UNAM Repository :: Browsing by Author "Mumbengegwi, Davis R."

Browsing by Author "Mumbengegwi, Davis R."

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Antimicrobial and antiplasmodial activity displayed by actinomycetes isolated from soils from Kavango and Hardap regions in Namibia
(2018) Iikasha, Albertina M.; Dushimemaria, Florence; Mbewe, Maria; Eiman, H.; Mumbengegwi, Davis R.
Plasmodium falciparum and multidrug resistant bacteria such as Mycobacterium avium, Staphylococcus aureus and Escherichia coli are among the top causes of morbidity and mortality especially in developing countries. These pathogens are responsible for the reported antibiotic resistance incidents globally. Due to the increase in antibiotic resistance worldwide, there is an urgent need for new bioactive compounds. This study aimed at determining the antiplasmodial and antimicrobial activity of secondary metabolites produced by soil actinomycetes. Soil samples were collected from Kavango and Hardap regions and cultured on various media to isolate and identify actinomycetes. Secondary metabolites produced were extracted using different solvents. The antimicrobial activity of different isolated secondary metabolites was determined against M. avium, S. aureus and E. coli. Antiplasmodial activity of four bioactive fractions with potent antibacterial activity was further determined against a chloroquine resistant (D10) P. falciparum strain at various concentrations. Bioactive compounds from two isolates displayed activity against M. avium, whilst another two showed activity against E. coli. None of the secondary metabolites displayed activity against S. aureus. A concentration dependent reduction in parasitaemia for P. falciparum was observed across all four fractions both after 24 and 48 h. These results display a vast potential antibacterial and antiplasmodial activity and should be considered for future drug development.
Assessing malaria risk at night-time venues in a low-transmission setting: A time-location sampling study in Zambezi, Namibia
(2011) Jacobson, Jerry O.; Smith, Jennifer L.; Cueto, Carmen; Chisenga, Mukosha; Roberts, Kathryn W.; Hsiang, M.; Gosling, Roly; Mumbengegwi, Davis R.; Bennett, Adam
Background:Identifying efficient and effective strategies to reach and monitor populations at greatest risk of malaria in low-transmission settings is a key challenge for malaria elimination. In Namibia’s Zambezi Region, transmis-sion is ongoing yet its drivers remain poorly understood. A growing literature suggests that night-time social activities may lead to malaria exposure that is beyond the reach of conventional preventive interventions, such as insecticide treated bed nets and indoor residual spraying.Methods:Formative research was conducted with community members in March, 2015 in the catchment areas of six randomly selected health facilities in the western Zambezi Region to identify night-time locations where large numbers of individuals regularly congregate. Using time-location sampling, a survey was conducted between March and May, 2015 at community-identified venues (bars and evening church services) to develop representative esti-mates of the prevalence of parasite infection and risk factors among venue-goers.Results:When compared to a contemporaneous household survey of the general population aged 15 and older (N =1160), venue-goers (N =480) were more likely to have spent the night away from their home recently (17.3% vs. 8.9%, P =0.008), report recent fever (65.2% vs. 36.9%, P < 0.001), and were less likely to have sought care for fever (37.9% vs. 52.1%, P =0.011). Venue-goers had higher, but not significantly different, rates of malaria infection (4.7% vs. 2.8%, P =0.740). Risk factors for malaria infection among venue-goers could not be determined due to the small number of infections identified, however self-reported fever was positively associated with outdoor livelihood activi-ties (adjusted odds ratio [AOR] =1.9, 95% CI 1.0–3.3), not wearing protective measures at the time of the survey (AOR =6.8, 9% CI 1.4–33.6) and having been bothered by mosquitos at the venue (AOR =2.7, 95% CI 1.5–4).Conclusions:Prevention measures and continued surveillance at night-time venues may be a useful complement to existing malaria elimination efforts.
