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Ogwang R, Murugu L, Nkumama IN, Nyamako L, Kai O, Mwai K, Murungi L, Idro R, Bejon P, Tuju J, Kinyanjui SM, Osier FHA. Bi-isotype immunoglobulins enhance antibody-mediated neutrophil activity against Plasmodium falciparum parasites. Front Immunol 2024; 15:1360220. [PMID: 38650925 PMCID: PMC11033408 DOI: 10.3389/fimmu.2024.1360220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 03/19/2024] [Indexed: 04/25/2024] Open
Abstract
Background Malaria remains a major global health priority, and monoclonal antibodies (mAbs) are emerging as potential new tools to support efforts to control the disease. Recent data suggest that Fc-dependent mechanisms of immunity are important mediators of protection against the blood stages of the infection, but few studies have investigated this in the context of mAbs. We aimed to isolate mAbs agnostic to cognate antigens that target whole merozoites and simultaneously induce potent neutrophil activity measured by the level of reactive oxygen species (ROS) production using an antibody-dependent respiratory burst (ADRB) assay. Methods We used samples from semi-immune adults living in coastal Kenya to isolate mAbs that induce merozoite-specific ADRB activity. We then tested whether modifying the expressed IgG1 isotype to an IgG-IgA Fc region chimera would enhance the level of ADRB activity. Results We isolated a panel of nine mAbs with specificity to whole merozoites. mAb J31 induced ADRB activity in a dose-dependent fashion. Compared to IgG1, our modified antibody IgG-IgA bi-isotype induced higher ADRB activity across all concentrations tested. Further, we observed a negative hook effect at high IgG1 mAb concentrations (i.e., >200 µg/mL), but this was reversed by Fc modification. We identified MSP3.5 as the potential cognate target of mAb J31. Conclusions We demonstrate an approach to engineer mAbs with enhanced ADRB potency against blood-stage parasites.
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Affiliation(s)
- Rodney Ogwang
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- College of Health Sciences, Makerere University, Kampala, Uganda
| | - Lewis Murugu
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | - Irene N. Nkumama
- Centre of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany
| | - Lydia Nyamako
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Oscar Kai
- 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
| | - Linda Murungi
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Richard Idro
- College of Health Sciences, Makerere University, Kampala, Uganda
- 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), 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
- Department of Biological Sciences, Pwani University, Kilifi, Kenya
| | - Sam Muchina Kinyanjui
- Centre for Geographic Medicine Research (Coast), Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Faith H. A. Osier
- Department of Life Sciences, Imperial College London, London, United Kingdom
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Kapulu MC, Muthumbi E, Otieno E, Rossi O, Ferruzzi P, Necchi F, Acquaviva A, Martin LB, Orindi B, Mwai K, Kibet H, Mwanzu A, Bigogo GM, Verani JR, Mbae C, Nyundo C, Agoti CN, Nakakana UN, Conti V, Bejon P, Kariuki S, Scott JAG, Micoli F, Podda A. Age-dependent acquisition of IgG antibodies to Shigella serotypes-a retrospective analysis of seroprevalence in Kenyan children with implications for infant vaccination. Front Immunol 2024; 15:1340425. [PMID: 38361949 PMCID: PMC10867106 DOI: 10.3389/fimmu.2024.1340425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Accepted: 01/12/2024] [Indexed: 02/17/2024] Open
Abstract
Background Shigellosis mainly affects children under 5 years of age living in low- and middle-income countries, who are the target population for vaccination. There are, however, limited data available to define the appropriate timing for vaccine administration in this age group. Information on antibody responses following natural infection, proxy for exposure, could help guide vaccination strategies. Methods We undertook a retrospective analysis of antibodies to five of the most prevalent Shigella serotypes among children aged <5 years in Kenya. Serum samples from a cross-sectional serosurvey in three Kenyan sites (Nairobi, Siaya, and Kilifi) were analyzed by standardized ELISA to measure IgG against Shigella sonnei and Shigella flexneri 1b, 2a, 3a, and 6. We identified factors associated with seropositivity to each Shigella serotype, including seropositivity to other Shigella serotypes. Results A total of 474 samples, one for each participant, were analyzed: Nairobi (n = 169), Siaya (n = 185), and Kilifi (n = 120). The median age of the participants was 13.4 months (IQR 7.0-35.6), and the male:female ratio was 1:1. Geometric mean concentrations (GMCs) for each serotype increased with age, mostly in the second year of life. The overall seroprevalence of IgG antibodies increased with age except for S. flexneri 6 which was high across all age subgroups. In the second year of life, there was a statistically significant increase of antibody GMCs against all five serotypes (p = 0.01-0.0001) and a significant increase of seroprevalence for S. flexneri 2a (p = 0.006), S. flexneri 3a (p = 0.006), and S. sonnei (p = 0.05) compared with the second part of the first year of life. Among all possible pairwise comparisons of antibody seropositivity, there was a significant association between S. flexneri 1b and 2a (OR = 6.75, 95% CI 3-14, p < 0.001) and between S. flexneri 1b and 3a (OR = 23.85, 95% CI 11-54, p < 0.001). Conclusion Children living in low- and middle-income settings such as Kenya are exposed to Shigella infection starting from the first year of life and acquire serotype-specific antibodies against multiple serotypes. The data from this study suggest that Shigella vaccination should be targeted to infants, ideally at 6 or at least 9 months of age, to ensure children are protected in the second year of life when exposure significantly increases.
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Affiliation(s)
- Melissa C. Kapulu
- KEMRI-Wellcome Trust Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Esther Muthumbi
- KEMRI-Wellcome Trust Programme, Kilifi, Kenya
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Omar Rossi
- GSK Vaccines Institute for Global Health, Siena, Italy
| | | | | | | | | | | | - Kennedy Mwai
- KEMRI-Wellcome Trust Programme, Kilifi, Kenya
- Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
| | | | | | - Godfrey M. Bigogo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Jennifer R. Verani
- Division of Global Health Protection, US Centers for Disease Control and Prevention, Nairobi, Kenya
| | - Cecilia Mbae
- Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | | | | | | | | | - Philip Bejon
- KEMRI-Wellcome Trust Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Samuel Kariuki
- Centre for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - J. Anthony G. Scott
- KEMRI-Wellcome Trust Programme, Kilifi, Kenya
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Audino Podda
- GSK Vaccines Institute for Global Health, Siena, Italy
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3
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Kimenyi KM, Akinyi MY, Mwikali K, Gilmore T, Mwangi S, Omer E, Gichuki B, Wambua J, Njunge J, Obiero G, Bejon P, Langhorne J, Abdi A, Ochola-Oyier LI. Distinct transcriptomic signatures define febrile malaria depending on initial infective states, asymptomatic or uninfected. BMC Infect Dis 2024; 24:140. [PMID: 38287287 PMCID: PMC10823747 DOI: 10.1186/s12879-024-08973-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/01/2024] [Indexed: 01/31/2024] Open
Abstract
BACKGROUND Cumulative malaria parasite exposure in endemic regions often results in the acquisition of partial immunity and asymptomatic infections. There is limited information on how host-parasite interactions mediate the maintenance of chronic symptomless infections that sustain malaria transmission. METHODS Here, we determined the gene expression profiles of the parasite population and the corresponding host peripheral blood mononuclear cells (PBMCs) from 21 children (< 15 years). We compared children who were defined as uninfected, asymptomatic and those with febrile malaria. RESULTS Children with asymptomatic infections had a parasite transcriptional profile characterized by a bias toward trophozoite stage (~ 12 h-post invasion) parasites and low parasite levels, while early ring stage parasites were characteristic of febrile malaria. The host response of asymptomatic children was characterized by downregulated transcription of genes associated with inflammatory responses, compared with children with febrile malaria,. Interestingly, the host responses during febrile infections that followed an asymptomatic infection featured stronger inflammatory responses, whereas the febrile host responses from previously uninfected children featured increased humoral immune responses. CONCLUSIONS The priming effect of prior asymptomatic infection may explain the blunted acquisition of antibody responses seen to malaria antigens following natural exposure or vaccination in malaria endemic areas.
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Affiliation(s)
- Kelvin M Kimenyi
- KEMRI‑Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biochemistry, University of Nairobi, Nairobi, Kenya
| | | | - Kioko Mwikali
- KEMRI‑Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Shaban Mwangi
- KEMRI‑Wellcome Trust Research Programme, Kilifi, Kenya
| | - Elisha Omer
- KEMRI‑Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - James Njunge
- KEMRI‑Wellcome Trust Research Programme, Kilifi, Kenya
| | - George Obiero
- Department of Biochemistry, University of Nairobi, Nairobi, Kenya
| | - Philip Bejon
- KEMRI‑Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Opi DH, Ndila CM, Uyoga S, Macharia AW, Fennell C, Ochola LB, Nyutu G, Siddondo BR, Ojal J, Shebe M, Awuondo KO, Mturi N, Peshu N, Tsofa B, Band G, Maitland K, Kwiatkowski DP, Rockett KA, Williams TN, Rowe JA. Non-O ABO blood group genotypes differ in their associations with Plasmodium falciparum rosetting and severe malaria. PLoS Genet 2023; 19:e1010910. [PMID: 37708213 PMCID: PMC10522014 DOI: 10.1371/journal.pgen.1010910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 09/26/2023] [Accepted: 08/08/2023] [Indexed: 09/16/2023] Open
Abstract
Blood group O is associated with protection against severe malaria and reduced size and stability of P. falciparum-host red blood cell (RBC) rosettes compared to non-O blood groups. Whether the non-O blood groups encoded by the specific ABO genotypes AO, BO, AA, BB and AB differ in their associations with severe malaria and rosetting is unknown. The A and B antigens are host RBC receptors for rosetting, hence we hypothesized that the higher levels of A and/or B antigen on RBCs from AA, BB and AB genotypes compared to AO/BO genotypes could lead to larger rosettes, increased microvascular obstruction and higher risk of malaria pathology. We used a case-control study of Kenyan children and in vitro adhesion assays to test the hypothesis that "double dose" non-O genotypes (AA, BB, AB) are associated with increased risk of severe malaria and larger rosettes than "single dose" heterozygotes (AO, BO). In the case-control study, compared to OO, the double dose genotypes consistently had higher odds ratios (OR) for severe malaria than single dose genotypes, with AB (OR 1.93) and AO (OR 1.27) showing most marked difference (p = 0.02, Wald test). In vitro experiments with blood group A-preferring P. falciparum parasites showed that significantly larger rosettes were formed with AA and AB host RBCs compared to OO, whereas AO and BO genotypes rosettes were indistinguishable from OO. Overall, the data show that ABO genotype influences P. falciparum rosetting and support the hypothesis that double dose non-O genotypes confer a greater risk of severe malaria than AO/BO heterozygosity.
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Affiliation(s)
- D. Herbert Opi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Carolyne M. Ndila
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Sophie Uyoga
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Alex W. Macharia
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Clare Fennell
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Lucy B. Ochola
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Gideon Nyutu
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Bethseba R. Siddondo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - John Ojal
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mohammed Shebe
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kennedy O. Awuondo
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Neema Mturi
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Norbert Peshu
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Benjamin Tsofa
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Gavin Band
- Wellcome Centre for Human Genetics, Oxford, United Kingdom
| | - Kathryn Maitland
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Institute for Global Health Innovation, Department of Surgery and Cancer, Imperial College, London, United Kingdom
| | | | | | - Thomas N. Williams
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Institute for Global Health Innovation, Department of Surgery and Cancer, Imperial College, London, United Kingdom
| | - J. Alexandra Rowe
- Centre for Immunity, Infection and Evolution, Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
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Brodeur KRN, Herculano A, Oliveira K. Clinical aspects of malarial retinopathy: a critical review. Pathog Glob Health 2023; 117:450-461. [PMID: 36262019 PMCID: PMC10262785 DOI: 10.1080/20477724.2022.2128568] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
This review will provide a better understanding of a set of signs known as malarial retinopathy. The discovery of this retinopathy in association with cerebral malaria is important because it best distinguishes patients with true cerebral malaria from those with coma due to other causes and incidental Plasmodium falciparum parasitemia. Identifying a comatose patient with malarial retinopathy increases the likelihood of an accurate severe or cerebral malaria diagnosis. As the World Health Organization does not specify that malarial retinopathy is one of the factors included in determining a cerebral malaria diagnosis, there are significant false-positive diagnoses of cerebral malaria. Once a cerebral malaria diagnosis is assigned, other possibilities and treatments are often excluded making an incorrect diagnosis of cerebral malaria potentially fatal. However, Plasmodium falciparum may also contribute to coma in some children with retinopathy-negative cerebral malaria, as this group is still not clinically well characterized, so all children with the WHO definition of cerebral malaria should be treated for severe malaria. Nevertheless, by raising awareness about malarial retinopathy, there could be a greater potential to accurately diagnose cerebral malaria and thus achieve more positive patient outcomes in the future. This literary review aims to raise awareness of the retinopathy by defining what it is to non-experts, explaining its pathology, clarifying the techniques needed to accurately diagnose malarial retinopathy, as well as the barriers that prevent clinicians from providing a proper diagnosis in malaria-endemic regions; and finally, discuss future directions to continue the study of malarial retinopathy.
