Research Publications (Health Sciences)

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Evaluating the Acute Toxicity of Estrogen Hormones and Wastewater Effluents Using Vibrio fischeri
(Taylor and Francis Online, 2015) Surujlal-Naicker, Swastika; Gupta, Sanjay Kumar; Bux, Faizal
Toxicity evaluation of environmental substances such as those in wastewater and contaminated water bodies has become an important part of environmental monitoring of pollution. The study evaluated the toxicity of estrogen hormones and the removal of toxicity in full-scale wastewater treatment plants (WWTPs) using the marine bacterium, Vibrio fischeri , and to determine if there is a correlation between the hormones and the toxicity in the effluents. Three different types of full-scale WWTPs were investigated and presence of estrogens in the treated wastewater was evaluated by enzyme linked immunoassay (ELISA). The toxicity of individual estrogens (E2, EE2, and a mixture of E1, E2, and E3) was investigated as well as influents and treated wastewater. The results revealed that all estrogen hormones had less than 50% inhibitions and fell in the Class II group that exhibits slight acute toxicity. The toxicity of the individual E2 hormone had higher inhibitions when compared to the individual synthetic EE2 and the mixture of the hormones. The toxicity results of the WWTP revealed that biological treatment can reduce the toxicity of the influent to an extent. The findings suggest that the residual estrogen contents as well as toxicity can be reduced in certain WWTPs.
The impact of hygiene and localised treatment on the quality of drinking water in Masaka, Rwanda
(Taylor & Francis, 2013-12-17) Uwimpuhwe, Monique; Reddy, Poovendhree; Barratt, Graham James; Bux, Faizal
The worldwide prevalence of waterborne diseases has been attributed to the lack of safe water, inadequate sanitation and hygiene. This study evaluated socio-demographic factors, microbiological quality of water at source and point of use (POU) at households, water handling and sanitation practices in a rural Rwandan community. Thirty ﬁve water samples from the source, Nyabarongo River, and water at point of use (POU) treated with the Slow Sand Filter (SSF) and Sˆur’Eau methods, were analysed for total coliform and faecal coliform counts. Turbidity was measured in household samples. A structured questionnaire regarding water collection, storage, usage and waterborne disease awareness was administered to 324 women. Despite the signiﬁcant reduction in coliforms and faecal coliforms from the Nyabarongo River following treatment using either SSF or Sˆur’Eau, the water at point of use was found to be unsafe for human consumption. The frequency of diarrheal diseases were signiﬁcantly higher among people who did not wash hands before food preparation (P = 0.002) and after using a toilet (P = 0.007) than among those who did. There was a statistically signiﬁcant association between education levels and water treatment practices at the households (P < 0.05). Participants had limited knowledge regarding water storage practices for prevention of household water contamination. A combination of treatment methods with appropriate water handling should be considered. In addition, education is a fundamental precursor to advocating water treatment at POU.
Molecular surveillance of tuberculosis-causing mycobacteria in wastewater
(Elsevier BV, 2022-02) Mtetwa, Hlengiwe N.; Amoah, Isaac Dennis; Kumari, Sheena; Bux, Faizal; Reddy, Poovendhree
The surveillance of tuberculosis infections has largely depended on clinical diagnostics and hospitalization data. The advancement in molecular methods creates an opportunity for the adoption of alternative surveillance systems, such as wastewater-based epidemiology. This study presents the use of conventional and advanced polymerase chain reaction techniques (droplet digital PCR) to determine the occurrence and concentration of total mycobacteria and members of the Mycobacterium tuberculosis complex (MTBC) in treated and untreated wastewater. Wastewater samples were taken from three wastewater treatment plants (WWTPs) in the city of Durban, South Africa, known for a high burden of TB/MDR-TB due to HIV infections. All untreated wastewater samples contained total mycobacteria and MTBC at varying percentages per WWTP studied. Other members of the MTBC related to tuberculosis infection in animals, M. bovis and M. caprae were also detected. The highest median concentration detected in untreated wastewater was up to 4.9 (±0.2) Log10 copies/ml for total mycobacteria, 4.0 (±0.85) Log10 copies/ml for MTBC, 3.9 (±0.54) Log10 copies/ml for M. tuberculosis, 2.7 (±0.42) Log10 copies/ml for M. africanum, 4.0 (±0.29) Log10 copies/ml for M. bovis and 4.5 (±0.52) Log10 copies/ml for M. caprae. Lower concentrations were detected in the treated wastewater, with a statistically significant difference (P-value ≤ 0.05) in concentrations observed. The log reduction achieved for these bacteria in the respective WWTPs was not statistically different, indicating that the treatment configuration did not have an impact on their removal. The detection of M. africanum in wastewater from South Africa shows that it is possible that some of the TB infections in the community could be caused by this mycobacterium. This study, therefore, highlights the potential of wastewater-based epidemiology for monitoring tuberculosis infections.
Wastewater-based surveillance of antibiotic resistance genes associated with tuberculosis treatment regimen in KwaZulu Natal, South Africa
(MDPI AG, 2021-11) Mtetwa, Hlengiwe N.; Amoah, Isaac Dennis; Kumari, Sheena; Bux, Faizal; Reddy, Poovendhree
Essential components of public health include strengthening the surveillance of infectious diseases and developing early detection and prevention policies. This is particularly important for drug-resistant tuberculosis (DR-TB), which can be explored by using wastewater-based surveillance. This study aimed to use molecular techniques to determine the occurrence and concentration of antibiotic-resistance genes (ARGs) associated with tuberculosis (TB) resistance in untreated and treated wastewater. Raw/untreated and treated (post-chlorination) wastewater samples were taken from three wastewater treatment plants (WWTPs) in South Africa. The ARGs were selected to target drugs used for first- and second-line TB treatment. Both conventional polymerase chain reaction (PCR) and the more advanced droplet digital PCR (ddPCR) were evaluated as surveillance strategies to determine the distribution and concentration of the selected ARGs. The most abundant ARG in the untreated wastewater was the rrs gene, associated with resistance to the aminoglycosides, specifically streptomycin, with median concentration ranges of 4.69-5.19 log copies/mL. In contrast, pncA gene, associated with resistance to the TB drug pyrazinamide, was the least detected (1.59 to 2.27 log copies/mL). Resistance genes associated with bedaquiline was detected, which is a significant finding because this is a new drug introduced in South Africa for the treatment of multi-drug resistant TB. This study, therefore, establishes the potential of molecular surveillance of wastewater for monitoring antibiotic resistance to TB treatment in communities.