Association of Human Papiloma Virus (HPV) 16 and 18 in breast cancer biopsies in Namibia
(University of Namibia, 2018) Mumbengegwi, Davis R.; Van Kent, Samuelia; Tambo, Munyaradzi
Cancer is a growing global health concern due to increased exposure to risk factors including infection by viruses such as human papillomavirus (HPV). HPV is associated with several cancers and may be an etiological agent contributing to increasing breast cancer cases in Namibia. This study investigated the association between HPV infection and breast cancer cases in Namibia. DNA was isolated from 47 breast tumour biopsies, (22 breast cancer positive and 25 negative) and analysed for HPV 16 and 18 sequences using PCR. HPV 16 and 18 were detected in 86.3 % and 81.8 % respectively, of breast cancer positive samples, whilst only 36 % and 48 % respectively, were found in breast cancer negative samples. In total 95.5 % of breast cancer positive samples were infected by at least either of HPV 16 or 18 compared to only 52 % of breast cancer negative samples. Infection with HPV 16 or 18 increases the risk of cervical cancer and possibly breast cancer, hence the results suggest that HPV may contribute to the increasing breast cancer statistics in Namibia. This is the first study in Namibia linking HPV and breast cancer, but a larger sample size will be required to power the study to make the findings statistically significant.
Evaluation of loop‑mediated isothermal amplification as a surveillance tool for malaria in reactive case detection moving towards elimination
(2018) Tambo, Munyaradzi; Auala, Joyce R.; Sturrock, Hugh J.; Kleinschmidt, Immo; Bock, Ronnie; Smith, Jennifer L.; Gosling, Roland; Mumbengegwi, Davis R.
Background: As malaria transmission decreases, the proportion of infections that are asymptomatic at any given time increases. This poses a challenge for diagnosis as routinely used rapid diagnostic tests (RDTs) miss asymptomatic malaria cases with low parasite densities due to poor sensitivity. Yet, asymptomatic infections can contribute to onward transmission of malaria and therefore act as infectious reservoirs and perpetuate malaria transmission. This study compared the performance of RDTs to loop-mediated isothermal amplification (LAMP) in the diagnosis of malaria during reactive active case detection surveillance. Methods: All reported malaria cases in the Engela Health District of Namibia were traced back to their place of residence and persons living within the four closest neighbouring houses to the index case (neighbourhood) were tested for malaria infection with RDTs and dried blood spots (DBS) were collected. LAMP and nested PCR (nPCR) were carried out on all RDTs and DBS. The same procedure was followed in randomly selected control neighbourhoods. Results: Some 3151 individuals were tested by RDT, LAMP and nPCR. Sensitivity of RDTs and LAMP were 9.30 and 95.50%, respectively, and specificities were 99.27 and 99.92%, respectively, compared to nPCR. LAMP carried out on collected RDTs showed a sensitivity and specificity of 95.35 and 99.85% compared to nPCR carried out on DBS. There were 2 RDT samples that were negative by LAMP but the corresponding DBS samples were positive by PCR. Conclusion: The study showed that LAMP had the equivalent performance as nPCR for the identification of Plasmodium falciparum infection. Given its relative simplicity to implement over more complex and time-consuming methods, such as PCR, LAMP is particularly useful in elimination settings where high sensitivity and ease of operation are important.
Evaluation of the Antiplasmodial Properties of Namibian Medicinal Plant Species, Moringa ovalifolia
(2017) Du Preez, Iwanette C.; Bussel, Rahl-Jeanne; Mumbengegwi, Davis R.
