Research Publications (Health Sciences)

Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/216

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Effects of resource limitation on habitat usage by the browser guild in Hluhluwe-iMfolozi Park, South Africa
(Cambridge University Press, 2013-01) O'Kane, Christopher A. J.; Page, Bruce R.; Macdonald, David W.; Duffy, Kevin Jan
Resource depletion and associated increases in interspeciﬁc competition are likely to inﬂuence differential habitat usage amongst a guild. We tested some prominent theoretical concepts using observed differences in seasonal habitat use amongst the savanna browser guild (elephant, giraffe, impala, kudu and nyala) in Hluhluwe-iMfolozi Park, South Africa. Herbivore locations (n = 3108) were recorded over 2 y using repeated road transects and, for elephant, GPS collars (187 254 downloads). Densities were calculated using a novel GIS approach designed to be a cost-effective method for annual censuses, but also able to cope with abrupt changes in visibility. Selectivity for (Manly’s α) vegetation types, and overlap (Schoener’s index) in vegetation type usage were calculated. Resource depletion in the dry season resulted in all members of the guild increasing selectivity for vegetation types (sum of absolute values away from the neutral value for Manly’s alpha for the guild: dry seasons 3.97, 5.16; corresponding wet seasons 3.12, 3.68), but decreasing interspeciﬁc overlap (80% of Schoener’s indices lower in dry season versus wet season). These effects were more marked over the second, more severe, dry season. We found support for the niche overlap hypothesis and the niche compression hypothesis. The Jarman–Bell principle was generally supported, although unexpectedly during the severe dry season elephant showed the most selectivity for vegetation type. The greater the resource depletion, the more relevant interspeciﬁc differences in habitat usage become in relation to the differential impacts of guild members.
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.
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.
Skin disease prevalence amongst rural communities in KwaZulu-Natal Province, South Africa
(2023-09-08) Naidoo, Kuben; Coopoosamy, Roger; Singh, Karishma; Krishna, Suresh Babu Naidu; Adam, Jamila
Little information is known of skin diseases within rural communities in KwaZulu-Natal, South Africa. There is an urgent need to identify plants with antimicrobial activity as there is an increase in the incidence of new and re emerging infectious diseases. The present study compares species from two different localities used to treat common skin diseases, the parts used, and the method used to prepare traditional cures. The prevalence of skin disease compared to other ailments were also compared. Traditional healers from northern (seven main districts) and mid-KwaZulu-Natal (three main districts) muthi markets were randomly selected and interviewed after obtaining consent. Data collected included the specific plants used to treat skin diseases, common names, parts of the plant used, the collection locality, and the conditions treated by the traditional healers. Fourteen plant species were collected and traded in northern KwaZulu-Natal based on their curative properties and their use to treat wounds, skin lesions, rashes, burns, and scratches compared to only six in mid-KwaZulu-Natal. Approximately 43 percent of species were common to all districts, possibly due to their wide distribution. People with skin diseases formed the majority of traditional healer consults. Most conditions were very similar, possibly due to rural communities following a similar lifestyle. Skin infections and eczema were commonly treated conditions, followed by acne, hair disorders, and bruises. Skin diseases are common amongst rural community dwellers in KwaZulu Natal regardless of location, possibly due to their association with HIV infection. The plants used by traditional healers to treat various conditions are related to geographical distribution and abundance patterns.
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.