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Affiliation(s)
- Ketan Raymond Nair Brodeur
- Laboratory of Experimental Neuropharmacology, Federal University of Pará, Belém, Pará, Brazil
- Fulbright US Student Program
- University of Michigan – Ann Arbor, Michigan, USA
| | - Anderson Herculano
- Laboratory of Experimental Neuropharmacology, Federal University of Pará, Belém, Pará, Brazil
| | - Karen Oliveira
- Laboratory of Experimental Neuropharmacology, Federal University of Pará, Belém, Pará, Brazil
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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] [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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7
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Blair PW, Kobba K, Kakooza F, Robinson ML, Candia E, Mayito J, Ndawula EC, Kandathil AJ, Matovu A, Aniku G, Manabe YC, Lamorde M. Aetiology of hospitalized fever and risk of death at Arua and Mubende tertiary care hospitals in Uganda from August 2019 to August 2020. BMC Infect Dis 2022; 22:869. [PMID: 36411415 PMCID: PMC9680122 DOI: 10.1186/s12879-022-07877-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 10/17/2022] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Epidemiology of febrile illness in Uganda is shifting due to increased HIV treatment access, emerging viruses, and increased surveillance. We investigated the aetiology and outcomes of acute febrile illness in adults presenting to hospital using a standardized testing algorithm of available assays in at Arua and Mubende tertiary care hospitals in Uganda. METHODS We recruited adults with a ≥ 38.0 °C temperature or history of fever within 48 h of presentation from August 2019 to August 2020. Medical history, demographics, and vital signs were recorded. Testing performed included a complete blood count, renal and liver function, malaria smears, blood culture, and human immunodeficiency virus (HIV). When HIV positive, testing included cryptococcal antigen, CD4 count, and urine lateral flow lipoarabinomannan assay for tuberculosis. Participants were followed during hospitalization and at a 1-month visit. A Cox proportional hazard regression was performed to evaluate for baseline clinical features and risk of death. RESULTS Of 132 participants, the median age was 33.5 years (IQR 24 to 46) and 58.3% (n = 77) were female. Overall, 73 (55.3%) of 132 had a positive microbiologic result. Among those living with HIV, 31 (68.9%) of 45 had at least one positive assay; 16 (35.6%) had malaria, 14 (31.1%) tuberculosis, and 4 (8.9%) cryptococcal antigenemia. The majority (65.9%) were HIV-negative; 42 (48.3%) of 87 had at least one diagnostic assay positive; 24 (27.6%) had positive malaria smears and 1 was Xpert MTB/RIF Ultra positive. Overall, 16 (12.1%) of 132 died; 9 (56.3%) of 16 were HIV-negative, 6 died after discharge. High respiratory rate (≥ 22 breaths per minute) (hazard ratio [HR] 8.05; 95% CI 1.81 to 35.69) and low (i.e., < 92%) oxygen saturation (HR 4.33; 95% CI 1.38 to 13.61) were identified to be associated with increased risk of death. CONCLUSION In those with hospitalized fever, malaria and tuberculosis were common causes of febrile illness, but most deaths were non-malarial, and most HIV-negative participants did not have a positive diagnostic result. Those with respiratory failure had a high risk of death.
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Affiliation(s)
- Paul W Blair
- John Hopkins University School of Medicine Division of Infectious Diseases, Baltimore, MD, USA.
- Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc., 6720A Rockledge Dr., Bethesda, MD, USA.
| | - Kenneth Kobba
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Francis Kakooza
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Matthew L Robinson
- John Hopkins University School of Medicine Division of Infectious Diseases, Baltimore, MD, USA
| | - Emmanuel Candia
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Jonathan Mayito
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Edgar C Ndawula
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
| | - Abraham J Kandathil
- John Hopkins University School of Medicine Division of Infectious Diseases, Baltimore, MD, USA
| | | | | | - Yukari C Manabe
- John Hopkins University School of Medicine Division of Infectious Diseases, Baltimore, MD, USA
| | - Mohammed Lamorde
- Infectious Diseases Institute, Makerere University, Kampala, Uganda
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8
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Mwai K, Nkumama I, Thairu A, Mburu J, Odera D, Kimathi R, Nyamako L, Tuju J, Kinyanjui S, Musenge E, Osier F. Malaria attributable fractions with changing transmission intensity: Bayesian latent class vs logistic models. Malar J 2022; 21:326. [DOI: 10.1186/s12936-022-04346-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 10/27/2022] [Indexed: 11/13/2022] Open
Abstract
Abstract
Background
Asymptomatic carriage of malaria parasites is common in high transmission intensity areas and confounds clinical case definitions for research studies. This is important for investigations that aim to identify immune correlates of protection from clinical malaria. The proportion of fevers attributable to malaria parasites is widely used to define different thresholds of parasite density associated with febrile episodes. The varying intensity of malaria transmission was investigated to check whether it had a significant impact on the parasite density thresholds. The same dataset was used to explore an alternative statistical approach, using the probability of developing fevers as a choice over threshold cut-offs. The former has been reported to increase predictive power.
Methods
Data from children monitored longitudinally between 2005 and 2017 from Junju and Chonyi in Kilifi, Kenya were used. Performance comparison of Bayesian-latent class and logistic power models in estimating malaria attributable fractions and probabilities of having fever given a parasite density with changing malaria transmission intensity was done using Junju cohort. Zero-inflated beta regressions were used to assess the impact of using probabilities to evaluate anti-merozoite antibodies as correlates of protection, compared with multilevel binary regression using data from Chonyi and Junju.
Results
Malaria transmission intensity declined from over 49% to 5% between 2006 and 2017, respectively. During this period, malaria attributable fraction varied between 27–59% using logistic regression compared to 10–36% with the Bayesian latent class approach. Both models estimated similar patterns of fevers attributable to malaria with changing transmission intensities. The Bayesian latent class model performed well in estimating the probabilities of having fever, while the latter was efficient in determining the parasite density threshold. However, compared to the logistic power model, the Bayesian algorithm yielded lower estimates for both attributable fractions and probabilities of fever. In modelling the association of merozoite antibodies and clinical malaria, both approaches resulted in comparable estimates, but the utilization of probabilities had a better statistical fit.
Conclusions
Malaria attributable fractions, varied with an overall decline in the malaria transmission intensity in this setting but did not significantly impact the outcomes of analyses aimed at identifying immune correlates of protection. These data confirm the statistical advantage of using probabilities over binary data.
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9
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Takashima E, Kanoi BN, Nagaoka H, Morita M, Hassan I, Palacpac NMQ, Egwang TG, Horii T, Gitaka J, Tsuboi T. Meta-Analysis of Human Antibodies Against Plasmodium falciparum Variable Surface and Merozoite Stage Antigens. Front Immunol 2022; 13:887219. [PMID: 35757771 PMCID: PMC9218060 DOI: 10.3389/fimmu.2022.887219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 05/11/2022] [Indexed: 11/30/2022] Open
Abstract
Concerted efforts to fight malaria have caused significant reductions in global malaria cases and mortality. Sustaining this will be critical to avoid rebound and outbreaks of seasonal malaria. Identifying predictive attributes that define clinical malaria will be key to guide development of second-generation tools to fight malaria. Broadly reactive antibodies against variable surface antigens that are expressed on the surface of infected erythrocytes and merozoites stage antigens are targets of naturally acquired immunity and prime candidates for anti-malaria therapeutics and vaccines. However, predicting the relationship between the antigen-specific antibodies and protection from clinical malaria remains unresolved. Here, we used new datasets and multiple approaches combined with re-analysis of our previous data to assess the multi-dimensional and complex relationship between antibody responses and clinical malaria outcomes. We observed 22 antigens (17 PfEMP1 domains, 3 RIFIN family members, merozoite surface protein 3 (PF3D7_1035400), and merozoites-associated armadillo repeats protein (PF3D7_1035900) that were selected across three different clinical malaria definitions (1,000/2,500/5,000 parasites/µl plus fever). In addition, Principal Components Analysis (PCA) indicated that the first three components (Dim1, Dim2 and Dim3 with eigenvalues of 306, 48, and 29, respectively) accounted for 66.1% of the total variations seen. Specifically, the Dim1, Dim2 and Dim3 explained 52.8%, 8.2% and 5% of variability, respectively. We further observed a significant relationship between the first component scores and age with antibodies to PfEMP1 domains being the key contributing variables. This is consistent with a recent proposal suggesting that there is an ordered acquisition of antibodies targeting PfEMP1 proteins. Thus, although limited, and further work on the significance of the selected antigens will be required, these approaches may provide insights for identification of drivers of naturally acquired protective immunity as well as guide development of additional tools for malaria elimination and eradication.
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Affiliation(s)
- Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Bernard N Kanoi
- Centre for Research in Infectious Diseases, Directorate of Research and Innovation, Mount Kenya University, Thika, Kenya
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Masayuki Morita
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Ifra Hassan
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Nirianne M Q Palacpac
- Department of Malaria Vaccine Development, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
| | | | - Toshihiro Horii
- Department of Malaria Vaccine Development, Research Institute for Microbial Diseases, Osaka University, Suita, Japan
| | - Jesse Gitaka
- Centre for Research in Infectious Diseases, Directorate of Research and Innovation, Mount Kenya University, Thika, Kenya
| | - Takafumi Tsuboi
- Division of Cell-Free Sciences, Proteo-Science Center, Ehime University, Matsuyama, Japan
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10
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Kimenyi KM, Wamae K, Ngoi JM, de Laurent ZR, Ndwiga L, Osoti V, Obiero G, Abdi AI, Bejon P, Ochola-Oyier LI. Maintenance of high temporal Plasmodium falciparum genetic diversity and complexity of infection in asymptomatic and symptomatic infections in Kilifi, Kenya from 2007 to 2018. Malar J 2022; 21:192. [PMID: 35725456 PMCID: PMC9207840 DOI: 10.1186/s12936-022-04213-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 06/03/2022] [Indexed: 11/30/2022] Open
Abstract
Background High levels of genetic diversity are common characteristics of Plasmodium falciparum parasite populations in high malaria transmission regions. There has been a decline in malaria transmission intensity over 12 years of surveillance in the community in Kilifi, Kenya. This study sought to investigate whether there was a corresponding reduction in P. falciparum genetic diversity, using msp2 as a genetic marker. Methods Blood samples were obtained from children (< 15 years) enrolled into a cohort with active weekly surveillance between 2007 and 2018 in Kilifi, Kenya. Asymptomatic infections were defined during the annual cross-sectional blood survey and the first-febrile malaria episode was detected during the weekly follow-up. Parasite DNA was extracted and successfully genotyped using allele-specific nested polymerase chain reactions for msp2 and capillary electrophoresis fragment analysis. Results Based on cross-sectional surveys conducted in 2007–2018, there was a significant reduction in malaria prevalence (16.2–5.5%: P-value < 0.001), however msp2 genetic diversity remained high. A high heterozygosity index (He) (> 0.95) was observed in both asymptomatic infections and febrile malaria over time. About 281 (68.5%) asymptomatic infections were polyclonal (> 2 variants per infection) compared to 46 (56%) polyclonal first-febrile infections. There was significant difference in complexity of infection (COI) between asymptomatic 2.3 [95% confidence interval (CI) 2.2–2.5] and febrile infections 2.0 (95% CI 1.7–2.3) (P = 0.016). Majority of asymptomatic infections (44.2%) carried mixed alleles (i.e., both FC27 and IC/3D7), while FC27 alleles were more frequent (53.3%) among the first-febrile infections. Conclusions Plasmodium falciparum infections in Kilifi are still highly diverse and polyclonal, despite the reduction in malaria transmission in the community. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04213-7.
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Affiliation(s)
- Kelvin M Kimenyi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya. .,Department of Biochemistry, University of Nairobi, Nairobi, Kenya.
| | - Kevin Wamae
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Joyce M Ngoi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,West Africa Centre for Cell Biology and Infectious Pathogen, Accra, Ghana
| | | | | | - Victor Osoti
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - George Obiero
- Department of Biochemistry, University of Nairobi, Nairobi, Kenya
| | | | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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11
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The impact of malaria-protective red blood cell polymorphisms on parasite biomass in children with severe Plasmodium falciparum malaria. Nat Commun 2022; 13:3307. [PMID: 35676275 PMCID: PMC9178016 DOI: 10.1038/s41467-022-30990-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 05/24/2022] [Indexed: 11/08/2022] Open
Abstract
Severe falciparum malaria is a major cause of preventable child mortality in sub-Saharan Africa. Plasma concentrations of P. falciparum Histidine-Rich Protein 2 (PfHRP2) have diagnostic and prognostic value in severe malaria. We investigate the potential use of plasma PfHRP2 and the sequestration index (the ratio of PfHRP2 to parasite density) as quantitative traits for case-only genetic association studies of severe malaria. Data from 2198 Kenyan children diagnosed with severe malaria, genotyped for 14 major candidate genes, show that polymorphisms in four major red cell genes that lead to hemoglobin S, O blood group, α-thalassemia, and the Dantu blood group, are associated with substantially lower admission plasma PfHRP2 concentrations, consistent with protective effects against extensive parasitized erythrocyte sequestration. In contrast the known protective ATP2B4 polymorphism is associated with higher plasma PfHRP2 concentrations, lower parasite densities and a higher sequestration index. We provide testable hypotheses for the mechanism of protection of ATP2B4.
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12
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Wamae K, Kimenyi KM, Osoti V, de Laurent ZR, Ndwiga L, Kharabora O, Hathaway NJ, Bailey JA, Juliano JJ, Bejon P, Ochola-Oyier LI. Amplicon sequencing as a potential surveillance tool for complexity of infection and drug resistance markers in Plasmodium falciparum asymptomatic infections. J Infect Dis 2022; 226:920-927. [PMID: 35429395 PMCID: PMC7613600 DOI: 10.1093/infdis/jiac144] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 04/14/2022] [Indexed: 11/16/2022] Open
Abstract
Background Genotyping Plasmodium falciparum subpopulations in malaria infections is an important aspect of malaria molecular epidemiology to understand within-host diversity and the frequency of drug resistance markers. Methods We characterized P. falciparum genetic diversity in asymptomatic infections and subsequent first febrile infections using amplicon sequencing (AmpSeq) of ama1 in Coastal Kenya. We also examined temporal changes in haplotype frequencies of mdr1, a drug-resistant marker. Results We found >60% of the infections were polyclonal (complexity of infection [COI] >1) and there was a reduction in COI over time. Asymptomatic infections had a significantly higher mean COI than febrile infections based on ama1 sequences (2.7 [95% confidence interval {CI}, 2.65–2.77] vs 2.22 [95% CI, 2.17–2.29], respectively). Moreover, an analysis of 30 paired asymptomatic and first febrile infections revealed that many first febrile infections (91%) were due to the presence of new ama1 haplotypes. The mdr1-YY haplotype, associated with chloroquine and amodiaquine resistance, decreased over time, while the NY (wild type) and the NF (modulates response to lumefantrine) haplotypes increased. Conclusions This study emphasizes the utility of AmpSeq in characterizing parasite diversity as it can determine relative proportions of clones and detect minority clones. The usefulness of AmpSeq in antimalarial drug resistance surveillance is also highlighted.
