Assessment of Microbial Quality of Vegetables Irrigated with Polluted Waters in Dar es Salaam City, Tanzania

This study was undertaken to assess microbial quality of fresh vegetables irrigated with polluted waters from Msimbazi River in Dar es Salaam City. Samples of river water were taken from seven sampling stations along Msimbazi River stretching 20.4 km from Pugu to Jangwani and its tributary (Ubungo River) at Mabibo. Vegetable samples of 5 different species were taken from two different vegetable gardens in different locations along Msimbazi river valley and its tributary (Ubungo river), and from six markets including one super market. The examination of samples was carried out in accordance with the standard methods. Results revealed that water from the Msimbazi River contains high concentration of salts and pathogenic organisms. Fecal coliforms were found in all river water samples with a maximum count of 2.1x106 cfu/100ml. Pollution of the river was increasing downstream and varies seasonally with wet season having poorer water quality than dry season. Vegetables from all the markets including super market were highly contaminated with fecal coliforms of up to 108 Cfu/kg-wet vegetables. Pathogenic organisms were detected on vegetables and all river water samples examined had Ascaris Lumbricoides except for the sample collected at Pugu station. Fresh vegetables were contaminated with pathogenic organisms such as Escherichia coli, Citrobacter ssp, Proteus ssp, Klebsiella ssp, Salmonella spp and Basillus spp. Vegetable samples collected from the markets were more contaminated than those collected from the gardens. High number of fecal coliforms in the markets was due to poor handling of these vegetable by contaminated hands and sprinkling of vegetables with polluted water to keep vegetables moist. It was concluded that water used for irrigating vegetables along river Msimbazi was highly polluted and vegetables from gardens and markets are not safe for consumption.