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BackgroundThe rat lungworm Angiostrongylus cantonensis can cause eosinophilic meningoencephalitis in humans. This nematode’s main definitive hosts are rodents and its intermediate hosts are snails. This parasite was first described in China and currently is dispersed across several Pacific islands, Asia, Australia, Africa, some Caribbean islands and most recently in the Americas. Here, we report the genetic variability among A. cantonensis isolates from different geographical locations in Brazil using mitochondrial cytochrome c oxidase subunit I (COI) gene sequences.MethodsThe isolates of A. cantonensis were obtained from distinct geographical locations of Brazil. Genomic DNAs were extracted, amplified by polymerase reaction, purified and sequenced. A partial sequence of COI gene was determined to assess their phylogenetic relationship.ResultsThe sequences of A. cantonensis were monophyletic. We identified a distinct clade that included all isolates of A. cantonensis from Brazil and Asia based on eight distinct haplotypes (ac1, ac2, ac3, ac4, ac5, ac6, ac7 and ac8) from a previous study. Interestingly, the Brazilian haplotype ac5 is clustered with isolates from Japan, and the Brazilian haplotype ac8 from Rio de Janeiro, São Paulo, Pará and Pernambuco states formed a distinct clade. There is a divergent Brazilian haplotype, which we named ac9, closely related to Chinese haplotype ac6 and Japanese haplotype ac7.ConclusionThe genetic variation observed among Brazilian isolates supports the hypothesis that the appearance of A. cantonensis in Brazil is likely a result of multiple introductions of parasite-carrying rats, transported on ships due to active commerce with Africa and Asia during the European colonization period. The rapid spread of the intermediate host, Achatina fulica, also seems to have contributed to the dispersion of this parasite and the infection of the definitive host in different Brazilian regions.

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Resumo: O caramujo africano invasor Achatina fulica foi introduzido no Brasil a partir de Estados do Sul e Sudeste em pelo menos três ocasiões. Atualmente sua distribuição já abrange 24 dos 26 estados e o Distrito Federal. Populações densas dessa espécie vêm causando incômodos à populações humanas, danos à jardins e pequenas plantações, além de atuarem como transmissoras de duas zoonoses (angiostrongilíase abdominal e meningoencefalite eosinofílica) e outras parasitoses de interesse veterinário. No presente estudo, apresentamos novas ocorrências de A. fulica no Estado do Rio de Janeiro (Brasil) assim como dados sobre as larvas de nematódeos de interesse médico e veterinário encontradas em exemplares dessa espécie coletados neste estado. A. fulica está presente em 26 municípios adicionais em relação aos dados obtidos em 2006, ano do último levantamento, representando um aumento de 50% no número de municípios infestados. Apenas nove dos 92 municípios do estado ainda não registram a presença dessa espécie. Larvas dos nematódeos Aelurostrongylus abstrusus, Rhabditis sp. e Strongyluris-like, todas com importância veterinária, foram encontradas em exemplares de A. fulica de onze municípios. A rápida dispersão de A. fulica evidencia a necessidade de planos de manejo contínuos e eficientes em todo o país visando o controle efetivo dessa invasão. A erradicação de A. fulica é pouco provável devido ao nível atual de infestação. Palavras-chave: Achatina fulica, Gastropoda, espécie invasora, distribuição, saúde pública.

The aim of this study was to analyse the infection dynamics ofAngiostrongylus cantonensis in its possible intermediate hosts over two years in an urban area in the state of Rio de Janeiro where the presence ofA. cantonensis had been previously recorded in molluscs. Four of the seven mollusc species found in the study were exotic.Bradybaena similaris was the most abundant, followed byAchatina fulica, Streptaxis sp., Subulina octona, Bulimulus tenuissimus, Sarasinula linguaeformis and Leptinaria unilamellata. Only A. fulica and B. similaris were parasitised by A. cantonensis and both presented co-infection with other helminths. The prevalence of A. cantonensisin A. fulica was more than 50% throughout the study. There was an inverse correlation between the population size ofA. fulica and the prevalence of A. cantonensis and abundance of the latter was negatively related to rainfall. The overall prevalence of A. cantonensis in B. similariswas 24.6%. A. fulica was the most important intermediary host of A. cantonensis in the studied area andB. similaris was secondary in importance for A. cantonensis transmission dynamics.