title: Freshwater gastropods of the Baixada Maranhense Microregion, an endemic area for schistosomiasis in the State of Maranhão, Brazil: I - qualitative study.
abstract: BACKGROUND
  The Baixada Maranhense Microregion currently has the highest prevalence of schistosomiasis in the State of Maranhão, likely because this parasitosis is characterized as an occupational disease, and increased contact with water increases the risk of infection by Schistosoma mansoni. This paper reports the results of the first comprehensive freshwater malacological survey performed in the Baixada Maranhense Microregion.
  
  
  METHODS
  Freshwater mollusks were collected from the twenty-one municipalities of the Baixada Maranhense Microregion and from Bacurituba and Cajapió and were evaluated for infection by trematodes.
  
  
  RESULTS
  A total of 9,129 mollusks were collected (sixteen species), which included the first records of six species in the State of Maranhão: Gundlachia radiata, G. ticaga, Hebetancylus moricandi, Plesiophysa guadeloupensis, Pomacea bridgesii diffusa and Omalonyx sp. Biomphalaria glabrata was found in five municipalities, whereas B. straminea was found in nine. Biomphalaria glabrata and B. straminea were observed in syntopy in Pinheiro and São Bento. Of the 990 specimens of B. glabrata and the 2,109 specimens of B. straminea that were exposed to and/or analyzed for the presence of larval trematodes, only a single specimen of B. glabrata (0.1%) from São Bento shed S. mansoni. Other larval trematodes were first observed in mollusks from the State of Maranhão.
  
  
  CONCLUSIONS
  These results indicate that the study area is epidemiologically important due to the presence of two natural vectors of schistosomiasis and the active transmission of schistosomiasis, which was confirmed in the infected specimen that was collected in this study.
authors.affiliation: Laboratório de Malacologia, Instituto Oswaldo Cruz, Rio de JaneiroRJ, Laboratório de Malacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, RJ.
authors.forename: Selma Patricia Diniz
authors.initials: SP
authors.lastname: Cantanhede
authors.affiliation: Laboratório de Malacologia, Instituto Oswaldo Cruz, Rio de JaneiroRJ, Laboratório de Malacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, RJ.
authors.forename: Monica Ammon
authors.initials: MA
authors.lastname: Fernandez
authors.affiliation: Laboratório de Malacologia, Instituto Oswaldo Cruz, Rio de JaneiroRJ, Laboratório de Malacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, RJ.
authors.forename: Aline Carvalho de
authors.initials: AC
authors.lastname: Mattos
authors.affiliation: Laboratório de Malacologia, Instituto Oswaldo Cruz, Rio de JaneiroRJ, Laboratório de Malacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, RJ.
authors.forename: Lângia Colli
authors.initials: LC
authors.lastname: Montresor
authors.affiliation: Departamento de Química e Biologia, Centro de Educação Ciências Exatas e Naturais, Universidade Estadual do Maranhão, São LuísMA, Departamento de Química e Biologia, Centro de Educação Ciências Exatas e Naturais, Universidade Estadual do Maranhão, São Luís, MA.
authors.forename: Nêuton
authors.initials: N
authors.lastname: Silva-Souza
authors.affiliation: Laboratório de Malacologia, Instituto Oswaldo Cruz, Rio de JaneiroRJ, Laboratório de Malacologia, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, RJ.
authors.forename: Silvana Carvalho
authors.initials: SC
authors.lastname: Thiengo
mesh_terms: D000818:Animals; D001938:Brazil; D004199:Disease Vectors / Q000145:classification*; D005618:Fresh Water; D049851:Gastropoda / Q000145:classification* / Q000469:parasitology; D011156:Population Density; D036301:Qualitative Research; D012552:Schistosomiasis / Q000635:transmission