Assessment of the Incidence of <i>Vibrio</i> spp. in Shrimp Farms Relative to Water Parameters and Their Molecular Detection in the Southwest Coastal Region of Bangladesh

In aquatic ecosystems, the incidence of Vibrio spp. is rising continually due to changes in water parameters. The study was undertaken to assess the incidence of Vibrio spp. in shrimp farms relative to water parameters and to perform their molecular detection. Maintaining three replications of each sample, overall, 360 shrimp, 360 water, and 360 sediments were randomly collected from the experimental units of 30 ponds in Khulna and Satkhira districts in each of the rainy and winter seasons. Temperature, ammonium, nitrite, pH, iron, and salinity were measured from water samples. The groEL gene of Vibrio cholerae, and toxR, trh, and tdh genes of Vibrio parahaemolyticus were identified through real-time polymerase chain reaction assay. Shrimp showed the highest mean total Vibrio spp. count (9.39 ± 0.34 log CFU/mL) in the rainy season. In the rainy season, shrimp represented 42.5%, water 17.5%, and sediment 19.16% Vibrio spp., whereas in the winter season, these were 38.33%, 14.16%, and 15.83%, respectively. Temperature and pH were at the highest average levels in the rainy and winter seasons, respectively. There was no significant relation between the incidence of Vibrio spp. and water parameters, except ammonium in the winter season. Here, 48.02% (85/177) isolates were positive for V. cholerae, 51.97% (92/177) for V. parahaemolyticus, 15.21% (14/92) for the trh gene, and 6.52% (6/92) for the tdh gene. None of the relations between water parameters and trh-positive V. parahaemolyticus was significant, except pH in the rainy season. The occurrence of Vibrio spp. in shrimp farms should be a burning issue for sustainable production.