1
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Poespoprodjo JR, Douglas NM, Ansong D, Kho S, Anstey NM. Malaria. Lancet 2023; 402:2328-2345. [PMID: 37924827 DOI: 10.1016/s0140-6736(23)01249-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 05/22/2023] [Accepted: 06/16/2023] [Indexed: 11/06/2023]
Abstract
Malaria is resurging in many African and South American countries, exacerbated by COVID-19-related health service disruption. In 2021, there were an estimated 247 million malaria cases and 619 000 deaths in 84 endemic countries. Plasmodium falciparum strains partly resistant to artemisinins are entrenched in the Greater Mekong region and have emerged in Africa, while Anopheles mosquito vectors continue to evolve physiological and behavioural resistance to insecticides. Elimination of Plasmodium vivax malaria is hindered by impractical and potentially toxic antirelapse regimens. Parasitological diagnosis and treatment with oral or parenteral artemisinin-based therapy is the mainstay of patient management. Timely blood transfusion, renal replacement therapy, and restrictive fluid therapy can improve survival in severe malaria. Rigorous use of intermittent preventive treatment in pregnancy and infancy and seasonal chemoprevention, potentially combined with pre-erythrocytic vaccines endorsed by WHO in 2021 and 2023, can substantially reduce malaria morbidity. Improved surveillance, better access to effective treatment, more labour-efficient vector control, continued drug development, targeted mass drug administration, and sustained political commitment are required to achieve targets for malaria reduction by the end of this decade.
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Affiliation(s)
- Jeanne Rini Poespoprodjo
- Centre for Child Health and Department of Child Health, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia; Timika Malaria Research Facility, Papuan Health and Community Development Foundation, Timika, Indonesia; Mimika District Hospital and District Health Authority, Timika, Indonesia; Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia.
| | - Nicholas M Douglas
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia; Department of Infectious Diseases, Christchurch Hospital, Te Whatu Ora Waitaha, Christchurch, New Zealand; Department of Medicine, University of Otago, Christchurch, New Zealand
| | - Daniel Ansong
- School of Medicine and Dentistry, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Steven Kho
- Timika Malaria Research Facility, Papuan Health and Community Development Foundation, Timika, Indonesia; Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
| | - Nicholas M Anstey
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia; Department of Infectious Diseases, Royal Darwin Hospital, Darwin, NT, Australia
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2
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Lin Y, Tebulo A, Small D, Seydel K, Taylor T, Zhang B. Using Malarial Retinopathy to Improve the Diagnosis of Pediatric Cerebral Malaria. Am J Trop Med Hyg 2023; 108:69-75. [PMID: 36509055 PMCID: PMC9833082 DOI: 10.4269/ajtmh.22-0547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 10/03/2022] [Indexed: 12/14/2022] Open
Abstract
In malaria endemic areas, a high proportion of children have detectable parasitemia but show no clinical symptoms. When comatose from a cause other than malaria, this group confounds the cerebral malaria (CM) definition, making accurate diagnosis challenging. One important biomarker of CM is malarial retinopathy, a set of specific features visible in the ocular fundus. In this study, we quantified the contribution of malarial retinopathy in discriminating malaria-caused coma from non-malaria-caused coma. We estimated that 10% of our study cohort of N = 1,192 patients who met the WHO clinical definition of CM in Malawi had non-malarial coma based on a Gaussian mixture model using the parasite protein Plasmodium falciparum histidine-rich protein-2. A classification based on platelets, white blood cells, and retinopathy significantly improved the discriminative power of a previously established model including only platelets plus white blood cells (area under the receiver operating characteristic curve: 0.89 versus 0.75, P value < 0.001). We conclude that malarial retinopathy is highly predictive of malaria-caused versus non-malaria-caused coma and recommend that an ocular funduscopic examination to determine malarial retinopathy status be included in the assessment of parasitemic comatose African children.
