Davis C Nwakanma

Davis C Nwakanma
MRC Unit the Gambia | MRC · Disease Control and Elimination

PhD Molecular Genetics

About

152
Publications
31,050
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3,227
Citations
Additional affiliations
October 2010 - October 2010
Broad Institute of MIT and Harvard
Position
  • Bioinformatic analysis of Anopheles gambiae microarray data
October 2003 - July 2006
University of Edinburgh
Position
  • Dynamics of gametocyte production of Plasmodium falciparum clones in nature.
January 2009 - present
Sultan Qaboos University

Publications

Publications (152)
Article
Full-text available
Background Malaria elimination in Senegal requires accurate diagnosis of all Plasmodium species. Plasmodium falciparum is the most prevalent species in Senegal, although Plasmodium malariae, Plasmodium ovale, and recently Plasmodium vivax have also been reported. Nonetheless, most malaria control tools, such as Histidine Rich Protein 2 rapid diagno...
Article
ABSTRACT Introduction: Sodium fluoride/potassium oxalate (NaF/KOx) tubes were once regarded as the gold- standard tubes for glucose analysis. Even though their ineffectiveness in immediately inhibiting glycolysis has been reported in several studies especially in the first 1–4 hours, they are still used in our clinical Biochemistry laboratory for g...
Article
Full-text available
Antimicrobial resistance is a global health threat and efforts to mitigate it is warranted, thus the need for local antibiograms to improve stewardship. This study highlights the process that was used to develop an antibiogram to monitor resistance at a secondary-level health facility to aid empirical clinical decision making in a sub-Saharan Afric...
Article
Full-text available
Background Carriers of persistent asymptomatic Plasmodium falciparum infections constitute an infectious reservoir that maintains malaria transmission. Understanding the extent of carriage and characteristics of carriers specific to endemic areas could guide use of interventions to reduce infectious reservoir. Methods In eastern Gambia, an all-age...
Article
Full-text available
Background: The coronavirus disease (COVID-19) pandemic resulted in an unprecedent global response for the development of COVID-19 vaccines. However, as viral mutations continue to occur, potentially decreasing the efficacy of currently available vaccines, and inequity of vaccine access continues, identifying safe and effective drugs to minimise se...
Article
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Background: The outbreak of COVID-19 disease and rapid spread of the virus outside China led to its declaration as a Public Health Emergency of International Concern (PHEIC) in January 2020. Key elements of the early intervention strategy focused on laboratory diagnosis and screening at points of entry and imposition of restrictions in crossborder...
Preprint
Full-text available
Background Carriers of persistent asymptomatic Plasmodium falciparum infections constitute an infectious reservoir that maintains malaria transmission. Understanding the extent of carriage and characteristics of carriers specific to endemic areas could guide use of interventions to reduce infectious reservoir. Methods In eastern Gambia, an all-age...
Preprint
Full-text available
Background Diagnostic microbiological capabilities remain a challenge in low- and middle-income countries resulting in major gaps. The global antimicrobial resistance burden has necessitated use of appropriate prescribing to curb the menace. This study highlights the process used to develop an antibiogram to monitor resistance at a secondary-level...
Article
Full-text available
Non-typhoidal Salmonella associated with multidrug resistance cause invasive disease in sub-Saharan Africa. Specific lineages of serovars Typhimurium and Enteritidis have been implicated. Here we characterized the genomic diversity of 100 clinical non-typhoidal Salmonella collected from 93 patients in 2001 from the eastern, and in 2006–2018 from th...
Article
Background: Recent studies have observed vectors resting predominantly outdoors in settings where anti-vector tools are extensively deployed, attributed to selection pressure from use of control tools. This present study examined if the outdoor resting behaviour in the vector population is random or indicative of a consistent preference of one rest...
Article
Background: Recent studies have observed vectors resting predominantly outdoors in settings where anti-vector tools are extensively deployed, attributed to selection pressure from use of control tools. This present study examined if the outdoor resting behaviour in the vector population is random or indicative of a consistent preference of one rest...
Article
Full-text available
The SARS-CoV-2 disease, first detected in Wuhan, China, in December 2019 has become a global pandemic and is causing an unprecedented burden on health care systems and the economy globally. While the travel history of index cases may suggest the origin of infection, phylogenetic analysis of isolated strains from these cases and contacts will increa...
Article
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The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is evolving differently in Africa than in other regions. Africa has lower SARS-CoV-2 transmission rates and milder clinical manifestations. Detailed SARS-CoV-2 epidemiologic data are needed in Africa. We used publicly available data to calculate SARS-CoV-2 infections per 1,00...