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Affiliation(s)
- Kevin Wamae
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kelvin M. Kimenyi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Biotechnology and Bioinformatics, University of Nairobi, Nairobi, Kenya
| | - Victor Osoti
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Oksana Kharabora
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Nicholas J. Hathaway
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Jeffrey A. Bailey
- Department of Pathology and Laboratory Medicine, Warren Alpert Medical School, Brown University, Providence, RI, USA
| | - Jonathan J. Juliano
- Division of Infectious Diseases, Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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13
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Addy JW, Bediako Y, Ndungu FM, Valetta JJ, Reid AJ, Mwacharo J, Ngoi JM, Wambua J, Otieno E, Musyoki J, Said K, Berriman M, Marsh K, Bejon P, Recker M, Langhorne J. 10-year longitudinal study of malaria in children: Insights into acquisition and maintenance of naturally acquired immunity. Wellcome Open Res 2022; 6:79. [PMID: 35141425 PMCID: PMC8822141 DOI: 10.12688/wellcomeopenres.16562.3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/31/2022] [Indexed: 01/26/2023] Open
Abstract
Background: Studies of long-term malaria cohorts have provided essential insights into how Plasmodium falciparum interacts with humans, and influences the development of antimalarial immunity. Immunity to malaria is acquired gradually after multiple infections, some of which present with clinical symptoms. However, there is considerable variation in the number of clinical episodes experienced by children of the same age within the same cohort. Understanding this variation in clinical symptoms and how it relates to the development of naturally acquired immunity is crucial in identifying how and when some children stop experiencing further malaria episodes. Where variability in clinical episodes may result from different rates of acquisition of immunity, or from variable exposure to the parasite. Methods: Using data from a longitudinal cohort of children residing in an area of moderate P. falciparum transmission in Kilifi district, Kenya, we fitted cumulative episode curves as monotonic-increasing splines, to 56 children under surveillance for malaria from the age of 5 to 15. Results: There was large variability in the accumulation of numbers of clinical malaria episodes experienced by the children, despite being of similar age and living in the same general location. One group of children from a particular sub-region of the cohort stopped accumulating clinical malaria episodes earlier than other children in the study. Despite lack of further clinical episodes of malaria, these children had higher asymptomatic parasite densities and higher antibody titres to a panel of P. falciparum blood-stage antigens. Conclusions: This suggests development of clinical immunity rather than lack of exposure to the parasite, and supports the view that this immunity to malaria disease is maintained by a greater exposure to P. falciparum, and thus higher parasite burdens. Our study illustrates the complexity of anti-malaria immunity and underscores the need for analyses which can sufficiently reflect the heterogeneity within endemic populations.
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Affiliation(s)
- John W.G. Addy
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
| | - Yaw Bediako
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | | | - John Joseph Valetta
- School of Mathematics and Statistics, University of St Andrews, St Andrews, UK
| | - Adam J. Reid
- Parasite Genomics, Wellcome Sanger Institute, Hixton, UK
| | | | | | - Joshua Wambua
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Edward Otieno
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Khadija Said
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Philip Bejon
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mario Recker
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, UK
| | - Jean Langhorne
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
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14
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Muthui MK, Takashima E, Omondi BR, Kinya C, Muasya WI, Nagaoka H, Mwai KW, Orindi B, Wambua J, Bousema T, Drakeley C, Blagborough AM, Marsh K, Bejon P, Kapulu MC. Characterization of Naturally Acquired Immunity to a Panel of Antigens Expressed in Mature P. falciparum Gametocytes. Front Cell Infect Microbiol 2021; 11:774537. [PMID: 34869075 PMCID: PMC8633105 DOI: 10.3389/fcimb.2021.774537] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Introduction Naturally acquired immune responses against antigens expressed on the surface of mature gametocytes develop in individuals living in malaria-endemic areas. Evidence suggests that such anti-gametocyte immunity can block the development of the parasite in the mosquito, thus playing a role in interrupting transmission. A better comprehension of naturally acquired immunity to these gametocyte antigens can aid the development of transmission-blocking vaccines and improve our understanding of the human infectious reservoir. Methods Antigens expressed on the surface of mature gametocytes that had not previously been widely studied for evidence of naturally acquired immunity were identified for protein expression alongside Pfs230-C using either the mammalian HEK293E or the wheat germ cell-free expression systems. Where there was sequence variation in the candidate antigens (3D7 vs a clinical isolate PfKE04), both variants were expressed. ELISA was used to assess antibody responses against these antigens, as well as against crude stage V gametocyte extract (GE) and AMA1 using archived plasma samples from individuals recruited to participate in malaria cohort studies. We analyzed antibody levels (estimated from optical density units using a standardized ELISA) and seroprevalence (defined as antibody levels greater than three standard deviations above the mean levels of a pool of malaria naïve sera). We described the dynamics of antibody responses to these antigens by identifying factors predictive of antibody levels using linear regression models. Results Of the 25 antigens selected, seven antigens were produced successfully as recombinant proteins, with one variant antigen, giving a total of eight proteins for evaluation. Antibodies to the candidate antigens were detectable in the study population (N = 216), with seroprevalence ranging from 37.0% (95% CI: 30.6%, 43.9%) for PSOP1 to 77.8% (95% CI: 71.6%, 83.1%) for G377 (3D7 variant). Responses to AMA1 and GE were more prevalent than those to the gametocyte proteins at 87.9% (95% CI: 82.8%, 91.9%) and 88.3% (95% CI: 83.1%, 92.4%), respectively. Additionally, both antibody levels and breadth of antibody responses were associated with age and concurrent parasitaemia. Conclusion Age and concurrent parasitaemia remain important determinants of naturally acquired immunity to gametocyte antigens. Furthermore, we identify novel candidates for transmission-blocking activity evaluation.
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Affiliation(s)
- Michelle K Muthui
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Eizo Takashima
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Brian R Omondi
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Christine Kinya
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - William I Muasya
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Hikaru Nagaoka
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Kennedy W Mwai
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Benedict Orindi
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Juliana Wambua
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Andrew M Blagborough
- Division of Microbiology and Parasitology, Department of Pathology, Cambridge University, Tennis Court Road, Cambridge, United Kingdom
| | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Philip Bejon
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Melissa C Kapulu
- Department of Biosciences, Kenya Medical Research Institute (KEMRI)-Wellcome Trust Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
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15
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Addy JW, Bediako Y, Ndungu FM, Valetta JJ, Reid AJ, Mwacharo J, Ngoi JM, Wambua J, Otieno E, Musyoki J, Said K, Berriman M, Marsh K, Bejon P, Recker M, Langhorne J. 10-year longitudinal study of malaria in children: Insights into acquisition and maintenance of naturally acquired immunity. Wellcome Open Res 2021; 6:79. [PMID: 35141425 PMCID: PMC8822141 DOI: 10.12688/wellcomeopenres.16562.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2021] [Indexed: 01/26/2023] Open
Abstract
Background: Studies of long-term malaria cohorts have provided essential insights into how Plasmodium falciparum interacts with humans, and influences the development of antimalarial immunity. Immunity to malaria is acquired gradually after multiple infections, some of which present with clinical symptoms. However, there is considerable variation in the number of clinical episodes experienced by children of the same age within the same cohort. Understanding this variation in clinical symptoms and how it relates to the development of naturally acquired immunity is crucial in identifying how and when some children stop experiencing further malaria episodes. Where variability in clinical episodes may result from different rates of acquisition of immunity, or from variable exposure to the parasite. Methods: Using data from a longitudinal cohort of children residing in an area of moderate P. falciparum transmission in Kilifi district, Kenya, we fitted cumulative episode curves as monotonic-increasing splines, to 56 children under surveillance for malaria from the age of 5 to 15. Results: There was large variability in the accumulation of numbers of clinical malaria episodes experienced by the children, despite being of similar age and living in the same general location. One group of children from a particular sub-region of the cohort stopped accumulating clinical malaria episodes earlier than other children in the study. Despite lack of further clinical episodes of malaria, these children had higher asymptomatic parasite densities and higher antibody titres to a panel of P. falciparum blood-stage antigens. Conclusions: This suggests development of clinical immunity rather than lack of exposure to the parasite, and supports the view that this immunity to malaria disease is maintained by a greater exposure to P. falciparum, and thus higher parasite burdens. Our study illustrates the complexity of anti-malaria immunity and underscores the need for analyses which can sufficiently reflect the heterogeneity within endemic populations.
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Affiliation(s)
- John W.G. Addy
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
| | - Yaw Bediako
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | | | - John Joseph Valetta
- School of Mathematics and Statistics, University of St Andrews, St Andrews, UK
| | - Adam J. Reid
- Parasite Genomics, Wellcome Sanger Institute, Hixton, UK
| | | | | | - Joshua Wambua
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Edward Otieno
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Khadija Said
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Philip Bejon
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mario Recker
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, UK
| | - Jean Langhorne
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
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16
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Kapulu MC, Njuguna P, Hamaluba M, Kimani D, Ngoi JM, Musembi J, Ngoto O, Otieno E, Billingsley PF. Safety and PCR monitoring in 161 semi-immune Kenyan adults following controlled human malaria infection. JCI Insight 2021; 6:e146443. [PMID: 34264864 PMCID: PMC8492329 DOI: 10.1172/jci.insight.146443] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 07/14/2021] [Indexed: 11/26/2022] Open
Abstract
BACKGROUNDNaturally acquired immunity to malaria is incompletely understood. We used controlled human malaria infection (CHMI) to study the impact of past exposure on malaria in Kenyan adults in relation to infection with a non-Kenyan parasite strain.METHODSWe administered 3.2 × 103 aseptic, purified, cryopreserved Plasmodium falciparum sporozoites (Sanaria PfSPZ Challenge, NF54 West African strain) by direct venous inoculation and undertook clinical monitoring and serial quantitative PCR (qPCR) of the 18S ribosomal RNA gene. The study endpoint was met when parasitemia reached 500 or more parasites per μL blood, clinically important symptoms were seen, or at 21 days after inoculation. All volunteers received antimalarial drug treatment upon meeting the endpoint.RESULTSOne hundred and sixty-one volunteers underwent CHMI between August 4, 2016, and February 14, 2018. CHMI was well tolerated, with no severe or serious adverse events. Nineteen volunteers (11.8%) were excluded from the analysis based on detection of antimalarial drugs above the minimal inhibitory concentration or parasites genotyped as non-NF54. Of the 142 volunteers who were eligible for analysis, 26 (18.3%) had febrile symptoms and were treated; 30 (21.1%) reached 500 or more parasites per μL and were treated; 53 (37.3%) had parasitemia without meeting thresholds for treatment; and 33 (23.2%) remained qPCR negative.CONCLUSIONWe found that past exposure to malaria, as evidenced by location of residence, in some Kenyan adults can completely suppress in vivo growth of a parasite strain originating from outside Kenya.TRIAL REGISTRATIONClinicalTrials.gov NCT02739763.FUNDINGWellcome Trust.
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Affiliation(s)
- Melissa C. Kapulu
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - 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
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom
| | - Domtila Kimani
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Joyce M. Ngoi
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Janet Musembi
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Omar Ngoto
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Edward Otieno
- Centre for Geographic Medicine Research, Coast, Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
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17
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Peterson I, Kapito-Tembo A, Bauleni A, Nyirenda O, Pensulo P, Still W, Valim C, Cohee L, Taylor T, Mathanga DP, Laufer M. Overdiagnosis of Malaria Illness in an Endemic Setting: A Facility-Based Surveillance Study in Malawi. Am J Trop Med Hyg 2021; 104:2123-2130. [PMID: 33939628 DOI: 10.4269/ajtmh.20-1209] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 03/03/2021] [Indexed: 11/07/2022] Open
Abstract
In endemic settings where asymptomatic malaria infections are common, malaria infection can complicate fever diagnosis. Factors influencing fever misdiagnosis, including accuracy of malaria rapid diagnostic tests (mRDTs) and the malaria-attributable fraction of fevers (MAF), require further investigation. We conducted facility-based surveillance in Malawi, from January 2012 through December 2013 in settings of high perennial (Chikhwawa), high seasonal (Thoylo), and moderate seasonal (Ndirande) malaria transmission. Consecutive patients presenting to outpatient departments were screened; those with suspected malaria illness were tested by mRDT or routine thick-smear microscopy. Test positivity rates (TPRs), positive predictive value (PPVs) of mRDTs, and MAFs were calculated by site, age, and season. Of 41,471 patients, 10,052 (24.2%) tested positive for malaria. The TPR was significantly greater in Chikhwawa (29.9%; 95% CI, 28.6-30.0) compared with Thyolo (13.2%; 95% CI, 12.5-13.7) and Ndirande (13.1%; 95% CI, 12.2-14.4). The overall PPV was 77.8% (95% CI, 76.8-78.7); it was lowest among infants (69.9%; 95% CI, 65.5-74.2) and highest among school-age children (81.9%; 95% CI, 80.3-83.4). Malaria infection accounted for about 50% of fevers in children younger than 5 years old with microscopy-confirmed Plasmodium falciparum infection, and less than 20% of such fevers in school-age children. Outpatient settings in Malawi had a high burden of malaria illness, but also possible overdiagnosis of malaria illness. Interventions to reduce malaria transmission and rapid testing for other common febrile illness may improve diagnostic clarity among outpatients in malaria endemic settings.
