Riverbed Sediments as Reservoirs of MultipleVibrio choleraeVirulence-Associated Genes: A Potential Trigger for Cholera Outbreaks in Developing Countries

Abstract

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 ofVibrio choleraein aquatic environments have paid little attention to bed sediments. Also, information on the presence of virulence-associated genes (VAGs) in environmentalctx-negativeV. choleraestrains in this region is lacking. Thus, we investigated the presence ofV. choleraeVAGs 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(hlyA)was the most isolated gene. The cholera toxin(ctxAB)and non-O1 heat-stable(stn/sto)genes were not detected. Genes were frequently detected at sites influenced by human activities. Thus, identification ofV. choleraeVAGs in sediments suggests the possible presence ofV. choleraeand identifies sediments of the Apies River as a reservoir for potentially pathogenicV. choleraewith possible public health implications.