Article
Full-text available
Background The scale-up of indoor residual spraying and long-lasting insecticidal nets, together with other interventions have considerably reduced the malaria burden in The Gambia. This study examined the biting and resting preferences of the local insecticide-resistant vector populations few years following scale-up of anti-vector interventions....
Preprint
Full-text available
Background Recent reports of a change in the resting behaviour of malaria vectors, from predominantly indoor resting to outdoor resting following blood feeding, have been attributed to selection pressure from use of vector control tools such as indoor residual spraying and long-lasting insecticide-treated nets. Recent studies have observed vectors...
Preprint
Full-text available
Background Recent reports of a change in the resting behaviour of malaria vectors, from predominantly indoor resting to outdoor resting following blood feeding, have been attributed to selection pressure from use of vector control tools such as indoor residual spraying and long-lasting insecticide-treated nets. Recent studies have observed vectors...
Article
Full-text available
Background Mosquito feeding assays using venous blood are commonly used for evaluating the transmission potential of malaria infected individuals. To improve the accuracy of these assays, care must be taken to prevent premature activation or inactivation of gametocytes before they are fed to mosquitoes. This can be challenging in the field where in...
Research
Full-text available
Full Blood Count (FBC) is a significant laboratory investigation often requested in clinical care and trials; laboratories should have comparable alternative methods for this test to ensure uninterrupted services. This study evaluated to what extent the Abbott CELL-DYN Ruby and Boule Medonic M-series haematology analysers can be used interchangeabl...
Preprint
Full-text available
Background Mosquito feeding assays using venous blood are commonly used for evaluating the transmission potential of malaria infected individuals. To improve the accuracy of these assays, care must be taken to prevent premature activation or inactivation of gametocytes before they are fed to mosquitoes. This can be challenging in the field where in...
Preprint
Full-text available
Non-typhoidal Salmonella associated with multidrug resistance cause invasive disease in sub-Saharan African. Specific lineages of serovars S . Typhimurium and S . Enteritidis are implicated. We characterised the genomic diversity of 100 clinical Non-typhoidal Salmonella collected from 93 patients in 2001 from the eastern and 2006 to 2018 in the wes...
Preprint
Full-text available
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is a positive-sense single stranded RNA virus with high human transmissibility. This study generated Whole Genome data to determine the origin and pattern of transmission of SARS-CoV-2 from the first six cases tested in The Gambia. Total RNA from SARS-CoV-2 was extracted from inactivated...
Preprint
Full-text available
Background The scale-up of indoor residual spraying and long-lasting insecticidal nets, together with other interventions have considerably reduced the malaria burden in The Gambia. This study examined the biting and resting preferences of the local insecticide-resistant vector populations few years following scale-up of anti-vector interventions....
Article
Full-text available
Background: Selection pressure from continued exposure to insecticides drives development of insecticide resistance and changes in resting behaviour of malaria vectors. There is need to understand how resistance drives changes in resting behaviour within vector species. The association between insecticide resistance and resting behaviour of Anophe...
Article
Full-text available
Background Sick newborns admitted to neonatal units in low-resource settings are at an increased risk of developing hospital-acquired infections due to poor clinical care practices. Clusters of infection, due to the same species, with a consistent antibiotic resistance profile, and in the same ward over a short period of time might be indicative of...
Conference Paper
Background: The introduction of PCV7 in August 2009 and PCV13 in May 2011 in The Gambia resulted in decline of IPD by 55% although changing serotypes are emerging. We retrospectively compare serotype prevalence before and after. Methods: Data for all blood and cerebrospinal fluid (CSF) between January 2005 and December 2015 were analysed. Surveill...
Preprint
Full-text available
Background Selection pressure from continued exposure to insecticides drives the development of insecticide resistance and changes in resting behavior of malaria vectors, which may support residual transmission in several endemic settings. There is a need to understand how resistance drives changes in resting behavior within vector species. Here, w...
Preprint
Full-text available
Background: Selection pressure from continued exposure to insecticides drives the development of insecticide resistance and changes in resting behavior of malaria vectors, which may support residual transmission in several endemic settings. There is a need to understand how resistance drives changes in resting behavior within vector species. Here,...
Preprint
Full-text available
Background Selection pressure from continued exposure to insecticides drives development of insecticide resistance and changes in resting behaviour of malaria vectors. There is need to understand how resistance drives changes in resting behaviour within vector species. The association between insecticide resistance and resting behaviour of Anophele...
