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Carlier MSA, Nyamu W, Makale J, Williams TN, Rowe JA, Kariuki SN. Dantu Blood Group Erythrocytes Form Large Plasmodium falciparum Rosettes Less Commonly. Am J Trop Med Hyg 2024; 110:436-443. [PMID: 38295409 PMCID: PMC10919173 DOI: 10.4269/ajtmh.23-0347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Accepted: 10/04/2023] [Indexed: 02/02/2024] Open
Abstract
Dantu erythrocytes, which express a hybrid glycophorin B/A protein, are protective against severe malaria. Recent studies have shown that Dantu impairs Plasmodium falciparum invasion by increasing erythrocyte membrane tension, but its effects on pathological host-parasite adhesion interactions such as rosetting, the binding of uninfected erythrocytes to P. falciparum-infected erythrocytes, have not been investigated previously. The expression of several putative host rosetting receptors-including glycophorin A (GYPA), glycophorin C (GYPC), complement receptor 1 (CR1), and band 3, which complexes with GYPA to form the Wrightb blood group antigen-are altered on Dantu erythrocytes. Here, we compare receptor expression, and rosetting at both 1 hour and 48 hours after mixing with mature trophozoite-stage Kenyan laboratory-adapted P. falciparum strain 11019 parasites in Dantu and non-Dantu erythrocytes. Dantu erythrocytes showed lower staining for GYPA and CR1, and greater staining for band 3, as observed previously, whereas Wrightb and GYPC staining did not vary significantly. No significant between-genotype differences in rosetting were seen after 1 hour, but the percentage of large rosettes was significantly less in both Dantu heterozygous (mean, 16.4%; standard error of the mean [SEM], 3.2) and homozygous donors (mean, 15.4%; SEM, 1.4) compared with non-Dantu erythrocytes (mean, 32.9%; SEM, 7.1; one-way analysis of variance, P = 0.025) after 48 hours. We also found positive correlations between erythrocyte mean corpuscular volume (MCV), the percentage of large rosettes (Spearman's rs = 0.5970, P = 0.0043), and mean rosette size (rs = 0.5206, P = 0.0155). Impaired rosetting resulting from altered erythrocyte membrane receptor expression and reduced MCV might add to the protective effect of Dantu against severe malaria.
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Affiliation(s)
- Molly S. A. Carlier
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Wilfred Nyamu
- Department of Epidemiology and Demography, KEMRI–Wellcome Trust Research Programme, Kilifi, Kenya
| | - Johnstone Makale
- Department of Epidemiology and Demography, KEMRI–Wellcome Trust Research Programme, Kilifi, Kenya
| | - Thomas N. Williams
- Department of Epidemiology and Demography, KEMRI–Wellcome Trust Research Programme, Kilifi, Kenya
- Institute of Global Health Innovation, Department of Surgery and Cancer, Imperial College London, United Kingdom
| | - J. Alexandra Rowe
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, United Kingdom
| | - Silvia N. Kariuki
- Department of Epidemiology and Demography, KEMRI–Wellcome Trust Research Programme, Kilifi, Kenya
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2
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Kariuki SN, Macharia AW, Makale J, Nyamu W, Hoffman SL, Kapulu MC, Bejon P, Rayner JC, Williams TN. The Dantu blood group prevents parasite growth in vivo: Evidence from a controlled human malaria infection study. eLife 2023; 12:e83874. [PMID: 37310872 DOI: 10.7554/elife.83874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Accepted: 05/11/2023] [Indexed: 06/15/2023] Open
Abstract
Background The long co-evolution of Homo sapiens and Plasmodium falciparum has resulted in the selection of numerous human genetic variants that confer an advantage against severe malaria and death. One such variant is the Dantu blood group antigen, which is associated with 74% protection against severe and complicated P. falciparum malaria infections in homozygous individuals, similar to that provided by the sickle haemoglobin allele (HbS). Recent in vitro studies suggest that Dantu exerts this protection by increasing the surface tension of red blood cells, thereby impeding the ability of P. falciparum merozoites to invade them and reducing parasite multiplication. However, no studies have yet explored this hypothesis in vivo. Methods We investigated the effect of Dantu on early phase P. falciparum (Pf) infections in a controlled human malaria infection (CHMI) study. 141 sickle-negative Kenyan adults were inoculated with 3.2 × 103 aseptic, purified, cryopreserved Pf sporozoites (PfSPZ Challenge) then monitored for blood-stage parasitaemia for 21 days by quantitative polymerase chain reaction (qPCR)analysis of the 18S ribosomal RNA P. falciparum gene. The primary endpoint was blood-stage P. falciparum parasitaemia of ≥500/μl while the secondary endpoint was the receipt of antimalarial treatment in the presence of parasitaemia of any density. On study completion, all participants were genotyped both for Dantu and for four other polymorphisms that are associated with protection against severe falciparum malaria: α+-thalassaemia, blood group O, G6PD deficiency, and the rs4951074 allele in the red cell calcium transporter ATP2B4. Results The primary endpoint was reached in 25/111 (22.5%) non-Dantu subjects in comparison to 0/27 (0%) Dantu heterozygotes and 0/3 (0.0%) Dantu homozygotes (p=0.01). Similarly, 49/111 (44.1%) non-Dantu subjects reached the secondary endpoint in comparison to only 7/27 (25.9%) and 0/3 (0.0%) Dantu heterozygotes and homozygotes, respectively (p=0.021). No significant impacts on either outcome were seen for any of the other genetic variants under study. Conclusions This study reveals, for the first time, that the Dantu blood group is associated with high-level protection against early, non-clinical, P. falciparum malaria infections in vivo. Learning more about the mechanisms involved could potentially lead to new approaches to the prevention or treatment of the disease. Our study illustrates the power of CHMI with PfSPZ Challenge for directly testing the protective impact of genotypes previously identified using other methods. Funding The Kenya CHMI study was supported by an award from Wellcome (grant number 107499). SK was supported by a Training Fellowship (216444/Z/19/Z), TNW by a Senior Research Fellowship (202800/Z/16/Z), JCR by an Investigator Award (220266/Z/20/Z), and core support to the KEMRI-Wellcome Trust Research Programme in Kilifi, Kenya (203077), all from Wellcome. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. For the purpose of Open Access, the authors have applied a CC BY public copyright license to any Author Accepted Manuscript version arising from this submission. Clinical trial number NCT02739763.
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Affiliation(s)
- Silvia N Kariuki
- Centre for Geographic Medicine Research (Coast), KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Alexander W Macharia
- Centre for Geographic Medicine Research (Coast), KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Johnstone Makale
- Centre for Geographic Medicine Research (Coast), KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Wilfred Nyamu
- Centre for Geographic Medicine Research (Coast), KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Melissa C Kapulu
- Centre for Geographic Medicine Research (Coast), KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Philip Bejon
- Centre for Geographic Medicine Research (Coast), KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Julian C Rayner
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Thomas N Williams
- Centre for Geographic Medicine Research (Coast), KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Institute for Global Health Innovation, Department of Surgery and Cancer, Imperial College London, London, United Kingdom
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Odera DO, Tuju J, Mwai K, Nkumama IN, Fürle K, Chege T, Kimathi R, Diehl S, Musasia FK, Rosenkranz M, Njuguna P, Hamaluba M, Kapulu MC, Frank R, Osier FHA, Abdi AI, Chi PC, de Laurent Z, Jao I, Kamuya D, Kamuyu G, Makale J, Murungi L, Musyoki J, Muthui M, Mwacharo J, Kariuki S, Mwanga D, Mwongeli J, Ndungu F, Njue M, Nyangweso G, Kimani D, Ngoi JM, Musembi J, Ngoto O, Otieno E, Ooko M, Shangala J, Wambua J, Mohammed KS, Omuoyo D, Mosobo M, Kibinge N, Kinyanjui S, Bejon P, Lowe B, Marsh K, Marsh V, Abebe Y, Billingsley PF, Sim BKL, Hoffman SL, James ER, Richie TL, Audi A, Olewe F, Oloo J, Ongecha J, Ongas MO, Koskei N, Bull PC, Hodgson SH, Kivisi C, Imwong M, Murphy SC, Ogutu B, Tarning J, Winterberg M, Williams TN. Anti-merozoite antibodies induce natural killer cell effector function and are associated with immunity against malaria. Sci Transl Med 2023; 15:eabn5993. [PMID: 36753561 DOI: 10.1126/scitranslmed.abn5993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Natural killer (NK) cells are potent immune effectors that can be activated via antibody-mediated Fc receptor engagement. Using multiparameter flow cytometry, we found that NK cells degranulate and release IFN-γ upon stimulation with antibody-opsonized Plasmodium falciparum merozoites. Antibody-dependent NK (Ab-NK) activity was largely strain transcending and enhanced invasion inhibition into erythrocytes. Ab-NK was associated with the successful control of parasitemia after experimental malaria challenge in African adults. In an independent cohort study in children, Ab-NK increased with age, was boosted by concurrent P. falciparum infections, and was associated with a lower risk of clinical episodes of malaria. Nine of the 14 vaccine candidates tested induced Ab-NK, including some less well-characterized antigens: P41, P113, MSP11, RHOPH3, and Pf_11363200. These data highlight an important role of Ab-NK activity in immunity against malaria and provide a potential mechanism for evaluating vaccine candidates.
