Raw-Fish-Eating Behavior and Fishborne Zoonotic Trematode Infection in People of Northern Vietnam

Abstract

Raw fish consumption in restaurants, for example, Sashimi style, is popular worldwide. In Vietnam, raw fish dishes are also traditionally prepared and consumed in private households. However, the habits of eating raw or otherwise inadequately cooked fish can be associated with risks of acquiring fishborne zoonotic trematode (FZT) infection. The present study was done in a fish-farming community in Nam Dinh, Vietnam, to obtain information about habits of eating raw fish dishes and risks for human FZT infection. Discussions were held in different groups divided by gender and age on raw-fish-eating behavior. A total of 180 household members were interviewed and their stool samples analyzed to identify risk factors of FZT infection. There was awareness about the risk of liver fluke infections from eating raw fish. However, many older people accepted these risks and continued eating raw fish, as they know effective drug treatment is available. Raw fish dishes are consumed at social gatherings from shared plates and dipping sauces using the same chop sticks. This is likely to pose risks of crosscontamination with FZT metacercariae to different food items as indicated by the finding that 25.8% of household members that stated not to have eaten raw fish were infected. In total, 32.2% fish farm household members were infected with FZT. The odds of FZT infection was 2.3 times higher (p = 0.013) for those eating raw fish than for those who did not eat raw fish. Among the people eating raw fish, those eating raw fish in restaurants had 3.6 times higher odds of FZT infection (p = 0.009) than people eating raw fish at home. A successful program to control FZT must be based on in-depth knowledge on the social and anthropological determinants of people's raw-fish-eating behavior and hygiene practices as well as production of FZT-free fish for human consumption.

High Reinfection Rate after Preventive Chemotherapy for Fishborne Zoonotic Trematodes in Vietnam

“…In this model we found that previous infection (representing risk behavior) was a significant risk factor for reinfection, whereas male gender and increasing age were not. This indicates that the seemingly close association between male gender, increasing age and reinfection we observed (crude numbers), is possibly confounded by risk behavior of eating raw fish, a tradition mostly common among men [27].…”

Higher attack rate of fish-borne trematodes (Heterophyidae) in common carp fingerlings (Cyprinus carpio) at lower fish weight

“…In general, intestinal flukes cause less severe pathology in humans (Toledo et al 2006), but have become increasingly important because of food safety requirements (Chai et al 2005). Therefore, and also considering the life-cycle of FZTs that involves primary intermediate snail hosts, secondary intermediate fish hosts and final hosts like humans, pigs, dogs, cats, or fish-eating birds (Anh et al 2010;Dung et al 2010;Lan Anh et al 2009;Phan et al 2010a;Phan et al 2011), intervention targeting the fish host in aquaculture settings might be an effective strategy.…”

Global status of fish-borne zoonotic trematodiasis in humans

“…In northern Vietnam, common fish species used to prepare raw fish dish, also called "gỏi cá", are silver carp (Hypophthalmichthys molitrix), grass carp (Ctenopharyngodon idellus), rohu (Labeo rohita), and mrigal (Cirrhinus mrigala) (Chi et al 2009;Phan et al 2011). In the rural areas, slices of raw fish are soaked twice in a mild saline (1-3% NaCl) solution, before mixed with rice powder and eaten with herbs and sauce (Chi et al 2009;Phan et al 2011). Mostly adult men eat raw fish, whereas women mainly eat herbs dipped into the sauce.…”

“…Children also have meals together with those eating raw fish, but the children consumed other types of food. In these places 32.2% of fish farm household members were infected with FZT (Phan et al 2011). In restaurants, raw fish is prepared in two different ways, i.e.…”