New insights into the coexistence of Contracaecum rudolphii A and Contracaecum rudolphii B (Nematoda: Anisakidae) in Phalacrocorax carbo sinensis from Sardinia: genetic variability and phylogenetic analysis.

Contracaecum sp. nematodes are important parasites of fish eating birds that can cause animal health problems. In the present study, specimens of Contracaecum rudolphii sensu lato, from the great cormorant Phalacrocorax carbo sinensis from Sardinia, were characterized based on morphological and molecular data. The morphological analysis allowed to identify all the fourth stage larvae (n = 1918) as Contracaecum sp., and adults, male (n = 5845) and female (n = 8312), as C. rudolphii sensu lato. Population genetics and phylogenetic relationships were inferred based on mitochondrial and nuclear markers. Multiple sequence alignment of the ribosomal internal transcribed spacer showed the coexistence of C. rudolphii A (n = 157), C. rudolphii B (n = 22) and a rare heterozygote of these species. Moreover, mitochondrial markers, namely NADH dehydrogenase subunits I (nad1), cytochrome c oxidase subunit (cox1 and cox2) and small subunit of rRNA (rrnS), showed that the studied C. rudolphii A populations had undergone bottleneck, or founder effect event, subsequent to a rapid population growth and expansion. The observed heterozygote is with a mitochondrial pattern of C. rudolphii B. Although, both Contracaecum species showed high genetic diversity, no genetic structure between localities was detected. Phylogenetic reconstructions supported the paraphyly of the avian Contracaecum species including C. ogmorhini (parasite of otariids).

Determination of Praziquantel in Sparus aurata L. after Administration of Medicated Animal Feed.

Praziquantel (PZQ) is an anthelmintic drug used in humans and animals against Platyhelminthes and in aquaculture in the Far East. Medicated feed is one of the most convenient forms of oral administration of drugs in aquaculture because it allows to treat a large population of fish in an easy way. However, this treatment may lead to residues in fish intended for human consumption. In this study, a liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was developed in order to verify the presence of PZQ in samples of Sparus aurata after oral administration of feed treated with PZQ. The method was validated according to international guidelines. It showed good recoveries, selectivity and sensitivity (LOD and LOQ were 3.0 and 9.3 ng/g, respectively), with precision and matrix effect values ≤ 15%. This method could also be applied to determine PZQ residue in other fish species and thus to evaluate the appropriate withdrawal time in treated fish intended for human consumption.