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Affiliation(s)
- Dennis O Odera
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany.,Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - James Tuju
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kennedy Mwai
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.,Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Irene N Nkumama
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Kristin Fürle
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Timothy Chege
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Rinter Kimathi
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Stefan Diehl
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Fauzia K Musasia
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Micha Rosenkranz
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Patricia Njuguna
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mainga Hamaluba
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Melissa C Kapulu
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Roland Frank
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | | | - Faith H A Osier
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany.,Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.,Department of Life Sciences, Imperial College London, UK
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Njunge JM, Tickell K, Diallo AH, Sayeem Bin Shahid ASM, Gazi MA, Saleem A, Kazi Z, Ali S, Tigoi C, Mupere E, Lancioni CL, Yoshioka E, Chisti MJ, Mburu M, Ngari M, Ngao N, Gichuki B, Omer E, Gumbi W, Singa B, Bandsma R, Ahmed T, Voskuijl W, Williams TN, Macharia A, Makale J, Mitchel A, Williams J, Gogain J, Janjic N, Mandal R, Wishart DS, Wu H, Xia L, Routledge M, Gong YY, Espinosa C, Aghaeepour N, Liu J, Houpt E, Lawley TD, Browne H, Shao Y, Rwigi D, Kariuki K, Kaburu T, Uhlig HH, Gartner L, Jones K, Koulman A, Walson J, Berkley J. The Childhood Acute Illness and Nutrition (CHAIN) network nested case-cohort study protocol: a multi-omics approach to understanding mortality among children in sub-Saharan Africa and South Asia. Gates Open Res 2022; 6:77. [PMID: 36415883 PMCID: PMC9646488 DOI: 10.12688/gatesopenres.13635.2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/06/2022] [Indexed: 08/10/2023] Open
Abstract
Introduction: Many acutely ill children in low- and middle-income settings have a high risk of mortality both during and after hospitalisation despite guideline-based care. Understanding the biological mechanisms underpinning mortality may suggest optimal pathways to target for interventions to further reduce mortality. The Childhood Acute Illness and Nutrition (CHAIN) Network ( www.chainnnetwork.org) Nested Case-Cohort Study (CNCC) aims to investigate biological mechanisms leading to inpatient and post-discharge mortality through an integrated multi-omic approach. Methods and analysis; The CNCC comprises a subset of participants from the CHAIN cohort (1278/3101 hospitalised participants, including 350 children who died and 658 survivors, and 270/1140 well community children of similar age and household location) from nine sites in six countries across sub-Saharan Africa and South Asia. Systemic proteome, metabolome, lipidome, lipopolysaccharides, haemoglobin variants, toxins, pathogens, intestinal microbiome and biomarkers of enteropathy will be determined. Computational systems biology analysis will include machine learning and multivariate predictive modelling with stacked generalization approaches accounting for the different characteristics of each biological modality. This systems approach is anticipated to yield mechanistic insights, show interactions and behaviours of the components of biological entities, and help develop interventions to reduce mortality among acutely ill children. Ethics and dissemination. The CHAIN Network cohort and CNCC was approved by institutional review boards of all partner sites. Results will be published in open access, peer reviewed scientific journals and presented to academic and policy stakeholders. Data will be made publicly available, including uploading to recognised omics databases. Trial registration NCT03208725.
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Affiliation(s)
- James M. Njunge
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kirkby Tickell
- Global Health and Epidemiology, University of Washington, Seattle, Seattle, USA
| | - Abdoulaye Hama Diallo
- Department of Public Health, Faculty of Health Sciences, University of Ouagadougou, Ouagadougou, Burkina Faso
| | | | - Md. Amran Gazi
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Ali Saleem
- Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Karachi, Pakistan
| | - Zaubina Kazi
- Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Karachi, Pakistan
| | - Syed Ali
- Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Karachi, Pakistan
| | - Caroline Tigoi
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Ezekiel Mupere
- Department of Paediatrics and Child Health, College of Health Sciences, Makerere University, Kampala, Uganda
| | | | - Emily Yoshioka
- Global Health and Epidemiology, University of Washington, Seattle, Seattle, USA
| | - Mohammod Jobayer Chisti
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Moses Mburu
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Moses Ngari
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Narshion Ngao
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Bonface Gichuki
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Elisha Omer
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Wilson Gumbi
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Benson Singa
- Kenya Medical Research Institute, Nairobi, Kenya
| | - Robert Bandsma
- Centre for Global Child Health, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biomedical Sciences, University of Malawi College of Medicine, Blantyre, Malawi
| | - Tahmeed Ahmed
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Wieger Voskuijl
- Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Centre for Global Child Health & Emma Children’s Hospital, Amsterdam, The Netherlands
| | - Thomas N. Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Institute of Global Health Innovation, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Alex Macharia
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | | | | | - Rupasri Mandal
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - David S. Wishart
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Hang Wu
- School of Food Science and Nutrition, University of Leeds, Leeds, UK
| | - Lei Xia
- School of Food Science and Nutrition, University of Leeds, Leeds, UK
| | - Michael Routledge
- School of Food Science and Nutrition, University of Leeds, Leeds, UK
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China
| | - Yun Yun Gong
- School of Food Science and Nutrition, University of Leeds, Leeds, UK
| | - Camilo Espinosa
- Departments of Anesthesiology, Pain, and Perioperative Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Department of Biomedical Data Science, Stanford University School of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Nima Aghaeepour
- Departments of Anesthesiology, Pain, and Perioperative Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Jie Liu
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia, USA
| | - Eric Houpt
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia, USA
| | | | | | - Yan Shao
- Wellcome Sanger Institute, Hinxton, UK
| | - Doreen Rwigi
- The Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Kevin Kariuki
- The Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Timothy Kaburu
- The Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Holm H. Uhlig
- Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford, Oxford, UK
- Department of Paediatrics and Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Lisa Gartner
- Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Kelsey Jones
- Kennedy Institute of Rheumatology, University of Oxford, Oxford, UK
- Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK
| | - Albert Koulman
- MRC Epidemiology Unit, University of Cambridge, Cambridge, UK
- NIHR BRC Nutritional Biomarker Laboratory, University of Cambridge, Cambridge, UK
| | - Judd Walson
- Global Health and Epidemiology, University of Washington, Seattle, Seattle, USA
| | - James Berkley
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Center for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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6
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Njunge JM, Tickell K, Diallo AH, Sayeem Bin Shahid ASM, Gazi MA, Saleem A, Kazi Z, Ali S, Tigoi C, Mupere E, Lancioni CL, Yoshioka E, Chisti MJ, Mburu M, Ngari M, Ngao N, Gichuki B, Omer E, Gumbi W, Singa B, Bandsma R, Ahmed T, Voskuijl W, Williams TN, Macharia A, Makale J, Mitchel A, Williams J, Gogain J, Janjic N, Mandal R, Wishart DS, Wu H, Xia L, Routledge M, Gong YY, Espinosa C, Aghaeepour N, Liu J, Houpt E, Lawley TD, Browne H, Shao Y, Rwigi D, Kariuki K, Kaburu T, Uhlig HH, Gartner L, Jones K, Koulman A, Walson J, Berkley J. The Childhood Acute Illness and Nutrition (CHAIN) network nested case-cohort study protocol: a multi-omics approach to understanding mortality among children in sub-Saharan Africa and South Asia. Gates Open Res 2022; 6:77. [PMID: 36415883 PMCID: PMC9646488 DOI: 10.12688/gatesopenres.13635.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2022] [Indexed: 02/15/2024] Open
Abstract
Introduction: Many acutely ill children in low- and middle-income settings have a high risk of mortality both during and after hospitalisation despite guideline-based care. Understanding the biological mechanisms underpinning mortality may suggest optimal pathways to target for interventions to further reduce mortality. The Childhood Acute Illness and Nutrition (CHAIN) Network ( www.chainnnetwork.org) Nested Case-Cohort Study (CNCC) aims to investigate biological mechanisms leading to inpatient and post-discharge mortality through an integrated multi-omic approach. Methods and analysis; The CNCC comprises a subset of participants from the CHAIN cohort (1278/3101 hospitalised participants, including 350 children who died and 658 survivors, and 270/1140 well community children of similar age and household location) from nine sites in six countries across sub-Saharan Africa and South Asia. Systemic proteome, metabolome, lipidome, lipopolysaccharides, haemoglobin variants, toxins, pathogens, intestinal microbiome and biomarkers of enteropathy will be determined. Computational systems biology analysis will include machine learning and multivariate predictive modelling with stacked generalization approaches accounting for the different characteristics of each biological modality. This systems approach is anticipated to yield mechanistic insights, show interactions and behaviours of the components of biological entities, and help develop interventions to reduce mortality among acutely ill children. Ethics and dissemination. The CHAIN Network cohort and CNCC was approved by institutional review boards of all partner sites. Results will be published in open access, peer reviewed scientific journals and presented to academic and policy stakeholders. Data will be made publicly available, including uploading to recognised omics databases. Trial registration NCT03208725.
