The aim was to define a sampling strategy of fish species that were the most relevant according to the risk of human exposure to fish parasites.
A risk ranking analysis has allowed the selection of 15 fish species based on the fish consumption data in France (INCA2 and CALYPSO data), the exposure of the consumer (fresh fish) and the prevalence of Anisakidae in fish (some existing data in the literature).
In the fish industry, the fish fillets are checked for the occurrence of Anisakid larvae by using candling systems. The fillet is trans-illuminated and this operation is tedious and exhausting for the human eye. In the frame of the Fish-Parasites action, the partners (PFI Nouvelles Vagues, LASMEA CNRS Clermont-Ferrand et ARBOR Technologies Landévant) aimed at developing a prototype allowing the more systematic larvae detection thanks to a system of computer assisted-intelligent vision.
The sampling of marine fish has been done according to the sampling scheme established by one of the partners (ANSES Maisons-Alfort) and thanks to the participation of the different partners to the research scientific Ifremer campaigns. Fish have also been sampled via fishermen or wholesale merchants.
In total, 9 members of the Fish-Parasites network got on board during 7 Ifremer campaigns for a total of 115 days at sea and 817 sampled fish. To complete this sampling, 969 marine fish were also collected from wholesale merchants or fishermen.
In total, 1786 marine fish were sampled by the Fish-Parasites network over a 30-months period.
Moreover, 138 freshwater fish (62 from the Geneva lake, 51 from the Bourget lake and 25 from the Annecy lake) as well as 1026 perch fillets (950 from the Geneva lake and 76 from the Annecy lake) were examined for the presence of Diphyllobothrium parasites (also known as the fish tapeworm).
Fish are thoroughly inspected looking for external parasites (ectoparasites of the gills, oral cavity or tegument). Then, fish are dissected to look for internal parasites (endoparasites). The dissection is performed on board or in the different laboratories of the partners (Ifremer Nantes, ANSES Boulogne s/mer, PFI Nouvelles Vagues).
The following steps are achieved following a standardized protocol:
• To identify the fish species
• To weigh and measure the fish
• To isolate and number the parasites per organ
• To preserve the parasites (ethanol 70% for molecular detection of Anisakidae and other worms)
• To preserve the intestinal contents in a 2,5% potassium dichromate (K2Cr2O7) solution (to preserve the viability of Cryptosporidium spp. oocysts)
• To scrap the intestinal and stomachal mucosa in RCL2 solution (for molecular detection of Cryptosporidium spp.)
• To take a piece of intestinal and stomachal mucosa in 10% buffered formol for later histological studies
• To store the fish fillets at -20°C for later pepsic digest (to isolate Anisakidae larvae)
