Ascaridoid nematodes in fish : occurrence, diversity, and evaluation of candling towards exploring the public health relevance in Belgium

Abstract

Ascaridoids are marine nematodes occurring in a wide range of fish hosts. In the intermediate fish host, L3 (third stage) larvae reside in the viscera (primary infection site) and can migrate, both post- and ante-mortem to the fish musculature. Humans are accidental dead-end host, and may develop gastro-intestinal complaints after ingestion of a viable larva, or acquire allergic symptoms even after ingestion of a dead larva or residual allergens. The industry is tasked with the detection and removal of these larvae, in absence of a fast, cheap, and highly sensitive detection technique. Remaining larvae may, besides representing a food safety problem, trigger consumers complaints. The objectives of this thesis were to estimate the occurrence of ascaridoids in fish destined for the Belgian market; and to assess the sensitivity of the current mostly used diagnostic tool in fish, namely candling