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Affiliation(s)
- Yuzhou Lin
- Department of Statistics, Harvard University, Cambridge, Massachusetts
| | - Andrew Tebulo
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Dylan Small
- Department of Statistics and Data Science, The Wharton School, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Karl Seydel
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan
| | - Terrie Taylor
- Blantyre Malaria Project, Kamuzu University of Health Sciences, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, Michigan State University, East Lansing, Michigan
| | - Bo Zhang
- Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Center, Seattle, Washington
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3
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Chao DL, Oron AP, Chabot-Couture G, Sopekan A, Nnebe-Agumadu U, Bates I, Piel FB, Nnodu O. Contribution of malaria and sickle cell disease to anaemia among children aged 6-59 months in Nigeria: a cross-sectional study using data from the 2018 Demographic and Health Survey. BMJ Open 2022; 12:e063369. [PMID: 36385021 PMCID: PMC9670918 DOI: 10.1136/bmjopen-2022-063369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVES To estimate the fraction of anaemia attributable to malaria and sickle cell disease (SCD) among children aged 6-59 months in Nigeria. DESIGN Cross-sectional analysis of data from Nigeria's 2018 Demographic and Health Survey (DHS). SETTING Nigeria. PARTICIPANTS 11 536 children aged 6-59 months from randomly selected households were eligible for participation, of whom 11 142 had complete and valid biomarker data required for this analysis. Maternal education data were available from 10 305 of these children. PRIMARY OUTCOME MEASURE Haemoglobin concentration. RESULTS We found that 70.6% (95% CI: 62.7% to 78.5%) of severe anaemia was attributable to malaria compared with 12.4% (95% CI: 11.1% to 13.7%) of mild-to-severe and 29.6% (95% CI: 29.6% to 31.8%) of moderate-to-severe anaemia and that SCD contributed 0.6% (95% CI: 0.4% to 0.9%), 1.3% (95% CI: 1.0% to 1.7%) and 10.6% (95% CI: 6.7% to 14.9%) mild-to-severe, moderate-to-severe and severe anaemia, respectively. Sickle trait was protective against anaemia and was associated with higher haemoglobin concentration compared with children with normal haemoglobin (HbAA) among malaria-positive but not malaria-negative children. CONCLUSIONS This approach used offers a new tool to estimate the contribution of malaria to anaemia in many settings using widely available DHS data. The fraction of anaemia among young children in Nigeria attributable to malaria and SCD is higher at more severe levels of anaemia. Prevention of malaria and SCD and timely treatment of affected individuals would reduce cases of severe anaemia.
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Affiliation(s)
- Dennis L Chao
- Institute for Disease Modeling, Bill & Melinda Gates Foundation, Seattle, Washington, USA
| | - Assaf P Oron
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, Washington, USA
| | | | - Alayo Sopekan
- Department of Public Health, Federal Ministry of Health, Abuja, Nigeria
| | - Uche Nnebe-Agumadu
- Department of Paediatrics, University of Abuja College of Health Sciences, Abuja, Nigeria
| | - Imelda Bates
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Frédéric B Piel
- Department of Epidemiology and Biostatistics, Imperial College London, London, UK
| | - Obiageli Nnodu
- Centre of Excellence for Sickle Cell Disease Research & Training (CESRTA), University of Abuja, Abuja, Nigeria
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4
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Srinamon K, Watson JA, Silamut K, Intharabut B, Phu NH, Diep PT, Lyke KE, Fanello C, von Seidlein L, Chotivanich K, Dondorp AM, Day NPJ, White NJ. The prognostic and diagnostic value of intraleukocytic malaria pigment in patients with severe falciparum malaria. Nat Commun 2022; 13:6882. [PMID: 36371433 PMCID: PMC9653500 DOI: 10.1038/s41467-022-34678-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 11/02/2022] [Indexed: 11/13/2022] Open
Abstract
Severe falciparum malaria is a major cause of death in tropical countries, particularly in African children. Rapid and accurate diagnosis and prognostic assessment are critical to clinical management. In 6027 prospectively studied patients diagnosed with severe malaria we assess the prognostic value of peripheral blood film counts of malaria pigment containing polymorphonuclear leukocytes (PMNs) and monocytes. We combine these results with previously published data and show, in an individual patient data meta-analysis (n = 32,035), that the proportion of pigment containing PMNs is predictive of in-hospital mortality. In African children the proportion of pigment containing PMNs helps distinguish severe malaria from other life-threatening febrile illnesses, and it adds to the prognostic assessment from simple bedside examination, and to the conventional malaria parasite count. Microscopy assessment of pigment containing PMNs is simple and rapid, and should be performed in all patients hospitalised with suspected severe malaria.