Background and Objective: Malaria is a major cause of morbidity and mortality in Sub-Saharan Africa but it is on the decline in some Southern African countries including Namibia, which is moving towards elimination of the disease. Despite the availability of effective medicines in Namibia, some communities do not accept allopathic medicines, preferring traditional medicines. This study was conducted to determine the phytochemistry and the efficacy of Moringa ovalifolia (M. ovalifolia ) an ethnomedicinal plant, to provide a basis for their integration into mainstream malaria case management. Materials and Methods: Moringa ovalifolia was screened for known classes of antimalarial phytochemicals using thin layer chromatography. In vitro antiplasmodial activity of aqueous and organic extracts from Moringa ovalifolia was measured using parasitaemia post-treatment with plant extracts as well as the IC50 values. Data analysis using two-way ANOVA to determine the significant interactions between plant extracts and plasmodic growth. Results: Phytochemical screening of M. ovalifolia revealed the presence of flavonoids, anthraquinones, coumarin, terpenoids and alkaloids. Against Plasmodium falciparum (P. falciparum) D10, the leaf extracts of M. ovalifolia were the most effective with IC50 values of 14.30 and 20.73 μg mLG1 for the organic and aqueous extracts, respectively. Conclusion: M. ovalifolia extracts exhibited moderate antiplasmodial properties in vitro and have potential as antimalarials. These findings provide a basis for further investigation into their phytochemistry as well as in vivo studies on their safety and efficacy to support their use as an alternative treatment for malaria.
FLASH: a next-generation CRISPR diagnostic for multiplexed detection of antimicrobial resistance sequences
(2019) Quan, Jenai; Langelier, Charles; Mumbengegwi, Davis R.
The growing prevalence of deadly microbes with resistance to previously life-saving drug therapies is a dire threat to human health. Detection of low abundance pathogen sequences remains a challenge for metagenomic Next Generation Sequencing (NGS). We introduce FLASH (Finding Low Abundance Sequences by Hybridization), a nextgeneration CRISPR/Cas9 diagnostic method that takes advantage of the efficiency, specificity and flexibility of Cas9 to enrich for a programmed set of sequences. FLASH-NGS achieves up to 5 orders of magnitude of enrichment and sub-attomolar gene detection with minimal background. We provide an open-source software tool (FLASHit) for guide RNA design. Here we applied it to detection of antimicrobial resistance genes in respiratory fluid and dried blood spots, but FLASH-NGS is applicable to all areas that rely on multiplex PCR.
Indigenous knowledge of medicinal plants used for the treatment of cancer
(University of Namibia Press, 2015) Dushimemaria, Florence; Mumbengegwi, Davis R.; Bock, Ronnie A.
The global burden of cancer continues to increase in both developed and developing countries. This is largely attributed to a growing aged population as both the numbers of people and life expectancies increase. Another important factor is the adoption of lifestyles that increase the risk of developing cancer (Jemal et al., 2011). Lifestyle choices, such as smoking tobacco, consuming alcohol, being physically inactive and eating unhealthily, contribute to the upsurge in cancer cases. Siegel, Naishadham and Jemal (2012) estimated that about 1,638,910 new incidences of cancer and about 577,190 deaths due to cancer occurred worldwide in 2012. They further estimated that 56% of the cancer cases and 64% of cancer-related deaths occurred in developing countries (Jemal et al., 2011), indicating that the developing world is gradually having to shoulder more of the burden and where cancer survival rates tend to be lower.
Indigenous knowledge of Namibia
(University of Namibia Press, 2015) Chinsembu, Kazhila C.; Cheikhyoussef, Ahmad; Mumbengegwi, Davis R.; Kandawa-Schulz, M.; Kasanda, Choshi D.; Kazembe, Lawrence N.
Why this book, Indigenous Knowledge of Namibia? Nowadays, indigenous knowledge has gained prominence and attracted public interest due to its numerous applications in science and innovation: biotechnology, health, bioprospecting, pharmaceuticals, medicinal plants, agriculture, food preparation, mathematics, natural resource management, climate change and astronomy. There are many niche players in the field of indigenous knowledge in Namibia and many studies being carried out. Thus, although not all aspects of Namibia's indigenous knowledge are covered in this book, most readers from various walks of life - laypersons, scholars and policy makers - will find this book a very useful companion. The content of this book serves as a good starting point, because 'we cannot go further into the future without looking deeper into the past' (anonymous). Through their laboratory and scientific studies, the authors of this book server as guides through the journey to discover and record the indigenous knowledge of Namibia society. More importantly, their individual and collective works endevour to add value to Namibia's indigenous knowledge. The voyage and value addition are aimed at bringing greater clarity to some of the most perplexing aspects of indigenous knowledge in Namibia. Authors are aware of local communities need to benefit from their indigenous knowledge. That being said, the aim of this book is not to appropriate the indigenous knowledge of local communities, as most indigenous knowledge is already in the public domain.
