Description, microhabitat selection and infection patterns of sealworm larvae (Pseudoterranova decipiens species complex, Nematoda: Ascaridoidea) in fish from Patagonia, Argentina.

HERNÁNDEZ-ORTS J.S; AZNAR F.J.; BLASCO-COSTA ; ALAMA-BERMEJO G.; CRESPO E.; RAGA J.A.; ESTEBAN MONTERO F.

Quebec

Congreso; 88TH ANNUAL MEETING OF THE AMERICAN SOCIETY OF PARASITOLOGISTS; 2013

Third stage larvae of the Pseudoterranova decipiens species complex (also known as sealworms) have been reported in at least 40 marine fish species belonging to 21 families and 10 orders along the South American coast. Sealworms are a cause for concern because they can infect humans who consume raw or undercooked fish (e.g. ceviche, a popular seafood dish from South America). However, despite their economic and zoonotic importance, morphological and molecular characterization of species of Pseudoterranova in South America is still underway. In this study we provide, molecular, morphological, and ecological data on the sealworm larvae in 542 individuals of 20 fish species from the neritic zone of the Patagonian Sea (Southwestern Atlantic). A total of 635 sealworm larvae were collected from 12 fish species. The most infected fish species was Prionotus nudigula (n = 32; prevalence [95% C.I.]: 100% [89.5-100]; mean intensity [95% C.I.]: 16.2 [12.5-20.9]), followed by Paralichthys isosceles (15; 26.7% [9.7-53.4]; 2.8 [1.0-5.5]), and Pseudopercis semifasciata (31; 25.8% [12.6-43.4]; 1.4 [1.0-1.6]). Most of the sealworms were collected from the muscles (mainly in the epaxial musculature), and to a lesser degree, from the mesenteries and liver. Sequences obtained for the mitochondrial cytochrome c oxidase subunit 1 gene (cox 1) of sealworms from P. nudigula formed a reciprocally monophyletic lineage with published sequences of P. cattani from definitive hosts. Morphology of sealworms from all the fish did no differ, but a discriminant analysis suggests that specimens from P. nudigula were significantly larger than those from other fish. Our results suggest that the most economically important fishes from this locality, i.e. Merluccius hubbsi, Genypterus blacodes and Seriolella porosa have low sealworm infections. Interestingly, despite the high density of pinnipeds (definitive hosts) inhabiting the Patagonian coast, levels of sealworm infection in large demersal fish from this area seem to be much lower than infections reported in demersal fish from the Northern Hemisphere.