Potential for shistosomiasis in a municipality of Rondônia, Brazilian Amazon

Abstract

Schistossomiasis is a parasitic disease, caused by helminths of the genus Schistosoma and transmitted in Brazil by snails of the genus Biomphalaria. The municipality of Ouro Preto do Oeste, Rondônia, in the Brazilian Amazon Region, has unusually registered more than 900 cases of schistosomiasis in the last 10 years. The aim of this study was to investigate de potential of transmission of schsitosomiasis in Ouro Preto do Oeste. A total of 1,196 people in a risk area for the disease transmission were requested to answer a clinical-epidemiological survey and to collect feces samples for examination. All the samples that underwent examination resulted negative for S. mansoni. Two hundred and sixty-eight snails were collected in the locality of Ouro Preto do Oeste in 32 different locations. Among these, 44% were classified as belonging to the genus Biomphalaria. Another sample of snails (146 specimens), collected at the same sites, were submitted to an in vitro challenge with Schistosoma mansoni, and none of them were able to transmit the parasite. Finally, we discuss the epidemiological importance of these findings and the lack of attention to a patient with the disease in a non-endemic area. We failed to detected any association between shistossomiasis and the snails from the genus Biomphalaria, that exists in the local, as the planorbids were unable to transmit Shistosoma mansoni. Perhaps the small sample and/or the stool examination technique can have contributed to the results. Further studies, in other localities of Rondônia and with a greater sample could put some light in this question. KEYWORDS: Schistosomiasis; Amazon; Transmission. Potencial de transmissão de esquistossomose em município de Rondônia, Amazônia brasileira RESUMOA esquistossomose é uma doença parasitária, causada por helmintos do gênero Schistosoma e transmitida no Brasil por caramujos do gênero Biomphalaria. O município de Ouro Preto do Oeste, Rondônia, Amazônia brasileira, notificou, de forma não usual, mais de 900 casos de esquistossomose mansônica nos últimos 10 anos. O objetivo deste estudo foi investigar o potencial de transmissão da esquistossomose em Ouro Preto do Oeste. Um total de 1.196 pessoas residindo em áreas de risco para a transmissão da doença foram abordadas para responderem um questionário clínico-epidemiológico e realização de exame parasitológico de fezes. Todas as amostras foram negativas para S. mansoni. Duzentos e sessenta e oito caramujos foram coletados em Ouro Preto do Oeste, de 32 localidades diferentes. Entre estes, 44% foram classificados como pertencendo ao gênero Biomphalaria. Outra amostra de caramujos (146 exemplares), coletada nos mesmos locais, foi submetida in vitro a cepas de Schistosoma mansoni, sendo todos incapazes de transmitirem o parasito. Por fim, discute-se a importância epidemiológica desses achados e a falta de atenção ao paciente portador da parasitose em áreas indenes. O estudo não conseguiu demonstrar a ocorrência de transmissão na localidade e nem a habilidade dos planorbídeos locais...

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