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Affiliation(s)
- Ingrid Peterson
- 1Center for Vaccine Development and Global Health, University of Maryland Baltimore, Baltimore, Maryland.,2Blantyre Malaria Project, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Atupele Kapito-Tembo
- 3Malaria Alert Center, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Andrew Bauleni
- 3Malaria Alert Center, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Osward Nyirenda
- 2Blantyre Malaria Project, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Paul Pensulo
- 2Blantyre Malaria Project, College of Medicine, University of Malawi, Blantyre, Malawi
| | - William Still
- 1Center for Vaccine Development and Global Health, University of Maryland Baltimore, Baltimore, Maryland
| | - Clarissa Valim
- 4Department of Global Health, Boston University School of Public Health, Boston, Massachusetts
| | - Lauren Cohee
- 1Center for Vaccine Development and Global Health, University of Maryland Baltimore, Baltimore, Maryland
| | - Terrie Taylor
- 5Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, Michigan
| | - Don P Mathanga
- 3Malaria Alert Center, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Miriam Laufer
- 1Center for Vaccine Development and Global Health, University of Maryland Baltimore, Baltimore, Maryland
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18
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Addy JW, Bediako Y, Ndungu FM, Valetta JJ, Reid AJ, Mwacharo J, Ngoi JM, Wambua J, Otieno E, Musyoki J, Said K, Berriman M, Marsh K, Bejon P, Recker M, Langhorne J. 10-year longitudinal study of malaria in children: Insights into acquisition and maintenance of naturally acquired immunity. Wellcome Open Res 2021; 6:79. [PMID: 35141425 PMCID: PMC8822141 DOI: 10.12688/wellcomeopenres.16562.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2021] [Indexed: 01/26/2023] Open
Abstract
Background: Studies of long-term malaria cohorts have provided essential insights into how Plasmodium falciparum interacts with humans, and influences the development of antimalarial immunity. Immunity to malaria is acquired gradually after multiple infections, some of which present with clinical symptoms. However, there is considerable variation in the number of clinical episodes experienced by children of the same age within the same cohort. Understanding this variation in clinical symptoms and how it relates to the development of naturally acquired immunity is crucial in identifying how and when some children stop experiencing further malaria episodes. Where variability in clinical episodes may result from different rates of acquisition of immunity, or from variable exposure to the parasite. Methods: Using data from a longitudinal cohort of children residing in an area of moderate P. falciparum transmission in Kilifi district, Kenya, we fitted cumulative episode curves as monotonic-increasing splines, to 56 children under surveillance for malaria from the age of 5 to 15. Results: There was large variability in the accumulation of numbers of clinical malaria episodes experienced by the children, despite being of similar age and living in the same general location. One group of children from a particular sub-region of the cohort stopped accumulating clinical malaria episodes earlier than other children in the study. Despite lack of further clinical episodes of malaria, these children had higher asymptomatic parasite densities and higher antibody titres to a panel of P. falciparum blood-stage antigens. Conclusions: This suggests development of clinical immunity rather than lack of exposure to the parasite, and supports the view that this immunity to malaria disease is maintained by a greater exposure to P. falciparum, and thus higher parasite burdens. Our study illustrates the complexity of anti-malaria immunity and underscores the need for analyses which can sufficiently reflect the heterogeneity within endemic populations.
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Affiliation(s)
- John W.G. Addy
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
| | - Yaw Bediako
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
- West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | | | - John Joseph Valetta
- School of Mathematics and Statistics, University of St Andrews, St Andrews, UK
| | - Adam J. Reid
- Parasite Genomics, Wellcome Sanger Institute, Hixton, UK
| | | | | | - Joshua Wambua
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Edward Otieno
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Khadija Said
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Kevin Marsh
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Philip Bejon
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mario Recker
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, UK
| | - Jean Langhorne
- Malaria Immunology Laboratory, Francis Crick Institute, London, UK
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19
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Omondi BR, Muthui MK, Muasya WI, Orindi B, Mwakubambanya RS, Bousema T, Drakeley C, Marsh K, Bejon P, Kapulu MC. Antibody Responses to Crude Gametocyte Extract Predict Plasmodium falciparum Gametocyte Carriage in Kenya. Front Immunol 2021; 11:609474. [PMID: 33633729 PMCID: PMC7902058 DOI: 10.3389/fimmu.2020.609474] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 12/17/2020] [Indexed: 11/18/2022] Open
Abstract
Background Malaria caused by Plasmodium falciparum remains a serious global public health challenge especially in Africa. Interventions that aim to reduce malaria transmission by targeting the gametocyte reservoir are key to malaria elimination and/or eradication. However, factors that are associated with gametocyte carriage have not been fully explored. Consequently, identifying predictors of the infectious reservoir is fundamental in the elimination campaign. Methods We cultured P. falciparum NF54 gametocytes (to stage V) and prepared crude gametocyte extract. Samples from a total of 687 participants (aged 6 months to 67 years) representing two cross-sectional study cohorts in Kilifi, Kenya were used to assess IgG antibody responses by ELISA. We also analyzed IgG antibody responses to the blood-stage antigen AMA1 as a marker of asexual parasite exposure. Gametocytemia and asexual parasitemia data quantified by microscopy and molecular detection (QT-NASBA) were used to determine the relationship with antibody responses, season, age, and transmission setting. Multivariable logistic regression models were used to study the association between antibody responses and gametocyte carriage. The predictive power of the models was tested using the receiver operating characteristic (ROC) curve. Results Multivariable logistic regression analysis showed that IgG antibody response to crude gametocyte extract predicted both microscopic (OR=1.81 95% CI: 1.06-3.07, p=0.028) and molecular (OR=1.91, 95% CI: 1.11-3.29, p=0.019) P. falciparum gametocyte carriage. Antibody responses to AMA1 were also associated with both microscopic (OR=1.61 95% CI: 1.08-2.42, p=0.020) and molecular (OR=3.73 95% CI: 2.03-6.74, p<0.001) gametocytemia. ROC analysis showed that molecular (AUC=0.897, 95% CI: 0.868-0.926) and microscopic (AUC=0.812, 95% CI: 0.758-0.865) multivariable models adjusted for gametocyte extract showed very high predictive power. Molecular (AUC=0.917, 95% CI: 0.891-0.943) and microscopic (AUC=0.806, 95% CI: 0.755-0.858) multivariable models adjusted for AMA1 were equally highly predictive. Conclusion In our study, it appears that IgG responses to crude gametocyte extract are not an independent predictor of gametocyte carriage after adjusting for AMA1 responses but may predict gametocyte carriage as a proxy marker of exposure to parasites. Serological responses to AMA1 or to gametocyte extract may facilitate identification of individuals within populations who contribute to malaria transmission and support implementation of transmission-blocking interventions.
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Affiliation(s)
- Brian R. Omondi
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biochemistry and Molecular Biology, Egerton University, Nakuru, Kenya
| | - Michelle K. Muthui
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - William I. Muasya
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Benedict Orindi
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Kevin Marsh
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Philip Bejon
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Melissa C. Kapulu
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
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20
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Amboko B, Stepniewska K, Macharia PM, Machini B, Bejon P, Snow RW, Zurovac D. Trends in health workers' compliance with outpatient malaria case-management guidelines across malaria epidemiological zones in Kenya, 2010-2016. Malar J 2020; 19:406. [PMID: 33176783 PMCID: PMC7659071 DOI: 10.1186/s12936-020-03479-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 11/02/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Health workers' compliance with outpatient malaria case-management guidelines has been improving, specifically regarding the universal testing of suspected cases and the use of artemisinin-based combination therapy (ACT) only for positive results (i.e., 'test and treat'). Whether the improvements in compliance with 'test and treat' guidelines are consistent across different malaria endemicity areas has not been examined. METHODS Data from 11 national, cross-sectional, outpatient malaria case-management surveys undertaken in Kenya from 2010 to 2016 were analysed. Four primary indicators (i.e., 'test and treat') and eight secondary indicators of artemether-lumefantrine (AL) dosing, dispensing, and counselling were measured. Mixed logistic regression models were used to analyse the annual trends in compliance with the indicators across the different malaria endemicity areas (i.e., from highest to lowest risk being lake endemic, coast endemic, highland epidemic, semi-arid seasonal transmission, and low risk). RESULTS Compliance with all four 'test and treat' indicators significantly increased in the area with the highest malaria risk (i.e., lake endemic) as follows: testing of febrile patients (OR = 1.71 annually; 95% CI = 1.51-1.93), AL treatment for test-positive patients (OR = 1.56; 95% CI = 1.26-1.92), no anti-malarial for test-negative patients (OR = 2.04; 95% CI = 1.65-2.54), and composite 'test and treat' compliance (OR = 1.80; 95% CI = 1.61-2.01). In the low risk areas, only compliance with test-negative results significantly increased (OR = 2.27; 95% CI = 1.61-3.19) while testing of febrile patients showed declining trends (OR = 0.89; 95% CI = 0.79-1.01). Administration of the first AL dose at the facility significantly increased in the areas of lake endemic (OR = 2.33; 95% CI = 1.76-3.10), coast endemic (OR = 5.02; 95% CI = 2.77-9.09) and semi-arid seasonal transmission (OR = 1.44; 95% CI = 1.02-2.04). In areas of the lowest risk of transmission and highland epidemic zone, none of the AL dosing, dispensing, and counselling tasks significantly changed over time. CONCLUSIONS There is variability in health workers' compliance with outpatient malaria case-management guidelines across different malaria-risk areas in Kenya. Major improvements in areas of the highest risk have not been seen in low-risk areas. Interventions to improve practices should be targeted geographically.
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Affiliation(s)
- Beatrice Amboko
- KEMRI-Wellcome Trust Research Programme, P.O. Box 43640-00100, Nairobi, Kenya.
| | - Kasia Stepniewska
- WorldWide Antimalarial Resistance Network, Oxford, UK
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Peter M Macharia
- KEMRI-Wellcome Trust Research Programme, P.O. Box 43640-00100, Nairobi, Kenya
| | - Beatrice Machini
- Division of National Malaria Programme, Ministry of Health, Nairobi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, P.O. Box 43640-00100, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Robert W Snow
- KEMRI-Wellcome Trust Research Programme, P.O. Box 43640-00100, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Dejan Zurovac
- KEMRI-Wellcome Trust Research Programme, P.O. Box 43640-00100, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
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21
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Campbell C, O’Sullivan TD. Quantitative diffuse optical spectroscopy for noninvasive measurements of the malaria pigment hemozoin. BIOMEDICAL OPTICS EXPRESS 2020; 11:5800-5813. [PMID: 33149987 PMCID: PMC7587291 DOI: 10.1364/boe.401771] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/05/2020] [Accepted: 09/11/2020] [Indexed: 05/15/2023]
Abstract
Hemozoin (Hz) is a crystal by-product of hemoglobin consumption by malaria parasites. There are currently no in vivo deep tissue sensing methods that can quantify Hz presence noninvasively, which would be advantageous for malaria research and treatment. In this work, we describe the broadband near-infrared optical characterization of synthetic Hz in static and dynamic tissue-simulating phantoms. Using hybrid frequency domain and continuous-wave near-infrared spectroscopy, we quantified the broadband optical absorption and scattering spectra of Hz and identified the presence of Hz at a minimum tissue-equivalent concentration of 0.014 µg/mL in static lipid emulsion phantoms simulating human adipose. We then constructed a whole blood-containing tissue-simulating phantom and demonstrated the detection of Hz at physiologically-relevant tissue oxygen saturations ranging from 70-90%. Our results suggest that quantitative diffuse optical spectroscopy may be useful for detecting deep tissue Hz in vivo.
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22
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Kamau A, Mtanje G, Mataza C, Mwambingu G, Mturi N, Mohammed S, Ong'ayo G, Nyutu G, Nyaguara A, Bejon P, Snow RW. Malaria infection, disease and mortality among children and adults on the coast of Kenya. Malar J 2020; 19:210. [PMID: 32552891 PMCID: PMC7301992 DOI: 10.1186/s12936-020-03286-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2020] [Accepted: 06/12/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Malaria transmission has recently fallen in many parts of Africa, but systematic descriptions of infection and disease across all age groups are rare. Here, an epidemiological investigation of parasite prevalence, the incidence of fevers associated with infection, severe hospitalized disease and mortality among children older than 6 months and adults on the Kenyan coast is presented. METHODS A prospective fever surveillance was undertaken at 6 out-patients (OPD) health-facilities between March 2018 and February 2019. Four community-based, cross sectional surveys of fever history and infection prevalence were completed among randomly selected homestead members from the same communities. Paediatric and adult malaria at Kilifi county hospital was obtained for the 12 months period. Rapid Diagnostic Tests (CareStart™ RDT) to detect HRP2-specific to Plasmodium falciparum was used in the community and the OPD, and microscopy in the hospital. Crude and age-specific incidence rates were computed using Poisson regression. RESULTS Parasite prevalence gradually increased from childhood, reaching 12% by 9 years of age then declining through adolescence into adulthood. The incidence rate of RDT positivity in the OPD followed a similar trend to that of infection prevalence in the community. The incidence of hospitalized malaria from the same community was concentrated among children aged 6 months to 4 years (i.e. 64% and 70% of all hospitalized and severe malaria during the 12 months of surveillance, respectively). Only 3.7% (12/316) of deaths were directly attributable to malaria. Malaria mortality was highest among children aged 6 months-4 years at 0.57 per 1000 person-years (95% CI 0.2, 1.2). Severe malaria and death from malaria was negligible above 15 years of age. CONCLUSION Under conditions of low transmission intensity, immunity to disease and the fatal consequences of infection appear to continue to be acquired in childhood and faster than anti-parasitic immunity. There was no evidence of an emerging significant burden of severe malaria or malaria mortality among adults. This is contrary to current modelled approaches to disease burden estimation in Africa and has important implications for the targeting of infection prevention strategies based on chemoprevention or vector control.
