Background: In countries that cholera outbreaks commonly occurs, surveillance of surface water is important to control the epidemics. Kappa phage (K139) of Vibrio cholerae is related to epidemic El Tor and O139 strains in various countries. Objectives: To study the relationships between V. cholerae 01 and vibriophages in surface water in Thai Binh and Hai Phong city and to determine the predictors of cholera outbreaks. Subjects and method: Total of 82 water samples were collected by shrimp swab method in Hai Phong and Thai Binh in June and September 2007, where cholera outbreaks occurred. The enriched culture method and direct peR were applied to define the relationships between vibriophages and V. cholerae 01 in surface water. Results: The rates of detecting kappa junction with chromosomes of V. cholerae 01 in Hai Phong and Thai Binh were 10% and 15% in June 2007, 35% and 41% in September 2007. The rates of detecting vibriophages in Hai Phong and Thai Binh were 15% and 15% in June 2007, 25% and 36% in September 2007. The rates of Fs1 and Fs2 detected by PCR method were 70% and 100% in Hai Phong at June and September 2007, and were 57% and 100% in Thai Binh at June and September 2007, respectively. V. cholerae 01, O139 weren\u2019t found in water samples. Conclusion: The presences of vibriophages (kappa phage and fs1 fs2) in surface water contaminated with V. cholerae 01 were dependent on the ability of the vibriophages to infect and lyse these bacteria. Vibriophages played a role in the transfer of cholera toxin and pathogenic factors. Surveillance by detecting V. cholerae 01 and vibriophages in surface water may be a feasible means of predicting outbreaks of cholera before a significant number of cases occur.
Vibrio cholerae 01 ; vibriophages ; surface water ; cholera outbreaks