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Affiliation(s)
- James M. Njunge
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kirkby Tickell
- Global Health and Epidemiology, University of Washington, Seattle, Seattle, USA
| | - Abdoulaye Hama Diallo
- Department of Public Health, Faculty of Health Sciences, University of Ouagadougou, Ouagadougou, Burkina Faso
| | | | - Md. Amran Gazi
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Ali Saleem
- Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Karachi, Pakistan
| | - Zaubina Kazi
- Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Karachi, Pakistan
| | - Syed Ali
- Department of Pediatrics and Child Health, Aga Khan University Hospital, Karachi, Karachi, Pakistan
| | - Caroline Tigoi
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Ezekiel Mupere
- Department of Paediatrics and Child Health, College of Health Sciences, Makerere University, Kampala, Uganda
| | | | - Emily Yoshioka
- Global Health and Epidemiology, University of Washington, Seattle, Seattle, USA
| | - Mohammod Jobayer Chisti
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Moses Mburu
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Moses Ngari
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Narshion Ngao
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Bonface Gichuki
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Elisha Omer
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Wilson Gumbi
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Benson Singa
- Kenya Medical Research Institute, Nairobi, Kenya
| | - Robert Bandsma
- Centre for Global Child Health, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Biomedical Sciences, University of Malawi College of Medicine, Blantyre, Malawi
| | - Tahmeed Ahmed
- Nutrition and Clinical Services Division, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | - Wieger Voskuijl
- Amsterdam UMC location, University of Amsterdam, Amsterdam, The Netherlands
- Amsterdam Centre for Global Child Health & Emma Children’s Hospital, Amsterdam, The Netherlands
| | - Thomas N. Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Institute of Global Health Innovation, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Alex Macharia
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | | | | | - Rupasri Mandal
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - David S. Wishart
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Hang Wu
- School of Food Science and Nutrition, University of Leeds, Leeds, UK
| | - Lei Xia
- School of Food Science and Nutrition, University of Leeds, Leeds, UK
| | - Michael Routledge
- School of Food Science and Nutrition, University of Leeds, Leeds, UK
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, China
| | - Yun Yun Gong
- School of Food Science and Nutrition, University of Leeds, Leeds, UK
| | - Camilo Espinosa
- Departments of Anesthesiology, Pain, and Perioperative Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Department of Biomedical Data Science, Stanford University School of Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Nima Aghaeepour
- Departments of Anesthesiology, Pain, and Perioperative Medicine, Stanford University School of Medicine, Stanford, CA, 94305, USA
| | - Jie Liu
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia, USA
| | - Eric Houpt
- Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia, USA
| | | | | | - Yan Shao
- Wellcome Sanger Institute, Hinxton, UK
| | - Doreen Rwigi
- The Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Kevin Kariuki
- The Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Timothy Kaburu
- The Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Holm H. Uhlig
- Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford, Oxford, UK
- Department of Paediatrics and Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Lisa Gartner
- Translational Gastroenterology Unit, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Kelsey Jones
- Kennedy Institute of Rheumatology, University of Oxford, Oxford, UK
- Gastroenterology Department, Great Ormond Street Hospital for Children, London, UK
| | - Albert Koulman
- MRC Epidemiology Unit, University of Cambridge, Cambridge, UK
- NIHR BRC Nutritional Biomarker Laboratory, University of Cambridge, Cambridge, UK
| | - Judd Walson
- Global Health and Epidemiology, University of Washington, Seattle, Seattle, USA
| | - James Berkley
- The Childhood Acute Illness and Nutrition Network, Nairobi, Kenya
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Center for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
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7
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Macharia AW, Mochamah G, Makale J, Howard T, Mturi N, Olupot-Olupot P, Färnert A, Ware RE, Williams TN. Case Report: β-thalassemia major on the East African coast. Wellcome Open Res 2022; 7:188. [PMID: 37811313 PMCID: PMC10551670 DOI: 10.12688/wellcomeopenres.17907.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/08/2022] [Indexed: 10/10/2023] Open
Abstract
Background: β-thalassemia is rare in sub-Saharan Africa and to our knowledge there has been no case of homozygous β-thalassemia major reported from this region. In a recent cohort study, we identified four β-thalassemia mutations among 83 heterozygous carriers in Kilifi, Kenya. One of the mutations identified was a rare β-globin gene initiation codon mutation (ATG➝ACG) (rs33941849). Here we present a patient with β-thalassemia major resulting from this mutation, only the second homozygous patient to have been reported. Methods: The female patient presented to Kilifi County Hospital aged two years with a one week left sided abdominal swelling. Clinical, hematological and genetic information were collected at admission and follow-up. Results: Admission bloods revealed marked anemia, with a hemoglobin (Hb) value of 6.6 g/dL and a low mean corpuscular volume of 64 fL. High performance liquid chromatography (HPLC) revealed the absence of HbA0 and elevated levels of HbF, suggesting a diagnosis of β-thalassemia major. Sequencing revealed that the child was homozygous for the rs33941849 initiation codon mutation. Conclusions: We hope that this study will create awareness regarding the presence of β-thalassemia as a potential public health problem in the East Africa region and will prompt the development of local guidelines regarding the diagnosis and management of this condition.
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Affiliation(s)
- Alexander W. Macharia
- Epidemiology and Demography Department, KEMRI/Wellcome Trust Kilifi, Kilifi, 254, Kenya
| | - George Mochamah
- Epidemiology and Demography Department, KEMRI/Wellcome Trust Kilifi, Kilifi, 254, Kenya
| | - Johnstone Makale
- Epidemiology and Demography Department, KEMRI/Wellcome Trust Kilifi, Kilifi, 254, Kenya
| | - Thad Howard
- Division of Hematology, Cincinnati Children's Hospital Medical Center, OH, USA
| | - Neema Mturi
- Epidemiology and Demography Department, KEMRI/Wellcome Trust Kilifi, Kilifi, 254, Kenya
| | - Peter Olupot-Olupot
- Mbale Clinical Research Institute, Mbale, Uganda
- Busitema University Faculty of Health Sciences, Mbale, Uganda
| | | | - Russell E. Ware
- Division of Hematology, Cincinnati Children's Hospital Medical Center, OH, USA
| | - Thomas N. Williams
- Epidemiology and Demography Department, KEMRI/Wellcome Trust Kilifi, Kilifi, 254, Kenya
- Institute for Global Health Innovation, Imperial College, London, UK
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8
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Gumba H, Opiyo M, Musyoki J, Mutunga M, Ngetsa C, Mwarumba S, Mosobo M, Njuguna S, Kai O, Lambisia AW, Kimani D, Cheruiyot R, Kiyuka P, Lewa C, Gicheru E, Tendwa M, Said Mohammed K, Osoti V, Makale J, Tawa B, Odundo C, Cheruiyot W, Nyamu W, Gumbi W, Mwacharo J, Nyamako L, Otieno E, Amadi D, Ouma N, Karia B, Thoya J, Karani A, Mugo D, Gichuki BM, Riako D, Mutua S, Gitonga JN, Ominde K, Wanjiku P, Mutiso A, Mwanzu A, Sein Y, Bartilol B, Mwangi S, Omuoyo DO, Morobe JM, de Laurent ZR, Mitsanze F, Mwakubia A, Rono M, Nyaguara A, Tsofa B, Bejon P, Agoti CN, Ochola-Oyier LI. Maintaining laboratory quality assurance and safety in a pandemic: Experiences from the KEMRI-Wellcome Trust Research Programme laboratory’s COVID-19 response. Wellcome Open Res 2022. [DOI: 10.12688/wellcomeopenres.16704.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Laboratory diagnosis plays a critical role in the containment of a pandemic. Strong laboratory quality management systems (QMS) are essential for laboratory diagnostic services. However, low laboratory capacities in resource-limited countries has made the maintenance of laboratory quality assurance, especially during a pandemic, a daunting task. In this paper, we describe our experience of how we went about providing diagnostic testing services for SARS-CoV-2 through laboratory reorganization, redefining of the laboratory workflow, and training and development of COVID-19 documented procedures, all while maintaining the quality assurance processes during the COVID-19 pandemic at the Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme (KWTRP) laboratory. The KWTRP laboratory managed to respond to the COVID-19 outbreak in Kenya by providing diagnostic testing for the coastal region of the country, while maintaining its research standard quality assurance processes. A COVID-19 team comprising of seven sub-teams with assigned specific responsibilities and an organizational chart with established reporting lines were developed. Additionally, a total of four training sessions were conducted for county Rapid Response Teams (RRTs) and laboratory personnel. A total of 11 documented procedures were developed to support the COVID-19 testing processes, with three for the pre-analytical phases, seven for the analytical phase, and one for the post-analytical phase. With the workflow re-organization, the development of appropriate standard operating procedures, and training, research laboratories can effectively respond to pandemic outbreaks while maintaining research standard QMS procedures.
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9
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Mohammed KS, de Laurent ZR, Omuoyo DO, Lewa C, Gicheru E, Cheruiyot R, Bartilol B, Mutua S, Musyoki J, Gumba H, Mwacharo J, Riako D, Mwangi SJ, Gichuki BM, Nyamako L, Karani A, Karanja H, Mugo D, Gitonga JN, Njuguna S, Gumbi W, Tawa B, Tendwa M, Cheruiyot W, Sein Y, Nyambu JK, Patta SO, Thani TS, Maitha EK, Kitole B, Mwakinangu MS, Muslih BS, Otieno JO, Nyiro JU, Kiyuka P, Ndwiga L, Wamae K, Kimani D, Makale J, Morobe JM, Osoti V, Lambisia AW, Odundo C, Mwarumba S, Mutunga M, Bejon P, Tsofa B, Agoti CN, Ochola-Oyier LI. An optimization of four SARS-CoV-2 qRT-PCR assays in a Kenyan laboratory to support the national COVID-19 rapid response teams. Wellcome Open Res 2022; 5:162. [PMID: 35330938 PMCID: PMC8921690 DOI: 10.12688/wellcomeopenres.16063.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/25/2022] [Indexed: 11/28/2022] Open
Abstract
Background: The COVID-19 pandemic relies on real-time polymerase chain reaction (qRT-PCR) for the detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), to facilitate roll-out of patient care and infection control measures. There are several qRT-PCR assays with little evidence on their comparability. We report alterations to the developers' recommendations to sustain the testing capability in a resource-limited setting. Methods: We used a SARS-CoV-2 positive control RNA sample to generate several 10-fold dilution series that were used for optimization and comparison of the performance of the four qRT-PCR assays: i) Charité Berlin primer-probe set, ii) European Virus Archive - GLOBAL (EVAg) primer-probe set, iii) DAAN premixed commercial kit and iv) Beijing Genomics Institute (BGI) premixed commercial kit. We adjusted the manufacturer- and protocol-recommended reaction component volumes for these assays and assessed the impact on cycle threshold (Ct) values. Results: The Berlin and EVAg E gene and RdRp assays reported mean Ct values within range of each other across the different titrations and with less than 5% difference. The DAAN premixed kit produced comparable Ct values across the titrations, while the BGI kit improved in performance following a reduction of the reaction components. Conclusion: We achieved a 2.6-fold and 4-fold increase in the number of tests per kit for the commercial kits and the primer-probe sets, respectively. All the assays had optimal performance when the primers and probes were used at 0.375X, except for the Berlin N gene assay. The DAAN kit was a reliable assay for primary screening of SARS-CoV-2 whereas the BGI kit's performance was dependent on the volumes and concentrations of both the reaction buffer and enzyme mix. Our recommendation for SARS-CoV-2 diagnostic testing in resource-limited settings is to optimize the assays available to establish the lowest volume and suitable concentration of reagents required to produce valid results.