Poster
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The association between AMR and Climate change is increasingly gaining attention. This poster presents evidence of this. It is imperative that countries take the threat of Climate change seriously to tackle two important pandemics
Article
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Background: Because clustering of Plasmodium falciparum infection had been noted previously, the clustering of infection was examined at four field sites in West Africa: Dangassa and Dioro in Mali, Gambissara in The Gambia and Madina Fall in Senegal. Methods: Clustering of infection was defined by the percent of persons with positive slides for...
Preprint
Full-text available
Mosquito control remains a central pillar of efforts to reduce malaria burden in sub-Saharan Africa. However, insecticide resistance is entrenched in malaria vector populations, and countries with high malaria burden face a daunting challenge to sustain malaria control with a limited set of surveillance and intervention tools. Here we report on the...
Article
Full-text available
Background. Invasive bacterial diseases cause significant disease and death in sub-Saharan Africa. Several are vaccine preventable, although the impact of new vaccines and vaccine policies on disease patterns in these communities is poorly understood owing to limited surveillance data. Methods. We conducted a hospital-based surveillance of invasive...
Article
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During infection, increasing pathogen load stimulates both protective and harmful aspects of the host response. The dynamics of this interaction are hard to quantify in humans, but doing so could improve understanding of the mechanisms of disease and protection. We sought to model the contributions of the parasite multiplication rate and host respo...
Article
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Background: We assessed the impact of exposure to P. falciparum on parasite kinetics, clinical symptoms, and functional immunity after controlled human malaria infection (CHMI) in two cohorts with different levels of previous malarial exposure. Methods: Nine adult males with high (sero-high) and ten with low (sero-low) previous exposure received...
Article
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Background: Staphylococcus aureus is a major human pathogen. Panton-Valentine leukocidin (PVL) is a virulence factor produced by some strains that causes leukocyte lysis and tissue necrosis. PVL-associated S. aureus (PVL-SA) predominantly causes skin and soft-tissue infections (SSTIs) but can also cause invasive infections such as necrotizing pneum...
Preprint
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Staphylococcus aureus (S. aureus) is a major human pathogen with several virulence factors. One of such virulence factors PVL was found to be high in clinical S. aureus of samples analyzed in our setting but antimicrobial resistance including methicillin resistance was low. 2 Abstract Background:
Article
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Background Developing and sustaining a data collection and management system (DCMS) is difficult in malaria-endemic countries because of limitations in internet bandwidth, computer resources and numbers of trained personnel. The premise of this paper is that development of a DCMS in West Africa was a critically important outcome of the West African...
Article
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Background: Mass drug administration (MDA) may further reduce malaria transmission in low transmission areas. The impact of MDA on dynamics of malaria transmission was determined in a prospective cohort study. Methods: Annual rounds of MDA with dihydroartemisinin-piperaquine (DP) were implemented over two years (2014 and 2015) in six village pai...
Article
Full-text available
Mass drug administration (MDA) may further reduce malaria transmission in low transmission areas. The impact of MDA on dynamics of malaria transmission was determined in a prospective cohort study. Annual rounds of MDA with dihydroartemisinin-piperaquine (DP) were implemented over two years (2014 and 2015) in six village pairs before the malaria tr...
Poster
Full-text available
Background. Plasmodium falciparum may evade complement-mediated host defense by hijacking complement Factor H (FH), a negative regulator of the alternative complement pathway. Plasma levels of FH vary between individuals and may therefore influence malaria susceptibility and severity. Methods. We measured convalescent FH plasma levels in 149 Gambia...
Preprint
Full-text available
The requirement for next generation anti-malarials to be both curative and transmission blockers necessitate the identification of molecular pathways essential for viability of both asexual and sexual parasite life stages. Here we identify a selective inhibitor to the Plasmodium falciparum protein kinase PfCLK3 which we use in combination with chem...
Article
Full-text available
Background Plasmodium falciparum may evade complement-mediated host defense by hijacking complement factor H (FH), a negative regulator of the alternative complement pathway. Plasma levels of FH vary between individuals and may therefore influence malaria susceptibility and severity. Methods We measured convalescent FH plasma levels in 149 Gambian...
Article
Full-text available
Genome sequences of 247 Plasmodium falciparum isolates collected in The Gambia in 2008 and 2014 were analysed to identify changes possibly related to the scale-up of antimalarial interventions that occurred during this period. Overall, there were 15 regions across the genomes with signatures of positive selection. Five of these were sweeps around k...
Preprint
Full-text available
Improved methods are needed to identify host mechanisms which directly protect against human infectious diseases in order to develop better vaccines and therapeutics. Pathogen load determines the outcome of many infections, and is a consequence of pathogen multiplication rate, duration of the infection, and inhibition or killing of pathogen by the...
