Epidemiology of Fish-Borne Zoonotic Trematodiasis

The World Health Organization has added fish-borne zoonotic trematodes (FZTs) infections to its list of emerging infectious diseases (Clausen et al. 2012). A review by Chai et al. (2009) mention that an estimated 40–50 million people (though an underestimate) are likely to be infected with foodborne trematodes worldwide. Most of them are located in Southeast Asia, including Korea, China, Thailand, Vietnam, Lao PDR, the Philippines, Indonesia, and India. The number of fish-borne zoonotic trematodes (FZTs), currently known to be involved in this area, is counted at least 59. FZTs’ life cycle involve first intermediate host (freshwater snails), second intermediate host (freshwater fish), and definitive host (human or other animals). These trematodes can be grouped into two main categories, the liver fluke group (Opisthorchiidae: 12 species) and the intestinal fluke group (Heterophyidae, 36 species; Echinostomatidae, 10 species; and Nanophyetidae, 1 species) (Qiu et al. 2017). They are primarily related to liver and biliary disorders and intestinal diseases, causing severe disease and economic burden (Yu and Mott 1994).