First report of the metacestode Caulobothrium sp. in the Peruvian scallop Argopecten purpuratus from Sechura Bay, Piura, Peru.

In recent parasitological surveys performed on the Peruvian scallop, Argopecten purpuratus, from bottom cultures of Sechura Bay, Piura, Peru, free and encysted metacestodes were frequently found in their gonads. The objective of this study was to identify this metacestode, determine their prevalence and intensity and briefly assess the histopathological impact in the affected tissues. A parasitological study of 890 scallops over a 3-year period was performed in order to determine the parasite prevalence and intensity. Microscopical observation of details of the scolex and histopathological study of the affected host tissues were performed as well as molecular characterization of the parasite based on 18S and 28S rDNA sequences. The prevalence of the metacestode was 82.2% in August of 2013, 90.4% in November of 2014, and 83.1% and 85.6% in April and September of 2015, respectively. The highest average intensity (218.4) was found in spring of 2014. The histopathological study showed that plerocercoids reduced the gonadal space where the ovules develop. The molecular characterization and phylogenetic analysis revealed that the metacestodes belong to the genus Caulobothrium having high sequence similarity to Caulobothrium opisthorchis. This study constitutes the first report of Caulobothrium metacestodes in the scallop A. purpuratus.