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Affiliation(s)
- Ketsanee Srinamon
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand
| | - James A. Watson
- grid.412433.30000 0004 0429 6814Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam ,grid.4991.50000 0004 1936 8948Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, New Richards Building, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LG UK ,grid.499581.8WorldWide Antimalarial Resistance Network, Oxford, UK
| | - Kamolrat Silamut
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand
| | - Benjamas Intharabut
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand
| | - Nguyen Hoan Phu
- grid.412433.30000 0004 0429 6814Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Pham Thi Diep
- grid.412433.30000 0004 0429 6814Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Kirsten E. Lyke
- grid.411024.20000 0001 2175 4264Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD USA
| | - Caterina Fanello
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand ,grid.4991.50000 0004 1936 8948Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, New Richards Building, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LG UK
| | - Lorenz von Seidlein
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand ,grid.4991.50000 0004 1936 8948Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, New Richards Building, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LG UK
| | - Kesinee Chotivanich
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand
| | - Arjen M. Dondorp
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand ,grid.4991.50000 0004 1936 8948Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, New Richards Building, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LG UK
| | - Nicholas P. J. Day
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand ,grid.4991.50000 0004 1936 8948Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, New Richards Building, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LG UK
| | - Nicholas J. White
- grid.10223.320000 0004 1937 0490Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand ,grid.4991.50000 0004 1936 8948Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, New Richards Building, Old Road Campus, Roosevelt Drive, Oxford, OX3 7LG UK
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5
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Ippolito MM, Robinson ML. Reducing misclassification bias in severe malaria research. Cell Rep Med 2022; 3:100789. [PMID: 36260989 PMCID: PMC9589118 DOI: 10.1016/j.xcrm.2022.100789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
By incorporating platelets and PfHRP2 into standard case definitions of severe falciparum malaria, Watson et al.1 increased diagnostic specificity to 93%. The approach trades off sensitivity and might introduce a selection bias but offers a helpful way to handle misclassification.
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Affiliation(s)
- Matthew M. Ippolito
- Department of Medicine, Divisions of Clinical Pharmacology and Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA,W. Harry Feinstone Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD 21205, USA,Corresponding author
| | - Matthew L. Robinson
- Department of Medicine, Division of Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA
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6
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Abstract
Severe malaria is a medical emergency. It is a major cause of preventable childhood death in tropical countries. Severe malaria justifies considerable global investment in malaria control and elimination yet, increasingly, international agencies, funders and policy makers are unfamiliar with it, and so it is overlooked. In sub-Saharan Africa, severe malaria is overdiagnosed in clinical practice. Approximately one third of children diagnosed with severe malaria have another condition, usually sepsis, as the cause of their severe illness. But these children have a high mortality, contributing substantially to the number of deaths attributed to ‘severe malaria’. Simple well-established tests, such as examination of the thin blood smear and the full blood count, improve the specificity of diagnosis and provide prognostic information in severe malaria. They should be performed more widely. Early administration of artesunate and broad-spectrum antibiotics to all children with suspected severe malaria would reduce global malaria mortality.
