Schistosomiasis mansoni in Bananal (State of Säo Paulo, Brazil). IV. study on the public awareness of its risks in the Palha District

A rather high prevalence of mansoni schistosomiasis has been observed in some localities of Bananal, State of Säo Paulo, during the past decade. The highest prevalence of schistosomiasis was found in the Palha District; it was thus considered adequate for an evaluation of public awareness of the risks involved in acquiring schistosomiasis, a likely outcome of certain behavior patterns. We interviewed 542 district-dwellers. The 5-to-39 age-group constituted 65.5 percent of the whole sample. Concerning the infection, 69.2 percent had hearsay information; 46.1 percent know the infection; 69.6 percent know how it is acquired; 31.5 percent know about the symptoms and 57.1 percent know what can be done to avoid infection; 17.7 percent declared to have acquired the infection at least once in their lifetime; 62.3 percent reported total or partial immersion in collections of water of Bananal, once or twice a week, 53.9 percent of these for bathing or fishing. Although most (91.7 percent) households have treated running water, are connected to the sewage network or have septic tanks, 9 percent of the people interviewed use to defecate on the field. It became clear that the educational messages aimed at this population had not been adequate, having failed to fulfil any expectations. The local people received only piecemeal and subjective information about their problem. The control of schistosomiasis requires an integrated practice, which includes the analysis of macro-determinant factors, such as basic sanitation, habitation, education and health care. In short, we require a multidisciplinary vision of the mechanisms of transmission of the infection, which depends upon adequate planning and well trained personnel, intent on their educational work, to attain satisfactory results

Specific identification of Biomphalaria tenagophila and Biomphalaria occidentalis populations by the low stringency polymerase chain reaction

Althrough Biomphalaria occidentalis and B. tenagophila are indisguishable on the basis of shell morphology and the majority of their genital organs, only the latter is susceptible to infection with Schistosoma mansoni. Thus, the identification of these species is fundamental to epidemiological studies of schistosomiasis. Here we describe a simple and rapid method for differentiating B. tenagophila from B. occidentalis based on low stringency polymere chain reaction and using a pair of primers specific for the amplification of the 18S rRNA gene. Analysis of the low stringency product profiles of populations of these snails from different geographical regions confirmed this approach as being applicable to the identification of B. tenagophila and B. occidentalis in cases where classical morphology is inconclusive.