Dientamoeba Fragilis: Description Of The Parasite, Diagnosis And Treatment

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Dientamoeba Fragilis: Description Of The Parasite, Diagnosis And Treatment
Dientamoeba Fragilis: Description Of The Parasite, Diagnosis And Treatment

Video: Dientamoeba Fragilis: Description Of The Parasite, Diagnosis And Treatment

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Video: Dientamoeba fragilis 2023, February
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  • Diagnostics
  • Treatment
  • Treatment regimens for amebiasis
  • You can defeat parasites!

Dientameba (Dientamoeba fragilis) was previously considered a microorganism belonging to the Rhizopoda type. The organism is unique in that it exists only in the form of a trophozoite with two nuclei. This explains its name - dientameba. Despite the loss of the tourniquet, the belonging of D.fragilis to the flagellate protozoa is confirmed by electron microscopic studies.

D.fragilis is a human parasite, although morphologically similar parasites have been found in monkeys in India and Panama. Dientamebes are organisms with significantly varying sizes from 3 to 18 µm (on average 7–12 µm). Hyaline pseudopodia with a characteristic leaf-shaped serrated edge (Fig. 92). The movement is forward, but organisms are active only in fresh samples of faeces. Vacuoles contain ingested bacteria that are visible through the cytoplasm. In living trophozoites, the nuclei are not visible. Typical organisms contain two nuclei, although forms with 3 and 4 nuclei are found.

What to do in such a situation? To get started, we recommend reading this article. This article details the methods of dealing with parasites. We also recommend contacting a specialist. Read the article >>>

dientamoeba fragilis
dientamoeba fragilis
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In stained preparations, D.fragilis are identified on the basis of a large proportion (up to 80%) of binuclear forms with a typical structure. The nuclear membrane is delicate and lacks peripheral chromatin. In the center of the nucleus lies a large mass, consisting of 4-8 individual granules, usually symmetrically organized.

Dientameba is able to exist in the conditions of the large intestine on the mucous surface of crypts - especially in accumulations of mucus lumps, which contributes to their resettlement. It does not swallow erythrocytes, does not invade tissues. In rare cases, mild mucous diarrhea may result from the presence of a large number of parasites in the intestines. Identification of loose stools, vague pain, constipation in 15-27% of infected people is sometimes attributed to dientameb.

Diagnostics

The diagnosis of amebiasis is established on the basis of data from the epidemiological history, the clinical picture of the disease and the results of laboratory tests.

The results of the parasitological examination are decisive for the diagnosis. The parasitological diagnosis of amebiasis is made when tissue and large vegetative forms, trophozoites-erythrophages are found in the test material. The material for research can be: feces, rectal smears taken during sigmoidoscopy, biopsy material of ulcerative lesions, aspirate the contents of a liver abscess, and tissue forms are localized mainly in the outer walls of the abscess, and not in necrotic masses located in the center.

From the first day of illness, microscopy of native smears from freshly excreted feces in saline and smears stained with Lugol's solution is performed. In the acute and subacute course of the disease, they look for a vegetative tissue form of amoeba, and in convalescents and asymptomatic carriers - a small luminal form and a cyst. It is also possible to prepare permanent preparations stained with Heidenhain hematoxylin. Identifying only the luminal forms and cysts of amoebas in the feces is not enough for the final diagnosis.

In the presence of clinical signs of intestinal amebiasis and negative results of parasitological studies, serological tests are used based on the identification of specific anti-amebic antibodies. Used RIF, RSK, ELISA, reactions of inhibition of hemagglutination and neutralization with paired sera (increase in antibody titer 4 or more times). Serologic tests are positive in 75% of patients with intestinal amebiasis and 95% of patients with extraintestinal amebiasis.

Diagnosis of parasitic diseases
Diagnosis of parasitic diseases
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To diagnose extraintestinal amebiasis, in addition to immunological, a comprehensive instrumental examination is carried out: ultrasound, X-ray examination, computed tomography and other methods that allow determining the localization, size and number of abscesses, as well as monitoring the results of treatment.

From modern research methods, the detection of antigens of dysentery amoebas in feces and other material using monoclonal antibodies is used; determination of parasitic DNA by PCR.

Treatment

In general, all drugs used to treat amoebiasis can be divided into 2 groups: "contact" or "luminal" (affecting the intestinal luminal forms) and systemic tissue amoebicides.

Luminal amoebicides are used to treat non-invasive amebiasis (asymptomatic carriers). Luminal amoebicides are also recommended to be prescribed after completion of treatment with tissue amoebocides to eliminate amoebas remaining in the intestine in order to prevent relapse. In particular, there are observations on the development of amoebic liver abscesses in persons with intestinal amebiasis who received only tissue amoebicides without the subsequent appointment of luminal amoebocides. In particular, a relapse of amoebic liver abscess was described in a patient 17 years after successfully healed, newly diagnosed liver abscess.