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Affiliation(s)
- Nicholas J White
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
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7
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White NJ, Watson JA, Uyoga S, Williams TN, Maitland KM. Substantial misdiagnosis of severe malaria in African children. Lancet 2022; 400:807. [PMID: 36088944 DOI: 10.1016/s0140-6736(22)01600-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 08/15/2022] [Indexed: 02/09/2023]
Affiliation(s)
- Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand; Centre for Global Health and Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
| | - James A Watson
- Centre for Global Health and Tropical Medicine, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Sophie Uyoga
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Thomas N Williams
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya; Institute of Global Health Innovation, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Kathryn M Maitland
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya; Institute of Global Health Innovation, Department of Surgery and Cancer, Imperial College London, London, UK
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8
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Uyoga S, Olupot-Olupot P, Connon R, Kiguli S, Opoka RO, Alaroker F, Muhindo R, Macharia AW, Dondorp AM, Gibb DM, Walker AS, George EC, Maitland K, Williams TN. Sickle cell anaemia and severe Plasmodium falciparum malaria: a secondary analysis of the Transfusion and Treatment of African Children Trial (TRACT). THE LANCET. CHILD & ADOLESCENT HEALTH 2022; 6:606-613. [PMID: 35785794 PMCID: PMC7613576 DOI: 10.1016/s2352-4642(22)00153-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 04/27/2022] [Accepted: 04/29/2022] [Indexed: 11/18/2022]
Abstract
BACKGROUND Sickle cell anaemia (SCA) has historically been associated with high levels of childhood mortality in Africa. Although malaria has a major contribution to this mortality, to date, the clinical pathology of malaria among children with SCA has been poorly described. We aimed to explore the relationship between SCA and Plasmodium falciparum malaria in further detail by investigating the burden and severity of malaria infections among children recruited with severe anaemia to the TRACT trial of blood transfusion in Africa. METHODS This study is a post-hoc secondary analysis of the TRACT trial data, conducted after trial completion. TRACT was an open-label, multicentre, factorial, randomised controlled trial enrolling children aged 2 months to 12 years who presented with severe anaemia (haemoglobin <6·0 g/dL) to four hospitals in Africa. This secondary analysis is restricted to Uganda, where the birth prevalence of SCA is approximately 1% and malaria transmission is high. Children were classified as normal (HbAA), heterozygous (HbAS), or homozygous (HbSS; SCA) for the rs334 A→T sickle mutation in HBB following batch-genotyping by PCR at the end of the trial. To avoid confounding from SCA-specific medical interventions, we considered children with an existing diagnosis of SCA (known SCA) separately from those diagnosed at the end of the trial (unknown SCA). The outcomes considered in this secondary analysis were measures of P falciparum parasite burden, features of severe malaria, and mortality at day 28 in malaria-positive children. FINDINGS Between Sept 17, 2014, and May 15, 2017, 3944 children with severe anaemia were enrolled into the TRACT trial. 3483 children from Uganda were considered in this secondary analysis. Overall, 1038 (30%) of 3483 Ugandan children had SCA. 1815 (78%) of 2321 children without SCA (HbAA) tested positive for P falciparum malaria, whereas the prevalence was significantly lower in children with SCA (347 [33%] of 1038; p<0·0001). Concentrations of plasma P falciparum histidine-rich protein 2 (PfHRP2), a marker of the total burden of malaria parasites within an individual, were significantly lower in children with either known SCA (median 8 ng/mL; IQR 0-57) or unknown SCA (7 ng/mL; 0-50) than in HbAA children (346 ng/mL; 21-2121; p<0·0001). In contrast to HbAA children, few HbSS children presented with classic features of severe and complicated malaria, but both the frequency and severity of anaemia were higher in HbSS children. We found no evidence for increased mortality at day 28 in those with SCA compared with those without SCA overall (hazard ratios 1·07 [95% CI 0·31-3·76] for known SCA and 0·67 [0·15-2·90] for unknown SCA). INTERPRETATION The current study suggests that children with SCA are innately protected against classic severe malaria. However, it also shows that even low-level infections can precipitate severe anaemic crises that would likely prove fatal without rapid access to blood transfusion services. FUNDING UK Medical Research Council, Wellcome, and UK National Institute for Health and Care Research.
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Affiliation(s)
- Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Peter Olupot-Olupot
- Busitema University Faculty of Health Sciences, Mbale Regional Referral Hospital, Mbale, Uganda; Mbale Clinical Research Institute, Mbale, Uganda
| | - Roisin Connon
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Sarah Kiguli
- Department of Paediatrics and Child Health, School of Medicine, Makerere University, Kampala, Uganda
| | - Robert O Opoka
- Department of Paediatrics and Child Health, School of Medicine, Makerere University, Kampala, Uganda
| | | | - Rita Muhindo
- Mbale Clinical Research Institute, Mbale, Uganda
| | | | - Arjen M Dondorp
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Diana M Gibb
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - A Sarah Walker
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Elizabeth C George
- Medical Research Council Clinical Trials Unit (MRC CTU) at University College London, London, UK
| | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Department of Infectious Disease and Institute of Global Health Innovation, Division of Medicine, Imperial College London, London, UK
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Department of Infectious Disease and Institute of Global Health Innovation, Division of Medicine, Imperial College London, London, UK.