An investigation into the antibacterial activity of pigmented secondary metabolites isolated from streptomyces from Windhoek soil
(University of Namibia, 2017) Iikasha, Albertina M.; Eiman, H.; Mumbengegwi, Davis R.
There is an increase in mortality from infectious diseases due to an increase in antibiotic resistance worldwide. Hence, his study aimed at investigating the antibacterial activity of Streptomyces that produces pigmented secondary metabolites .The soil samples were collected from 3 different sites in Windhoek. Streptomyces were isolated on starch case in agar. Biochemical and physiological tests were used to identify Streptomyces species. Case in slantagar method was used for preliminary anti-bacterial test. Chloroform and n-Hexane were used to extract secondary metabolites by solvent-liquid extraction method.Thin layer chromatography plates were used for antibacterial activity of the isolated secondary tabolites.Minimum inhibitory concentration of isolated secondary metabolites was determined by the broth dilution method at concentrations ranging from 50to1.5 μg/ml. Six out of nine Streptomyces isolates showed antibacterial activity against at least one of three test bacteria. Streptomyces isolate 1exhibited potentactivityof19.5mm ± 0.056 against M. avium. Different pigmented secondary metabolites were produced and showed antibacterial activity against at least against one of three test organism. Streptomyces isolate 4 and 6 showed the lowest minimum inhibitory concentration of 6.25 μg/ml against M. avium and E. faecialis. The results showed that Windhoek soil contain antibiotic producing Streptomyces.
Is there a correlation between malaria incidence and IRS coverage in western Zambezi region, Namibia?
(2018) Mumbengegwi, Davis R.; Sturrock, Hugh J.; Hsiang, M.; Roberts, Kathryn W.; Kleinschmidt, Immo; Nghipumbwa, M.H.; Uusiku, Petrina; Smith, Jennifer L.; Bennet, A.; Kizito, W.; Takarinda, K.C.; Ade, S.; Gosling, Roly
Setting: A comparison of routine Namibia National Malaria Programme data (reported) vs. household survey data (administrative) on indoor residual spraying (IRS) in western Zambezi region, Namibia, for the 2014–2015 malaria season. Objectives: To determine 1) IRS coverage (administrative and reported), 2) its effect on malaria incidence, and 3) reasons for non-uptake of IRS in western Zambezi region, Namibia, for the 2014–2015 malaria season. Design: This was a descriptive study. Results: IRS coverage in western Zambezi region was low, ranging from 42.3% to 52.2% for administrative coverage vs. 45.9–66.7% for reported coverage. There was no significant correlation between IRS coverage and malaria incidence for this region (r = –0.45, P = 0.22). The main reasons for households not being sprayed were that residents were not at home during spraying times or that spray operators did not visit the households. Conclusions: IRS coverage in western Zambezi region, Namibia, was low during the 2014–2015 malaria season because of poor community engagement and awareness of times for spray operations within communities. Higher IRS coverage could be achieved through improved community engagement. Better targeting of the highest risk areas by the use of malaria surveillance will be required to mitigate malaria transmission.
Isolation and Genus identification of bacteria from urine contaminated soils of Windhoek
(University of Namibia, 2016) Haindongo, Erastus H.; Bock, Ronnie A.; Nafuka, Sylvia N.; Mumbengegwi, Davis R.
Public urination is a common sight in the vicinity of drinking establishments in Katutura, as well as other open spaces around Windhoek. A study was conducted to determine if there was a shift in the balance of the microflora in urine contaminated soils. It was hypothesized that, given soils from the same geographic region but under distinct urine conditions, the identity and counts of the pathogenic and actinobacteria communities would vary. For the purpose of this study, pathogenic microorganisms were limited to those known to cause infections of the urinary tract. Soil samples from 4 contaminated locations (Ara-Dorado, Hakahana, Eveline and Greenwell Matongo suburbs) and controls were qualitatively tested for urease activity. Selective media was used for the isolation and enumeration of pathogenic and beneficial actinobacterial colonies. Dorado showed the greatest extend of urease activity>>>Hakahana and Eveline>>Green well matongo. There is a significant difference between the colony counts at a contaminated and non-contaminated (control) site, p = 0.019(= 0.05). The results indicated that public urination introduces pathogenic bacteria, causing a shift in the balance of the normal flora.