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Affiliation(s)
| | | | | | - Clement Lewa
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | | | | | - Horace Gumba
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Debra Riako
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Lydia Nyamako
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Angela Karani
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Henry Karanja
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Daisy Mugo
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Susan Njuguna
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Wilson Gumbi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Brian Tawa
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Yiakon Sein
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - John K. Nyambu
- Department Of Health Services, Taita-Taveta County Government, Taita-Taveta, Kenya
| | - Shem O. Patta
- Department Of Health Services, Mombasa County Government, Mombasa, Kenya
| | | | | | | | | | | | | | | | | | | | - Kevin Wamae
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | - Victor Osoti
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Calleb Odundo
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, UK
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10
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Kapulu MC, Kimani D, Njuguna P, Hamaluba M, Otieno E, Kimathi R, Tuju J, Sim BKL, Abdi AI, Abebe Y, Bejon P, Billingsley PF, Bull PC, de Laurent Z, Hoffman SL, James ER, Kariuki S, Kinyanjui S, Kivisi C, Makale J, Marsh K, Mohammed KS, Mosobo M, Musembi J, Musyoki J, Muthui M, Mwacharo J, Mwai K, Ngoi JM, Ngoto O, Nkumama I, Ndungu F, Odera D, Ogutu B, Olewe F, Omuoyo D, Ong’echa J, Osier F, Richie TL, Shangala J, Wambua J, Williams TN. Controlled human malaria infection (CHMI) outcomes in Kenyan adults is associated with prior history of malaria exposure and anti-schizont antibody response. BMC Infect Dis 2022; 22:86. [PMID: 35073864 PMCID: PMC8785382 DOI: 10.1186/s12879-022-07044-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 01/11/2022] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
Individuals living in endemic areas acquire immunity to malaria following repeated parasite exposure. We sought to assess the controlled human malaria infection (CHMI) model as a means of studying naturally acquired immunity in Kenyan adults with varying malaria exposure.
Methods
We analysed data from 142 Kenyan adults from three locations representing distinct areas of malaria endemicity (Ahero, Kilifi North and Kilifi South) enrolled in a CHMI study with Plasmodium falciparum sporozoites NF54 strain (Sanaria® PfSPZ Challenge). To identify the in vivo outcomes that most closely reflected naturally acquired immunity, parameters based on qPCR measurements were compared with anti-schizont antibody levels and residence as proxy markers of naturally acquired immunity.
Results
Time to endpoint correlated more closely with anti-schizont antibodies and location of residence than other parasite parameters such as growth rate or mean parasite density. Compared to observational field-based studies in children where 0.8% of the variability in malaria outcome was observed to be explained by anti-schizont antibodies, in the CHMI model the dichotomized anti-schizont antibodies explained 17% of the variability.
Conclusions
The CHMI model is highly effective in studying markers of naturally acquired immunity to malaria.
Trial registration Clinicaltrials.gov number NCT02739763. Registered 15 April 2016
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11
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Abuga KM, Muriuki JM, Uyoga SM, Mwai K, Makale J, Mogire RM, Macharia AW, Mohammed S, Muthumbi E, Mwarumba S, Mturi N, Bejon P, Scott JAG, Nairz M, Williams TN, Atkinson SH. Hepcidin regulation in Kenyan children with severe malaria and non-typhoidal Salmonella bacteremia. Haematologica 2021; 107:1589-1598. [PMID: 34498446 PMCID: PMC9244826 DOI: 10.3324/haematol.2021.279316] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Indexed: 11/09/2022] Open
Abstract
Malaria and invasive non-typhoidal Salmonella (NTS) are life-threatening infections that often co-exist in African children. The iron-regulatory hormone hepcidin is highly upregulated during malaria and controls the availability of iron, a critical nutrient for bacterial growth. We investigated the relationship between Plasmodium falciparum malaria and NTS bacteremia in all pediatric admissions aged <5 years between August 1998 and October 2019 (n=75,034). We then assayed hepcidin and measures of iron status in five groups: (1) children with concomitant severe malarial anemia (SMA) and NTS (SMA+NTS, n=16); and in matched children with (2) SMA (n=33); (3) NTS (n=33); (4) cerebral malaria (CM, n=34); and (5) community-based children. SMA and severe anemia without malaria were associated with a 2-fold or more increased risk of NTS bacteremia, while other malaria phenotypes were not associated with increased NTS risk. Children with SMA had lower hepcidin/ferritin ratios (0.10; interquartile range [IQR]: 0.03-0.19) than those with CM (0.24; IQR: 0.14-0.69; P=0.006) or asymptomatic malaria (0.19; IQR: 0.09-0.46; P=0.01) indicating suppressed hepcidin levels. Children with SMA+NTS had lower hepcidin levels (9.3 ng/mL; IQR: 4.7-49.8) and hepcidin/ferritin ratios (0.03; IQR: 0.01-0.22) than those with NTS alone (105.8 ng/mL; IQR: 17.3-233.3; P=0.02 and 0.31; IQR: 0.06-0.66; P=0.007, respectively). Since hepcidin degrades ferroportin on the Salmonella-containing vacuole, we hypothesize that reduced hepcidin in children with SMA might contribute to NTS growth by modulating iron availability for bacterial growth. Further studies are needed to understand how the hepcidin-ferroportin axis might mediate susceptibility to NTS in severely anemic children.
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Affiliation(s)
- Kelvin M. Abuga
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Department of Public Health, School of Human and Health Sciences, Pwani University, Kilifi, Kenya,Kelvin M. Abuga
| | - John Muthii Muriuki
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Sophie M. Uyoga
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Kennedy Mwai
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | - Johnstone Makale
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Reagan M. Mogire
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Open University, KEMRI-Wellcome Trust Research Program – Accredited Research Center, Kilifi, Kenya
| | - Alex W. Macharia
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Open University, KEMRI-Wellcome Trust Research Program – Accredited Research Center, Kilifi, Kenya
| | - Shebe Mohammed
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Esther Muthumbi
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Salim Mwarumba
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Neema Mturi
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | - Philip Bejon
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - J. Anthony G. Scott
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Manfred Nairz
- Department of Internal Medicine II, Medical University Innsbruck, Innsbruck, Austria
| | - Thomas N. Williams
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK,Department of Infectious Diseases and Institute of Global Health Innovation, Imperial College, London, UK
| | - Sarah H. Atkinson
- Kenya Medical Research Institute (KEMRI) Center for Geographic Medicine Research, KEMRI-Wellcome Trust Research Program, Kilifi, Kenya,Center for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK,Department of Pediatrics, University of Oxford, Oxford, UK,Sarah H. Atkinson
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12
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Gumba H, Opiyo M, Musyoki J, Mutunga M, Ngetsa C, Mwarumba S, Mosobo M, Njuguna S, Kai O, Lambisia AW, Kimani D, Cheruiyot R, Kiyuka P, Lewa C, Gicheru E, Tendwa M, Said Mohammed K, Osoti V, Makale J, Tawa B, Odundo C, Cheruiyot W, Nyamu W, Gumbi W, Mwacharo J, Nyamako L, Otieno E, Amadi D, Ouma N, Karia B, Thoya J, Karani A, Mugo D, Gichuki BM, Riako D, Mutua S, Gitonga JN, Ominde K, Wanjiku P, Mutiso A, Mwanzu A, Sein Y, Bartilol B, Mwangi S, Omuoyo DO, Morobe JM, de Laurent ZR, Mitsanze F, Mwakubia A, Rono M, Nyaguara A, Tsofa B, Bejon P, Agoti CN, Ochola-Oyier LI. Maintaining laboratory quality assurance and safety in a pandemic: Experiences from the KEMRI-Wellcome Trust Research Programme laboratory’s COVID-19 response. Wellcome Open Res 2021. [DOI: 10.12688/wellcomeopenres.16704.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Laboratory diagnosis plays a critical role in the containment of a pandemic. Strong laboratory quality management systems (QMS) are essential for laboratory diagnostic services. However, low laboratory capacities in resource-limited countries has made the maintenance of laboratory quality assurance, especially during a pandemic, a daunting task. In this paper, we describe our experience of how we went about providing diagnostic testing services for SARS-CoV-2 through laboratory reorganization, redefining of the laboratory workflow, and training and development of COVID-19 documented procedures, all while maintaining the quality assurance processes during the COVID-19 pandemic at the Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme (KWTRP) laboratory. The KWTRP laboratory managed to respond to the COVID-19 outbreak in Kenya by providing diagnostic testing for the coastal region of the country, while maintaining its research standard quality assurance processes. A COVID-19 team comprising of seven sub-teams with assigned specific responsibilities and an organizational chart with established reporting lines were developed. Additionally, a total of four training sessions were conducted for county Rapid Response Teams (RRTs) and laboratory personnel. A total of 11 documented procedures were developed to support the COVID-19 testing processes, with three for the pre-analytical phases, seven for the analytical phase, and one for the post-analytical phase. With the workflow re-organization, the development of appropriate standard operating procedures, and training, research laboratories can effectively respond to pandemic outbreaks while maintaining research standard QMS procedures.
