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Amoebiasis - Diagnostics
Last reviewed: 20.11.2021
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The simplest and most reliable diagnosis of intestinal amebiasis is the microscopic examination of faeces for the detection of vegetative forms (trophozoites) and cysts. Trophozoites are better to identify in patients with diarrhea, and cysts - in a decorated stool. Primary microscopy examines native preparations from fresh samples of feces with saline. To identify trophozoites, amebic preparations are stained with Lugol's solution or buffered methylene blue. To identify cysts, native preparations prepared from fresh or preservative-treated faeces are stained with iodine. Detection of amoebas is more effective in the immediate investigation of feces after the appointment of a laxative. In practice, the methods of enrichment, in particular, ether formalin precipitation, are also used. However, only cysts can be detected by enrichment, since trophozoites are deformed. Detection of cysts only does not confirm the presence of invasive amebiasis. In recent years, a sensitive and specific PCR method has been developed that makes it possible to identify E. Histolytica and E. Disparently in faeces relatively quickly and easily.
With clinical data indicating a possible bowel injury, it is recommended to perform recto- or colonoscopy to obtain a biopsy material. These methods can identify ulcers in the intestines, amebears, strictures and other pathological changes. A characteristic feature of changes in amebiasis is focal, rather than diffuse type of lesion. Diagnosis of amebiasis of the extra-intestinal, in particular liver abscess, is carried out with the help of ultrasound and CT, which allow to determine the localization, size, number of abscesses, and also to monitor the results of treatment. X-ray examination allows to reveal the high standing of the dome of the diaphragm, the presence of effusion in the pleural cavity, abscesses in the lungs. If necessary, aspirate the contents of the liver abscess, but the probability of identifying amoebas in necrotic masses is small, since they are usually located along the periphery of the lesion.
Specific anti-amoebic antibodies with serological methods (ELISA, NERIF) are found in 75-80% of patients with invasive intestinal amebiasis and in 96-100% - with extraintestinal lesions; even in asymptomatic E. Histolytica carriers, positive results can reach 10%. These tests are especially useful for the diagnosis of extraintestinal amebiasis. Since in these cases in the feces the invasive stages of E. Histolytica, as a rule, are absent. In endemic foci, serological diagnosis of amoebiasis is recommended for all patients with suspected amebiasis, which glucocorticoids are planning to prescribe.
Indications for consultation of other specialists
Consultation of the surgeon if necessary differential diagnosis with surgical diseases or suspicion of surgical complications, with liver abscess; consultation pulmonologist - with abscess of the lung.
Indications for hospitalization
Clinical, epidemiological, treatment during acute exacerbation, table number 2, 4.
Differential diagnosis of amebiasis
Differential diagnosis of amebiasis is carried out with balantidiasis, shigellosis, campylobacteriosis, ulcerative colitis, in tropical countries - with some helminthiases occurring with manifestations of hemocolitis (intestinal schistosomiasis, trichocephalosis, etc.).
[6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16]