Riverbed Sediments as Reservoirs of Multiple Virulence-Associated Genes: A Potential Trigger for Cholera Outbreaks in Developing Countries.

Africa remains the most cholera stricken continent in the world as many people lacking access to safe drinking water rely mostly on polluted rivers as their main water sources. However, studies in these countries investigating the presence of in aquatic environments have paid little attention to bed sediments. Also, information on the presence of virulence-associated genes (VAGs) in environmental -negative strains in this region is lacking. Thus, we investigated the presence of VAGs in water and riverbed sediment of the Apies River, South Africa. Altogether, 120 samples (60 water and 60 sediment samples) collected from ten sites on the river (January and February 2014) were analysed using PCR. Of the 120 samples, 37 sediment and 31 water samples were positive for at least one of the genes investigated. The haemolysin gene was the most isolated gene. The cholera toxin and non-O1 heat-stable genes were not detected. Genes were frequently detected at sites influenced by human activities. Thus, identification of VAGs in sediments suggests the possible presence of and identifies sediments of the Apies River as a reservoir for potentially pathogenic with possible public health implications.