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The objective this study was to determine the occurrence of the species Entamoeba histolytica/Entamoeba díspar in clinical samples of ambulatory patients in Pernambuco. A specific assay for Entamoeba histolytica was used in this study, which identified no positive fecal samples among the 213 patients. These results confirm that E. dispar is the dominant species in Pernambuco State.

The genetic variability of Entamoeba dispar strains was investigated in 39 positive isolates on a survey of 1783 individuals from two different cities of Northeast Brazil (Recife and Macaparana) using two polymorphic species-specific loci (loci 1-2 and 5-6). A combinatory clustering analysis revealed no geographical correlation and remarkable genetic polymorphism among all the isolates examined. Nevertheless, a comparison of the frequency of eight individual PCR products, shared by both Recife and Macaparana populations, for the two loci, showed that only one product of locus 5-6 was significantly different between the two cities. These results suggested that the Macaparana population is infected by similar strains and that locus 5-6 shows potential in assaying questions related to the molecular epidemiology of this region.

Exames parasitológicos foram realizados em amostras fecais de 663 indivíduos residindo em três cidades do estado de Pernambuco, Nordeste brasileiro: Recife, Palmares e Bodocó. A população de Bodocó, situada na região do semi-árido de Pernambuco, foi investigada para amebíase e comparada com a do Recife, cidade metropolitana com cerca de 1,3 milhões de habitantes, e com outra da zona de plantação de cana-de-açucar do estado, Palmares. Não foi observada evidência da presença de cêpas invasivas de E. histolytica nesses habitantes desde que aquelas isoladas das amostras fecais, com zimodomas dos tipos I, III, IV, VIII, IX, X, XVII e XVIII, são reconhecidas como não patogênicas. Ademais, a prevalência de helmintos intestinais e de infecções por protozoários mostrou que esses indivíduos são infectados por outros agentes responsáveis por quadros diarréicos. Parasitological examinations were carried out on 663 individuals of three different cities of Pernambuco State, Northeastern Brazil: Recife, Palmares and Bodocó. The population from a drought area of Pernambuco State, Bodocó, was investigated for amoebiasis and compared with Recife, metropolitan city (about 1.3 million of inhabitants) and another inland community, Palmares, located inside of the sugar-cane plantation region of the State. No evidence of invasive strains of E. histolytica were found in these inhabitants, provided that the isolated zymodemes I, III, IV, VIII, IX, X, XVII and XVIII are recognized as nonpathogenic strains of E. histolytica. Furthermore, the prevalence of intestinal helminths and other protozoan infections showed that these individuals are infected by other agents responsible for diarrhoeal diseases.

The pathogenicity of 47 strains of Entamoeba histolytica isolated in Pernambuco, Brazil, was examined using the polymerase chain reaction (PCR) followed by restriction-endonuclease digestion. Electrophoretic patterns of PCR products digested with HinfI revealed that all strains were nonpathogenic. The results were entirely in accord with phenotypic properties such as isoenzyme patterns and the failure to bind a pathogenic-isolate-specific monoclonal antibody. When the sensitivity of PCR was examined, amplified products could be detected from template DNA equivalent to five trophozoites. These observations indicate that PCR amplification of genomic DNA and subsequent restriction-enzyme digestion is a useful strategy for obtaining a sensitive and accurate diagnosis. The present study also demonstrates that nonpathogenic strains of E. histolytica predominate in northeastern Brazil.

Parasitological examinations were carried out during July to December, 1989, on 485 inhabitants of four villages in São Lourenço da Mata, 25 km northwest of Recife, Pernambuco, Brazil. Approximately 99.6% of the inhabitants were infected with at least one species of intestinal parasites. A high prevalence of Schistosoma mansoni (82.1%), hookworm (80.2%) Trichuris trichiura (69.9%), Ascaris lumbricoides (61.9%) and Entamoeba coli (36.7%) infections were demonstrated. Test tube cultivation revealed that the most common species of hookworm in this region was Necator americanus (88.4%), and also that the prevalence of Strongyloides stercoralis was 5.8%. Three hundred and thirty-four sera were serologically examined for amoebiasis by the gel diffusion precipitation test (GDP) and enzyme-linked immunosorbent assay (ELISA). No positive reaction was observed in all sera as examined by GDP, while 24 sera were positive by ELISA.