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River water sources and diarrhoeic stools of residents in the Venda Region, Limpopo Province of South Africa were analysed for the prevalence of Escherichia coli (E. coli) and the presence of virulence genes among the isolates. A control group of 100 nondiarrhoeic stool samples was included. Escherichia coli was isolated and identified by standard cultural and biochemical methods. Pathogenicity of environmental and human isolates was determined by amplification of genes associated with virulence of E. coli, using specific primers.Of a total of 228 water and river sediment samples screened, E. coli was recovered from 200 (87.7%), and 135 (67.5%) of these had one or more genes associated with pathogenicity. The highest frequency of isolation of pathogenic strains was found in Ritavi River water and sediment (80.6%), followed by Lotanyanda River (76.9%), and the least (45.8%) in Nzhelele River 2. Escherichia coli was recovered from all of the 252 diarrhoeic stools tested (100%), and 119 (47.28%) of these had one or more genes associated with pathogenicity. The frequency of isolation of potential pathogenic E. coli from humans was highly significant (t = 6.3; pd•0.01) in comparison to water isolates. Cytotoxic necrotizing Factor 1 (cnf1) and cytotoxic necrotising Factor 2 (cnf2) coding for necrotoxigenic E. coli (NEC); bundle-forming pilus (bfpA) and enteropathogenic attachment and effacement (eaeA) coding for enteropathogenic E. coli (EPEC), occurred in 35% and 34% respectively of river isolates. Heat-stable (ST) and heat-labile (LT) toxin genes coding for enterotoxigenic (ETEC) and Shiga-like toxin 1 (Stx1) and Shiga-like toxin 2 (Stx2) coding for Shiga-like toxin-producing E. coli (STEC) were not encountered in the river isolates. Isolates from stool samples had 21.8% and 12.6% of EPEC and NEC strains respectively; while enterotoxigenic (ETEC), Shiga-like toxin-producing (STEC) and enteroaggregative E. coli (EAEC) had a prevalence of 5%, 5.8% and 5.8% respectively. One human isolate possessed stx2 and eaeA indicating E. coli O157: H7. No genes associated with pathogenicity were observed in human non-diarrhoeic stool isolates. Results have revealed a possibility of a recycling of pathogenic E. coli strains, particularly the EPEC and NEC strains, between the water sources and the local population.

SummaryMicrosporidia were initially recognized as pathogens of insects and fish but have recently emerged as an important group of human pathogens, especially in immune-compromised individuals, such as those with HIV infection. In this study, we used a PCR-RFLP assay confirmed by quantitative real-time PCR and trichrome staining to determine the prevalence of microsporidian infections among hospital patients and school children in Vhembe region. Enterocytozoon bieneusi was the only microsporidian species detected in these stool samples. It was found in 33 (12.9%) of 255 samples from the hospitals and in 3 (4.5%) of 67 samples from primary school children and was significantly associated (P = 0.039) with diarrhea in HIV-positive patients (21.6%) compared to HIV-negative individuals (9%). However, microsporidian infections were not associated with intestinal inflammation as indicated by the lactoferrin test. These results suggest that microsporidia might be a cause of secretory diarrhea in HIV-positive patients. To our knowledge, this is the first report of E. bieneusi in the Vhembe region of South Africa. Further investigations are needed in order to clarify the pathogenesis of E. bieneusi in HIV-positive patients. Authors' contributions: AS, CLO, ST and RLG conceived the study; AS, ST, LMW and RLG designed the study; RLG provided supplies for the laboratory studies that were conducted in his laboratory; AS ran all the laboratory analysis; AS, CLO, LMW and RLG participated in the data analysis; AS and RLG drafted the paper; CLO, ST, LMW and RLG critically revised the manuscript for important intellectual content. All authors revised and approved the final version of the manuscript. AS and RLG are guarantors of the paper. Conflict of interest: None declared.Ethical approval: The study was approved by the research and ethical committee of the University of Venda and the Department of Health and Welfare and the Department of Education in Polokwane, Limpopo Province, South Africa, before the initiation of the study. The molecular analysis was conducted according to the University of Virginia ethics guidelines on non-identified samples.

From October to November 2004, and from July to September 2005, a survey of 55 plants was conducted in five District Municipalities (Cacadu, Chris Hani, Amathola, Ukhahlamba and O.R. Tambo) of the Eastern Cape Province, with the aim of examining the disinfection practices used in small rural systems of the Eastern Cape and their effect on the quality of drinking water they supply to the communities.Eighty six percent of the visited plants were treating surface water while 7% were treating groundwater and another 7% were treating both ground-and surface water. The majority of plants surveyed employed some variation of conventional treatment (coagulation, flocculation, sedimentation, filtration, chlorination). Turbidity values in 55% of the plants were within the acceptable SABS limits while the other 45% showed high values.Out of the 55 surveyed plants only 18% complied with the SABS recommended limits in terms of microbiological quality. The major factors that contributed to high bacterial numbers were high turbidity and inefficient chemical (coagulant and chlorine) dosing, which led to low chlorine residuals. It was also noted that although some plants had low bacterial numbers at the point of treatment, bacterial re-growth occurred in the distribution system, thereby compromising the quality of water at the point of use.The worst technical problems encountered tended to be at the newly commissioned or upgraded plants where properly trained operators had yet to be appointed or where the existing staff lack proficiency in the use of the upgraded systems or why certain modifications to the treatment process were being made.Operators were lacking in the required technical knowledge such as flow rate and chemical dosing to effectively execute their duties. Lack of communication between consultants, operators and municipal officials on technical issues relating to plant operation appeared to be a problem.The results of this study gave conclusive evidence that rural water treatment plants are still failing to produce safe drinking water.