engleski

Anisakis spp. from large pelagic fish off Eastern Adriatic - molecular identification and risk analysis

Nematodes of the genus Anisakis Dujardin, 1845 are considered an emerging public health issue due to anisakiasis, a zoonotic disease caused by consumption of raw or lightly processed infected seafood. Previous study conducted in county of Dalmatia, Croatia, has shown particularly high anti-Anisakis IgE seroprevalence among island population where thermally unprocessed, salted or marinated fish is a staple food. In order to assess occurrence of Anisakis larvae in fish frequently consumed among Dalmatian island population and possible health risks, we concentrated in collecting large and valuable four pelagic fish species, caught off the coast of Dalmatian islands (chub macekerel, Scomber japonicus, horse mackerel, Trachurus trachurus, little tunny, Euthynnus alletteratus and atlantic bluefin tuna, Thunnus thynnus). Fish were eviscerated, filleted into butterfly fillets, pressed under hydraulic press and examined under UV light to reveal the presence of larvae in visceral mass and fillets. Prevalence, mean intensity and mean abundance were calculated using Quantitative Parasitology 3.0 software. For molecular identification genomic DNA was isolated. A ~650 bp fragment of mitochondrial cytochrome oxidase 2 (COX2) locus was amplified and sequenced. Obtained sequences were aligned and a phylogenetic tree has been inferred using Bayesian Inference. In total 349 Anisakis larvae were isolated, while total prevalence was 64, 4% (Sterne's exact 95% CI 0, 48 to 0, 77), mean intensity 12, 03 (bootstrap 95% CI 7, 03 to 20, 55) and mean abundance 7, 76 (boostrap 95% CI 4, 16 to 13, 67). All three values differ between species, with highest prevalence observed in little tunny (E. alletteratus), while highest mean intensity and mean abundance were observed in chub mackerel (S. japonicus). Molecular identification revealed A. pegreffii to be the predominant species, while only few A. simplex were identified. Although both A. pegreffii and A. simplex are capable of penetrating into fish muscle, the later has up to 12 times higher ability to migrate postmortem into fillets. Given this fact and epidemiological data collected, the risk of infection by consumption of targeted fish among Dalmatian island population is moderate.

Risk assessment; Anisakidae; Mediterranean Sea; cytochrome oxidase 2

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