Mary Oguike

Mary Oguike
London School of Hygiene and Tropical Medicine | LSHTM · Department of Immunology and Infection

About

60
Publications
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1,104
Citations

Publications

Publications (60)
Article
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Objectives: This study identifies and characterises circulating Plasmodium species in three provinces of Mindanao approaching malaria elimination. Methods: RDT, microscopic examination and PCR were used to detect malaria parasites. PCR-positive isolates were genotyped for polymorphisms in loci of interest. Results: 2,639 participants were surv...
Article
Background: In Nigeria, indiscriminate use of antimalarial drugs may contribute to the threat of drug resistance, but this has not been evaluated among people living with human immunodeficiency virus (HIV). Methods: HIV-positive adults attending a university hospital HIV clinic and HIV-negative adult volunteers from the university hospital commu...
Article
Background: Human ovale malaria is caused by the two closely related species, Plasmodium ovale curtisi and P. ovale wallikeri. Both species are known to relapse from quiescent hepatic forms months or years after the primary infection occurred. Although some studies have succeeded in establishing mosquito transmission for ovale malaria, none have s...
Article
Background: Plasmodium ovale and Plasmodium malariae infections are scarcely studied in sub-Saharan Africa, where the Plasmodium falciparum species predominates. The objective of this study is to investigate the prevalence of P. ovale and P. malariae infections and their relationship with common red blood cell polymorphisms in a cohort of 509 indi...
Preprint
Full-text available
Human ovale malaria is caused by the two closely related species Plasmodium ovale curtisi and P. ovale wallikeri. Both species are known to relapse from quiescent hepatic forms months or years after the primary infection occurred. Although some studies have succeeded in establishing mosquito transmission for ovale malaria, none have specifically de...
Data
Models of P. falciparum DHPS wild type I431 in β-2 and mutant I431V. The wild type Ile side-chain shows hydrophobic interaction with side chain of Leu 395 in β-1 which is lost when Ile is replaced by Val. The proximity of the mutable residues 436 and 437 in flexible loop 2 to this destabilization of the relationship between the C-terminal regions o...
Article
Full-text available
There are few published reports of mutations in dihydropteroate synthetase (dhps) and dihydrofolate reductase (dhfr) genes in P. falciparum populations in Nigeria, but one previous study has recorded a novel dhps mutation at codon 431 among infections imported to the United Kingdom from Nigeria. To assess how widespread this mutation is among paras...
Article
Full-text available
We demonstrate, for the first time, the multiplexed determination of microbial species from whole blood using the paper-folding technique of origami to enable the sequential steps of DNA extraction, loop-mediated isothermal amplification (LAMP), and array-based fluorescence detection. A low-cost handheld flashlight reveals the presence of the final...
Article
We demonstrate, for the first time, the multiplexed determination of microbial species from whole blood using the paper-folding technique of origami to enable the sequential steps of DNA extraction, loop-mediated isothermal amplification (LAMP), and array-based fluorescence detection. A low-cost handheld flashlight reveals the presence of the final...
Article
Full-text available
Malaria in humans is caused by six species of . Plasmodium parasites, of which the nuclear genome sequences for the two . Plasmodium ovale spp., . P. ovale curtisi and . P. ovale wallikeri, and . Plasmodium malariae have not yet been analyzed. Here we present an analysis of the nuclear genome sequences of these three parasites, and describe gene fa...
Article
Full-text available
Background: Gametocytes are responsible for transmission of malaria from human to mosquito. Artemisinin combination therapy (ACT) reduces post-treatment gametocyte carriage, dependent upon host, parasite and pharmacodynamic factors. The gametocytocidal properties of antimalarial drugs are important for malaria elimination efforts. An individual pa...
Article
Full-text available
