IDENTIFICATION OF SALMONELLA AND VIBRIO IN WATER AND MWANZA GULF, LAKE VICTORIA, TANZANIA

Abstract

A cross sectional study to identify Salmonella and Vibrio species in water and fish in Mwanza Gulf, Lake Victoria was conducted during April to May 2012. A total of 30 water and 82 fish samples were collected and analyzed for Salmonella, Vibrio cholera and Vibrio parahaemolyticus. In water, the overall prevalence of Salmonella spp, Vibrio cholerae and Vibrio parahaemolyticus was 13.3%, 20% and 23.3%, respectively. Out of 15 water samples collected in beaches, contamination by Salmonella spp, V. cholerae and V. paraheamolyticius was 6.7%, 20% and 20%, respectively. In ponds, only V. parahaemolyticus was isolated in two out of three water samples. The prevalence of Salmonella spp and V. cholerae was 25% and 16.7% for V. parahaemolyticus in 12 river water samples. In fish, prevalence of Salmonella spp. on the surface, gills and intestines of fish was 19.5%, 4.9% and 2.2% (n=41); V. cholerae on the surface, gills and intestines of fish was 53.7%, 17.1% and 4.9% (n=41); and for V. parahaemolyticus it was 14.6%, 2.4% and 22% (n=41) respectively. Based on findings from this study, it was evident that there are some enteric pathogens of public health importance in fish and water in Lake Victoria and rivers emptying water into the lake. Detection of Salmonella spp, V. cholerae and V. parahaemolyticus in upstream water samples and fish before processing suggests that fish and water may be unsafe for human consumption. Thus it implies the necessity for application of HACCP system along the fish supply chain from fishing to processing establishments.