Malaria risk factors in northern Namibia: The importance of occupation rage and mobility in characterizing high-risk population
(PLOS ONE, 2021) Smith, Jennifer L.; Mumbengegwi, Davis R.; Haindongo, Erastus H.; Cueto, Carmen; Roberts, Kathryn W.; Gosling, Roly; Uusiku, Petrina; Kleinschmidt, Immo; Bennett, Adam; Sturrock, Hugh J.
In areas of low and unstable transmission, malaria cases occur in populations with lower access to malaria services and interventions, and in groups with specific malaria risk exposures often away from the household. In support of the Namibian National Vector Borne Disease Program’s drive to better target interventions based upon risk, we implemented a health facility-based case control study aimed to identify risk factors for symptomatic malaria in Zambezi Region, northern Namibia. A total of 770 febrile individuals reporting to 6 health facilities and testing positive by rapid diagnostic test (RDT) between February 2015 and April 2016 were recruited as cases; 641 febrile individuals testing negative by RDT at the same health facilities through June 2016 were recruited as controls. Data on socio-demographics, housing construction, overnight travel, use of malaria prevention and outdoor behaviors at night were collected through interview and recorded on a tablet-based questionnaire. Remotely-sensed environmental data were extracted for geo-located village residence locations. Multivariable logistic regression was conducted to identify risk factors and latent class analyses (LCA) used to identify and characterize high-risk subgroups. The majority of participants (87% of cases and 69% of controls) were recruited during the 2016 transmission season, an outbreak year in Southern Africa. After adjustment, cases were more likely to be cattle herders (Adjusted Odds Ratio (aOR): 4.46 95%CI 1.05–18.96), members of the police or other security personnel (aOR: 4.60 95%CI: 1.16–18.16), and pensioners/unemployed persons (aOR: 2.25 95%CI 1.24–4.08), compared to agricultural workers (most common category). Children (aOR 2.28 95%CI 1.13–4.59) and self-identified students were at higher risk of malaria (aOR: 4.32 95%CI 2.31–8.10). Other actionable risk factors for malaria included housing and behavioral characteristics, including traditional home construction and sleeping in an open structure (versus modern structure: aOR: 2.0195%CI 1.45–2.79 and aOR: 4.76 95%CI: 2.14–10.57); cross border travel in the prior 30days (aOR: 10.55 95%CI 2.94–37.84); and outdoor agricultural work at night (aOR: 2.09 95%CI 1.12–3.87). Malaria preventive activities were all protective and included personal use of an insecticide treated net (ITN) (aOR: 0.61 95%CI 0.42–0.87), adequate household ITN coverage (aOR: 0.63 95%CI 0.42–0.94), and household indoor residual spraying (IRS) in the past year (versus never sprayed: (aOR: 0.63 95%CI 0.44–0.90). A number of environmental factors were associated with increased risk of malaria, including lower temperatures, higher rainfall and increased vegetation for the 30 days prior to diagnosis and residing more than 5 minutes from a health facility. LCA identified six classes of cases, with class membership strongly correlated with occupation, age and select behavioral risk factors. Use of ITNs and IRS coverage was similarly low across classes. For malaria elimination these high-risk groups will need targeted and tailored intervention strategies, for example, by implementing alternative delivery methods of interventions through schools and worksites, as well as the use of specific interventions that address outdoor transmission.
Malaria risk in young male travelers but local transmission persists: A case–control study in low transmission Namibia
(2017) Smith, Jennifer L.; Auala, Joyce R.; Haindongo, Erastus H.; Uusiku, Petrina; Gosling, Roly; Kleinschmidt, Immo; Mumbengegwi, Davis R.; Sturrock, Hugh J.