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Affiliation(s)
- Alice Kamau
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
| | - Grace Mtanje
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Christine Mataza
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Ministry of Health, Kilifi County Government, Kilifi, Kenya
| | | | - Neema Mturi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Gideon Nyutu
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Amek Nyaguara
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Robert W Snow
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
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23
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Mandal RK, Crane RJ, Berkley JA, Gumbi W, Wambua J, Ngoi JM, Ndungu FM, Schmidt NW. Longitudinal Analysis of Infant Stool Bacteria Communities Before and After Acute Febrile Malaria and Artemether-Lumefantrine Treatment. J Infect Dis 2020; 220:687-698. [PMID: 30590681 PMCID: PMC6639600 DOI: 10.1093/infdis/jiy740] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 12/22/2018] [Indexed: 12/24/2022] Open
Abstract
Background Gut microbiota were recently shown to impact malaria disease progression and outcome, and prior studies have shown that Plasmodium infections increase the likelihood of enteric bacteria causing systemic infections. Currently, it is not known whether Plasmodium infection impacts human gut microbiota as a prelude to bacteremia or whether antimalarials affect gut microbiota. Our goal was to determine to what degree Plasmodium infections and antimalarial treatment affect human gut microbiota. Methods One hundred Kenyan infants underwent active surveillance for malaria from birth to 10 months of age. Each malaria episode was treated with artemether-lumefantrine (AL). Any other treatments, including antibiotics, were recorded. Stool samples were collected on an approximately biweekly basis. Ten children were selected on the basis of stool samples having been collected before (n = 27) or after (n = 17) a malaria episode and without antibiotics having been administered between collections. These samples were subjected to 16S ribosomal ribonucleic acid gene (V3–V4 region) sequencing. Results Bacterial community network analysis revealed no obvious differences in the before and after malaria/AL samples, which was consistent with no difference in alpha and beta diversity and taxonomic analysis at the family and genus level with one exception. At the sequence variant (SV) level, akin to bacterial species, only 1 of the top 100 SVs was significantly different. In addition, predicted metagenome analysis revealed no significant difference in metagenomic capacity between before and after malaria/AL samples. The number of malaria episodes, 1 versus 2, explained significant variation in gut microbiota composition of the infants. Conclusions In-depth bioinformatics analysis of stool bacteria has revealed for the first time that human malaria episode/AL treatment have minimal effects on gut microbiota in Kenyan infants.
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Affiliation(s)
- Rabindra K Mandal
- Department of Microbiology and Immunology, University of Louisville, Kentucky
| | - Rosie J Crane
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, United Kingdom
| | - James A Berkley
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, United Kingdom
| | - Wilson Gumbi
- KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | - Nathan W Schmidt
- Department of Microbiology and Immunology, University of Louisville, Kentucky
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24
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Aniweh Y, Nyarko PB, Charles-Chess E, Ansah F, Osier FHA, Quansah E, Thiam LG, Kamuyu G, Marsh K, Conway DJ, Tetteh KKA, Awandare GA. Plasmodium falciparum Merozoite Associated Armadillo Protein (PfMAAP) Is Apically Localized in Free Merozoites and Antibodies Are Associated With Reduced Risk of Malaria. Front Immunol 2020; 11:505. [PMID: 32318061 PMCID: PMC7155890 DOI: 10.3389/fimmu.2020.00505] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 03/05/2020] [Indexed: 11/19/2022] Open
Abstract
Understanding the functional role of proteins expressed by Plasmodium falciparum is an important step toward unlocking potential targets for the development of therapeutic or diagnostic interventions. The armadillo (ARM) repeat protein superfamily is associated with varied functions across the eukaryotes. Therefore, it is important to understand the role of members of this protein family in Plasmodium biology. The Plasmodium falciparum armadillo repeats only (PfARO; Pf3D7_0414900) and P. falciparum merozoite organizing proteins (PfMOP; Pf3D7_0917000) are armadillo-repeat containing proteins previously characterized in P. falciparum. Here, we describe the characterization of another ARM repeat-containing protein in P. falciparum, which we have named the P. falciparum Merozoites-Associated Armadillo repeats protein (PfMAAP). Antibodies raised to three different synthetic peptides of PfMAAP show apical staining of free merozoites and those within the mature infected schizont. We also demonstrate that the antibodies raised to the PfMAAP peptides inhibited invasion of erythrocytes by merozoites from different parasite isolates. In addition, naturally acquired human antibodies to the N- and C- termini of PfMAAP are associated with a reduced risk of malaria in a prospective cohort analysis.
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Affiliation(s)
- Yaw Aniweh
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
| | - Prince B. Nyarko
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Essel Charles-Chess
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Felix Ansah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Faith H. A. Osier
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
- Centre for Infectious Diseases, Parasitology, Heidelberg University Hospital, Heidelberg, Germany
- Department of Biochemistry, Pwani University, Kilifi, Kenya
- Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
| | - Evelyn Quansah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Laty Gaye Thiam
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
| | - Gathoni Kamuyu
- Division of Medicine, Department of Respiratory Medicine, UCL, London, United Kingdom
| | - Kevin Marsh
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
- Nuffield Department of Clinical Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, United Kingdom
- Division of Infectious Diseases, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden
| | - David J. Conway
- Department of Infection Biology, London School of Tropical Medicine and Hygiene, London, United Kingdom
| | - Kevin K. A. Tetteh
- Department of Infection Biology, London School of Tropical Medicine and Hygiene, London, United Kingdom
| | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
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25
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Wamae K, Wambua J, Nyangweso G, Mwambingu G, Osier F, Ndung'u F, Bejon P, Ochola-Oyier LI. Transmission and Age Impact the Risk of Developing Febrile Malaria in Children with Asymptomatic Plasmodium falciparum Parasitemia. J Infect Dis 2020; 219:936-944. [PMID: 30307567 PMCID: PMC6386809 DOI: 10.1093/infdis/jiy591] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 10/10/2018] [Indexed: 11/13/2022] Open
Abstract
Background Plasmodium falciparum infections lead to febrile illness unless the host has sufficient immunity, in which case infection may cause no immediate symptoms (ie, “asymptomatic parasitemia”). Previous studies are conflicting on the role of asymptomatic parasitemia in determining the risk of developing febrile malaria. Methods We monitored 2513 children (living in Kilifi, Kenyan Coast) by blood smears in 17 cross-sectional surveys to identify asymptomatic parasitemia and used active surveillance over 11325 child-years of follow-up to detect febrile malaria. We evaluated the interaction between transmission intensity, age, and asymptomatic parasitemia in determining the risk of developing febrile malaria. Results In the moderate and high transmission intensity settings, asymptomatic parasitemia was associated with a reduced risk of febrile malaria in older children (> 3 years), while in the lower transmission setting, asymptomatic parasitemia was associated with an increased risk of febrile malaria in children of all ages. Additionally, the risk associated with asymptomatic parasitemia was limited to the first 90 days of follow-up. Conclusions Asymptomatic parasitemia is modified by transmission intensity and age, altering the risk of developing febrile episodes and suggesting that host immunity plays a prominent role in mediating this process.
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Affiliation(s)
- Kevin Wamae
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - Juliana Wambua
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - George Nyangweso
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - Gabriel Mwambingu
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - Faith Osier
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya
| | - Francis Ndung'u
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya.,Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, United Kingdom
| | - Philip Bejon
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya.,Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, University of Oxford, United Kingdom
| | - Lynette Isabella Ochola-Oyier
- Kenya Medical Research Institute Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Biotechnology and Bioinformatics, University of Nairobi, Kenya
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26
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Kapulu MC, Njuguna P, Hamaluba MM. Controlled Human Malaria Infection in Semi-Immune Kenyan Adults (CHMI-SIKA): a study protocol to investigate in vivo Plasmodium falciparum malaria parasite growth in the context of pre-existing immunity. Wellcome Open Res 2019; 3:155. [PMID: 31803847 PMCID: PMC6871356 DOI: 10.12688/wellcomeopenres.14909.2] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2019] [Indexed: 01/09/2023] Open
Abstract
Malaria remains a major public health burden despite approval for implementation of a partially effective pre-erythrocytic malaria vaccine. There is an urgent need to accelerate development of a more effective multi-stage vaccine. Adults in malaria endemic areas may have substantial immunity provided by responses to the blood stages of malaria parasites, but field trials conducted on several blood-stage vaccines have not shown high levels of efficacy. We will use the controlled human malaria infection (CHMI) models with malaria-exposed volunteers to identify correlations between immune responses and parasite growth rates in vivo. Immune responses more strongly associated with control of parasite growth should be prioritized to accelerate malaria vaccine development. We aim to recruit up to 200 healthy adult volunteers from areas of differing malaria transmission in Kenya, and after confirming their health status through clinical examination and routine haematology and biochemistry, we will comprehensively characterize immunity to malaria using >100 blood-stage antigens. We will administer 3,200 aseptic, purified, cryopreserved Plasmodium falciparum sporozoites (PfSPZ Challenge) by direct venous inoculation. Serial quantitative polymerase chain reaction to measure parasite growth rate in vivo will be undertaken. Clinical and laboratory monitoring will be undertaken to ensure volunteer safety. In addition, we will also explore the perceptions and experiences of volunteers and other stakeholders in participating in a malaria volunteer infection study. Serum, plasma, peripheral blood mononuclear cells and whole blood will be stored to allow a comprehensive assessment of adaptive and innate host immunity. We will use CHMI in semi-immune adult volunteers to relate parasite growth outcomes with antibody responses and other markers of host immunity. Registration: ClinicalTrials.gov identifier NCT02739763.
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Affiliation(s)
- Melissa C. Kapulu
- KEMRI-Wellcome Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University Oxford, Oxford, UK
| | | | | | - CHMI-SIKA Study Team
- KEMRI-Wellcome Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University Oxford, Oxford, UK
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27
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Greenhouse B, Smith DL, Rodríguez-Barraquer I, Mueller I, Drakeley CJ. Taking Sharper Pictures of Malaria with CAMERAs: Combined Antibodies to Measure Exposure Recency Assays. Am J Trop Med Hyg 2019; 99:1120-1127. [PMID: 30298804 PMCID: PMC6221205 DOI: 10.4269/ajtmh.18-0303] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Antibodies directed against malaria parasites are easy and inexpensive to measure but remain an underused surveillance tool because of a lack of consensus on what to measure and how to interpret results. High-throughput screening of antibodies from well-characterized cohorts offers a means to substantially improve existing assays by rationally choosing the most informative sets of responses and analytical methods. Recent data suggest that high-resolution information on malaria exposure can be obtained from a small number of samples by measuring a handful of properly chosen antibody responses. In this review, we discuss how standardized multi-antibody assays can be developed and efficiently integrated into existing surveillance activities, with potential to greatly augment the breadth and quality of information available to direct and monitor malaria control and elimination efforts.
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Affiliation(s)
- Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, California.,Chan Zuckerberg Biohub, San Francisco, California
| | - David L Smith
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, Washington
| | | | - Ivo Mueller
- Institute Pasteur, Paris, France.,Walter and Eliza Hall Institute of Medical Research, Parkville, Australia
| | - Chris J Drakeley
- London School of Hygiene & Tropical Medicine, London, United Kingdom
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28
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Muriuki JM, Mentzer AJ, Band G, Gilchrist JJ, Carstensen T, Lule SA, Goheen MM, Joof F, Kimita W, Mogire R, Cutland CL, Diarra A, Rautanen A, Pomilla C, Gurdasani D, Rockett K, Mturi N, Ndungu FM, Scott JAG, Sirima SB, Morovat A, Prentice AM, Madhi SA, Webb EL, Elliott AM, Bejon P, Sandhu MS, Hill AVS, Kwiatkowski DP, Williams TN, Cerami C, Atkinson SH. The ferroportin Q248H mutation protects from anemia, but not malaria or bacteremia. SCIENCE ADVANCES 2019; 5:eaaw0109. [PMID: 31517041 PMCID: PMC6726445 DOI: 10.1126/sciadv.aaw0109] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 08/06/2019] [Indexed: 06/10/2023]
Abstract
Iron acquisition is critical for life. Ferroportin (FPN) exports iron from mature erythrocytes, and deletion of the Fpn gene results in hemolytic anemia and increased fatality in malaria-infected mice. The FPN Q248H mutation (glutamine to histidine at position 248) renders FPN partially resistant to hepcidin-induced degradation and was associated with protection from malaria in human studies of limited size. Using data from cohorts including over 18,000 African children, we show that the Q248H mutation is associated with modest protection against anemia, hemolysis, and iron deficiency, but we found little evidence of protection against severe malaria or bacteremia. We additionally observed no excess Plasmodium growth in Q248H erythrocytes ex vivo, nor evidence of selection driven by malaria exposure, suggesting that the Q248H mutation does not protect from malaria and is unlikely to deprive malaria parasites of iron essential for their growth.