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13
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Muriuki JM, Mentzer AJ, Mitchell R, Webb EL, Etyang AO, Kyobutungi C, Morovat A, Kimita W, Ndungu FM, Macharia AW, Ngetsa CJ, Makale J, Lule SA, Musani SK, Raffield LM, Cutland CL, Sirima SB, Diarra A, Tiono AB, Fried M, Gwamaka M, Adu-Afarwuah S, Wirth JP, Wegmüller R, Madhi SA, Snow RW, Hill AVS, Rockett KA, Sandhu MS, Kwiatkowski DP, Prentice AM, Byrd KA, Ndjebayi A, Stewart CP, Engle-Stone R, Green TJ, Karakochuk CD, Suchdev PS, Bejon P, Duffy PE, Davey Smith G, Elliott AM, Williams TN, Atkinson SH. Malaria is a cause of iron deficiency in African children. Nat Med 2021; 27:653-658. [PMID: 33619371 PMCID: PMC7610676 DOI: 10.1038/s41591-021-01238-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 01/12/2021] [Indexed: 12/12/2022]
Abstract
Malaria and iron deficiency (ID) are common and interrelated public health problems in African children. Observational data suggest that interrupting malaria transmission reduces the prevalence of ID1. To test the hypothesis that malaria might cause ID, we used sickle cell trait (HbAS, rs334 ), a genetic variant that confers specific protection against malaria2, as an instrumental variable in Mendelian randomization analyses. HbAS was associated with a 30% reduction in ID among children living in malaria-endemic countries in Africa (n = 7,453), but not among individuals living in malaria-free areas (n = 3,818). Genetically predicted malaria risk was associated with an odds ratio of 2.65 for ID per unit increase in the log incidence rate of malaria. This suggests that an intervention that halves the risk of malaria episodes would reduce the prevalence of ID in African children by 49%.
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Affiliation(s)
- John Muthii Muriuki
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
- Open University, KEMRI-Wellcome Trust Research Programme, Accredited Research Centre, Kilifi, Kenya.
| | - Alexander J Mentzer
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
| | - Ruth Mitchell
- Medical Research Council (MRC) Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Emily L Webb
- MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Anthony O Etyang
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Alireza Morovat
- Department of Clinical Biochemistry, Oxford University Hospitals, Oxford, UK
| | - Wandia Kimita
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Francis M Ndungu
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Alex W Macharia
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Caroline J Ngetsa
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Johnstone Makale
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Swaib A Lule
- MRC/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Solomon K Musani
- Department of Medicine, University of Mississippi Medical Center, Jackson, MS, USA
| | - Laura M Raffield
- Department of Genetics, University of North Carolina, Chapel Hill, NC, USA
| | - Clare L Cutland
- South African Medical Research Council: Vaccines and Infectious Diseases Analytical Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Sodiomon B Sirima
- Groupe de Recherche Action en Sante (GRAS), 06 BP 10248, Ouagadougou, Burkina Faso
| | - Amidou Diarra
- Groupe de Recherche Action en Sante (GRAS), 06 BP 10248, Ouagadougou, Burkina Faso
| | - Alfred B Tiono
- Groupe de Recherche Action en Sante (GRAS), 06 BP 10248, Ouagadougou, Burkina Faso
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Moses Gwamaka
- Mother Offspring Malaria Studies (MOMS) Project, Seattle Biomedical Research Institute, Seattle, WA, USA
- Muheza Designated District Hospital, Muheza, Tanzania
- University of Dar es Salaam, Mbeya College of Health and Allied Sciences, Mbeya, Tanzania
| | - Seth Adu-Afarwuah
- Department of Nutrition and Food Science, University of Ghana, Legon, Ghana
| | | | | | - Shabir A Madhi
- South African Medical Research Council: Vaccines and Infectious Diseases Analytical Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Robert W Snow
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Adrian V S Hill
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Centre for Clinical Vaccinology and Tropical Medicine and the Jenner Institute Laboratories, University of Oxford, Oxford, UK
| | - Kirk A Rockett
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Sanger Institute, Hinxton, UK
| | | | - Dominic P Kwiatkowski
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK
- Wellcome Sanger Institute, Hinxton, UK
| | - Andrew M Prentice
- MRC Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | | | | | | | - Reina Engle-Stone
- Department of Nutrition, University of California, Davis, Davis, CA, USA
| | - Tim J Green
- SAHMRi Women and Kids, South Australian Health and Medical Research Institute, Adelaide, South Australia, Australia
- School of Medicine, The University of Adelaide, Adelaide, South Australia, Australia
| | - Crystal D Karakochuk
- Food, Nutrition, and Health, University of British Columbia, Vancouver, British Columbia, Canada
| | - Parminder S Suchdev
- Department of Pediatrics, Emory University and Emory Global Health Institute, Atlanta, GA, USA
| | - Philip Bejon
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - George Davey Smith
- Medical Research Council (MRC) Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, UK
| | - Alison M Elliott
- MRC/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, Entebbe, Uganda
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, UK
| | - Thomas N Williams
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Department of Infectious Diseases and Institute of Global Health Innovation, Imperial College, London, UK
| | - Sarah H Atkinson
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine Research, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Department of Paediatrics, University of Oxford, Oxford, UK.
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14
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Agoti CN, Mutunga M, Lambisia AW, Kimani D, Cheruiyot R, Kiyuka P, Lewa C, Gicheru E, Tendwa M, Said Mohammed K, Osoti V, Makale J, Tawa B, Odundo C, Cheruiyot W, Nyamu W, Gumbi W, Mwacharo J, Nyamako L, Otieno E, Amadi D, Thoya J, Karani A, Mugo D, Musyoki J, Gumba H, Mwarumba S, M. Gichuki B, Njuguna S, Riako D, Mutua S, Gitonga JN, Sein Y, Bartilol B, Mwangi SJ, O. Omuoyo D, M. Morobe J, de Laurent ZR, Bejon P, Ochola-Oyier LI, Tsofa B. Pooled testing conserves SARS-CoV-2 laboratory resources and improves test turn-around time: experience on the Kenyan Coast. Wellcome Open Res 2021; 5:186. [PMID: 33134555 PMCID: PMC7590893 DOI: 10.12688/wellcomeopenres.16113.2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2020] [Indexed: 12/15/2022] Open
Abstract
Background. International recommendations for the control of the coronavirus disease 2019 (COVID-19) pandemic emphasize the central role of laboratory testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent, at scale. The availability of testing reagents, laboratory equipment and qualified staff are important bottlenecks to achieving this. Elsewhere, pooled testing (i.e. combining multiple samples in the same reaction) has been suggested to increase testing capacities in the pandemic period. Methods. We discuss our experience with SARS-CoV-2 pooled testing using real-time reverse transcription polymerase chain reaction (RT-PCR) on the Kenyan Coast. Results. In mid-May, 2020, our RT-PCR testing capacity for SARS-CoV-2 was improved by ~100% as a result of adoption of a six-sample pooled testing strategy. This was accompanied with a concomitant saving of ~50% of SARS-CoV-2 laboratory test kits at both the RNA extraction and RT-PCR stages. However, pooled testing came with a slight decline of test sensitivity. The RT-PCR cycle threshold value (ΔCt) was ~1.59 higher for samples tested in pools compared to samples tested singly. Conclusions. Pooled testing is a useful strategy to increase SARS-CoV-2 laboratory testing capacity especially in low-income settings.
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Affiliation(s)
- Charles N. Agoti
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
- Department of Biomedical Sciences, Pwani University, Kilifi, Kenya
| | - Martin Mutunga
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Arnold W. Lambisia
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Domtila Kimani
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Robinson Cheruiyot
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Patience Kiyuka
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Clement Lewa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Elijah Gicheru
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Metrine Tendwa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Khadija Said Mohammed
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Victor Osoti
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Johnstone Makale
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Brian Tawa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Calleb Odundo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Wesley Cheruiyot
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Wilfred Nyamu
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Wilson Gumbi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Jedidah Mwacharo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Lydia Nyamako
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Edward Otieno
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - David Amadi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Janet Thoya
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Angela Karani
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Daisy Mugo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Jennifer Musyoki
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Horace Gumba
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Salim Mwarumba
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Bonface M. Gichuki
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Susan Njuguna
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Debra Riako
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Shadrack Mutua
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - John N. Gitonga
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Yiakon Sein
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Brian Bartilol
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Shaban J. Mwangi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Donwilliams O. Omuoyo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - John M. Morobe
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Zaydah R. de Laurent
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Philip Bejon
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
- Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, UK
| | - Lynette Isabella Ochola-Oyier
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Benjamin Tsofa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
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15
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Kariuki SN, Marin-Menendez A, Introini V, Ravenhill BJ, Lin YC, Macharia A, Makale J, Tendwa M, Nyamu W, Kotar J, Carrasquilla M, Rowe JA, Rockett K, Kwiatkowski D, Weekes MP, Cicuta P, Williams TN, Rayner JC. Red blood cell tension protects against severe malaria in the Dantu blood group. Nature 2020; 585:579-583. [PMID: 32939086 PMCID: PMC7116803 DOI: 10.1038/s41586-020-2726-6] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 06/19/2020] [Indexed: 01/06/2023]
Abstract
Malaria has had a major effect on the human genome, with many protective polymorphisms-such as the sickle-cell trait-having been selected to high frequencies in malaria-endemic regions1,2. The blood group variant Dantu provides 74% protection against all forms of severe malaria in homozygous individuals3-5, a similar degree of protection to that afforded by the sickle-cell trait and considerably greater than that offered by the best malaria vaccine. Until now, however, the protective mechanism has been unknown. Here we demonstrate the effect of Dantu on the ability of the merozoite form of the malaria parasite Plasmodium falciparum to invade red blood cells (RBCs). We find that Dantu is associated with extensive changes to the repertoire of proteins found on the RBC surface, but, unexpectedly, inhibition of invasion does not correlate with specific RBC-parasite receptor-ligand interactions. By following invasion using video microscopy, we find a strong link between RBC tension and merozoite invasion, and identify a tension threshold above which invasion rarely occurs, even in non-Dantu RBCs. Dantu RBCs have higher average tension than non-Dantu RBCs, meaning that a greater proportion resist invasion. These findings provide both an explanation for the protective effect of Dantu, and fresh insight into why the efficiency of P. falciparum invasion might vary across the heterogenous populations of RBCs found both within and between individuals.
