The objective of this study was to determine the prevalence of S. enterica, V. cholerae, and V. parahaemolyticus in shrimp, clam and blood cockle
and also to identify the presence of serogroups O1/O139 and ctxA gene of V. cholerae by m-PCR technique. A total of 120 samples (40 shrimp samples, 40 clam samples and 40 blood cockle samples) were collected from the wholesale markets in the lower streams of Dong Nai river (Dong Nai province), and Sai Gon river (Ho Chi Minh city) for this study. The studied results showed that prevalence of S. enterica, V. cholerae, and V. parahaemolyticus, in all shrimp, clam, and blood cockle samples was 26.7 percent, 70.8 percent and 56.7 percent respectively. In particular, the prevalence of S. enterica in shrimp, clam, and blood cockle samples was 7.5 percent, 42.5 percent, and 30.0 percent respectively. Similarly, the prevalence of V. choleraewas 17.5 percent, 97.5 percent, and 97.5 percent, and the prevalence of V. parahaemolyticus was 12.5 percent, 82.5 percent, and 75 percent.