Etymologia: Opisthorchis

fed to farm cats, which are major reservoir hosts for fishborne liver and intestinal trematodes. Infections (prevalence 8.3%) in snakehead fish (Channa spp.) also represent a food safety risk, because snakehead fish are cultured in Vietnam and are sometimes eaten raw or inadequately cooked. In addition to O. viverrini flukes, metacercariae of the zoonotic intestinal flukes Centrocestus formosanus, Haplorchis taichui, and H. yokogawi were recovered from snakehead and barb fish (online Technical Appendix Table 1), all of which are common throughout Southeast Asia (1). The results of this study demonstrate that the human liver fluke O. viverrini is endemic to Vietnam and that it is being naturally transmitted to fish species that are often consumed raw or inadequately cooked. For determination of the prevalence, distribution, and epidemiology of O. viverrini flukes in fish, humans, and reservoir hosts (e.g., cats and dogs), these results need to be extended, especially because aquaculture is a growing industry in Vietnam.