ORCID Profile
0000-0002-7001-3865
Current Organisations
National Institute for Communicable Diseases
,
NSW Office of Environment and Heritage
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Publisher: Elsevier BV
Date: 05-2010
Publisher: Elsevier BV
Date: 2004
Publisher: American Geophysical Union (AGU)
Date: 2014
DOI: 10.1002/2013JC009284
Publisher: Springer Science and Business Media LLC
Date: 16-02-2021
DOI: 10.1186/S12936-021-03635-Z
Abstract: South Africa aims to eliminate malaria transmission by 2023. However, despite sustained vector control efforts and case management interventions, the Vhembe District remains a malaria transmission hotspot. To better understand Plasmodium falciparum transmission dynamics in the area, this study characterized the genetic ersity of parasites circulating within the Vhembe District. A total of 1153 falciparum-positive rapid diagnostic tests (RDTs) were randomly collected from seven clinics within the district, over three consecutive years (2016, 2017 and 2018) during the wet and dry malaria transmission seasons. Using 26 neutral microsatellite markers, differences in genetic ersity were described using a multiparameter scale of multiplicity of infection (MOI), inbreeding metric (Fws), number of unique alleles (A), expected heterozygosity ( He ), multilocus linkage disequilibrium (LD) and genetic differentiation, and were associated with temporal and geospatial variances. A total of 747 (65%) s les were successfully genotyped. Moderate to high genetic ersity (mean He = 0.74 ± 0.03) was observed in the parasite population. This was ascribed to high allelic richness (mean A = 12.2 ± 1.2). The majority of s les (99%) had unique multi-locus genotypes, indicating high genetic ersity in the s le set. Complex infections were observed in 66% of s les (mean MOI = 2.13 ± 0.04), with 33% of infections showing high within-host ersity as described by the Fws metric. Low, but significant LD (standardised index of association, ISA = 0.08, P 0.001 ) was observed that indicates recombination of distinct clones. Limited impact of temporal (F ST range − 0.00005 to 0.0003) and spatial (F ST = − 0.028 to 0.023) variation on genetic ersity existed during the s ling timeframe and study sites respectively. Consistent with the Vhembe District’s classification as a ‘high’ transmission setting within South Africa, P. falciparum ersity in the area was moderate to high and complex. This study showed that genetic ersity within the parasite population reflects the continued residual transmission observed in the Vhembe District. This data can be used as a reference point for the assessment of the effectiveness of on-going interventions over time, the identification of imported cases and/or outbreaks, as well as monitoring for the potential spread of anti-malarial drug resistance.
Publisher: American Society of Civil Engineers
Date: 11-05-2007
Publisher: Coastal Education and Research Foundation
Date: 03-03-2016
DOI: 10.2112/SI75-238.1
Publisher: MDPI AG
Date: 23-12-2017
DOI: 10.3390/RS10010011
Publisher: Springer Science and Business Media LLC
Date: 29-06-2022
DOI: 10.1186/S12936-022-04224-4
Abstract: Independent emergence and spread of artemisinin-resistant Plasmodium falciparum malaria have recently been confirmed in Africa, with molecular markers associated with artemisinin resistance increasingly detected. Surveillance to promptly detect and effectively respond to anti-malarial resistance is generally suboptimal in Africa, especially in low transmission settings where therapeutic efficacy studies are often not feasible due to recruitment challenges. However, these communities may be at higher risk of anti-malarial resistance. From March 2018 to February 2020, a sequential mixed-methods study was conducted to evaluate the feasibility of the near-real-time linkage of in idual patient anti-malarial resistance profiles with their case notifications and treatment response reports, and map these to fine scales in Nkomazi sub-district, Mpumalanga, a pre-elimination area in South Africa. Plasmodium falciparum molecular marker resistance profiles were linked to 55.1% (2636/4787) of notified malaria cases, 85% (2240/2636) of which were mapped to healthcare facility, ward and locality levels. Over time, linkage of in idual malaria case demographic and molecular data increased to 75.1%. No artemisinin resistant validated/associated Kelch-13 mutations were detected in the 2385 PCR positive s les. Almost all 2812 s les assessed for lumefantrine susceptibility carried the wildtype mdr 86ASN and crt 76LYS alleles, potentially associated with decreased lumefantrine susceptibility. Routine near-real-time mapping of molecular markers associated with anti-malarial drug resistance on a fine spatial scale provides a rapid and efficient early warning system for emerging resistance. The lessons learnt here could inform scale-up to provincial, national and regional malaria elimination programmes, and may be relevant for other antimicrobial resistance surveillance.
