title: Biomphalaria species distribution and its effect on human Schistosoma mansoni infection in an irrigated area used for rice cultivation in northeast Brazil.
abstract: The role of irrigated areas for the spread of schistosomiasis is of worldwide concern. The aim of the present study was to investigate the spatial distribution of the intermediate snail host Biomphalaria in an area highly endemic for schistosomiasis due to Schistosoma mansoni, evaluating the relationship between irrigation and types of natural water sources on one hand, and the influence of place and time of water exposure on the intensity of human infection on the other. A geographical information system (GIS) was used to map the distribution of the intermediate snail hosts in Ilha das Flores, Sergipe, Brazil, combined with a clinical/epidemiological survey. We observed a direct correlation between the intensity of human infection with S. mansoni and irrigation projects. Malacological studies to identify snail species and infection rates showed that B. glabrata is the main species responsible for human schistosomiasis in the municipality, but that B. straminea also plays a role. Our results provide evidence for a competitive selection between the two snail species in rice fields with a predominance of B. glabrata in irrigation systems and B. straminea in natural water sources.
authors.affiliation: Laboratório de Biologia Molecular, Departamento de Medicina, Hospital Universitário, Universidade Federal de Sergipe, Rua Cláudio Batista, s/n, Hospital Universitário, 49.060-100, Aracaju, Sergipe, Brazil.
authors.forename: Delmany Moitinho
authors.initials: DM
authors.lastname: Barboza
authors.forename: Cangjie
authors.initials: C
authors.lastname: Zhang
authors.forename: Nathaly Cardoso
authors.initials: NC
authors.lastname: Santos
authors.forename: Marília Matos Bezerra Lemos
authors.initials: MM
authors.lastname: Silva
authors.forename: Carla Virgínia Vieira
authors.initials: CV
authors.lastname: Rollemberg
authors.forename: Fabio Jorge Ramalho
authors.initials: FJ
authors.lastname: de Amorim
authors.forename: Marlene Tiduko
authors.initials: MT
authors.lastname: Ueta
authors.forename: Claudia Moura
authors.initials: CM
authors.lastname: de Melo
authors.forename: José Antônio Pacheco
authors.initials: JA
authors.lastname: de Almeida
authors.forename: Verónica de Lourdes Sierpe
authors.initials: Vde L
authors.lastname: Jeraldo
authors.forename: Amélia Ribeiro
authors.initials: AR
authors.lastname: de Jesus
mesh_terms: D057914:Agricultural Irrigation; D000818:Animals; D001700:Biomphalaria; D001938:Brazil / Q000453:epidemiology; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D016208:Databases, Factual; D016021:Epidemiologic Studies; D040362:Geographic Information Systems; D006801:Humans; D012275:Oryza; D015995:Prevalence; D012555:Schistosomiasis mansoni / Q000453:epidemiology* / Q000635:transmission; D012908:Snails; D018709:Statistics, Nonparametric