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Affiliation(s)
- John Muthii Muriuki
- Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - Alexander J. Mentzer
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Gavin Band
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - James J. Gilchrist
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Department of Paediatrics, University of Oxford, Oxford, UK
| | | | - Swaib A. Lule
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene and Tropical Medicine, London, UK
| | - Morgan M. Goheen
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
- University of North Carolina School of Medicine, CB 7435, Chapel Hill, North Carolina USA
| | - Fatou Joof
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Wandia Kimita
- Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - Reagan Mogire
- Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - Clare L. Cutland
- Medical Research Council: Respiratory and Meningeal Pathogens Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Amidou Diarra
- Centre de Recherche Action en Sante (GRAS), 06 BP 10248, Ouagadougou 06, Burkina Faso
| | - Anna Rautanen
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | | | | | - Kirk Rockett
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Neema Mturi
- Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - Francis M. Ndungu
- Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
| | - J. Anthony G. Scott
- Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
- London School of Hygiene and Tropical Medicine, London, UK
| | - Sodiomon B. Sirima
- Centre de Recherche Action en Sante (GRAS), 06 BP 10248, Ouagadougou 06, Burkina Faso
| | - Alireza Morovat
- Department of Clinical Biochemistry, Oxford University Hospitals, Oxford, UK
| | - Andrew M. Prentice
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Shabir A. Madhi
- Medical Research Council: Respiratory and Meningeal Pathogens Research Unit, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Emily L. Webb
- London School of Hygiene and Tropical Medicine, London, UK
| | - Alison M. Elliott
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe, Uganda
- London School of Hygiene and Tropical Medicine, London, UK
| | - Philip Bejon
- Kenya Medical Research Institute (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
| | - Dominic P. Kwiatkowski
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Wellcome Sanger Institute, Hinxton, Cambridge, UK
| | - Thomas N. Williams
- Kenya Medical Research Institute (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 Medicine, Imperial College, London, UK
| | - Carla Cerami
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Sarah H. Atkinson
- Kenya Medical Research Institute (KEMRI) Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Paediatrics, University of Oxford, Oxford, UK
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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29
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Dollat M, Talla C, Sokhna C, Diene Sarr F, Trape JF, Richard V. Measuring malaria morbidity in an area of seasonal transmission: Pyrogenic parasitemia thresholds based on a 20-year follow-up study. PLoS One 2019; 14:e0217903. [PMID: 31246965 PMCID: PMC6597048 DOI: 10.1371/journal.pone.0217903] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2018] [Accepted: 05/22/2019] [Indexed: 01/12/2023] Open
Abstract
Introduction Asymptomatic carriage of P. falciparum is frequent in areas endemic for malaria and individual diagnosis of clinical malaria attacks is still difficult. We investigated the impact of changes in malaria endemicity on the diagnostic criteria for malaria attacks in an area of seasonal malaria transmission. Methods We analyzed the longitudinal data collected over 20 years from a daily survey of all inhabitants of Ndiop, a rural community in central Senegal, in a logistic regression model to investigate the relationship between the level of Plasmodium falciparum parasitemia and the risk of fever, with the aim of determining the best parasitemia thresholds for attributing to malaria a fever episode. Results A total of 34,136 observations recorded from July 1993 to December 2013 from 850 individuals aged from 1 day to 87 years were included. P. falciparum asymptomatic carriage declined from 36% to 1% between 1993 and 2013. A total of 9,819 fever episodes were associated with a positive blood film for P. falciparum. Using age-dependent parasitemia thresholds for attributing to malaria a fever episode, we recorded 6,006 malaria attacks during the study period. Parasitemia thresholds seemed to be lower during the low-to-zero transmission season and tended to decrease with changes in control policies. The number of clinical malaria attacks was overestimated for all age groups throughout the study when all fever episodes associated with P. falciparum parasitemia were defined as malaria attacks. Conclusion Pyrogenic thresholds are particularly sensitive to changes in malaria epidemiology and are therefore an interesting tool to accurately assess the burden of malaria in the context of declining transmission.
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Affiliation(s)
- Marion Dollat
- Unité d'Epidémiologie des Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Sénégal
- Service de Maladies Infectieuses et Tropicales, Hôpital Avicenne, Assistance Publique-Hôpitaux de Paris (AP-HP), Paris, France
- * E-mail:
| | - Cheikh Talla
- Unité d'Epidémiologie des Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Sénégal
| | - Cheikh Sokhna
- Laboratoire de Paludologie, Institut de Recherche pour le Développement, Dakar, Sénégal
| | - Fatoumata Diene Sarr
- Unité d'Epidémiologie des Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Sénégal
| | - Jean-François Trape
- Laboratoire de Paludologie, Institut de Recherche pour le Développement, Dakar, Sénégal
| | - Vincent Richard
- Unité d'Epidémiologie des Maladies Infectieuses, Institut Pasteur de Dakar, Dakar, Sénégal
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30
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Perspectives on Point-of-Care Ultrasound Use in Pediatric Tropical Infectious Disease. CLINICAL PEDIATRIC EMERGENCY MEDICINE 2019. [DOI: 10.1016/j.cpem.2019.06.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Muthui MK, Mogeni P, Mwai K, Nyundo C, Macharia A, Williams TN, Nyangweso G, Wambua J, Mwanga D, Marsh K, Bejon P, Kapulu MC. Gametocyte carriage in an era of changing malaria epidemiology: A 19-year analysis of a malaria longitudinal cohort. Wellcome Open Res 2019; 4:66. [PMID: 31223663 PMCID: PMC6557001 DOI: 10.12688/wellcomeopenres.15186.2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2019] [Indexed: 12/19/2022] Open
Abstract
Background: Interventions to block malaria transmission from humans to mosquitoes are currently in development. To be successfully implemented, key populations need to be identified where the use of these transmission-blocking and/or reducing strategies will have greatest impact. Methods: We used data from a longitudinally monitored cohort of children from Kilifi county located along the Kenyan coast collected between 1998-2016 to describe the distribution and prevalence of gametocytaemia in relation to transmission intensity, time and age. Data from 2,223 children accounting for 9,134 person-years of follow-up assessed during cross-sectional surveys for asexual parasites and gametocytes were used in logistic regression models to identify factors predictive of gametocyte carriage in this cohort. Results: Our analysis showed that children 1-5 years of age were more likely to carry microscopically detectable gametocytes than their older counterparts. Carrying asexual parasites and recent episodes of clinical malaria were also strong predictors of gametocyte carriage. The prevalence of asexual parasites and of gametocyte carriage declined over time, and after 2006, when artemisinin combination therapy (ACT) was introduced, recent episodes of clinical malaria ceased to be a predictor of gametocyte carriage. Conclusions: Gametocyte carriage in children in Kilifi has fallen over time. Previous episodes of clinical malaria may contribute to the development of carriage, but this appears to be mitigated by the use of ACTs highlighting the impact that gametocidal antimalarials can have in reducing the overall prevalence of gametocytaemia when targeted on acute febrile illness.
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Affiliation(s)
- Michelle K Muthui
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Polycarp Mogeni
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya.,African Health Research Institute, Durban, Congella, 4013, Private bag X7, South Africa
| | - Kennedy Mwai
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya.,Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, Parktown, 2193, 27 St Andrews Road, South Africa
| | - Christopher Nyundo
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Alex Macharia
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Thomas N Williams
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya.,Department of Medicine, Imperial College London, St Mary's Campus, London, W21NY, UK
| | - George Nyangweso
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Juliana Wambua
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Daniel Mwanga
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Kevin Marsh
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Philip Bejon
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Melissa C Kapulu
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
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32
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Muthui MK, Mogeni P, Mwai K, Nyundo C, Macharia A, Williams TN, Nyangweso G, Wambua J, Mwanga D, Marsh K, Bejon P, Kapulu MC. Gametocyte carriage in an era of changing malaria epidemiology: A 19-year analysis of a malaria longitudinal cohort. Wellcome Open Res 2019; 4:66. [PMID: 31223663 PMCID: PMC6557001 DOI: 10.12688/wellcomeopenres.15186.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/22/2019] [Indexed: 10/25/2023] Open
Abstract
Background: Interventions to block malaria transmission from humans to mosquitoes are currently in development. To be successfully implemented, key populations need to be identified where the use of these transmission-blocking and/or reducing strategies will have greatest impact. Methods: We used data from a longitudinally monitored cohort of children from Kilifi county located along the Kenyan coast collected between 1998-2016 to describe the distribution and prevalence of gametocytaemia in relation to transmission intensity, time and age. Data from 2,223 children accounting for 9,134 person-years of follow-up assessed during cross-sectional surveys for asexual parasites and gametocytes were used in logistic regression models to identify factors predictive of gametocyte carriage in this cohort. Results: Our analysis showed that children 1-5 years of age were more likely to carry microscopically detectable gametocytes than their older counterparts. Carrying asexual parasites and recent episodes of clinical malaria were also strong predictors of gametocyte carriage. The prevalence of asexual parasites and of gametocyte carriage declined over time, and after 2006, when artemisinin combination therapy (ACT) was introduced, recent episodes of clinical malaria ceased to be a predictor of gametocyte carriage. Conclusions: Gametocyte carriage in children in Kilifi has fallen over time. Previous episodes of clinical malaria may contribute to the development of carriage, but this appears to be mitigated by the use of ACTs highlighting the impact that gametocidal antimalarials can have in reducing the overall prevalence of gametocytaemia when targeted on acute febrile illness.
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Affiliation(s)
- Michelle K. Muthui
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Polycarp Mogeni
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
- African Health Research Institute, Durban, Congella, 4013, Private bag X7, South Africa
| | - Kennedy Mwai
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
- Epidemiology and Biostatistics Division, School of Public Health, University of the Witwatersrand, Johannesburg, Parktown, 2193, 27 St Andrews Road, South Africa
| | - Christopher Nyundo
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Alex Macharia
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Thomas N. Williams
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
- Department of Medicine, Imperial College London, St Mary's Campus, London, W21NY, UK
| | - George Nyangweso
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Juliana Wambua
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Daniel Mwanga
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Kevin Marsh
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Philip Bejon
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Melissa C. Kapulu
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
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Muriuki JM, Mentzer AJ, Kimita W, Ndungu FM, Macharia AW, Webb EL, Lule SA, Morovat A, Hill AVS, Bejon P, Elliott AM, Williams TN, Atkinson SH. Iron Status and Associated Malaria Risk Among African Children. Clin Infect Dis 2019; 68:1807-1814. [PMID: 30219845 PMCID: PMC6522755 DOI: 10.1093/cid/ciy791] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 09/10/2018] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND It remains unclear whether improving iron status increases malaria risk, and few studies have looked at the effect of host iron status on subsequent malaria infection. We therefore aimed to determine whether a child's iron status influences their subsequent risk of malaria infection in sub-Saharan Africa. METHODS We assayed iron and inflammatory biomarkers from community-based cohorts of 1309 Kenyan and 1374 Ugandan children aged 0-7 years and conducted prospective surveillance for episodes of malaria. Poisson regression models were fitted to determine the effect of iron status on the incidence rate ratio (IRR) of malaria using longitudinal data covering a period of 6 months. Models were adjusted for age, sex, parasitemia, inflammation, and study site. RESULTS At baseline, the prevalence of iron deficiency (ID) was 36.9% and 34.6% in Kenyan and Ugandan children, respectively. ID anemia (IDA) affected 23.6% of Kenyan and 17.6% of Ugandan children. Malaria risk was lower in children with ID (IRR, 0.7; 95% confidence interval [CI], 0.6, 0.8; P < .001) and IDA (IRR, 0.7; 95% CI, 0.6, 0.9; P = .006). Low transferrin saturation (<10%) was similarly associated with lower malaria risk (IRR, 0.8; 95% CI, 0.6, 0.9; P = .016). However, variation in hepcidin, soluble transferrin receptors (sTfR), and hemoglobin/anemia was not associated with altered malaria risk. CONCLUSIONS ID appears to protect against malaria infection in African children when defined using ferritin and transferrin saturation, but not when defined by hepcidin, sTfR, or hemoglobin. Additional research is required to determine causality. CLINICAL TRIALS REGISTRATION ISRCTN32849447.
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Affiliation(s)
| | - Alexander J Mentzer
- Wellcome Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford
| | - Wandia Kimita
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Emily L Webb
- London School of Hygiene and Tropical Medicine, United Kingdom
| | - Swaib A Lule
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Alireza Morovat
- Department of Clinical Biochemistry, Oxford University Hospitals
| | - Adrian V S Hill
- Centre for Clinical Vaccinology and Tropical Medicine and the Jenner Institute Laboratories, University of Oxford
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford
| | - Alison M Elliott
- London School of Hygiene and Tropical Medicine, United Kingdom
- Medical Research Council/Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Medicine, Imperial College, London
| | - Sarah H Atkinson
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford
- Department of Paediatrics, University of Oxford, United Kingdom
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34
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Bediako Y, Adams R, Reid AJ, Valletta JJ, Ndungu FM, Sodenkamp J, Mwacharo J, Ngoi JM, Kimani D, Kai O, Wambua J, Nyangweso G, de Villiers EP, Sanders M, Lotkowska ME, Lin JW, Manni S, Addy JWG, Recker M, Newbold C, Berriman M, Bejon P, Marsh K, Langhorne J. Repeated clinical malaria episodes are associated with modification of the immune system in children. BMC Med 2019; 17:60. [PMID: 30862316 PMCID: PMC6415347 DOI: 10.1186/s12916-019-1292-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 02/18/2019] [Indexed: 01/25/2023] Open
Abstract
BACKGROUND There are over 200 million reported cases of malaria each year, and most children living in endemic areas will experience multiple episodes of clinical disease before puberty. We set out to understand how frequent clinical malaria, which elicits a strong inflammatory response, affects the immune system and whether these modifications are observable in the absence of detectable parasitaemia. METHODS We used a multi-dimensional approach comprising whole blood transcriptomic, cellular and plasma cytokine analyses on a cohort of children living with endemic malaria, but uninfected at sampling, who had been under active surveillance for malaria for 8 years. Children were categorised into two groups depending on the cumulative number of episodes experienced: high (≥ 8) or low (< 5). RESULTS We observe that multiple episodes of malaria are associated with modification of the immune system. Children who had experienced a large number of episodes demonstrated upregulation of interferon-inducible genes, a clear increase in circulating levels of the immunoregulatory cytokine IL-10 and enhanced activation of neutrophils, B cells and CD8+ T cells. CONCLUSION Transcriptomic analysis together with cytokine and immune cell profiling of peripheral blood can robustly detect immune differences between children with different numbers of prior malaria episodes. Multiple episodes of malaria are associated with modification of the immune system in children. Such immune modifications may have implications for the initiation of subsequent immune responses and the induction of vaccine-mediated protection.
