime admixing, is more rare - bloods. Abdominal pains join a diarrhoeia in some days and are expressed unsharply.

Quickly progressing flow is characterised by simultaneous appearance of a diarrhoeia and the expressed painful syndrome. Slime and blood in a feces are taped already in 1-3rd days of illness. Pains colicy, expressed enough, strengthen at a defecation. A body temperature, as a rule, the subfebrile. The exhausted patients against a hypovitaminosis can have an acute beginning with fast development of a grave condition.

At an endoscopy (a proctosigmoidoscope, fibro scope) inflammatory changes in range of direct and sigmoid intestines are found in an initial stage in 42 % of patients. Dynamics of changes is original. For 2-3rd day from the beginning of disease against a normal mucosa hyperemia fields (diameter 5-20 mm), a little towering over level of invariable departments of an intestine become perceptible. From 4-5th day of illness on a place of these fields of a hyperemia fine nodules and ulcers (to 5 mm in diameter) from which at pressing curdled masses of yellowish colour are excreted are taped. Round ulcers small region hyperemias. From 6th illness till 14th day ulcers in the dimension to 20 mm with the saped edges and filled in necrotic masses are found. Thus, changes of a mucosa of an intestine typical for an amebiasis are formed within the first 2 weeks of illness. At quickly progressing flow similar changes are found for 6-8th day of illness.

After the acute season long remission is usually observed, then disease becomes aggravated again and chronic forms can proceed till 10 years and more. They proceed in two clinical forms - recurring and continuous accept chronic flow. Without specific antiparasitic treatment. At the relapsing form of an exacerbation are replaced by remissions during which time patients note only small dyspeptic the phenomena (unsharply expressed meteorism, a rumble in a gaste, pains without certain localisation). At an exacerbation the state of health of patients essential is not broken, the body temperature remains normal. The expressed pains in the right half of gaste, in ileocecal range (the appendicitis is quite often wrongly diagnosed), chair disorder at this time become perceptible.

At continuous flow of a chronic amebiasis patients do not have on the substance of the remission seasons though disease proceeds also that with intensifying of all implications (an abdominal pain, the diarrhoeia alternating with constipations, a chair with a blood admixing, the body temperature), with their some weakening sometimes raises. At long flow of the chronic form the asthenic syndrome, food decline, a hypochromia anaemia educe.

Complications. The important feature of an amebiasis is development of complications. To intestinal complications of an amebiasis carry the general and circumscribed (encysted) peritonitis owing to intestine punching, an ameboma, an intestinal bleeding, abaissement of a mucosa of a rectum. Narrowing of an intestine and an ameboma can lead to development of impassability of an intestine. The ameboma represents a tumorous infiltrate in an intestine side, at consecutive infection apposition can abscess.

The amebic hepatitis, abscesses of a liver, brain, lungs concern abenteric complications, skin lesions. Liver abscesses (individual and plural) and an amebic hepatitis which histologycal also shows original microabscesses of a liver are more often observed. The amebic abscess (abscesses) of a liver can educe both during the acute season, and after long time (till several years). At acute flow of an abscess at the majority of patients become perceptible a fervescence to febrile digits, the fever of quite often hectic type with repeated cold fits, educes delicacy. In all cases pains in right hypochondrium become perceptible. The pain strengthens at body concussion, irradiates in the right shoulder or a scapula. At survey the diverticulum in right hypochondrium is sometimes taped. Hepatic dullness is enlarged upwards, at a palpation the fluctuating tumescence on a forward surface of a liver can be defined. At a blood analysis almost in all cases are defined neutrophilic a leukocytosis and rising Erythrocyte Sedimentation Rate.

At chronic abscesses intoxication symptoms are expressed weakly, a body temperature subfebrile or normal. The amebic abscess can break in surrounding organs and to lead to formation of the subphrenic abscess poured or an encysted peritonitis, a purulent pleuritis, a pericarditis. The is hepatic-bronchial fistula with an expectoration of a considerable quantity of a purulent sputum of brown colour can be formed. Sometimes the liver abscess breaks through integuments, in these cases in the field of a fistula the amebic lesion of a skin can educe. The abscess of lungs arises not only as a result of break of pus from a liver, but also hematogenically. Abscesses of lungs are well taped at a X-ray inspection. Amebic abscesses of a brain, on semiology a little differing from abscesses of a brain of other aetiology are sometimes observed.

Diagnosis and the differential diagnosis. It is necessary to think of amebiasis possibility in cases of the long disease proceeding with a lesion of a colon at moderately expressed signs of the general intoxication. The indicating on stay of the patient in precinctive district on an amebiasis is especially important. Besides clinical data in diagnostics results of a proctosigmoidoscope have essential value, and in the absence of characteristic changes of a mucosa of distal departments of a colon it is possible to spend fibro scope. Diagnostic value has detection of characteristic ulcers of a mucosa with the saped edges and surrounded with region hyperemias. During an endoscopy the capture of a stuff for parasitologic research is possible.

As laboratory acknowledgement of an intestinal amebiasis detection of the big vegetative (histic) form of an ameba with phagocytized erythrocytes serves. To investigate excrements follows not later than 20 mines after a defecation as histic forms of amebas are quickly blasted. Excrements for research are necessary for collecting in the glasswares disinfected by autoclaving as even insignificant admixings of chemical disinfectants lead to death of amebas. Positive takes manage to be received more often at parasitologic research of the stuff taken at a proctosigmoidoscope from amebic ulcers.

Serological diagnostics by means of reaction of the indirect immunofluorescence is used also, allowing to find specific antibodies in Serum of patients (diagnostic titer 1:80 and above). At patients this reaction is positive in 90-100 %, at carriers of luminal forms it negative. At liver abscesses this reaction is positive at all patients in a high caption. Reaction of an indirect hemagglutination with a specific diagnosticum as it happens positive not only at patients, but also at earlier infected with histolytic amebas is less informative. Detection of cysts and luminal forms does not confirm the amebiasis diagnosis though forces to suspect this disease.

Amebic abscesses of a liver are very accurately taped at its ultrasonic research, and also at radioisotope scanning of a liver. Auxiliary methods of their diagnostics are the X-ray inspection (high standing of the right dome of a diaphragm) and a laparoscopy.

At carrying out of differential diagnostics it is necessary to mean not only infectious, but also therapeutic illnesses. In the absence of a fever and the expressed symptoms of the general intoxication it is necessary to differentiate with a nonspecific ulcerative colitis, at persons is more senior 50 years - with diverticular illness, in the presence of hypovitaminosis symptoms - with a pellagra. At women intestinal disorders can be caused a colon endometriosis (communication with a menstrual cycle). Intestinal bleedings are possible at colon neoplasms, at Henoch-Schonlein purpura. At rise in temperature and the general intoxication differential diagnostics spend with a dysentery, a campilobacteriosis, a balanthidiasis, illness of the Cron, a schistosomiasis. Amebic abscesses of a liver, lungs, a brain differentiate from abscesses of other aetiology.