title: Does the trematode Centrocestus formosanus affect the locomotory activity of the mollusc Melanoides tuberculatus?
abstract: BACKGROUND
  Melanoides tuberculatus (Müller, 1774) (Thiaridae), an introduced gastropod mollusc with a wide geographical distribution in the Neotropics, is the intermediate host of the trematode Centrocestus formosanus (Nishigori, 1924) (Heterophyidae). This parasite is considered to be pathogenic to humans. The aim of the present work was to evaluate the locomotory activity of uninfected M. tuberculatus compared with those naturally infected with C. formosanus.
  
  
  RESULTS
  The locomotory activity of each mollusc was recorded using an image analysis biomonitoring system, Videomex-V, to evaluate and quantify the parameters of 'Stereotypic' and 'Resting time'. The Generalized Estimating Equation analysis of locomotory activity of M. tuberculatus infected with C. formosanus revealed significant differences compared with uninfected molluscs for the parameters 'Stereotypic time' and 'Resting time' with a reduction of movement. The variations in the values of the monitoring intervals recorded showed a significant difference for the infected molluscs in the case of Stereotypic time, with an irregular locomotory activity pattern, as compared to that of uninfected molluscs. The analysis of the standard length of all molluscs did not exhibit any correlation with locomotory activity, showing that C. formosanus is able to alter the locomotory activity of its snail host regardless of the standard length.
  
  
  CONCLUSIONS
  The trematode C. formosanus affects the locomotory activity of the mollusc M. tuberculatus by reducing its movement and causing it to exhibit an irregular pattern of activity, both of which are independent of the snail's standard length.
authors.affiliation: Laboratório de Avaliação e Promoção da Saúde Ambiental, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av, Brasil, 4,365, Manguinhos, Rio de Janeiro 21040-360, Brazil.
authors.forename: Everton Gustavo Nunes
authors.initials: EG
authors.lastname: dos Santos
authors.forename: Viviane da Silva
authors.initials: Vda S
authors.lastname: Costa
authors.forename: Cláudia Portes
authors.initials: CP
authors.lastname: Santos
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods; D006578:Heterophyidae / Q000472:pathogenicity*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008124:Locomotion; D008974:Mollusca / Q000469:parasitology* / Q000502:physiology*; D014201:Trematode Infections / Q000469:parasitology / Q000473:pathology