Background Gametocytes are responsible for transmission of malaria from human to mosquito. Artemisinin combination therapy (ACT) reduces post-treatment gametocyte carriage, dependent upon host, parasite and pharmacodynamic factors. The gametocytocidal properties of antimalarial drugs are important for malaria elimination efforts. An individual pati...
Data
Additional file 2: Figure S1. Relationship between gametocytaemia on enrolment and baseline haemoglobin concentration, parasitaemia and patient age. The predicted probability of gametocyte carriage at enrolment is plotted from the multivariate model; the line indicates the best fit, the shaded area the 95 % CI. Only patients from studies with gamet...
Data
Additional file 3: Table S2. Independent risk factors for the prevalence of gametocytaemia at enrolment in children aged 1–5 years. Logistic multivariable analysis by region with prevalence of gametocytaemia at enrolment as dependent variable. Nobs, Number of observations; Npos, Number of positive observations. The relationship between gametocyte p...
Data
Additional file 8: Table S7. Sensitivity analysis: variation in model coefficients after exclusion of individual studies. 1 Estimates as obtained in the final multivariate models and listed in main tables. 2 RSD, Relative standard deviation was calculated as a ratio of standard deviation to mean of the estimates (odds ratio or hazard ratio) calcula...
Data
Additional file 9: Figure S2. Development of gametocytaemia after treatment evaluated in patients with no gametocytaemia on enrolment and full 28-day follow-up. A: Development of gametocytaemia by artemisinin combination therapy. B: Development of gametocytaemia by treatment outcome. (TIF 284 kb)
Data
Additional file 4: Table S3. The effect of treatment dosing on the appearance of gametocytaemia in participants without microscopically detected gametocytaemia before treatment (time to gametocytaemia) and clearance of gametocytaemia in participants with gametocytaemia at enrolment (time to clearance). All analyses of time to clearance are adjusted...
Data
Additional file 7: Table S6. Factors associated with the development of gametocytaemia after enrolment in individuals who were gametocyte-free before treatment with artemisinin combination therapy. Cox regression model for time to gametocytaemia. Only patients with complete 28-day follow-up are included. (DOC 35 kb)
Data
Additional file 1: Table S1. Overview of all included studies. 1 The sensitivity of microscopy methods was classified into one of four categories: 1 = studies in which slides were specifically read for gametocytes, reviewing at least 100 microscopic high power fields or against ≥ 1000 white blood cells (WBC); 2 = microscopists specifically instruct...
Data
Additional file 5: Table S4. Factors associated with the clearance of gametocytaemia after enrolment in individuals who were gametocytaemic before treatment with artemisinin combination therapy. Nobs, Number of observations; N cleared, Number of patients with day of clearance of gametocytaemia recorded. Derived haemoglobin, conversion from haematoc...
Data
Full-text available
Additional file 6: Table S5. Risk of bias in individual studies included in the analysis. ACT, Artemisinin combination therapy. 1 For trials with non-ACTs, data were only analysed for gametocytaemia on enrolment and regimens, arms, randomization, concealment of treatment, sequence generation and treatment blinding are given as not applicable (NA)....
Article
Full-text available
BACKGROUND: Gametocytes are responsible for transmission of malaria from human to mosquito. Artemisinin combination therapy (ACT) reduces post-treatment gametocyte carriage, dependent upon host, parasite and pharmacodynamic factors. The gametocytocidal properties of antimalarial drugs are important for malaria elimination efforts. An individual pat...
Article
Full-text available
Background: The use of antimalarial drugs for prevention and treatment is a major strategy in the prevention of malaria in pregnancy. Although sulphadoxine-pyrimethamine (SP) is currently recommended for intermittent preventive treatment of malaria during pregnancy in Nigeria, previously used drugs for prophylaxis such as chloroquine (CQ) and pyri...
Article
Full-text available
Objectives Polymorphisms in the lysosomal transporter encoded by the pfcrt gene directly impact on Plasmodium falciparum susceptibility to aminoquinolines. The Lys76Thr mutation is the critical change conferring chloroquine resistance in vitro and in vivo, but always occurs with additional non-synonymous changes in the pfcrt coding sequence. We sou...