Background: A key component of malaria elimination campaigns is the identification and targeting of high risk populations. To characterize high risk populations in north central Namibia, a prospective health facility-based case–control study was conducted from December 2012–July 2014. Cases (n = 107) were all patients presenting to any of the 46 health clinics located in the study districts with a confirmed Plasmodium infection by multi-species rapid diagnostic test (RDT). Population controls (n = 679) for each district were RDT negative individuals residing within a household that was randomly selected from a census listing using a two-stage sampling procedure. Demographic, travel, socio-economic, behavioural, climate and vegetation data were also collected. Spatial patterns of malaria risk were analysed. Multivariate logistic regression was used to identify risk factors for malaria. Results: Malaria risk was observed to cluster along the border with Angola, and travel patterns among cases were comparatively restricted to northern Namibia and Angola. Travel to Angola was associated with excessive risk of malaria in males (OR 43.58 95% CI 2.12–896), but there was no corresponding risk associated with travel by females. This is the first study to reveal that gender can modify the effect of travel on risk of malaria. Amongst non-travellers, male gender was also associated with a higher risk of malaria compared with females (OR 1.95 95% CI 1.25–3.04). Other strong risk factors were sleeping away from the household the previous night, lower socioeconomic status, living in an area with moderate vegetation around their house, experiencing moderate rainfall in the month prior to diagnosis and living <15 km from the Angolan border. Conclusions: These findings highlight the critical need to target malaria interventions to young male travellers, who have a disproportionate risk of malaria in northern Namibia, to coordinate cross-border regional malaria prevention initiatives and to scale up coverage of prevention measures such as indoor residual spraying and long-lasting insecticide nets in high risk areas if malaria elimination is to be realized.
Medicinal value of Aptosimum albomarginatum (Marloth and Engl.), Albizia anthelmintica (A. Rich Brongn.) and Dicoma schinzii (O. Hoffm.) to a small community living at Gochas, southern Namibia
(2017) Walter, Sunette; Beukes, Mervyn; Mumbengegwi, Davis R.; Bock, Ronnie
Traditional medicine is widely used, but its effectiveness is often questioned. Biofilm-producing bacteria and fungi are important in difficult-to-treat persistent and recurrent infections. The present study investigated the anti-biofilm properties of crude methanolic extracts from three medicinal plants used in Namibia, namely Aptosimum albomarginatum (Marloth and Engl.), Albizia anthelmintica (A. Rich Brongn.) and Dicoma schinzii (O. Hoffm.). Biofilm formation, inhibition and eradication were determined using microtiter plate assay. Extracts were tested against Escherichia coli ATCC 700928, Staphylococcus aureus ATCC 12600, S. aureus U3300, Bacillus subtilis ATCC 13933, Streptococcus mutans ATCC 25175, Streptococcus sanguinis ATCC 10556, Pseudomonas aeruginosa and Candida albicans. All isolates were strong biofilm producers. A. albomarginatum root extract moderately inhibited biofilm formation in S. mutans ATCC 25175 (60.0%), E. coli ATCC 700928 (51.6%) and P. aeruginosa (49.1%). A. anthelmintica twigs caused 58.4% biofilm inhibition in C. albicans and eradicated S. aureus U3300 biofilm by 74.8%. D. schinzii leaf extract inhibited P. aeruginosa biofilm by 67.3%, and in addition broke down S. mutans ATCC 25175 biofilm by 44.2%. These results validate the usefulness of the three plants as traditional medicine in some instances.
Molecular detection of P. vivax and P. ovale foci of infection in asymptomatic and symptomatic children in Northern Namibia
(2019) Haiyambo, Daniel H.; Uusiku, Petrina; Mumbengegwi, Davis R.; Pernica, Jeff M.; Bock, Ronnie; Malleret, Benoit; Renia, Laurent; Greco, Beatrice; Quaye, Isaac K.
