Controlling trematodiases in Vietnam: actuality, challenges and trends for resolving these problems

Abstract

Food-borne zoonotic trematodes (FZT) constitute an important problem in Vietnam. Several approaches have been conducted to control FZT infection, but the achieved results are not satisfied. Causes of this problem can be divided into five categories (1) the local people in endemic areas still consume raw or undercook food, i.g. raw vegetables, dishes made of raw fish and vegetables, baked crabs etc.; (2) poor management of manure from the husbandry; (3) the migration of people from endemic areas to other places; (4) the spread of Asia cuisine, which has various raw food dishes, e.g. sushi, sashimi; (5) the complex of life cycle of FZT. One method to control FZT is to disrupt the life cycle of the first intermediate host snails. Options for snail control in aquaculture systems are not many, and probably are limited to use of a few chemicals and otherwise will have to be based on mechanical and biological means. Snail control in aquaculture ponds may be more limited as we have to take into consideration the survival of fishes because of their toxicity. Ecological measures of controlling snails are mainly done prior to stocking fish, i.e. as part of pond preparation. However, the recovery of snail population is very quick, so we should release molluscivore fish species as black carp (Mylopharyngodon piceus) into aquaculture ponds for control snails too. Small size of black carp (30-300g) could be used in both nursery ponds and growth-up ponds in Northern Vietnam.