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Affiliation(s)
| | | | - Adam J Reid
- Wellcome Genome Campus, Wellcome Sanger Institute, Hinxton, Cambridgeshire, UK
| | | | | | - Jan Sodenkamp
- Francis Crick Institute, London, UK.,Present Address: Transla TUM, Zentralinstitut für translationale Krebsforschung der Technischen Universität München, Munich, Germany
| | | | - Joyce Mwongeli Ngoi
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya.,Present Address: West African Centre for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | | | - Oscar Kai
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Etienne P de Villiers
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya.,Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Mandy Sanders
- Wellcome Genome Campus, Wellcome Sanger Institute, Hinxton, Cambridgeshire, UK
| | - Magda Ewa Lotkowska
- Wellcome Genome Campus, Wellcome Sanger Institute, Hinxton, Cambridgeshire, UK
| | - Jing-Wen Lin
- Francis Crick Institute, London, UK.,Present Address: Division of Pediatric Infectious Diseases, State Key Laboratory of Biotherapy, Sichuan University and Collaboration Innovation Centre, Chengdu, China
| | | | | | | | - Chris Newbold
- Wellcome Genome Campus, Wellcome Sanger Institute, Hinxton, Cambridgeshire, UK.,Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, UK
| | - Matthew Berriman
- Wellcome Genome Campus, Wellcome Sanger Institute, Hinxton, Cambridgeshire, UK
| | - Philip Bejon
- KEMRI/Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kevin Marsh
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Malerba P, Kaminstein D, Brunetti E, Manciulli T. Is there a role for bedside ultrasound in malaria? A survey of the literature. J Ultrasound 2019; 23:13-21. [PMID: 30852774 DOI: 10.1007/s40477-019-00371-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Accepted: 02/27/2019] [Indexed: 01/05/2023] Open
Abstract
PURPOSE Point-of-care ultrasound (POCUS) has proven utility in the evaluation and treatment of many tropical diseases. Its role in malaria has been studied, but its value for the clinician at the bedside is unclear. Our review aimed at summarizing the existing studies to assess the usefulness, if any, of POCUS in treating malaria. METHODS We used Boolean operators using keywords "malaria", "acoustic", "ultrasound", "echography", and "ultrasonography" to search PubMed, Scopus, and Science Direct in three languages (Italian, French, and English). RESULTS We found 22 eligible references. Organs explored include the liver, spleen, heart, optic nerve sheath diameter (ONSD), kidney, lungs, and cerebral vasculature. Multiple pathologic findings by ultrasound are reported, but few demonstrate clinical utility. Current studies involve small numbers of patients, and a few trends emerge when studies are compared. The ability to combine study results is limited due to the significant heterogeneity that exists between studies in regards to both methods of evaluation and the reporting of organ pathology and malaria severity. CONCLUSIONS AND ASSESSMENT A review of the current literature indicates that the use of ultrasound by clinicians adds little to the diagnostic evaluation of patients with malaria. Our review did find that measurements of the spleen, lungs, optic nerve sheath diameter, and cerebral blood flow have potential utility in specific patient populations. Further studies are needed to evaluate whether this utility persists when a larger sample size is used.
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Affiliation(s)
- Paolo Malerba
- Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Viale Brambilla 74, 27100, Pavia, PV, Italy
| | - Daniel Kaminstein
- Department of Emergency Medicine, Medical College of Georgia at Augusta University, Augusta, Georgia
| | - Enrico Brunetti
- Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Viale Brambilla 74, 27100, Pavia, PV, Italy
- Department of Infectious Diseases, IRCCS Policlinico San Matteo Hospital Fundation, Pavia, Italy
| | - Tommaso Manciulli
- Department of Clinical-Surgical, Diagnostic and Pediatric Sciences, University of Pavia, Viale Brambilla 74, 27100, Pavia, PV, Italy.
- PhD School of Experimental Medicine, University of Pavia, Pavia, Italy.
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Performance of Antigen Concentration Thresholds for Attributing Fever to Malaria among Outpatients in Angola. J Clin Microbiol 2019; 57:JCM.01901-18. [PMID: 30626660 DOI: 10.1128/jcm.01901-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Accepted: 01/02/2019] [Indexed: 11/20/2022] Open
Abstract
The density of malaria parasites is a key determinant of whether an infected individual develops fever. While the pyrogenic threshold for malaria parasite density has been well studied, there are no analogous data on the antigen levels associated with fever during infection. Samples from 797 afebrile and 457 febrile outpatients from two provinces in Angola with known concentrations of histidine-rich protein 2 (HRP2), aldolase, and lactate dehydrogenase (LDH) antigens were analyzed by Bayesian latent class modeling to attribute malarial etiology to the fevers and to estimate the sensitivity and specificity of different antigen thresholds for detection of malaria fevers. Among patients with aldolase or LDH levels detectable with a bead-based assay, the concentrations of these two antigens did not differ between afebrile and febrile patients. In contrast, the concentrations of HRP2 were substantially higher in febrile HRP2-positive patients than in afebrile HRP2-positive patients. When HRP2 concentrations were considered, the malaria-attributable fractions of fever cases were 0.092 in Huambo Province and 0.39 in Uíge Province. Diagnostic tests detecting HRP2 with limits of detection (LODs) in the range of 3,000 to 10,000 pg/µl would provide ideal sensitivity and specificity for determination of malarial etiology among febrile persons.
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Uyoga S, Macharia AW, Ndila CM, Nyutu G, Shebe M, Awuondo KO, Mturi N, Peshu N, Tsofa B, Scott JAG, Maitland K, Williams TN. The indirect health effects of malaria estimated from health advantages of the sickle cell trait. Nat Commun 2019; 10:856. [PMID: 30787300 PMCID: PMC6382840 DOI: 10.1038/s41467-019-08775-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 01/29/2019] [Indexed: 12/01/2022] Open
Abstract
Most estimates of the burden of malaria are based on its direct impacts; however, its true burden is likely to be greater because of its wider effects on overall health. Here we estimate the indirect impact of malaria on children's health in a case-control study, using the sickle cell trait (HbAS), a condition associated with a high degree of specific malaria resistance, as a proxy indicator for an effective intervention. We estimate the odds ratios for HbAS among cases (all children admitted to Kilifi County Hospital during 2000-2004) versus community controls. As expected, HbAS protects strongly against malaria admissions (aOR 0.26; 95%CI 0.22-0.31), but it also protects against other syndromes, including neonatal conditions (aOR 0.79; 0.67-0.93), bacteraemia (aOR 0.69; 0.54-0.88) and severe malnutrition (aOR 0.67; 0.55-0.83). The wider health impacts of malaria should be considered when estimating the potential added benefits of effective malaria interventions.
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Affiliation(s)
- Sophie Uyoga
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Alex W Macharia
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Carolyne M Ndila
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Gideon Nyutu
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Mohammed Shebe
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Kennedy O Awuondo
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Neema Mturi
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Norbert Peshu
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - Benjamin Tsofa
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
| | - J Anthony G Scott
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Kathryn Maitland
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya
- Department of Medicine, Imperial College, St Mary's Hospital, London, W21NY, UK
| | - Thomas N Williams
- Department of Epidemiology and Demography, KEMRI/Wellcome Trust Research Programme, PO Box 230, Kilifi, 80108, Kenya.
- Department of Medicine, Imperial College, St Mary's Hospital, London, W21NY, UK.
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Kamau A, Mwangangi JM, Rono MK, Mogeni P, Omedo I, Midega J, Scott JAG, Bejon P. Variation in the effectiveness of insecticide treated nets against malaria and outdoor biting by vectors in Kilifi, Kenya. Wellcome Open Res 2019; 2:22. [PMID: 30542660 DOI: 10.12688/wellcomeopenres.11073.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/29/2017] [Indexed: 11/20/2022] Open
Abstract
Background: Insecticide treated nets (ITNs) protect humans against bites from the Anopheles mosquito vectors that transmit malaria, thereby reducing malaria morbidity and mortality. It has been noted that ITN use leads to a switch from indoor to outdoor feeding among these vectors. It might be expected that outdoor feeding would undermine the effectiveness of ITNs that target indoors vectors, but data are limited. Methods: We linked homestead level geospatial data to clinical surveillance data at a primary healthcare facility in Kilifi County in order to map geographical heterogeneity in ITN effectiveness and observed vector feeding behaviour using landing catches and CDC light traps in six selected areas of varying ITN effectiveness. We quantified the interaction between mosquitoes and humans to evaluate whether outdoor vector biting is a potential explanation for the variation in ITN effectiveness. Results: We observed 37% and 46% visits associated with positive malaria slides among ITN users and non-ITN-users, respectively; ITN use was associated with 32% protection from malaria (crude OR = 0.68, 95% CI: 0.64, 0.73). We obtained modification of ITN effectiveness by geographical area (p=0.016), and identified 6 hotspots using the spatial scan statistic. Majority of mosquitoes were caught outdoor (60%) and were of the An. funestus group (75%). The overall propensity to feed at times when most people were asleep was high; the vast majority of the Anopheles mosquitoes were caught at times when most people are indoors asleep. Estimates for the proportion of human-mosquito contact between the first and last hour when most humans were asleep was consistently high across all locations, ranging from 0.83 to 1.00. Conclusion: Our data do not provide evidence of an epidemiological association between microgeographical variations in ITN effectiveness and variations in the microgeographical distribution of outdoor biting.
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Affiliation(s)
- Alice Kamau
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Joseph M Mwangangi
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Integrated Vector and Disease Management Cluster, International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya
| | - Martin K Rono
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya
| | - Polycarp Mogeni
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Irene Omedo
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Janet Midega
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Centre for Genomics and Global Health, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - J Anthony G Scott
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
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Kapulu MC, Njuguna P, Hamaluba MM. Controlled Human Malaria Infection in Semi-Immune Kenyan Adults (CHMI-SIKA): a study protocol to investigate in vivo Plasmodium falciparum malaria parasite growth in the context of pre-existing immunity. Wellcome Open Res 2018; 3:155. [PMID: 31803847 PMCID: PMC6871356 DOI: 10.12688/wellcomeopenres.14909.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2018] [Indexed: 10/20/2023] Open
Abstract
Malaria remains a major public health burden despite approval for implementation of a partially effective pre-erythrocytic malaria vaccine. There is an urgent need to accelerate development of a more effective multi-stage vaccine. Adults in malaria endemic areas may have substantial immunity provided by responses to the blood stages of malaria parasites, but field trials conducted on several blood-stage vaccines have not shown high levels of efficacy. We will use controlled human malaria infection (CHMI) studies with malaria-exposed volunteers to identify correlations between immune responses and parasite growth rates in vivo. Immune responses more strongly associated with control of parasite growth should be prioritized to accelerate malaria vaccine development. We aim to recruit up to 200 healthy adult volunteers from areas of differing malaria transmission in Kenya, and after confirming their health status through clinical examination and routine haematology and biochemistry, we will comprehensively characterize immunity to malaria using >100 blood-stage antigens. We will administer 3,200 aseptic, purified, cryopreserved Plasmodium falciparum sporozoites (PfSPZ Challenge) by direct venous inoculation. Serial quantitative polymerase chain reaction to measure parasite growth rate in vivo will be undertaken. Clinical and laboratory monitoring will be undertaken to ensure volunteer safety. In addition, we will also explore the perceptions and experiences of volunteers and other stakeholders in participating in a malaria volunteer infection study. Serum, plasma, peripheral blood mononuclear cells and extracted DNA will be stored to allow a comprehensive assessment of adaptive and innate host immunity. We will use CHMI in semi-immune adult volunteers to relate parasite growth outcomes with antibody responses and other markers of host immunity. Registration: ClinicalTrials.gov identifier NCT02739763.
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Affiliation(s)
- Melissa C. Kapulu
- KEMRI-Wellcome Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University Oxford, Oxford, UK
| | | | | | - CHMI-SIKA Study Team
- KEMRI-Wellcome Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University Oxford, Oxford, UK
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40
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Kamau A, Mwangangi JM, Rono MK, Mogeni P, Omedo I, Midega J, Scott JAG, Bejon P. Variation in the effectiveness of insecticide treated nets against malaria and outdoor biting by vectors in Kilifi, Kenya. Wellcome Open Res 2018; 2:22. [PMID: 30542660 PMCID: PMC6281023 DOI: 10.12688/wellcomeopenres.11073.4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/27/2018] [Indexed: 12/27/2022] Open
Abstract
Background: Insecticide treated nets (ITNs) protect humans against bites from the
Anopheles mosquito vectors that transmit malaria, thereby reducing malaria morbidity and mortality. It has been noted that ITN use leads to a switch from indoor to outdoor feeding among these vectors. It might be expected that outdoor feeding would undermine the effectiveness of ITNs that target indoors vectors, but data are limited. Methods: We linked homestead level geospatial data to clinical surveillance data at a primary healthcare facility in Kilifi County in order to map geographical heterogeneity in ITN effectiveness and observed vector feeding behaviour using landing catches and CDC light traps in six selected areas of varying ITN effectiveness. We quantified the interaction between mosquitoes and humans to evaluate whether outdoor vector biting is a potential explanation for the variation in ITN effectiveness. Results: We observed 37% and 46% visits associated with positive malaria slides among ITN users and non-ITN-users, respectively; ITN use was associated with 32% protection from malaria (crude OR = 0.68, 95% CI: 0.64, 0.73). We obtained modification of ITN effectiveness by geographical area (p=0.016), and identified 6 hotspots using the spatial scan statistic. Majority of mosquitoes were caught outdoor (60%) and were of the
An. funestus group (75%). The overall propensity to feed at times when most people were asleep was high; the vast majority of the
Anopheles mosquitoes were caught at times when most people are indoors asleep. Estimates for the proportion of human-mosquito contact between the first and last hour when most humans were asleep was consistently high across all locations, ranging from 0.83 to 1.00. Conclusion: Our data do not provide evidence of an epidemiological association between microgeographical variations in ITN effectiveness and variations in the microgeographical distribution of outdoor biting.
