The stool examination reports amoeba cysts: should you treat in the face of over diagnosis and lack of specificity of light microscopy?

Amoebiasis is a common clinical diagnosis in tropical settings and clinicians continue to treat asymptomatic carriers diagnosed by light microscopy. A minority of carriers, however, are infected with Entamoeba histolytica and the remaining with the non-pathogenic Entamoeba dispar. We compared the diagnostic results of 298 asymptomatic residents of Aracaju, Brazil, obtained by different diagnostic methods, and ascertained their clinical symptoms, to highlight the implications for practitioners. Fifty-eight (19.4%) specimens were amoebae positive by microscopy. Of these, 38 (13%) were E. histolytica/E. dispar enzyme-linked immunosorbent assay (ELISA) positive and 4 (1%) E histolytica ELISA positive. The frequent use of anti-amoebic treatment on the basis of non-specific symptoms and the findings of light microscopy tests is not justified. Methods for the specific diagnosis of E. histolytica infection for developing countries are urgently needed.