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Affiliation(s)
- Silvia N Kariuki
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Viola Introini
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Benjamin J Ravenhill
- Cambridge Institute for Medical Research, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Yen-Chun Lin
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Alex Macharia
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Johnstone Makale
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Metrine Tendwa
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Wilfred Nyamu
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jurij Kotar
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | | | - J Alexandra Rowe
- Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Kirk Rockett
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Dominic Kwiatkowski
- Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK
- Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
- Big Data Institute, University of Oxford, Oxford, UK
| | - Michael P Weekes
- Cambridge Institute for Medical Research, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Pietro Cicuta
- Cavendish Laboratory, University of Cambridge, Cambridge, UK.
| | - Thomas N Williams
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
- Institute of Global Health Innovation, Imperial College London, London, UK.
- Department of Infectious Disease, Imperial College London, London, UK.
| | - Julian C Rayner
- Wellcome Sanger Institute, Wellcome Genome Campus, Cambridge, UK.
- Cambridge Institute for Medical Research, School of Clinical Medicine, University of Cambridge, Cambridge, UK.
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16
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Uyoga S, Wanjiku P, Rop JC, Makale J, Macharia AW, Nyutu GM, Shebe M, Awuondo KA, Mturi N, Woodrow CJ, Dondorp AM, Maitland K, Williams TN. Plasma Plasmodium falciparum Histidine-Rich Protein-2 concentrations in children with malaria infections of differing severity in Kilifi, Kenya. Clin Infect Dis 2020; 73:e2415-e2423. [PMID: 32772115 PMCID: PMC8492128 DOI: 10.1093/cid/ciaa1141] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Indexed: 11/13/2022] Open
Abstract
Background Most previous studies support a direct link between total parasite load and the clinical severity of Plasmodium falciparum malaria infections. Methods We estimated P. falciparum parasite loads in 3 groups of children with malaria infections of differing severity: (1) children with World Health Organization–defined severe malaria (n = 1544), (2) children admitted with malaria but without features of severity (n = 200), and (3) children in the community with asymptomatic parasitemia (n = 33). Results Peripheral parasitemias were highest in those with uncomplicated malaria (geometric mean [GM] parasite count, 111 064/μL; 95% confidence interval, CI, 86 798–141 819/μL), almost 3 times higher than in those with severe malaria (39 588/μL; 34 990–44 791/μL) and >100 times higher than in those with asymptomatic malaria (1092/μL; 523–2280/μL). However, the GM P. falciparum histidine-rich protein 2 (PfHRP2) values (95% CI) increased with severity, being 7 (4–12) ng/mL in asymptomatic malaria, 843 (655–1084) ng/mL in uncomplicated malaria, and 1369 (1244–1506) ng/mL in severe malaria. PfHRP2 concentrations were markedly lower in the subgroup of patients with severe malaria and concomitant invasive bacterial infections of blood or cerebrospinal fluid (GM concentration, 312 ng/mL; 95% CI, 175–557 ng/mL; P < .001) than in those without such infections (1439 ng/mL; 1307–1584; P < .001). Conclusions The clinical severity of malaria infections related strongly to the total burden of P. falciparum parasites. A quantitative test for plasma concentrations of PfHRP2 could be useful in identifying children at the greatest clinical risk and identifying critically ill children in whom malaria is not the primary cause.
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Affiliation(s)
- Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Jesse C Rop
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | | | | | - Neema Mturi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Charles 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, UK
| | - Arjen 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, UK
| | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Department of Infectious Diseases, Imperial College, London, UK
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Department of Infectious Diseases, Imperial College, London, UK
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17
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Agoti CN, Mutunga M, Lambisia AW, Kimani D, Cheruiyot R, Kiyuka P, Lewa C, Gicheru E, Tendwa M, Said Mohammed K, Osoti V, Makale J, Tawa B, Odundo C, Cheruiyot W, Nyamu W, Gumbi W, Mwacharo J, Nyamako L, Otieno E, Amadi D, Thoya J, Karani A, Mugo D, Musyoki J, Gumba H, Mwarumba S, M. Gichuki B, Njuguna S, Riako D, Mutua S, Gitonga JN, Sein Y, Bartilol B, Mwangi SJ, O. Omuoyo D, M. Morobe J, de Laurent ZR, Bejon P, Ochola-Oyier LI, Tsofa B. Pooled testing conserves SARS-CoV-2 laboratory resources and improves test turn-around time: experience on the Kenyan Coast. Wellcome Open Res 2020; 5:186. [PMID: 33134555 PMCID: PMC7590893 DOI: 10.12688/wellcomeopenres.16113.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/31/2020] [Indexed: 12/15/2022] Open
Abstract
Background. International recommendations for the control of the coronavirus disease 2019 (COVID-19) pandemic emphasize the central role of laboratory testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the etiological agent, at scale. The availability of testing reagents, laboratory equipment and qualified staff are important bottlenecks to achieving this. Elsewhere, pooled testing (i.e. combining multiple samples in the same reaction) has been suggested to increase testing capacities in the pandemic period. Methods. We discuss our experience with SARS-CoV-2 pooled testing using real-time reverse transcription polymerase chain reaction (RT-PCR) on the Kenyan Coast. Results. In mid-May, 2020, our RT-PCR testing capacity for SARS-CoV-2 was improved by ~100% as a result of adoption of a six-sample pooled testing strategy. This was accompanied with a concomitant saving of ~50% of SARS-CoV-2 laboratory test kits at both the RNA extraction and RT-PCR stages. However, pooled testing came with a slight decline of test sensitivity. The RT-PCR cycle threshold value (ΔCt) was ~1.59 higher for samples tested in pools compared to samples tested singly. Conclusions. Pooled testing is a useful strategy to increase SARS-CoV-2 laboratory testing capacity especially in low-income settings.
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Affiliation(s)
- Charles N. Agoti
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
- Department of Biomedical Sciences, Pwani University, Kilifi, Kenya
| | - Martin Mutunga
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Arnold W. Lambisia
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Domtila Kimani
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Robinson Cheruiyot
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Patience Kiyuka
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Clement Lewa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Elijah Gicheru
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Metrine Tendwa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Khadija Said Mohammed
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Victor Osoti
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Johnstone Makale
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Brian Tawa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Calleb Odundo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Wesley Cheruiyot
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Wilfred Nyamu
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Wilson Gumbi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Jedidah Mwacharo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Lydia Nyamako
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Edward Otieno
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - David Amadi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Janet Thoya
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Angela Karani
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Daisy Mugo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Jennifer Musyoki
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Horace Gumba
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Salim Mwarumba
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Bonface M. Gichuki
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Susan Njuguna
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Debra Riako
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Shadrack Mutua
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - John N. Gitonga
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Yiakon Sein
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Brian Bartilol
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Shaban J. Mwangi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Donwilliams O. Omuoyo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - John M. Morobe
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Zaydah R. de Laurent
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Philip Bejon
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
- Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, UK
| | - Lynette Isabella Ochola-Oyier
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
| | - Benjamin Tsofa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Centre for Geographic Medicine Research, Kilifi, Kenya
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18
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Mohammed KS, de Laurent ZR, Omuoyo DO, Lewa C, Gicheru E, Cheruiyot R, Bartilol B, Mutua S, Musyoki J, Gumba H, Mwacharo J, Riako D, Mwangi SJ, Gichuki BM, Nyamako L, Karani A, Karanja H, Mugo D, Gitonga JN, Njuguna S, Gumbi W, Tawa B, Tendwa M, Cheruiyot W, Sein Y, Nyambu JK, Patta SO, Thani TS, Maitha EK, Kitole B, Mwakinangu MS, Muslih BS, Otieno JO, Nyiro JU, Kiyuka P, Ndwiga L, Wamae K, Kimani D, Makale J, Morobe JM, Osoti V, Lambisia AW, Odundo C, Mwarumba S, Mutunga M, Bejon P, Tsofa B, Agoti CN, Ochola-Oyier LI. An optimisation of four SARS-CoV-2 qRT-PCR assays in a Kenyan laboratory to support the national COVID-19 rapid response teams. Wellcome Open Res 2020; 5:162. [PMID: 35330938 PMCID: PMC8921690 DOI: 10.12688/wellcomeopenres.16063.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2020] [Indexed: 05/13/2024] Open
Abstract
Background: The global COVID-19 outbreak relies on a quantitative real-time polymerase chain reaction (qRT-PCR) for the detection of severe acute respiratory syndrome coronavirus (SARS-CoV-2), to facilitate the roll-out of patient care and infection control measures. There are several qRT-PCR assays with little evidence on their comparability. We report alterations to the developers' recommendations to sustain the testing capability in our setting, where the supply of testing reagents is limited. Methods: Standards generated from a serially-diluted positive control and previously identified positive/negative samples were used to determine the optimal volumes of the qRT-PCR reagents and to evaluate the validity and performance of four assays: Charité Berlin and European Virus Archive - GLOBAL (EVAg) primer-probe sets, and DAAN and Beijing Genomics Institute (BGI) premixed commercial kits. A multiplex and singleplex RT-PCR kit was used with the two primer-probe sets and the recommended assay volumes of the two premixed kits were altered. Results: In comparison to the multiplex RT-PCR kit, the singleplex RT-PCR kit combined with the primer-probe sets yielded consistent cycle threshold (Ct) values across the different titrations tested. The DAAN premixed kit produced comparable Ct values across the titrations, while the BGI kit showed incomparable Ct values and inconsistent results between batches using the manufacturer's recommended volumes. Conclusion: We achieved a 2.5-fold and 4-fold increase in the number of tests/kit for the premixed kits and the primer-probe sets, respectively. The primer-probe set assays were reliable and consistent, and we preferred a combination of an EVAg and a Berlin target. Any inconclusive result was repeated by different individuals following the same protocol. DAAN was a consistent and reliable assay even at lower concentrations from the stated recommendations. BGI in contrast, required dilution to improve its performance and was hence an assay that was used in combination with EVAg or Berlin targets.
