Zoonotic food-borne trematodes are transmitted to humans via aquatic vegetables, fish, crabs and crayfish as part of the freshwater ecosystem. Though both parasites may be delivered by the same food vehicle, the infective metacercariae are found in different biological food vehicles making global comparisons and food-safety surveillance difficult. A systematic evidence synthesis was performed as an integrative approach and included: indexed biomedical literature, systematic reviews, meta-analyses, primary prevalence surveys and authoritative WHO and EFSA reports. Evidence was grouped into three prespecified pathways as follows: (1) Fasciola spp. on aquatic vegetation; (2) Clonorchis spp., Opisthorchis spp. and Paragonimus spp. on freshwater crustaceans. Pooled estimates were not recalculated, but primary surveys were compared based on food vehicle, host species, production system and diagnostic method. Quantitative evidence was most well developed for fish-borne trematodes. The prevalence of C. sinensis metacercariae in fish was estimated from 71 studies and found to be 30.5%, with figures of 35.1, 29.7 and 8.4% in China, Korea and Vietnam, respectively. Overall prevalence of zoonotic trematodes in individual Vietnamese and Lao surveys ranged from about 40 to 69%. The prevalence of these second intermediate hosts in China was 52.07% for P. westermani and 31.10% for P. skrjabini. Fasciola metacercariae of edible aquatic plants were poorly documented: only F. hepatica DNA was found in 2 of 500 samples of water-dropwort in Korea and low but persistent metacercarial contamination of natural beds of watercress was found in France over a long period.  The presence of zoonotic metacercariae in freshwater food systems is widespread; however, there is unevenness among the evidence both taxonomically and geographically. Estimates based on fish, crustacean and plant should not be combined into a single prevalence estimate without stratification. For credible global surveillance, food-unit sampling, species confirmation, viability assessment and metadata for the supply chain must be harmonized.

To Cite This Article: Mohamed K, 2026. Systematic evidence of the association of zoonotic metacercaria of trematodes with seafood. Pak Vet J, 46(9): 2311-2318. http://dx.doi.org/10.29261/pakvetj/2026.217