ABSTRACT
Contracaecum spp., a member of the Anisakidae family, presents significant challenges to both the marketability of fish and public health due to its zoonotic potential. This study explores the prevalence and seasonal variation of Contracaecum larvae in 100 randomly collected samples of Nile tilapia from Assiut Governorate, Egypt. Detailed microscopic and ultrastructural examinations were conducted, which were further supplemented by molecular sequencing and phylogenetic analysis. Our findings revealed an overall prevalence rate of 24%, with a notably high correlation between Contracaecum infection and the summer season, showing an infection rate of 50%. Molecular analysis identified Contracaecum multipapillatum as the dominant species in the region. Additionally, we explored the effectiveness of marine extracts-specifically Sarcophyton and Dendronephthya-as alternatives to conventional anthelmintics. In vitro assessments demonstrated that these extracts were highly effective in altering larval morphology and reducing viability in a time-dose dependent manner, with IC₅₀ values of 12.52 mg/mL for Sarcophyton and 14.25 mg/mL for Dendronephthya. Treatment led to significant morphological changes observed through scanning electron microscopy, including severe cuticular damage and edema, as well as destruction at both the anterior and posterior ends. This study highlights the impact of Contracaecum larvae on fish in Assiut and presents promising marine-derived anthelmintic properties.
Keywords: Assiut, Contracecum, Sarcophyton sp. and Dendronephthya sp