Knowledge of the foci of plasmodium species infections is critical for a country with an elimination agenda. Namibia is targeting malaria elimination by 2020. To support decision making regarding targeted intervention, we examined for the first time, the foci of Plasmodium species infections and regional prevalence in northern Namibia, using nested and quantitative polymerase chain PRC methods.
Moving towards malaria elimination: Trends and attributes of cases in Kavango region, Namibia, 2010–2014
(2018) Nghipumbwa, M.H.; Ade, S.; Kizito, W.; Takarinda, K.C.; Uusiku, Petrina; Mumbengegwi, Davis R.
Setting: Kavango, a ‘moderate’ transmission risk region located in north-eastern Namibia, borders Angola, a country with higher malaria transmission levels. Objective: To determine 1) the trends in malaria incidence between 2010 and 2014 in Kavango, 2) the socio- demographic and clinical characteristics of confirmed cases in 2014, and 3) associated risk factors of cases classified as imported. Design: This was a retrospective study of malaria case investigation forms conducted in all 52 public health facilities in 2014. Incidence was derived from aggregate routine surveillance data from the Health Information System (HIS). Results: During the 5-year study, incidence fell from 53.6 to 3.6 cases per 1000 population, then increased again to 47.3/1000. Fifty-five per cent of cases were males, and 49% were aged between 5 and 17 years. Of the 2014 cases, 23% were imported, and were associated with higher odds of severe malaria (adjusted odds ratio [aOR] 1.8; 95%CI 1.01–3.29), not having long-lasting insecticide treated nets (aOR 2.1, 95%CI, 1.3–3.4) and not receiving insecticide residual spraying (aOR 3.2, 95%CI, 2.1–5.1). Conclusion: Sporadic outbreaks in the 5-year period posed a threat to malaria elimination. Better targeting of vector control interventions, strong cross-border collaboration and robust health promotion will be key to achieving malaria elimination.
Phytochemical analysis and in vitro anti-plasmodial activity of selected ethnomedicinal plants used to treat malaria associated symptoms in northern Namibia
(University of Namibia, 2013) Nafuka, Sylvia N.; Mumbengegwi, Davis R.
The search for biologically active compounds from plants is of importance for discovery of novel medicine against infectious diseases such as malaria. The aims of this study were to identify ethno-medicinal plants that are used to treat malaria-associated symptoms in traditional settings in northern Namibia; to detect and quantify the presence of major anti-plasmodial phytochemicals to evaluate the anti-plasmodial activity against Plasmodium falciparum 3D7A strain of the extracts of lead plants. Ten plants were identified through a survey conducted by the Multidisciplinary Research Centre at the University of Namibia. Nineteen methanolic extracts from 10 selected ethnomedicinal plants were prepared and analyzed using Thin Layer Chromatography (TLC) to detect classes of anti-plasmodial phytochemical compounds. Furthermore, total phenolic and alkaloids were also quantified. Furthermore, in vitro anti-plasmodial activity of crude methanol and aqueous extracts at 5, 10 and 50 mg/ml was evaluated against P. falciparum 3D7A strain at 1% parasitaemia and 2% hematocrit after 48 hours. The study revealed the presence of at least one of the major anti-plasmodial classes of compounds such as terpenoids, alkaloids, anthraquinones, flavonoids and coumarins in all the plant extracts analyzed. Out of 10 plant species, Mundulea sericea’s shoots indicated the presence of all five major anti-plasmodial phytochemical. The plants species studied show a high estimate of total alkaloids (0.37- 21.21 mg/1g of extracts) and phenolics (99. 58 - 444.07 GA/E mg/ml). Methanol extracts of M. sericea, D. mespiliformis and Cyphostemma spp showed the best anti-plasmodial activity with range of IC50 values from 3.179 to 3.523 mg/ml. The presence of anti-plasmodial phytochemical classes of compounds and high in vitro anti-plasmodial activity of selected plants extracts support the further investigation of these plants, as potential sources of novel anti-plasmodial compounds for malaria drug discovery.
Phytochemical investigation on Namibian plants for anti-malaria compounds
(University of Namibia, 2012) Du Preez, Iwanette C.; Mumbengegwi, Davis R.
