SEROEPIDEMIOLOGY OF ENTAMOEBA-HISTOLYTICA IN A SLUM IN NORTHEASTERN BRAZIL

Infection with the human pathogenic parasite Entamoeba histolytica has not been well-characterized in northeastern Brazil. In this study, th e prevalence of E. histolytica infection in a slum in northeastern Bra zil was assayed using an enzyme-linked immunosorbent assay (ELISA) for antibodies against the galactose/N-acetyI-D-galactosamine (Gal/GalNAc )-inhibitable adherence lectin of E. histolytica. Sera from a total of 335 individuals were examined for anti-Gal/GalNAc lectin antibodies. The overall seropositivity was 24.7%; 29.4% of females and 19.4% of ma les were positive. Among different age groups there was a peak of 40% positivity in the 6-14-year-old age group. There was also familial clu stering of seropositivity. To examine colonization, stool samples from 155 people were examined microscopically for the presence of the para site. Fourteen of 155 stools (9.0%) were identified as containing E. h istolytica or nonpathogenic E. dispar. These 14 positive stools were a nalyzed with an ELISA that detects Gal/GalNAc lectin antigen and can d istinguish between E. histolytica and E. dispar. Four stools (29%) wer e positive for E. histolytica and the remaining 10 were identified as E. dispar-positive. Although the overall colonization rate by microsco py was only 9%, with a third identified as E. histolytica, up to 40% o f older children develop serologic evidence of having experienced path ogenic E. histolytica infection. The results of this study demonstrate that this community in northeastern Brazil is highly endemic for E. h istolytica with infection rates similar to other developing nations.