Resumo

REYES, L  e  LEON, R. Diferenciación de Entamoeba histolytica / entamoeba dispar y  los nuevos hallazgos en la patogénesis de la amibiasis intestinal. Rev. costarric. cienc. méd [online]. 2002, vol.23, n.3-4, pp.161-173. ISSN 0253-2948.

The introduction of molecular techniques allowed the differentiation of Entamoeba histomica from E. dispar, a comensal ameba morphologically indistinguisable from E. histolytica. Pathogenic mechanisms of E. histolytica inciudes the presence of a galactosa binding lectin that attachs trophozoites to intestinal epithelial cells. Also pore-forming peptides termed amebopores have been demonstrated, this peptides oligomerize after insertion in the cell membrane and form waterfilled channels through which ions and other molecules can pass, causing cell lysis. Cysteine proteasas have also been characterized as a viruience factor responsable of the degradation of the extracellular matrix and the evasion of the immune response by degradation of IgA, disruption of IgG, and degradation of anaphylotoxins C3a and C5a. The new epidemiological findings around the worid by the use of molecular technics are also discussed. In Costa Rica seroprevalence of 7,3% in E.histoyica / E.dispar cysts positive patients is taken an indication that the majority of the infections are caused by E. dispar. Antibody are present only in E. histoyica infection. As far as diagnosis, the finding of trofozoites with enguifed eritrocytes in fresh fecal samples or biopses correlates with E. histoyica. On the other hand, cysts of both protozoa are indistinguisable. Several immunological technics are available for the determination of antigen in stool samples or antibodies in sera.

Palavras-chave : pathogenesis; epidemiology; diferencial diagnosis.