Publisher: Springer Science and Business Media LLC
Date: 03-09-2019
Publisher: Coastal Education and Research Foundation
Date: 05-2009
DOI: 10.2112/08-1032.1
Publisher: Elsevier BV
Date: 08-2021
Publisher: Oxford University Press (OUP)
Date: 11-08-2020
Abstract: Since the World Health Organization recommended single low-dose (0.25 mg/kg) primaquine (PQ) in combination with artemisinin-based combination therapies (ACTs) in areas of low transmission or artemisinin-resistant Plasmodium falciparum, several single-site studies have been conducted to assess efficacy. An in idual patient meta-analysis to assess gametocytocidal and transmission-blocking efficacy of PQ in combination with different ACTs was conducted. Random effects logistic regression was used to quantify PQ effect on (1) gametocyte carriage in the first 2 weeks post treatment and (2) the probability of infecting at least 1 mosquito or of a mosquito becoming infected. In 2574 participants from 14 studies, PQ reduced PCR-determined gametocyte carriage on days 7 and 14, most apparently in patients presenting with gametocytemia on day 0 (odds ratio [OR], 0.22 95% confidence interval [CI], .17–.28 and OR, 0.12 95% CI, .08–.16, respectively). Rate of decline in gametocyte carriage was faster when PQ was combined with artemether-lumefantrine (AL) compared to dihydroartemisinin-piperaquine (DP) (P = .010 for day 7). Addition of 0.25 mg/kg PQ was associated with near complete prevention of transmission to mosquitoes. Transmission blocking is achieved with 0.25 mg/kg PQ. Gametocyte persistence and infectivity are lower when PQ is combined with AL compared to DP.
Publisher: Elsevier BV
Date: 11-2004
Publisher: American Meteorological Society
Date: 05-2013
Abstract: The cross-shelf dynamics up- and downstream of the separation of the South Pacific Ocean’s Western Boundary Current (WBC) are studied using two years of high-resolution velocity and temperature measurements from mooring arrays. The shelf circulation is dominated by the East Australian Current (EAC) and its eddy field, with mean poleward depth-integrated magnitudes on the shelf break of 0.35 and 0.15 m s−1 up- and downstream of the separation point, respectively. The high cross-shelf variability is analyzed though a momentum budget, showing a dominant geostrophic balance at both locations. Among the secondary midshelf terms, the bottom stress influence is higher upstream of the separation point while the wind stress is dominant downstream. This study investigates the response of the velocity and temperature cross-shelf structure to both wind and EAC intrusions. Despite the deep water (up to 140 m), the response to a dominant along-shelf wind stress forcing is a classic two-layer Ekman structure. During weak winds, the shelf encroachment of the southward current drives an onshore Ekman flow in the bottom boundary layer. Both the bottom velocity and the resultant bottom cross-shelf temperature gradient are proportional to the magnitude of the encroaching current, with similar linear regressions up- and downstream of the WBC separation. The upwelled water is then subducted below the EAC upstream of the separation point. Such current-driven upwelling is shown to be the dominant driver of cold water uplift in the EAC-dominated region, with significant impacts expected on nutrient enrichment and thus on biological productivity.
Publisher: Elsevier BV
Date: 08-2010
Publisher: Elsevier BV
Date: 05-2001
Publisher: American Meteorological Society
Date: 10-2014
Publisher: Coastal Education and Research Foundation
Date: 04-2004
Publisher: Elsevier BV
Date: 09-2009
Publisher: Coastal Education and Research Foundation
Date: 03-03-2016
DOI: 10.2112/SI75-191.1
Publisher: Springer Science and Business Media LLC
Date: 15-04-2020
DOI: 10.1186/S12936-020-03227-3
Abstract: KwaZulu-Natal, one of South Africa’s three malaria endemic provinces, is nearing malaria elimination, reporting fewer than 100 locally-acquired cases annually since 2010. Despite sustained implementation of essential interventions, including annual indoor residual spraying, prompt case detection using malaria rapid diagnostics tests and treatment with effective artemisinin-based combination therapy, low-level focal transmission persists in the province. This malaria prevalence and entomological survey was therefore undertaken to identify the drivers of this residual transmission. Malaria prevalence as well as malaria knowledge, attitudes and practices among community members and mobile migrant populations within uMkhanyakude district, KwaZulu-Natal were assessed during a community-based malaria prevalence survey. All consenting participants were tested for malaria by both conventional and highly-sensitive falciparum-specific rapid diagnostic tests. Finger-prick filter-paper blood spots were also collected from all participants for downstream parasite genotyping analysis. Entomological investigations were conducted around the surveyed households, with potential breeding sites geolocated and larvae collected for species identification and insecticide susceptibility testing. A random selection of households were assessed for indoor residual spray quality by cone bioassay. A low malaria prevalence was confirmed in the study area, with only 2% (67/2979) of the participants found to be malaria positive by both conventional and highly-sensitive falciparum-specific rapid diagnostic tests. Malaria prevalence however differed markedly between the border market and community (p 0001), with the majority of the detected malaria carriers (65/67) identified as asymptomatic Mozambican nationals transiting through the informal border market from Mozambique to economic hubs within South Africa. Genomic analysis of the malaria isolates revealed a high degree of heterozygosity and limited genetic relatedness between the isolates supporting the hypothesis of limited local malaria transmission within the province. New potential vector breeding sites, potential vector populations with reduced insecticide susceptibility and areas with sub-optimal vector intervention coverage were identified during the entomological investigations. If KwaZulu-Natal is to successfully halt local malaria transmission and prevent the re-introduction of malaria, greater efforts need to be placed on detecting and treating malaria carriers at both formal and informal border crossings with transmission blocking anti-malarials, while ensuring optimal coverage of vector control interventions is achieved.