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9
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White NJ. The assessment of antimalarial drug efficacy in vivo. Trends Parasitol 2022; 38:660-672. [PMID: 35680541 PMCID: PMC7613059 DOI: 10.1016/j.pt.2022.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 11/19/2022]
Abstract
Currently recommended methods of assessing the efficacy of uncomplicated falciparum malaria treatment work less well in high-transmission than in low-transmission settings. There is also uncertainty how to assess intermittent preventive therapies and seasonal malaria chemoprevention (SMC), and Plasmodium vivax radical cure. A pharmacometric antimalarial resistance monitoring (PARM) approach is proposed specifically for evaluating slowly eliminated antimalarial drugs in areas of high transmission. In PARM antimalarial drug concentrations at recurrent parasitaemia are measured to identify outliers (i.e., recurrent parasitaemias in the presence of normally suppressive drug concentrations) and to evaluate changes over time. PARM requires characterization of pharmacometric profiles but should be simpler and more sensitive than current molecular genotyping-based methodologies. PARM does not require parasite genotyping and can be applied to the assessment of both prevention and treatment.
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Affiliation(s)
- Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford University, Oxford, UK.
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10
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Watson JA, Uyoga S, Wanjiku P, Makale J, Nyutu GM, Mturi N, George EC, Woodrow CJ, Day NPJ, Bejon P, Opoka RO, Dondorp AM, John CC, Maitland K, Williams TN, White NJ. Improving the diagnosis of severe malaria in African children using platelet counts and plasma PfHRP2 concentrations. Sci Transl Med 2022; 14:eabn5040. [PMID: 35857826 PMCID: PMC7613613 DOI: 10.1126/scitranslmed.abn5040] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Severe malaria caused by Plasmodium falciparum is difficult to diagnose accurately in children in high-transmission settings. Using data from 2649 pediatric and adult patients enrolled in four studies of severe illness in three countries (Bangladesh, Kenya, and Uganda), we fitted Bayesian latent class models using two diagnostic markers: the platelet count and the plasma concentration of P. falciparum histidine-rich protein 2 (PfHRP2). In severely ill patients with clinical features consistent with severe malaria, the combination of a platelet count of ≤150,000/μl and a plasma PfHRP2 concentration of ≥1000 ng/ml had an estimated sensitivity of 74% and specificity of 93% in identifying severe falciparum malaria. Compared with misdiagnosed children, pediatric patients with true severe malaria had higher parasite densities, lower hematocrits, lower rates of invasive bacterial disease, and a lower prevalence of both sickle cell trait and sickle cell anemia. We estimate that one-third of the children enrolled into clinical studies of severe malaria in high-transmission settings in Africa had another cause of their severe illness.
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Affiliation(s)
- James A. Watson
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK,Corresponding author.