Article
Full-text available
BACKGROUND Passive therapy with convalescent plasma provides an early opportunity to intervene in Ebola virus disease (EVD). Methods for field screening and selection of potential donors and quantifying plasma antibody are needed. STUDY DESIGN AND METHODS Recombinant Ebola virus glycoprotein (EBOV GP) was formatted into immunoglobulin G‐capture, c...
Article
Full-text available
Background Systematic treatment of all individuals living in the same compound of a clinical malaria case may clear asymptomatic infections and possibly reduce malaria transmission, where this is focal. High and sustained coverage is extremely important and requires active community engagement. This study explores a community-based approach to trea...
Article
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Background: In 2012, the World Health Organization recommended blocking the transmission of Plasmodium falciparum with single low-dose primaquine (SLDPQ, target dose 0.25 mg base/kg body weight), without testing for glucose-6-phosphate dehydrogenase deficiency (G6PDd), when treating patients with uncomplicated falciparum malaria. We sought to deve...
Article
Full-text available
Antimalarial interventions have yielded significant decline in malaria prevalence in The Gambia, where Artemether-Lumefantrine (AL) has been used as first line antimalarial for a decade. Clinical Plasmodium falciparum isolates collected from 2012 to 2015 were analysed ex vivo for antimalarial susceptibility and genotyped for drug resistance markers...
Preprint
Full-text available
The pathogenesis of severe Plasmodium falciparum malaria is incompletely understood. Since the pathogenic stage of the parasite is restricted to blood, dual RNA-sequencing of host and parasite transcripts in blood can reveal their interactions at a systemic scale. Here we identify human and parasite gene expression associated with severe disease fe...
Article
Full-text available
Background The monitoring of Plasmodium falciparum sensitivity to anti-malarial drugs is a necessity for effective case management of malaria. This species is characterized by a strong resistance to anti-malarial drugs. In Senegal, the first cases of chloroquine resistance were reported in the Dakar region in 1988 with nearly 7% population prevalen...
Article
The pathogenesis of severe Plasmodium falciparum malaria is incompletely understood. Since the pathogenic stage of the parasite is restricted to blood, dual RNA-sequencing of host and parasite transcripts in blood can reveal their interactions at a systemic scale. Here we identify human and parasite gene expression associated with severe disease fe...
Article
Objectives: To simultaneously estimate the prevalence of antibodies against Coxiella burnetii (Q fever) among adults and small ruminants, and C. burnetii shedding prevalence among small ruminants in households in the Kiang West district of The Gambia; and to assess associated risk factors. Methods: Sera of 599 adults and 615 small ruminants from...
Article
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RESUME L'émergence de la résistance aux antipaludiques était associée á l'accroissement dramatique de la mortalité due au paludisme dans certaines régions endémiques. Au Bénin, le paludisme est primairement causé par Plasmodium falciparum, l'une des espèces qui infectent l'homme. Le changement dans la politique de contrôle et de traitement du palud...
Article
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Background Brucellosis is a worldwide zoonosis with significant impact on rural livelihoods and a potentially underestimated contributor to febrile illnesses. The aim of this study was to estimate the seroprevalence of brucellosis in humans and small ruminants in The Gambia. Methods The study was carried out in rural and urban areas. In 12 rural v...
Data
Animal and Flock data. Sheet A: data on all included animals. Sheet B: data on the included small ruminant flocks. Sheet C: explanatory Data Dictionary. (XLSX)
Article
Full-text available
Background Previous genome-wide analyses of single nucleotide variation in Plasmodium falciparum identified evidence of an extended haplotype region on chromosome 6 in West Africa, suggesting recent positive selection. Such a pattern is not seen in samples from East Africa or South East Asia, so it could be marking a selective process specific to W...
Article
Full-text available
Background: Asymptomatic low-density gametocyte carriers represent the majority of malaria-infected individuals. However, the impact of recommended treatment with single low dose of primaquine and an artemisinin-based combination therapy to reduce transmission in this group is unknown. Methods: This was a four-arm, open label, randomized control...
Article
Full-text available
Background The use of artemisinin as a monotherapy resulted in the emergence of artemisinin resistance in 2005 in Southeast Asia. Monitoring of artemisinin combination therapy (ACT) is critical in order to detect and prevent the spread of resistance in endemic areas. Ex vivo studies and genotyping of molecular markers of resistance can be used as p...
Article
Full-text available
In 2006, artemether-lumefantrine (AL) became the first-line treatment of uncomplicated malaria in Senegal, Mali, and the Gambia. To monitor its efficacy, between August 2011 and November 2014, children with uncomplicated Plasmodium falciparum malaria were treated with AL and followed up for 42 days. A total of 463 subjects were enrolled in three si...