Publisher: Springer Science and Business Media LLC
Date: 04-05-2018
DOI: 10.1038/S41598-018-25410-Y
Abstract: Broad scale assessments of impacts associated with sea level rise have mainly been undertaken using ocean water level data from tide gauges located in harbours and ports assuming that these can be applied directly in mapping inundation throughout estuaries. On many coasts, however, exposure to sea level rise comes about through inundation adjacent to rivers and estuaries, in many instances far from the ocean. In this study, we examine the potential impacts of sea level rise within the erse estuaries of South East Australia. We use an extensive and long-term water level data set, which show that water levels within the different types of estuaries vary from ocean water levels. We map potential inundation scenarios for each estuary using an approach which improves on the commonly used bath tub method by allowing for variation in tidal processes both between and along estuaries. We identify considerable exposure to future sea level rise, and variable suitability of the bath tub method within different estuaries. Exposure is particularly high around tidal lake systems, where reduced tidal ranges have allowed development to occur in relative proximity to present sea level, and around larger coastal rivers, which feature extensive low-lying plains exposed to potential inundation.
Publisher: American Society of Tropical Medicine and Hygiene
Date: 15-06-2022
Publisher: Coastal Education and Research Foundation
Date: 03-03-2016
DOI: 10.2112/SI75-198.1
Publisher: MDPI AG
Date: 20-12-2017
DOI: 10.3390/JMSE5040061
Publisher: Springer Science and Business Media LLC
Date: 27-05-2020
DOI: 10.1007/S12237-020-00756-7
Abstract: The potential response of shoreface depositional environments to sea level rise over the present century and beyond remains poorly understood. The shoreface is shaped by wave action across a sedimentary seabed and may aggrade or deflate depending on the balance between time-averaged wave energy and the availability and character of sediment, within the context of the inherited geological control. For embayed and accommodation-dominated coastal settings, where shoreline change is particularly sensitive to cross-shore sediment transport, whether the shoreface is a source or sink for coastal sediment during rising sea level may be a crucial determinant of future shoreline change. While simple equilibrium-based models (e.g. the Bruun Rule) are widely used in coastal risk planning practice to predict shoreline change due to sea level rise, the relevance of fundamental model assumptions to the shoreface depositional setting is often overlooked due to limited knowledge about the geomorphology of the nearshore seabed. We present high-resolution mapping of the shoreface-inner shelf in southeastern Australia from airborne lidar and vessel-based multibeam echosounder surveys, which reveals a more complex seabed than was previously known. The mapping data are used to interpret the extent, depositional character and morphodynamic state of the shoreface, by comparing the observed geomorphology to theoretical predictions from wave-driven sediment transport theory. The benefits of high-resolution seabed mapping for improving shoreline change predictions in practice are explored by comparing idealised shoreline change modelling based on our understanding of shoreface geomorphology and morphodynamics before and after the mapping exercise.
Publisher: MDPI AG
Date: 22-03-2019
DOI: 10.3390/GEOSCIENCES9030141
Abstract: In 2017, the New South Wales (NSW) Office of Environment and Heritage (OEH) initiated a state-wide mapping program, SeaBed NSW, which systematically acquires high-resolution (2–5 m cell size) multibeam echosounder (MBES) and marine LiDAR data along more than 2000 km of the subtropical-to-temperate southeast Australian continental shelf. This program considerably expands upon existing efforts by OEH to date, which have mapped approximately 15% of NSW waters with these technologies. The delivery of high volumes of new data, together with the vast repository of existing data, highlights the need for a standardised, automated approach to classify seabed data. Here we present a methodological approach with new procedures to semi-automate the classification of high-resolution bathymetry and intensity (backscatter and reflectivity) data into a suite of data products including classifications of seabed morphology (landforms) and composition (substrates, habitats, geomorphology). These methodologies are applied to two case study areas representing newer (Wollongong, NSW) and older (South Solitary Islands, NSW) MBES datasets to assess the transferability of classification techniques across input data of varied quality. The suite of seabed classifications produced by this study provide fundamental baseline data on seabed shape, complexity, and composition which will inform regional risk assessments and provide insights into bio ersity and geo ersity.
Location: South Africa
No related grants have been discovered for Bradley Morris.