title: A longitudinal study of Angiostrongylus cantonensis in an urban population of Rattus norvegicus in Brazil: the influences of seasonality and host features on the pattern of infection.
abstract: BACKGROUND
  The nematode Angiostrongylus cantonensis is a zoonotic parasite and the most important cause of eosinophilic meningitis worldwide in humans. In Brazil, this disease has been reported in the states of Espírito Santo and Pernambuco. The parasite has been detected in the naturally infected intermediate host, in the states of Rio de Janeiro, Pernambuco and Santa Catarina. The murid Rattus norvegicus R. rattus were recently reported to be naturally infected in Brazil. In this study, we conducted a two-year investigation of the dissemination pattern of A. cantonensis in R. norvegicus in an urban area of Rio de Janeiro state, Brazil, and examined the influence of seasonality, year, host weight and host gender on parasitological parameters of A. cantonensis in rats.
  
  
  METHODS
  The study was conducted in an area of Trindade, São Gonçalo municipality, Rio de Janeiro, Brazil. Prevalence of infected rats, intensity and abundance of A. cantonensis were calculated, and generalized linear models were created and compared to verify the contribution of host gender, host weight, year and seasonality to the variations in A. cantonensis abundance and prevalence in rats.
  
  
  RESULTS
  The prevalence of A. cantonensis infection was stable during the rainy (71%, CI 58.9- 81.6) and dry seasons (71%, CI 57.9-80.8) and was higher in older rats and in females. Seasonality, host weight (used as a proxy of animal age) and gender were all contributing factors to variation in parasite abundance, with females and heavier (older) animals showing larger abundance of parasites, and extreme values of parasite abundance being more frequent in the dry season.
  
  
  CONCLUSIONS
  The high prevalence of this parasite throughout the study suggests that its transmission is stable and that conditions are adequate for the spread of the parasite to previously unaffected areas. Dispersion of the parasite to new areas may be mediated by males that tend to have larger dispersal ability, while females may be more important for maintaining the parasite on a local scale due to their higher prevalence and abundance of infection. A multidisciplinary approach considering the ecological distribution of the rats and intermediate hosts, as well as environmental features is required to further understand the dynamics of angiostrongyliasis.
authors.forename: Raquel O
authors.initials: RO
authors.lastname: Simões
authors.affiliation: Laboratório de Biologia e Parasitologia de Mamíferos Silvestres Reservatórios, Instituto Oswaldo Cruz, Av, Brasil 4365 Manguinhos, 21040-360 Rio de Janeiro, RJ, Brazil. maldonad@ioc.fiocruz.br.
authors.forename: Arnaldo
authors.initials: A
authors.lastname: Maldonado Júnior
authors.forename: Natalie
authors.initials: N
authors.lastname: Olifiers
authors.forename: Juberlan S
authors.initials: JS
authors.lastname: Garcia
authors.forename: Ana Valéria F A
authors.initials: AV
authors.lastname: Bertolino
authors.forename: José L
authors.initials: JL
authors.lastname: Luque
mesh_terms: D000367:Age Factors; D017185:Angiostrongylus cantonensis / Q000235:genetics / Q000302:isolation & purification*; D000818:Animals; D001835:Body Weight; D001938:Brazil / Q000453:epidemiology; D005260:Female; D005843:Geography; D006790:Host-Parasite Interactions; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D015995:Prevalence; D011891:Rain; D051381:Rats; D012376:Rodent Diseases / Q000453:epidemiology* / Q000469:parasitology; D012621:Seasons; D017206:Strongylida Infections / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*