| | - Sophie Uyoga
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Coast, Kilifi 80108, Kenya
| | - Perpetual Wanjiku
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Coast, Kilifi 80108, Kenya
| | - Johnstone Makale
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Coast, Kilifi 80108, Kenya
| | - Gideon M. Nyutu
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Coast, Kilifi 80108, Kenya
| | - Neema Mturi
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Coast, Kilifi 80108, Kenya
| | - Elizabeth C. George
- Medical Research Council Clinical Trials Unit, University College London, London, UK
| | - Charles J. Woodrow
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Nicholas P. J. Day
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Philip Bejon
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK,KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Coast, Kilifi 80108, Kenya
| | - Robert O. Opoka
- Makerere University, Department of Paediatrics and Child Health, Kampala, Uganda
| | - Arjen M. Dondorp
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Chandy C. John
- Department of Pediatrics, Indiana University, Indiana, IN, USA
| | - Kathryn Maitland
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Coast, Kilifi 80108, Kenya,Institute of Global Health Innovation, Department of Surgery and Cancer, Imperial College, London, UK
| | - Thomas N. Williams
- KEMRI Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Coast, Kilifi 80108, Kenya,Institute of Global Health Innovation, Department of Surgery and Cancer, Imperial College, London, UK
| | - Nicholas J. White
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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11
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Uyoga S, Watson JA, Wanjiku P, Rop JC, Makale J, Macharia AW, Kariuki SN, Nyutu GM, Shebe M, Mosobo M, Mturi N, Rockett KA, Woodrow CJ, Dondorp AM, Maitland K, White NJ, Williams TN. The impact of malaria-protective red blood cell polymorphisms on parasite biomass in children with severe Plasmodium falciparum malaria. Nat Commun 2022; 13:3307. [PMID: 35676275 PMCID: PMC9178016 DOI: 10.1038/s41467-022-30990-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 05/24/2022] [Indexed: 11/08/2022] Open
Abstract
Severe falciparum malaria is a major cause of preventable child mortality in sub-Saharan Africa. Plasma concentrations of P. falciparum Histidine-Rich Protein 2 (PfHRP2) have diagnostic and prognostic value in severe malaria. We investigate the potential use of plasma PfHRP2 and the sequestration index (the ratio of PfHRP2 to parasite density) as quantitative traits for case-only genetic association studies of severe malaria. Data from 2198 Kenyan children diagnosed with severe malaria, genotyped for 14 major candidate genes, show that polymorphisms in four major red cell genes that lead to hemoglobin S, O blood group, α-thalassemia, and the Dantu blood group, are associated with substantially lower admission plasma PfHRP2 concentrations, consistent with protective effects against extensive parasitized erythrocyte sequestration. In contrast the known protective ATP2B4 polymorphism is associated with higher plasma PfHRP2 concentrations, lower parasite densities and a higher sequestration index. We provide testable hypotheses for the mechanism of protection of ATP2B4.
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Affiliation(s)
- S Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
| | - J A Watson
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
| | - P Wanjiku
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - J C Rop
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - J Makale
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - A W Macharia
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - S N Kariuki
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - G M Nyutu
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - M Shebe
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - M Mosobo
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - N Mturi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - K A Rockett
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - C J Woodrow
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - A M Dondorp
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - K Maitland
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Surgery and Cancer, Institute of Global Health Innovation, Imperial College, London, UK
| | - N J White
- Mahidol-Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - T N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
- Department of Surgery and Cancer, Institute of Global Health Innovation, Imperial College, London, UK.
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12
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Gilchrist JJ, Kariuki SN, Watson JA, Band G, Uyoga S, Ndila CM, Mturi N, Mwarumba S, Mohammed S, Mosobo M, Alasoo K, Rockett KA, Mentzer AJ, Kwiatkowski DP, Hill AVS, Maitland K, Scott JAG, Williams TN. BIRC6 modifies risk of invasive bacterial infection in Kenyan children. eLife 2022; 11:77461. [PMID: 35866869 PMCID: PMC9391038 DOI: 10.7554/elife.77461] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 07/22/2022] [Indexed: 11/23/2022] Open
Abstract
Invasive bacterial disease is a major cause of morbidity and mortality in African children. Despite being caused by diverse pathogens, children with sepsis are clinically indistinguishable from one another. In spite of this, most genetic susceptibility loci for invasive infection that have been discovered to date are pathogen specific and are not therefore suggestive of a shared genetic architecture of bacterial sepsis. Here, we utilise probabilistic diagnostic models to identify children with a high probability of invasive bacterial disease among critically unwell Kenyan children with Plasmodium falciparum parasitaemia. We construct a joint dataset including 1445 bacteraemia cases and 1143 severe malaria cases, and population controls, among critically unwell Kenyan children that have previously been genotyped for human genetic variation. Using these data, we perform a cross-trait genome-wide association study of invasive bacterial infection, weighting cases according to their probability of bacterial disease. In doing so, we identify and validate a novel risk locus for invasive infection secondary to multiple bacterial pathogens, that has no apparent effect on malaria risk. The locus identified modifies splicing of BIRC6 in stimulated monocytes, implicating regulation of apoptosis and autophagy in the pathogenesis of sepsis in Kenyan children.
