Estrutura da comunidade de helmintos parasitos em Rattus norvegicus (Rodentia: Muridae) no município de São Gonçalo, Estado do Rio de Janeiro, Brasil com ênfase no parasitismo por Angiostrongylus cantonensis (Nematoda: Angiostrongylidae)

Abstract

The aim of this study was to describe the helminth community composition and structure of synanthropic rodent Rattus norvegicus from Trindade located in São Gonçalo, Rio de Janeiro, Brazil. The specific objectives were (1) perform the specific identification of the gastrointestinal helminths collected, (2) determine the influence of abiotic factors: temperature, rainfall; biotic factors: age and sex of host; and associations between helminth species in the structure of the component community of gastrointestinal helminths (3) investigate the pattern of infection of Angiostrongylus cantonensis in these animals during two years, and evaluate the influence of seasonality, as well as the host age and sex, on the observed parasitological parameters (4) determine the prevalence of Calodium hepaticum in R. norvegicus in urban area. One hundred and fourteen R. norvegicus were collected during 2010 and 2011. A total of eight species of helminths was found parasitizing R. norvegicus, of which six species were collected from the gastrointestinal tract. There was a negative correlation between the prevalence of cestode Raillietina sp. and nematode Heterakis spumosa along time of the study. Significant co-occurrence was observed between Nipostrongylus brasiliensis and Strongyloides venezuelensis and between N. brasiliensis and H. spumosa. There was no significant relationship with any independent variable and the occurrence of N. brasiliensis, H. spumosa and Raillietina sp. in univariate logistic regression analyze. The nematodes N. brasiliensis and S. venezuelensis were dominant in the helminth community. The prevalence of A. cantonensis infection remained stable during the rainy and dry season: 71% with a confidence interval of 95% (58.9 to 81.6) and 71%, 95% CI (57.9 to 80.8), respectively, significantly higher in female rats. Seasonality, the host sex and age contributed to variation in parasite abundance, with females and older (heavier) animals showing significantly higher abundances. The prevalence of infection by C. hepaticum was 45% with no significant difference between sex and age of the rodents. The high prevalence of A. cantonensis infection throughout the study suggests a stable pattern of transmission and adequate conditions for the parasite spread. Dispersion of the parasite to new areas may be mediated by males that tend to have larger dispersion ability, while females may be more important for maintaining the parasite on a local. Thus, 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 transmission of angiostrongyliasis and others parasites. Therefore, the presence of rodents infected near the peridomicile is a substantial risk to human health.