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