Discriminação da infecção causada pela Entamoeba histolytica (Schaudinn, 1903) e Entamoeba dispar (Brumpt, 1925) em escolares da rede pública da cidade de Maceió-AL

Abstract

Amebiasis is a severe infection caused by the protozoan parasite Entamoeba histolytica (Schaudinn, 1903). This species is morphologically indistinguishable from Entamoeba dispar (Brumpt, 1925), considered to be non-pathogenic and unable to cause invasive illness. The differentiation between these two species by immunological and molecular biology techniques is important to determine the epidemiological situation, therapeutic intervention, and profilaxis of invasive amebiasis. The aim of this study was to discriminate infection caused by E. histolytica and E.dispar in schoolchildren population in the city of Maceió, Alagoas. A cross-sectional study was carried out among 1,003 students in state public schools. Stool examination by sedimentation technique was conducted in order to evaluate frequency of enteroparasites, and for screening of students infected with E. histolytica/E. dispar complex. Positive exams for Entamoeba cysts were further submitted to antigen detection assay by enzyme-linked immunosorbent assay (ELISA), and polymerase chain reaction (PCR), for specific diagnosis of the infection. Frequency of intestinal parasites among the examined population was high, being detected 54.8% (550/1,003) students harbouring at least one species of helminth or protozoan parasites. Most of the students families (57.5%), belonged to class D economic level according to the Brazilian Economic Classification Criteria. Of the total assessed 83.1% had an income ≤ 1 minimum wage and lived in households with 2-5 residents. Polymerase chain reaction (PCR) was standardized extracting DNA from the stool using Stool Kit PSP (Invitek ®). The primers selected by in silico analysis based on virtual performance for amplification of E. histolytica and E. dispar were p11plus/p12plus and p13plus/p14plus, respectively. The prevalence of amebiasis among schoolchildren diagnosed by ELISA was 3.0% (30/1,003) and by PCR 2.8% (28/1,003), but the difference was not statistically significant (p> 0.05). The overall prevalence of E. dispar in schoolchildren was 5.0% (50/1,003). Both techniques (ELISA and PCR) were appropriate for differential diagnosis of E. histolytica and E. dispar. However, ELISA has advantages such as its rapid and easy execution. The results indicates the importance of specific diagnostic techniques for amoebiasis detection in the population.