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Affiliation(s)
- James J Gilchrist
- Department of Paediatrics, University of OxfordOxfordUnited Kingdom,MRC–Weatherall Institute of Molecular Medicine, University of OxfordOxfordUnited Kingdom,Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Silvia N Kariuki
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - James A Watson
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom,Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityBangkokThailand
| | - Gavin Band
- Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Carolyne M Ndila
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Neema Mturi
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Salim Mwarumba
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Shebe Mohammed
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Moses Mosobo
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Kaur Alasoo
- Institute of Computer Science, University of TartuTartuEstonia
| | - Kirk A Rockett
- Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Alexander J Mentzer
- Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Dominic P Kwiatkowski
- Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom,Wellcome Sanger InstituteCambridgeUnited Kingdom
| | - Adrian VS Hill
- Wellcome Centre for Human Genetics, University of OxfordOxfordUnited Kingdom,The Jenner Institute, University of OxfordOxfordUnited Kingdom
| | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya,Division of Medicine, Imperial CollegeLondonUnited Kingdom
| | - J Anthony G Scott
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya,Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical MedicineLondonUnited Kingdom
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya,Institute for Global Health Innovation, Department of Surgery and Cancer, Imperial CollegeLondonUnited Kingdom
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13
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Abstract
BACKGROUND Plasmodium vivax infects an estimated 7 million people every year. Previously, vivax malaria was perceived as a benign condition, particularly when compared to falciparum malaria. Reports of the severe clinical impacts of vivax malaria have been increasing over the last decade. METHODS AND FINDINGS We describe the main clinical impacts of vivax malaria, incorporating a rapid systematic review of severe disease with meta-analysis of data from studies with clearly defined denominators, stratified by hospitalization status. Severe anemia is a serious consequence of relapsing infections in children in endemic areas, in whom vivax malaria causes increased morbidity and mortality and impaired school performance. P. vivax infection in pregnancy is associated with maternal anemia, prematurity, fetal loss, and low birth weight. More than 11,658 patients with severe vivax malaria have been reported since 1929, with 15,954 manifestations of severe malaria, of which only 7,157 (45%) conformed to the World Health Organization (WHO) diagnostic criteria. Out of 423 articles, 311 (74%) were published since 2010. In a random-effects meta-analysis of 85 studies, 68 of which were in hospitalized patients with vivax malaria, we estimated the proportion of patients with WHO-defined severe disease as 0.7% [95% confidence interval (CI) 0.19% to 2.57%] in all patients with vivax malaria and 7.11% [95% CI 4.30% to 11.55%] in hospitalized patients. We estimated the mortality from vivax malaria as 0.01% [95% CI 0.00% to 0.07%] in all patients and 0.56% [95% CI 0.35% to 0.92%] in hospital settings. WHO-defined cerebral, respiratory, and renal severe complications were generally estimated to occur in fewer than 0.5% patients in all included studies. Limitations of this review include the observational nature and small size of most of the studies of severe vivax malaria, high heterogeneity of included studies which were predominantly in hospitalized patients (who were therefore more likely to be severely unwell), and high risk of bias including small study effects. CONCLUSIONS Young children and pregnant women are particularly vulnerable to adverse clinical impacts of vivax malaria, and preventing infections and relapse in this groups is a priority. Substantial evidence of severe presentations of vivax malaria has accrued over the last 10 years, but reporting is inconsistent. There are major knowledge gaps, for example, limited understanding of the underlying pathophysiology and the reason for the heterogenous geographical distribution of reported complications. An adapted case definition of severe vivax malaria would facilitate surveillance and future research to better understand this condition.