Article
Full-text available
Background: Artemisinin-resistant Plasmodium falciparum has emerged in the Greater Mekong sub-region and poses a major global public health threat. Slow parasite clearance is a key clinical manifestation of reduced susceptibility to artemisinin. This study was designed to establish the baseline values for clearance in patients from Sub-Saharan Afri...
Article
Full-text available
Background Artemether–lumefantrine is the most widely used artemisinin-based combination therapy for malaria, although treatment failures occur in some regions. We investigated the effect of dosing strategy on efficacy in a pooled analysis from trials done in a wide range of malaria-endemic settings. Methods We searched PubMed for clinical trials...
Article
Full-text available
Plasmodium ovale curtisi and Plasmodium ovale wallikeri are distinct species of malaria parasite which are sympatric throughout the tropics, except for the Americas. Despite this complete overlap in geographic range, these two species do not recombine. Although morphologically very similar, the two taxa must possess distinct characters which preven...
Article
Full-text available
Objective: To evaluate the comparative efficacy and safety of artemether-lumefantrine (AL), artesunate-amodiaquine (ASAQ) and artesunate-amodiaquine-chlorpheniramine (AQC) for the treatment of acute uncomplicated malaria among Southwest Nigerian children. Subjects and methods: One hundred and sixty children aged 6 months to 14 years with acute u...
Article
Full-text available
Two hundred and seventy four asymptomatic Ghanaian school-children aged 5 to 17 years were screened for malaria parasites by examination of blood films. One hundred and fifty five microscopically-positive individuals were treated with dihydroartemisinin-piperaquine and followed for 3 weeks. Retrospective species-specific PCR of all 274 screened sam...
Article
Full-text available
Ovale malaria is caused by two closely related species of protozoan parasite: Plasmodium ovale curtisi and Plasmodium ovale wallikeri Although clearly distinct genetically, there have been no studies comparing the morphology, life cycle or epidemiology of these parasites. We tested the hypothesis that the two species differ in the duration of laten...
Conference Paper
Full-text available
The chloroquine resistance transporter located on the membrane of the parasite digestive vacuole is believed to influence access of chloroquine transport to its target. Data from transfection studies has proposed a role for polymorphisms in the pfcrt locus in mediating susceptibility to various antimalarial drugs, particularly the 4-aminoquinolines...
Article
Full-text available
Molecular markers for surveillance of Plasmodium falciparum resistance to current antimalarials are sorely needed. A 28-day efficacy study of artemether-lumefantrine in eastern Sudan identified 5 treatment failures among 100 evaluable patients; 9 further individuals were parasite positive by PCR during follow-up. Polymorphisms in pfatpase6 and pfmd...
Conference Paper
Full-text available
The chloroquine resistance transporter gene located on the membrane of the parasite digestive vacuole is believed to mediate chloroquine transport to its site of action. Data from transfection studies has proposed a role for polymorphisms in pfcrt in mediating susceptibility to various antimalarial drugs, particularly the aminoquinolines chloroquin...
Article
Full-text available
It has been proposed that ovale malaria in humans is caused by two closely related but distinct species of malaria parasite, Plasmodium ovale curtisi and Plasmodium ovale wallikeri. It was recently shown that these two parasite types are sympatric at the country level. However, it remains possible that localised geographic, temporal or ecological b...
Article
Full-text available
Malaria in humans is caused by apicomplexan parasites belonging to 5 species of the genus Plasmodium. Infections with Plasmodium ovale are widely distributed but rarely investigated, and the resulting burden of disease is not known. Dimorphism in defined genes has led to P. ovale parasites being divided into classic and variant types. We hypothesiz...

Projects

Project (1)
Project
This is an operations research that aims to assess the effect of an innovative community oriented resource persons (CORP) supervision package on quality of care given by CORP, as well as on CORP motivation and retention, in order to inform future iCCM implementation.