In conditions where it is impossible to prevent re-infection, the use of luminal amoebocides is impractical. In these situations, it is recommended to prescribe luminal amoebicides only for epidemiological indications, for example, to persons whose professional activities may contribute to the infection of others, in particular to employees of catering establishments.

Translucent amoebicides

  • Etofamide (Kythnos®)
  • Clefamide
  • Diloxanide furoate
  • Paromomycin

For the treatment of invasive amoebiasis, systemic tissue amoebicides are used. The drugs of choice from this group are 5-nitroimidazoles, which are used both for the treatment of intestinal amebiasis and abscesses of any localization.

Systemic tissue amoebicides

5 - nitroimidazoles:

  • Metronidazole (Trichopol®, Flagil®)
  • Tinidazole (Tiniba®, Fasizhin®)
  • Ornidazole (Tiberal®)
  • Secnidazole
Metronidazole: vaginal tablets, cost, instructions for use
Metronidazole: vaginal tablets, cost, instructions for use
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In addition to drugs from the 5-nitroimidazole group, for the treatment of invasive amebiasis and, above all, amoebic liver abscesses, it is recommended to use Dehydroemethine dihydrochloride (not registered in the Russian Federation) and Chloroquine.

Treatment regimens for amebiasis

Intestinal amebiasis:

  • Metronidazole - orally 30 mg / kg / day in 3 divided doses for 8-10 days
  • or
  • Tinidazole - up to 12 years old - 50 mg / kg / day (max. 2 g) in 1 dose for 3 days;
  • over 12 years old - 2 g / day in 1 reception for 3 days
  • or
  • Ornidazole - up to 12 years old - 40 mg / kg / day (max. 2 g) in 2 divided doses for 3 days;
  • over 12 years old - 2 g / day in 2 doses for 3 days
  • or
  • Secnidazole - up to 12 years - 30 mg / kg / day (max. 2 g) in 1 dose for 3 days;
  • over 12 years old - 2 g / day in 1 reception for 3 days

Amoebic abscess:

  • Metronidazole - 30 mg / kg / day in 3 divided doses for 8-10 days
  • or
  • Tinidazole - up to 12 years old - 50 mg / kg / day (max. 2 g) in 1 dose for 5-10 days;
  • over 12 years old - 2 g / day in 1 reception for 5-10 days
  • or
  • Ornidazole - up to 12 years old - 40 mg / kg / day (max. 2 g) in 2 divided doses for 5-10 days;
  • over 12 years old -2 g / day in 2 doses for 5-10 days
  • or
  • Secnidazole - up to 12 years - 30 mg / kg / day (max. 2 g) in 1 dose for 3 days;
  • over 12 years old - 2 g / day in 1 reception for 3 days

Alternative treatment regimen for amoebic abscess:

  • Dehydroemetine dihydrochloride - 1 mg / kg / day IM (no more than 60 mg) for 4-6 days
  • Simultaneously or immediately after completion of the course of dehydroemetine for amoebic liver abscesses, chloroquine is recommended - 600 mg of base per day for 2 days, then 300 mg of base per day for 2-3 weeks

After completing the course of 5-nitroimidazoles or dehydroemethine, in order to eliminate the remaining amoebas in the intestine, luminal amoebicides are used:

  • Etofamide - 20 mg / kg / day in 2 divided doses for 5-7 days
  • Paromomycin -1000 mg / day in 2 divided doses for 5-10 days

In clinically pronounced cases with an appropriate epidemiological history, when a large number of non-pathogenic amoeba species are found in the feces, it is also recommended to treat with amoebicides, since in these cases there is a high probability of concomitant E. histolytica infection.

Oral amoeba
Oral amoeba
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The heterogeneity of the pathological process and clinical manifestations in amebiasis in different geographic regions, the presence of strains resistant to standard chemotherapy regimens with 5-nitroimidazoles, require varying treatment regimens, taking into account the experience gained in a particular area.

Severe patients with amoebic dysentery, due to possible intestinal perforation and the development of peritonitis, are recommended to additionally prescribe antibacterial drugs that are active against the intestinal microflora.

Aspiration (or percutaneous drainage) is recommended for large abscesses (more than 6 cm), localization of the abscess in the left lobe of the liver or high in the right lobe of the liver, severe abdominal pain and tension in the abdominal wall due to the possible threat of abscess rupture, as well as in the absence of effect from chemotherapy within 48 hours from the start. Aspiration is also recommended for abscesses of unknown etiology. If closed drainage is impossible, abscess rupture and peritonitis develops, open surgical treatment is performed.

With the appointment of corticosteroids in patients with amebiasis, severe complications can develop, up to the development of toxic megacolon. In this regard, if it is necessary to treat residents of endemic areas with a high risk of infection with E. histolytica with corticosteroids, a preliminary examination for amebiasis is necessary. In case of doubtful results, it is advisable to prescribe preventive amoebocides followed by corticosteroids.

Currently, amoebiasis is an almost completely curable disease, provided early diagnosis and adequate therapy.

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