Anisakid larvae in the liver of cod (Gadus morhua) L. from the southern Baltic Sea

In the present investigation a sample of 490 cod (Gadus morhua) was examined from three regions in the southern Baltic Sea (the Polish Exclusive Economic Zone, EEZ). Three species of anisakid nematodes with zoonotic potential, namely species of Contracaecum, Anisakis and Pseudoterranova, were found in the liver of cod, with Contracaecum being the most dominant species. The prevalence of infection was highest in the Western Baltic (22.5%) compared to the Central Baltic (10.4%) and the Gulf of Gdansk (3.4%). Generalized linear models (GLMs) were applied to analyse the prevalence of infection with Anisakis sp. and Contracaecum sp. relative to biological and spatial parameters. The effect of the sampling region, age and body length of the fish were significant in both GLMs. The effect of region was higher in the Western Baltic than in other regions. The prevalence of infection was correlated with the length of the fish and was higher in adult compared with sub-adult fish. These results suggest that the prevalence of infection with anisakid nematodes (especially Contracaecum sp.) in cod sampled in Polish waters of the Baltic Sea has significantly increased compared with previous studies undertaken over the past few decades.