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Affiliation(s)
| | - Prabin Dahal
- Infectious Diseases Data Observatory–IDDO, Oxford, United Kingdom
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Mayfong Mayxay
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Institute of Research and Education Development (IRED), University of Health Sciences, Ministry of Health, Vientiane, Laos
- Lao–Oxford–Mahosot Hospital–Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Laos
| | - Elizabeth A. Ashley
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
- Lao–Oxford–Mahosot Hospital–Wellcome Trust Research Unit, Mahosot Hospital, Vientiane, Laos
- * E-mail:
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14
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Ebel ER, Uricchio LH, Petrov DA, Egan ES. Revisiting the malaria hypothesis: accounting for polygenicity and pleiotropy. Trends Parasitol 2022; 38:290-301. [PMID: 35065882 PMCID: PMC8916997 DOI: 10.1016/j.pt.2021.12.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 12/20/2021] [Accepted: 12/21/2021] [Indexed: 10/19/2022]
Abstract
The malaria hypothesis predicts local, balancing selection of deleterious alleles that confer strong protection from malaria. Three protective variants, recently discovered in red cell genes, are indeed more common in African than European populations. Still, up to 89% of the heritability of severe malaria is attributed to many genome-wide loci with individually small effects. Recent analyses of hundreds of genome-wide association studies (GWAS) in humans suggest that most functional, polygenic variation is pleiotropic for multiple traits. Interestingly, GWAS alleles and red cell traits associated with small reductions in malaria risk are not enriched in African populations. We propose that other selective and neutral forces, in addition to malaria prevalence, explain the global distribution of most genetic variation impacting malaria risk.
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15
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Watson JA, Ndila CM, Uyoga S, Macharia A, Nyutu G, Mohammed S, Ngetsa C, Mturi N, Peshu N, Tsofa B, Rockett K, Leopold S, Kingston H, George EC, Maitland K, Day NPJ, Dondorp AM, Bejon P, Williams TN, Holmes CC, White NJ. Improving statistical power in severe malaria genetic association studies by augmenting phenotypic precision. eLife 2021; 10:e69698. [PMID: 34225842 PMCID: PMC8315799 DOI: 10.7554/elife.69698] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 06/22/2021] [Indexed: 12/14/2022] Open
Abstract
Severe falciparum malaria has substantially affected human evolution. Genetic association studies of patients with clinically defined severe malaria and matched population controls have helped characterise human genetic susceptibility to severe malaria, but phenotypic imprecision compromises discovered associations. In areas of high malaria transmission, the diagnosis of severe malaria in young children and, in particular, the distinction from bacterial sepsis are imprecise. We developed a probabilistic diagnostic model of severe malaria using platelet and white count data. Under this model, we re-analysed clinical and genetic data from 2220 Kenyan children with clinically defined severe malaria and 3940 population controls, adjusting for phenotype mis-labelling. Our model, validated by the distribution of sickle trait, estimated that approximately one-third of cases did not have severe malaria. We propose a data-tilting approach for case-control studies with phenotype mis-labelling and show that this reduces false discovery rates and improves statistical power in genome-wide association studies.
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Affiliation(s)
- James A Watson
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityBangkokThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Carolyne M Ndila
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityBangkokThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Alexander Macharia
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Gideon Nyutu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Shebe Mohammed
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Caroline Ngetsa
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Neema Mturi
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Norbert Peshu
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Benjamin Tsofa
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Kirk Rockett
- The Wellcome Sanger InstituteCambridgeUnited Kingdom
- Wellcome Trust Centre for Human Genetics, University of OxfordOxfordUnited Kingdom
| | - Stije Leopold
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityBangkokThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Hugh Kingston
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityBangkokThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Elizabeth C George
- Medical Research Council Clinical Trials Unit, University College LondonLondonUnited Kingdom
| | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
- Institute of Global Health Innovation, Imperial College, LondonLondonUnited Kingdom
| | - Nicholas PJ Day
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityBangkokThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Arjen M Dondorp
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityBangkokThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
| | - Philip Bejon
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-CoastKilifiKenya
- Institute of Global Health Innovation, Imperial College, LondonLondonUnited Kingdom
| | - Chris C Holmes
- Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
- Department of Statistics, University of OxfordOxfordUnited Kingdom
| | - Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol UniversityBangkokThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of OxfordOxfordUnited Kingdom
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