- Title
- Assessment of the water quality, incidence of enteric viruses and microbial risk in the Buffalo River in the Eastern Cape Province of South Africa
- Creator
- Chigor, Vincent Nnamdigadi https://orcid.org/0000-0002-0811-4526
- Subject
- Water quality
- Subject
- Water -- Microbiology
- Date Issued
- 2013-03
- Date
- 2013-03
- Type
- Doctoral theses
- Type
- text
- Identifier
- http://hdl.handle.net/10353/24272
- Identifier
- vital:62596
- Description
- Buffalo River is an important water resource in the Eastern Cape Province of South Africa. Over a 1-year period (August 2010–July 2011), the water quality and incidence of human enteric viruses (HEntVs) was assessed, using standard methods and molecular techniques and a total 72 composite water samples collected monthly from a total of 6 sites located on the river and three dams along its course. The sites were selected based on a number of factors including geographical location, anthropogenic activity/major water use, rural/urban status and access. A total of 13 physicochemical parameters were determined using the standard methods. The counts of faecal indicator bacteria (FIB) including total coliforms (TC), faecal coliforms (FC) and enterococci (ENT) were determined by the membrane filtration technique. HEntVs were concentrated using an adsorption-elution method based on cation (Al3+)-coated membrane filter. Real-time quantitative polymerase chain reaction (qPCR) was used for the detection and quantification of human adenoviruses (HAdV), and real-time reverse transcriptase-PCR (RT-qPCR) was used for the quantitative detection of hepatitis A virus (HAV), human rotaviruses (RoV) and enteroviruses (EnV). The detected HAdV were characterized by multiplex conventional/semi-nested PCR methods. The risks for human health constituted by exposure to the detected HEntVs at the six sites were evaluated by a static quantitative microbial risk assessment (QMRA) using both the exponential and beta-Poisson models. Water temperature ranged from 11 to 28oC, while pH varied from 6.6 to 10.7, and turbidity from 1.7 to 133 NTU. Electrical conductivity (EC), total dissolved solids (TDS) and salinity showed drastic variations (42.3-46693 μS/cm, 20.3–23350 mg/L and 0.02–33.8 PSU respectively). The concentrations of other parameters ranged as follows: chloride (3.7–168 mg/L); DO (6.9–11.1); BOD (0.6–9.4); COD (3.7–45.9); nitrite-nitrogen (0.02–0.21); nitrate-nitrogen (1–4.47); and orthophosphate (0.01–1.72). TC, FC and ENT counts were high and ranged from 1.9 × 102–3.8 × 107 cfu/100 mL, 0–3.0×105 cfu/100 mL and 0–5.3 × 105 cfu/100 mL for TC, FC and ENT respectively. Significantly (P<0.05) higher concentrations of FC and ENT were observed at the sampling sites located at the lower reaches of the river compared to the upper reaches. The FIB counts mostly exceeded the maximum limits recommended by national and international guidelines for safe fresh produce irrigation, domestic applications, full-contact recreation and livestock watering. Significant (P<0.01) positive correlations existed between TDS and salinity (r=0.921), between turbidity and each of TC (r=0.552) and FC (r=0.425), as well as between BOD and each of TC (r=0.282), FC (r=0.472) and ENT (r=0.552). Phosphate correlated positively with FC (r=0.424), and nitrate also with the same, FC (r=0.460). A strong positive correlation existed between FC and ENT (r=0.915). There existed a significant (P˂0.01) inverse correlation between enteric viruses and each of water temperature (r=-0.191) and pH (r=-0.234). No correlation could be deduced between enteric viruses and all the tested chemical and bacteriological parameters. HAV, HAdV, RoV and EnV were detected in 43.1percent, 34.7percent, 13.9percent and 9.7percent respectively of the total 72 water samples tested. Two or more viruses were detected in 22.2 percent of the samples. HAdV were detected at 5 of the 6 sampling sites with concentrations ranging from 1.2×101 genome copies (GC)/litre to 4.71×103 GC/litre. Epidemiologically important serotypes, Ad40/41 constituted 83.3percent, while Ad21 made up 16.7percent of all the HAdV detected. HAV was detected at all the sites in significantly (p < 0.05) varying concentrations that ranged from 1.5 × 101–1.9 × 105 GC/litre compared to RoV and EnV. Neither of RoV nor EnV was detected at any of the dams. The detected concentrations at the non-dam sites ranged from 2.5 × 101–2.1 × 103 GC/litre and 1.3 × 101–8.6 × 101 GC/litre for RoV and EnV respectively. The values for the estimated daily risks of enteric virus infection varied with sites and exposure scenario, and ranged from 7.31×10-3–1 (for HAdV), 4.23×10-2–6.54×10-1 (RoV), 2.32×10-4–1.73×10-1 (HAV) and 1.32×10-4–5.70×10-2 (EnV). The yearly risks of infection in individuals exposed to the river/dam water via drinking, recreational, domestic or irrigational activities were unacceptably high, exceeding the acceptable yearly risk of 0.01percent (10-4 infection/person/year) recommended by the USEPA for drinking water. The risks of illness and of death from infection ranged from 6.58×10-5–5.0×10-1 and 6.58×10-9–5.0×10-5 respectively. Data on the physicochemical and bacteriological parameters showed that the Buffalo River water quality was poor, and deteriorated in the plains compared to the upper reaches. These water quality data, the presence of enteric viruses and the QMRA data, that revealed unacceptably high risks of enteric virus infections, and of illness and mortality from the infections, show that the Buffalo River and its dams are contaminated waters that constitute significant public health hazards. Provision of adequate sanitary infrastructure will help prevent source water contamination, and public health education aimed at improving personal, household and community hygiene is imperative. Monitoring enteric viruses in rivers and source water dams is necessary and useful as a risk assessment tool for the exposed population. Future research should consider a comprehensive characterization of the detected viruses. This work is both a significant contribution to the molecular epidemiology of enteric viruses and the first report on molecular detection and quantification of enteric viruses in surface waters in the Eastern Cape.
- Description
- Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (262 leaves)
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
- Rights
- All Rights Reserved
- Rights
- Open Access
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UFH Department of Biochemistry & Microbiology
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