Amoebiasis

Simon Drysdale
More..
print
Stool Microscopy
Stool microscopy can demonstrate cysts or trophozoites but usually cannot differentiate different species of amoeba (i.e. E. histolytica versus E. dispar versus E. moshkovskii). Noting ingested erythrocytes within amoeba is suggestive of E. histolytica, but can also be found in the usually non-pathogenic E. dispar. At least three stool samples on separate days should be examined and this can detect up to 95% of infections.

Antigen tests can reliably (>95%) distinguish between E. histolytica and E. dispar and are commercially available. They can be used on both stool and serum samples and are more sensitive than stool microscopy. In endemic areas they are especially useful as serological tests may be difficult to interpret.

Serological tests are useful in non-endemic settings but much less so in endemic areas as up to 35% of asymptomatic individuals in endemic areas will have antibodies from a previous infection. Thus a negative test can exclude the disease but a positive test could infer acute or previous infection. Over 90% of individuals develop antibodies to E. histolytica whereas antibodies are not generally formed against E. dispar. Antibodies are present from five to seven days after acute infection and can persist for many years.

Molecular techniques, including polymerase chain reaction (PCR), are more sensitive and specific than either microscopy or antigen tests but are expensive and not yet widely available.

In ambiguous cases histological samples from either colonoscopy biopsies or surgical samples can be examined for amoebic trophozoites or cysts. Histology may show non-specific mucosal inflammation or amoebic ulcers. Samples are best obtained from ulcer margins. Microscopy, antigen tests or molecular techniques can be used to examine histological samples for amoeba.

Imaging of the gastrointestinal tract using ultrasound, CT or MRI may be useful in some cases.

There are several techniques for diagnosing amoebic dysentery including direct microscopy, antigen detection, serology, molecular techniques and histology from intestinal biopsies.
Stool microscopy can demonstrate cysts or trophozoites but usually cannot differentiate different species of amoeba (i.e. E. histolytica versus E. dispar versus E. moshkovskii). Noting ingested erythrocytes within amoeba is suggestive of E. histolytica, but can also be found in the usually non-pathogenic E. dispar. At least three stool samples on separate days should be examined and this can detect up to 95% of infections.


References
Amoebiasis Amoebiasis 2/13/2016
<< Amoebiasis - Differential Diagnoses Amoebiasis Treatment >>
ask doctor
Ask a Doctor
Disclaimer: The information given by www.pediatriconcall.com is provided by medical and paramedical & Health providers voluntarily for display & is meant only for informational purpose. The site does not guarantee the accuracy or authenticity of the information. Use of any information is solely at the user's own risk. The appearance of advertisement or product information in the various section in the website does not constitute an endorsement or approval by Pediatric Oncall of the quality or value of the said product or of claims made by its manufacturer.