Seasonal Pattern of Pathogenic V. cholerae and V. paraheamolyticus in Surface Water of Dhaka, Bangladesh.

V. cholerae and V. parahaemolyticus are responsible for majority of the Vibrio-related infections world wide. In this observational study, we selected three important river and pondsites of Dhaka city, Bangladesh to observe the presence of pathogenic V. cholerae, and V. parahaemolyticus. Surface water samples were collected from July 2013 to April 2014. Identification of V. cholerae was confirmed by the presence of ompW gene by PCR. Vibrio cholerae was found in the unique dual peak (March to May and September to November) patternin Mirpur-1 Mazar pond and Abdullahpur bridge river site, like many other studies reported earlier in Dhaka with only one exception of finding V. cholerae in the month of July 2013 in Mirpur-1 Mazar pond. A single peak was found from September to November in Mirpur-1 river sites. The ctxB positive non- O1 V. cholerae has also been reported. The presence of ctxB gene was observed by MAMA PCR. The O1 and O139 serogroups were confirmed by O1rfb and O139 rfb genes in PCR. Both classical and El-Tor biotypes were observed in this one year round study. V. paraheamolyticus was confirmed by the presence of ToxRVP gene and all the strains were negative for tdh pathogenic gene by PCR. This study observed for the first time the seasonal pattern of V. parahaemolyticus in water bodies in Bangladesh showing a peak from February to April in all three sampling sites and another additional peak which span from August to September in Mirpur-1 Mazar pond, Dhaka, Bangladesh.