# Determinants of Ascaridoid Nematode Infection and Anisakis‐Related Zoonotic Exposure Risk in Eastern Mediterranean Gadiformes Fishes

## TL;DR

This study examines nematode parasites in two fish species from the Eastern Mediterranean, finding that Anisakis larvae pose a minor but real zoonotic risk, especially in certain parts of the fish.

## Contribution

The study provides new insights into the seasonal and physiological factors influencing Anisakis infection in sympatric fish species and quantifies the zoonotic risk using a QRA approach.

## Key findings

- Anisakis pegreffii was the dominant nematode species in both European hake and greater forkbeard.
- Infection levels correlated more with host physiological state and seasonality than with fish size.
- Only a small proportion of larvae were found in edible muscle tissue, suggesting minimal direct zoonotic risk.

## Abstract

Larvae of ascaridoid nematodes, particularly Anisakis spp., are common parasites of commercially important marine fishes and may represent a zoonotic hazard following ingestion of raw or undercooked seafood. We investigated the ascaridoid fauna of the sympatric European hake (Merluccius merluccius) and greater forkbeard (Phycis blennoides) from the Ionian Sea (Eastern Mediterranean), integrating host biometric and seasonal drivers with molecular identification and quantitative risk assessment (QRA) for the zoonotic Anisakis pegreffii. Anisakis pegreffii was the dominant species in both hosts, followed by Hysterothylacium aduncum; other detected taxa included A. typica, A. ziphidarum, Skrjabinisakis physeteris, and H. fabri. In both hosts, the larval abundance exhibited marked seasonal peaks in summer and correlated more strongly with host liver and gonad condition indices, suggesting that seasonality, togheter with host physiological state, rather than size alone, modulates infection levels. Most larvae were found in the visceral non edible parts of the fish, while only a small proportion of these were detected in skeletal muscles (2.6% in hake and 0.6% in forkbeard), primarily in the anterior ventral fillet portion. QRA indicated a low per‐meal probability of anisakiasis from untreated hake (~1 case per 52,609 meals). These findings highlight species‐specific, trophically mediated infection patterns and reinforce that European hake and greater forkbeard represent minor but nonnegligible sources of zoonotic risk. Preventive measures, including immediate evisceration, proper freezing or cooking, and selective fillet trimming, are recommended to minimize human exposure.