Malaria is on the decline in Namibia due to interventions by the Ministry of Health and Social Services (MoHSS) and the country is moving towards pre-elimination of the disease. However, barriers such as resistance of the uptake of interventions by "at risk" communities, e.g. lack of treatment seeking behavior for WHO recommended ACT's exist. Some communities in malaria-endemic areas do not accept Western medicine, preferring traditional medicines as prescribed by traditional healers. It is important to balance people's cultural beliefs and practices with the MoHSS's objective of malaria elimination by 2020. To facilitate integration of traditional treatments into mainstream malaria case management, documentation and validation of the treatments to allow their safe and effective use have to be carried out. This study was conducted to document and validate the use of seven plants native to Namibia, targeted on the basis of their indigenous uses which suggest their toxicity to Plasmodium parasites. Crude extracts were prepared using methanol-dichloromethane (1/1V/V) and distilled water at 60 C. The extracts were further Partitioned with chloroform-methanol water (12/6/lV/V). Preliminary phytochemical screening was performed to detect the presence of selected Antiplasmodial compounds. Phytochemical tests revealed the presence of anthraquinones, flavonoids, terpenoids, coumarines, and glycosides; alkaloids and steroids were not detected. Paradoxically, thin-layer chromatography analysis on the crude extracts of the same plants tested positive for all compounds. The presence of these phytochemicals and the data generated support the ethno-medicinal uses for these plants
Rondomized anticancer and cytotoxicity activities of Guibourtia Coleosperma and Diospyros Chamaethamnus
(2017) Dushimemaria, Florence; Du Preez, Iwanette C.; Mumbengegwi, Davis R.
Background: Plants have consistently proven to be a reliable and yet not fully explored source of medicines. In light of this, there is a constant demand for new treatment regimens for cancer. Namibia has a rich diversity of plant species of over 4300 with 17 % of them being endemic to Namibia. Plants growing in Namibia’s diverse climatic zones produce many secondary metabolites as part of adaptation to their environment. This article focused on the screening of such phytochemicals and their cytotoxic and anticancer properties in vitro. Two Namibian plants Diospyros chamaethamnus and Guibourtia coleosperma were randomly selected for this purpose. Materials and Methods: The plants were screened for the presence of coumarins, alkaloids, flavonoids, anthraquinones, steroids and terpenoids using thin layer chromatography. Anticancer screening was performed on a panel of three cancer cell lines, while cytotoxicity was determined using a human fibroblast cell line, both using the SRB method. Results: Alkaloids, anthraquinones, flavonoids and steroids were detected in both organic and aqueous extracts of the two plants. The organic plant extracts had a greater anti-proliferative effect on the cancer cell lines than the aqueous extracts; the D. chamaethamnus organic root extract was the most potent with an IC50 of 16.08, 29.12 and 24.67 μg/mL against TK10, UACC62 and MCF7 cells, respectively. Furthermore, cytotoxicity analysis revealed the non-toxic nature of the extracts, except for the organic root extract of D. chamaethamnus that showed significant cytotoxicity (IC50 13.03 μg/mL). Conclusion: D. chamaethamnus is a potential candidate for the development of a plant based cancer treatment. The study showed the value of random screening in drug discovery from plants for pharmacological activity that is unrelated to their ethnomedicinal uses.
Spatial clustering of patent and sub-patent malaria infections in northern Namibia: Implications for surveillance and response strategies for elimination
(2017) Smith, Jennifer L.; Auala, Joyce R.; Tambo, Munyaradzi; Haindongo, Erastus H.; Katokele, Stark; Uusiku, Petrina; Gosling, Roly; Kleinschmidt, Immo; Mumbengegwi, Davis R.; Sturrock, Hugh J.
Reactive case detection (RACD) around passively detected malaria cases is a strategy to identify and treat hotspots of malaria transmission. This study investigated the unproven assumption on which this approach is based, that in low transmission settings, infections cluster over small scales.

Browsing by Author "Mumbengegwi, Davis R."

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