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Affiliation(s)
| | | | | | - Clement Lewa
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | | | | | - Horace Gumba
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Debra Riako
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Lydia Nyamako
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Angela Karani
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Henry Karanja
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Daisy Mugo
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Susan Njuguna
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Wilson Gumbi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Brian Tawa
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Yiakon Sein
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - John K. Nyambu
- Department Of Health Services, Taita-Taveta County Government, Taita-Taveta, Kenya
| | - Shem O. Patta
- Department Of Health Services, Mombasa County Government, Mombasa, Kenya
| | | | | | | | | | | | | | | | | | | | - Kevin Wamae
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | - Victor Osoti
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Calleb Odundo
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, Oxford, UK
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Macharia AW, Mochamah G, Uyoga S, Ndila CM, Nyutu G, Tendwa M, Nyatichi E, Makale J, Ware RE, Williams TN. β-Thalassemia pathogenic variants in a cohort of children from the East African coast. Mol Genet Genomic Med 2020; 8:e1294. [PMID: 32394645 PMCID: PMC7336762 DOI: 10.1002/mgg3.1294] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/09/2020] [Accepted: 04/11/2020] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND β-Thalassemia is rare in sub-Saharan Africa. Previous studies have suggested that it is limited to specific parts of West Africa. Based on hemoglobin A2 (HbA2 ) concentrations measured by HPLC, we recently speculated that β-thalassemia might also be present on the East African coast of Kenya. Here, we follow this up using molecular methods. METHODS We used raised hemoglobin A2 (HbA2 ) values (> 4.0% of total Hb) to target all HbAA members of a cohort study in Kilifi, Kenya, for HBB sequencing for β-thalassemia (n = 99) together with a sample of HbAA subjects with lower HbA2 levels. Because HbA2 values are artifactually raised in subjects carrying sickle hemoglobin (HbS) we sequenced all participants with an HPLC pattern showing HbS without HbA (n = 116) and a sample with a pattern showing both HbA and HbS. RESULTS Overall, we identified 83 carriers of four separate β-thalassemia pathogenic variants: three β0 -thalassemia [CD22 (GAA→TAA), initiation codon (ATG→ACG), and IVS1-3' end del 25bp] and one β+ -thalassemia pathogenic variants (IVS-I-110 (G→A)). We estimated the minimum allele frequency of all variants combined within the study population at 0.3%. CONCLUSIONS β-Thalassemia is present in Kilifi, Kenya, an observation that has implications for the diagnosis and clinical care of children from the East Africa region.
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Affiliation(s)
| | | | - Sophie Uyoga
- KEMRI-Wellcome Trust Research ProgrammeKilifiKenya
| | | | - Gideon Nyutu
- KEMRI-Wellcome Trust Research ProgrammeKilifiKenya
| | | | | | | | - Russell E. Ware
- Cincinnati Children’s Hospital Medical CenterCincinnatiOHUSA
| | - Thomas N. Williams
- KEMRI-Wellcome Trust Research ProgrammeKilifiKenya
- Department of MedicineImperial CollegeSt Mary’s HospitalLondonUK
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20
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Uyoga S, Macharia AW, Mochamah G, Ndila CM, Nyutu G, Makale J, Tendwa M, Nyatichi E, Ojal J, Otiende M, Shebe M, Awuondo KO, Mturi N, Peshu N, Tsofa B, Maitland K, Scott JAG, Williams TN. The epidemiology of sickle cell disease in children recruited in infancy in Kilifi, Kenya: a prospective cohort study. Lancet Glob Health 2019; 7:e1458-e1466. [PMID: 31451441 PMCID: PMC7024980 DOI: 10.1016/s2214-109x(19)30328-6] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Revised: 07/02/2019] [Accepted: 07/05/2019] [Indexed: 02/07/2023]
Abstract
BACKGROUND Sickle cell disease is the most common severe monogenic disorder in humans. In Africa, 50-90% of children born with sickle cell disease die before they reach their fifth birthday. In this study, we aimed to describe the comparative incidence of specific clinical outcomes among children aged between birth and 5 years with and without sickle cell disease, who were resident within the Kilifi area of Kenya. METHODS This prospective cohort study was done on members of the Kilifi Genetic Birth Cohort Study (KGBCS) on the Indian Ocean coast of Kenya. Recruitment to the study was facilitated through the Kilifi Health and Demographic Surveillance System (KHDSS), which covers a resident population of 260 000 people, and was undertaken between Jan 1, 2006, and April 30, 2011. All children who were born within the KHDSS area and who were aged 3-12 months during the recruitment period were eligible for inclusion. Participants were tested for sickle cell disease and followed up for survival status and disease-specific admission to Kilifi County Hospital by passive surveillance until their fifth birthday. Children with sickle cell disease were offered confirmatory testing and care at a dedicated outpatient clinic. FINDINGS 15 737 infants were recruited successfully to the KGBCS, and 128 (0·8%) of these infants had sickle cell disease, of whom 70 (54·7%) enrolled at the outpatient clinic within 12 months of recruitment. Mortality was higher in children with sickle cell disease (58 per 1000 person-years of observation, 95% CI 40-86) than in those without sickle cell disease (2·4 per 1000 person-years of observation, 2·0-2·8; adjusted incidence rate ratio [IRR] 23·1, 95% CI 15·1-35·3). Among children with sickle cell disease, mortality was lower in those who enrolled at the clinic (adjusted IRR 0·26, 95% CI 0·11-0·62) and in those with higher levels of haemoglobin F (HbF; adjusted IRR 0·40, 0·17-0·94). The incidence of admission to hospital was also higher in children with sickle cell disease than in children without sickle cell disease (210 per 1000 person-years of observation, 95% CI 174-253, vs 43 per 1000 person-years of observation, 42-45; adjusted IRR 4·80, 95% CI 3·84-6·15). The most common reason for admission to hospital among those with sickle cell disease was severe anaemia (incidence 48 per 1000 person-years of observation, 95% CI 32-71). Admission to hospital was lower in those with a recruitment HbF level above the median (IRR 0·43, 95% CI 0·24-0·78; p=0·005) and those who were homozygous for α-thalassaemia (0·07, 0·01-0·83; p=0·035). INTERPRETATION Although morbidity and mortality were high in young children with sickle cell disease in this Kenyan cohort, both were reduced by early diagnosis and supportive care. The emphasis must now move towards early detection and prevention of long-term complications of sickle cell disease. FUNDING Wellcome Trust.
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Affiliation(s)
- Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | - Gideon Nyutu
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | - John Ojal
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mark Otiende
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Neema Mturi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Norbert Peshu
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Faculty of Medicine, Imperial College, St Mary's Hospital, London, UK
| | - J Anthony G Scott
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; London School of Hygiene & Tropical Medicine, London, UK; INDEPTH Network, Accra, Ghana
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; London School of Hygiene & Tropical Medicine, London, UK; INDEPTH Network, Accra, Ghana.
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21
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Macharia AW, Uyoga S, Ndila C, Nyutu G, Makale J, Tendwa M, Nyatichi E, Ojal J, Atkinson S, Williams TN. The population dynamics of hemoglobins A, A 2, F and S in the context of the hemoglobinopathies HbS and α-thalassemia in Kenyan infants. Haematologica 2018; 104:e184-e186. [PMID: 30467202 DOI: 10.3324/haematol.2018.199596] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Alex W Macharia
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Sophie Uyoga
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Carolyne Ndila
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Gideon Nyutu
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Johnstone Makale
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Metrine Tendwa
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Emily Nyatichi
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - John Ojal
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Sarah Atkinson
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Department of Paediatrics, John Radcliffe Hospital, Oxford, UK
| | - Thomas N Williams
- Department of Epidemiology and Demography, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Department of Medicine, Imperial College, St Mary's Hospital, London, UK
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22
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Macharia AW, Mochamah G, Uyoga S, Ndila CM, Nyutu G, Makale J, Tendwa M, Nyatichi E, Ojal J, Shebe M, Awuondo KO, Mturi N, Peshu N, Tsofa B, Scott JAG, Maitland K, Williams TN. The clinical epidemiology of sickle cell anemia In Africa. Am J Hematol 2018; 93:363-370. [PMID: 29168218 PMCID: PMC6175377 DOI: 10.1002/ajh.24986] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 11/20/2017] [Indexed: 12/17/2022]
Abstract
Sickle cell anemia (SCA) is the commonest severe monogenic disorders of humans. The disease has been highly characterized in high‐income countries but not in sub‐Saharan Africa where SCA is most prevalent. We conducted a retrospective cohort study of all children 0–13 years admitted from within a defined study area to Kilifi County Hospital in Kenya over a five‐year period. Children were genotyped for SCA retrospectively and incidence rates calculated with reference to population data. Overall, 576 of 18,873 (3.1%) admissions had SCA of whom the majority (399; 69.3%) were previously undiagnosed. The incidence of all‐cause hospital admission was 57.2/100 person years of observation (PYO; 95%CI 52.6–62.1) in children with SCA and 3.7/100 PYO (95%CI 3.7–3.8) in those without SCA (IRR 15.3; 95%CI 14.1–16.6). Rates were higher for the majority of syndromic diagnoses at all ages beyond the neonatal period, being especially high for severe anemia (hemoglobin <50 g/L; IRR 58.8; 95%CI 50.3–68.7), stroke (IRR 486; 95%CI 68.4–3,450), bacteremia (IRR 23.4; 95%CI 17.4–31.4), and for bone (IRR 607; 95%CI 284–1,300), and joint (IRR 80.9; 95%CI 18.1–362) infections. The use of an algorithm based on just five clinical features would have identified approximately half of all SCA cases among hospital‐admitted children with a number needed to test to identify each affected patient of only fourteen. Our study illustrates the clinical epidemiology of SCA in a malaria‐endemic environment without specific interventions. The targeted testing of hospital‐admitted children using the Kilifi Algorithm provides a pragmatic approach to early diagnosis in high‐prevalence countries where newborn screening is unavailable.
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Affiliation(s)
| | | | - Sophie Uyoga
- KEMRI/Wellcome Trust Research Programme, Kilifi; Kenya
| | | | - Gideon Nyutu
- KEMRI/Wellcome Trust Research Programme, Kilifi; Kenya
| | | | | | | | - John Ojal
- KEMRI/Wellcome Trust Research Programme, Kilifi; Kenya
| | | | | | - Neema Mturi
- KEMRI/Wellcome Trust Research Programme, Kilifi; Kenya
| | - Norbert Peshu
- KEMRI/Wellcome Trust Research Programme, Kilifi; Kenya
| | | | - J. Anthony G. Scott
- KEMRI/Wellcome Trust Research Programme, Kilifi; Kenya
- London School of Hygiene and Tropical Medicine; London WC1E 7HT United Kingdom
- INDEPTH Network; Accra Ghana
| | - Kathryn Maitland
- KEMRI/Wellcome Trust Research Programme, Kilifi; Kenya
- Faculty of Medicine; Imperial College, St Mary's Hospital; London W21NY United Kingdom
| | - Thomas N. Williams
- KEMRI/Wellcome Trust Research Programme, Kilifi; Kenya
- INDEPTH Network; Accra Ghana
- Faculty of Medicine; Imperial College, St Mary's Hospital; London W21NY United Kingdom
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23
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Etyang AO, Wandabwa CK, Kapesa S, Muthumbi E, Odipo E, Wamukoya M, Ngomi N, Haregu T, Kyobutungi C, Williams TN, Makale J, Macharia A, Cruickshank JK, Smeeth L, Scott JAG. Blood Pressure and Arterial Stiffness in Kenyan Adolescents With the Sickle Cell Trait. Am J Epidemiol 2018; 187:199-205. [PMID: 28992220 PMCID: PMC5860135 DOI: 10.1093/aje/kwx232] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/22/2017] [Indexed: 01/28/2023] Open
Abstract
The potential association between sickle cell trait (SCT) and increased arterial stiffness/blood pressure (BP) has not been evaluated in detail despite its association with stroke, sudden death, and renal disease. We performed 24-hour ambulatory BP monitoring and arterial stiffness measurements in adolescents raised in a malaria-free environment in Kenya. Between December 2015 and June 2016, 938 randomly selected adolescents (ages 11–17 years) who had been continuous residents of Nairobi from birth were invited to participate in the study. Standard clinic BP measurement was performed, followed by 24-hour ambulatory BP monitoring and arterial stiffness measurement using an Arteriograph24 (TensioMed Ltd., Budapest, Hungary) device. SCT status was determined using DNA genotyping in contemporaneously collected blood samples. Of the 938 adolescents invited to participate, 609 (65%) provided complete data for analysis. SCT was present in 103 (15%). Mean 24-hour systolic and diastolic BPs were 116 (standard deviation (SD), 11.5) mm Hg and 64 (SD, 7) mm Hg, respectively, in children with SCT and 117 (SD, 11.4) mm Hg and 64 (SD, 6.8) mm Hg, respectively, in non-SCT children. Mean pulse wave velocity (PWV) was 7.1 (SD, 0.8) m/second and 7.0 (SD, 0.8) m/second in SCT and non-SCT children, respectively. We observed no differences in PWV or in any clinic or ambulatory BP-derived measures between adolescents with and without SCT. These data suggest that SCT does not independently influence BP or PWV.
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Affiliation(s)
- Anthony O Etyang
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | | | - Emily Odipo
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Nicholas Ngomi
- African Population and Health Research Center, Nairobi, Kenya
| | - Tilahun Haregu
- African Population and Health Research Center, Nairobi, Kenya
| | | | - Thomas N Williams
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
- Imperial College London, London, United Kingdom
| | | | - Alex Macharia
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Liam Smeeth
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - J Anthony G Scott
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
- London School of Hygiene and Tropical Medicine, London, United Kingdom
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24
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Etyang AO, Khayeka-Wandabwa C, Kapesa S, Muthumbi E, Odipo E, Wamukoya M, Ngomi N, Haregu T, Kyobutungi C, Tendwa M, Makale J, Macharia A, Cruickshank JK, Smeeth L, Scott JAG, Williams TN. Blood Pressure and Arterial Stiffness in Kenyan Adolescents With α +Thalassemia. J Am Heart Assoc 2017; 6:JAHA.117.005613. [PMID: 28381468 PMCID: PMC5533038 DOI: 10.1161/jaha.117.005613] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Background Recent studies have discovered that α‐globin is expressed in blood vessel walls where it plays a role in regulating vascular tone. We tested the hypothesis that blood pressure (BP) might differ between normal individuals and those with α+thalassemia, in whom the production of α‐globin is reduced. Methods and Results The study was conducted in Nairobi, Kenya, among 938 adolescents aged 11 to 17 years. Twenty‐four‐hour ambulatory BP monitoring and arterial stiffness measurements were performed using an arteriograph device. We genotyped for α+thalassemia by polymerase chain reaction. Complete data for analysis were available for 623 subjects; 223 (36%) were heterozygous (−α/αα) and 47 (8%) were homozygous (−α/−α) for α+thalassemia whereas the remaining 353 (55%) were normal (αα/αα). Mean 24‐hour systolic BP ±SD was 118±12 mm Hg in αα/αα, 117±11 mm Hg in −α/αα, and 118±11 mm Hg in −α/−α subjects, respectively. Mean 24‐hour diastolic BP ±SD in these groups was 64±8, 63±7, and 65±8 mm Hg, respectively. Mean pulse wave velocity (PWV)±SD was 7±0.8, 7±0.8, and 7±0.7 ms−1, respectively. No differences were observed in PWV and any of the 24‐hour ambulatory BP monitoring‐derived measures between those with and without α+thalassemia. Conclusions These data suggest that the presence of α+thalassemia does not affect BP and/or arterial stiffness in Kenyan adolescents.
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Affiliation(s)
- Anthony O Etyang
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya .,London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | | | - Emily Odipo
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | | | - Nicholas Ngomi
- African Population and Health Research Centre, Nairobi, Kenya
| | - Tilahun Haregu
- African Population and Health Research Centre, Nairobi, Kenya
| | | | | | | | - Alex Macharia
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya
| | | | - Liam Smeeth
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - J Anthony G Scott
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya.,London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Program, Kilifi, Kenya.,Imperial College, London, United Kingdom
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25
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Shah SS, Macharia A, Makale J, Uyoga S, Kivinen K, Craik R, Hubbart C, Wellems TE, Rockett KA, Kwiatkowski DP, Williams TN. Genetic determinants of glucose-6-phosphate dehydrogenase activity in Kenya. BMC Med Genet 2014; 15:93. [PMID: 25201310 PMCID: PMC4236593 DOI: 10.1186/s12881-014-0093-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Accepted: 07/31/2014] [Indexed: 11/20/2022]
Abstract
Background The relationship between glucose-6-phosphate dehydrogenase (G6PD) deficiency and clinical phenomena such as primaquine-sensitivity and protection from severe malaria remains poorly defined, with past association studies yielding inconsistent and conflicting results. One possibility is that examination of a single genetic variant might underestimate the presence of true effects in the presence of unrecognized functional allelic diversity. Methods We systematically examined this possibility in Kenya, conducting a fine-mapping association study of erythrocyte G6PD activity in 1828 Kenyan children across 30 polymorphisms at or around the G6PD locus. Results We demonstrate a strong functional role for c.202G>A (rs1050828), which accounts for the majority of variance in enzyme activity observed (P=1.5×10−200, additive model). Additionally, we identify other common variants that exert smaller, intercorrelated effects independent of c.202G>A, and haplotype analyses suggest that each variant tags one of two haplotype motifs that are opposite in sequence identity and effect direction. We posit that these effects are of biological and possible clinical significance, specifically noting that c.376A>G (rs1050829) augments 202AG heterozygote risk for deficiency trait by two-fold (OR = 2.11 [1.12 - 3.84], P=0.014). Conclusions Our results suggest that c.202G>A is responsible for the majority of the observed prevalence of G6PD deficiency trait in Kenya, but also identify a novel role for c.376A>G as a genetic modifier which marks a common haplotype that augments the risk conferred to 202AG heterozygotes, suggesting that variation at both loci merits consideration in genetic association studies probing G6PD deficiency-associated clinical phenotypes.
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Affiliation(s)
- Shivang S Shah
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK.
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