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Affiliation(s)
- Alice Kamau
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Joseph M Mwangangi
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Integrated Vector and Disease Management Cluster, International Centre of Insect Physiology and Ecology, Nairobi, Kenya.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya
| | - Martin K Rono
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Pwani University Bioscience Research Centre, Pwani University, Kilifi, Kenya
| | - Polycarp Mogeni
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Irene Omedo
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Janet Midega
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Centre for Genomics and Global Health, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - J Anthony G Scott
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, OX3 7FZ, UK
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Kamau A, Mwangangi JM, Rono MK, Mogeni P, Omedo I, Midega J, Scott JAG, Bejon P. Variation in the effectiveness of insecticide treated nets against malaria and outdoor biting by vectors in Kilifi, Kenya. Wellcome Open Res 2018; 2:22. [DOI: 10.12688/wellcomeopenres.11073.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Insecticide treated nets (ITNs) protect humans against bites from the Anopheles mosquito vectors that transmit malaria, thereby reducing malaria morbidity and mortality. It has been noted that ITN use leads to a switch from indoor to outdoor feeding among these vectors. It might be expected that outdoor feeding would undermine the effectiveness of ITNs that target indoors vectors, but data are limited. Methods: We linked homestead level geospatial data to clinical surveillance data at a primary healthcare facility in Kilifi County in order to map geographical heterogeneity in ITN effectiveness and observed vector feeding behaviour using landing catches and CDC light traps in six selected areas of varying ITN effectiveness. We quantified the interaction between mosquitoes and humans to evaluate whether outdoor vector biting is a potential explanation for the variation in ITN effectiveness. Results: We observed 37% and 46% visits associated with positive malaria slides among ITN users and non-ITN-users, respectively; ITN use was associated with 32% protection from malaria (crude OR = 0.68, 95% CI: 0.64, 0.73). We obtained significant modification of ITN effectiveness by geographical area (p=0.016), and identified significant hotspots using the spatial scan statistic. Majority of mosquitoes were caught outdoor (60%) and were of the An. funestus group (75%). The overall propensity to feed at times when most people are indoor was high; the vast majority of the Anopheles mosquitoes were caught at times when most people are indoor. Estimates for the proportion of human-mosquito contact between the first and last hour when most humans were indoor was consistently high, ranging from 0.83 to 1.00. Conclusion: Our data do not provide evidence of an epidemiological association between microgeographical variations in ITN effectiveness and variations in the microgeographical distribution of outdoor biting.
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van Beek AE, Sarr I, Correa S, Nwakanma D, Brouwer MC, Wouters D, Secka F, Anderson STB, Conway DJ, Walther M, Levin M, Kuijpers TW, Cunnington AJ. Complement Factor H Levels Associate With Plasmodium falciparum Malaria Susceptibility and Severity. Open Forum Infect Dis 2018; 5:ofy166. [PMID: 30087905 PMCID: PMC6059171 DOI: 10.1093/ofid/ofy166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 07/10/2018] [Indexed: 12/14/2022] Open
Abstract
Background Plasmodium falciparum may evade complement-mediated host defense by hijacking complement Factor H (FH), a negative regulator of the alternative complement pathway. Plasma levels of FH vary between individuals and may therefore influence malaria susceptibility and severity. Methods We measured convalescent FH plasma levels in 149 Gambian children who had recovered from uncomplicated or severe P. falciparum malaria and in 173 healthy control children. We compared FH plasma levels between children with malaria and healthy controls, and between children with severe (n = 82) and uncomplicated malaria (n = 67). We determined associations between FH plasma levels and laboratory features of severity and used multivariate analyses to examine associations with FH when accounting for other determinants of severity. Results FH plasma levels differed significantly between controls, uncomplicated malaria cases, and severe malaria cases (mean [95% confidence interval], 257 [250 to 264], 288 [268 to 309], and 328 [313 to 344] µg/mL, respectively; analysis of variance P < .0001). FH plasma levels correlated with severity biomarkers, including lactate, parasitemia, and parasite density, but did not correlate with levels of PfHRP2, which represent the total body parasite load. Associations with severity and lactate remained significant when adjusting for age and parasite load. Conclusions Natural variation in FH plasma levels is associated with malaria susceptibility and severity. A prospective study will be needed to strengthen evidence for causation, but our findings suggest that interfering with FH binding by P. falciparum might be useful for malaria prevention or treatment.
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Affiliation(s)
- Anna E van Beek
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory of the Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands.,Department of Pediatric Hematology, Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Centre, Amsterdam, the Netherlands
| | - Isatou Sarr
- Medical Research Council Unit, The Gambia at London School of Hygiene and Tropical Medicine
| | - Simon Correa
- Medical Research Council Unit, The Gambia at London School of Hygiene and Tropical Medicine
| | - Davis Nwakanma
- Medical Research Council Unit, The Gambia at London School of Hygiene and Tropical Medicine
| | - Mieke C Brouwer
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory of the Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
| | - Diana Wouters
- Department of Immunopathology, Sanquin Research and Landsteiner Laboratory of the Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
| | - Fatou Secka
- Medical Research Council Unit, The Gambia at London School of Hygiene and Tropical Medicine
| | - Suzanne T B Anderson
- Medical Research Council Unit, The Gambia at London School of Hygiene and Tropical Medicine
| | - David J Conway
- Department of Pathogen and Molecular Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Michael Walther
- Medical Research Council Unit, The Gambia at London School of Hygiene and Tropical Medicine
| | - Michael Levin
- Section of Paediatrics, Imperial College London, London, United Kingdom
| | - Taco W Kuijpers
- Department of Pediatric Hematology, Immunology and Infectious Diseases, Emma Children's Hospital, Academic Medical Centre, Amsterdam, the Netherlands.,Department of Blood Cell Research, Sanquin Research and Landsteiner Laboratory of the Academic Medical Centre, University of Amsterdam, Amsterdam, the Netherlands
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Good MF, Miller LH. Interpreting challenge data from early phase malaria blood stage vaccine trials. Expert Rev Vaccines 2018; 17:189-196. [PMID: 29382292 DOI: 10.1080/14760584.2018.1435278] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION As the quest for an effective blood stage malaria vaccine continues, there is increasing reliance on the use of controlled human malaria infections (CHMI) in non-endemic settings to test vaccine efficacy at the earliest possible time. This is seen as a way to accelerate vaccine research and quickly eliminate candidates with poor efficacy. Areas covered: The data from these studies need to be carefully examined and interpreted in light of the very different roles that antibody and cellular immunity play in protection and within the context of the distinct clinical sensitivities of volunteers living in malaria-non-endemic countries compared to those living in endemic countries. With current strategies, it is likely that vaccines with protective immunological 'signatures' will be missed and potentially good candidates discarded. Expert commentary: Efficacy data from early phase vaccine trials in non-endemic countries should not be used to decide whether or not to proceed to vaccine trials in endemic countries.
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Affiliation(s)
- Michael F Good
- a Institute for Glycomics , Griffith University , Queensland , Australia.,b Department of Medical Microbiology and Immunology, University of Alberta , Edmonton , Canada
| | - Louis H Miller
- c Malaria Cell Biology Section, National Institute of Allergy and Infectious Diseases , National Institutes of Health , Bethesda , MD , USA
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44
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Kamau A, Mwangangi JM, Rono MK, Mogeni P, Omedo I, Midega J, Scott JAG, Bejon P. Variation in the effectiveness of insecticide treated nets against malaria and outdoor biting by vectors in Kilifi, Kenya. Wellcome Open Res 2018; 2:22. [DOI: 10.12688/wellcomeopenres.11073.2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2018] [Indexed: 11/20/2022] Open
Abstract
Background: Insecticide treated nets (ITNs) protect humans against bites from the Anopheles mosquito vectors that transmit malaria, thereby reducing malaria morbidity and mortality. It has been noted that ITN use leads to a switch from indoor to outdoor feeding among these vectors. It might be expected that outdoor feeding would undermine the effectiveness of ITNs that target indoors vectors, but data are limited. Methods: We linked homestead level geospatial data to clinical surveillance data at a primary healthcare facility in Kilifi County in order to map geographical heterogeneity in ITN effectiveness and observed vector feeding behaviour using landing catches and CDC light traps in six selected areas of varying ITN effectiveness. We quantified the interaction between mosquitoes and humans to evaluate whether outdoor vector biting is a potential explanation for the variation in ITN effectiveness. Results: We observed 37% and 46% visits associated with positive malaria slides among ITN users and non-ITN-users, respectively; ITN use was associated with 32% protection from malaria (crude OR = 0.68, 95% CI: 0.64, 0.73). We obtained significant modification of ITN effectiveness by geographical area (p=0.016), and identified significant hotspots using the spatial scan statistic. Majority of mosquitoes were caught outdoor (60%) and were of the An. funestus group (75%). The overall propensity to feed at times when most people are indoor was high; the vast majority of the Anopheles mosquitoes were caught at times when most people are indoor. Estimates for the proportion of human-mosquito contact between the first and last hour when most humans were indoor was consistently high, ranging from 0.83 to 1.00. Conclusion: Our data therefore do not support the hypothesis that outdoor biting limits the effectiveness of ITNs in our study area.
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45
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Mogeni P, Williams TN, Omedo I, Kimani D, Ngoi JM, Mwacharo J, Morter R, Nyundo C, Wambua J, Nyangweso G, Kapulu M, Fegan G, Bejon P. Detecting Malaria Hotspots: A Comparison of Rapid Diagnostic Test, Microscopy, and Polymerase Chain Reaction. J Infect Dis 2017; 216:1091-1098. [PMID: 28973672 PMCID: PMC5853881 DOI: 10.1093/infdis/jix321] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 07/06/2017] [Indexed: 12/21/2022] Open
Abstract
Background Malaria control strategies need to respond to geographical hotspots of transmission. Detection of hotspots depends on the sensitivity of the diagnostic tool used. Methods We conducted cross-sectional surveys in 3 sites within Kilifi County, Kenya, that had variable transmission intensities. Rapid diagnostic test (RDT), microscopy, and polymerase chain reaction (PCR) were used to detect asymptomatic parasitemia, and hotspots were detected using the spatial scan statistic. Results Eight thousand five hundred eighty-one study participants were surveyed in 3 sites. There were statistically significant malaria hotspots by RDT, microscopy, and PCR for all sites except by microscopy in 1 low transmission site. Pooled data analysis of hotspots by PCR overlapped with hotspots by microscopy at a moderate setting but not at 2 lower transmission settings. However, variations in degree of overlap were noted when data were analyzed by year. Hotspots by RDT were predictive of PCR/microscopy at the moderate setting, but not at the 2 low transmission settings. We observed long-term stability of hotspots by PCR and microscopy but not RDT. Conclusion Malaria control programs may consider PCR testing to guide asymptomatic malaria hotspot detection once the prevalence of infection falls.
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Affiliation(s)
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Faculty of Medicine, Imperial College London
| | - Irene Omedo
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Joyce M Ngoi
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Richard Morter
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,The Jenner Institute, Nuffield Department of Medicine, University of Oxford
| | | | | | | | - Melissa Kapulu
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford
| | - Gregory Fegan
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Swansea Trials Unit, Swansea University Medical School, Swansea, United Kingdom
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford
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46
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Mugyenyi CK, Elliott SR, Yap XZ, Feng G, Boeuf P, Fegan G, Osier FFH, Fowkes FJI, Avril M, Williams TN, Marsh K, Beeson JG. Declining Malaria Transmission Differentially Impacts the Maintenance of Humoral Immunity to Plasmodium falciparum in Children. J Infect Dis 2017; 216:887-898. [PMID: 28973483 DOI: 10.1093/infdis/jix370] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Accepted: 07/31/2017] [Indexed: 12/13/2022] Open
Abstract
Background We investigated the poorly understood impact of declining malaria transmission on maintenance of antibodies to Plasmodium falciparum merozoite antigens and infected erythrocytes (IEs), including functional immunity. Methods In a 3-year longitudinal cohort of 300 Kenyan children, antibodies to different AMA1 and MSP2 alleles of merozoites, IE surface antigens, and antibody functional activities were quantified. Results Over a period in which malaria transmission declined markedly, AMA1 and MSP2 antibodies decreased substantially; estimated half-lives of antibody duration were 0.8 year and 1-3 years, respectively. However, 69%-74% of children maintained their seropositivity to AMA1 alleles and 42%-52% to MSP2 alleles. Levels and prevalence of antimerozoite antibodies were consistently associated with increasing age and concurrent parasitemia. Antibodies promoting opsonic phagocytosis of merozoites declined rapidly (half-life, 0.15 years). In contrast, complement-fixing antibodies to merozoites did not decline and antibodies to IE surface antigens expressing virulent phenotypes were much better maintained (half-life, 4-10 years). Conclusions A decline in malaria transmission is associated with reduction in naturally acquired immunity. However, loss of immunity is not universal; some key functional responses and antibodies to IEs were better maintained and these may continue to provide some protection. Findings have implications for malaria surveillance and control measures and informing vaccine development.
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Affiliation(s)
- Cleopatra K Mugyenyi
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi.,Burnet Institute, Melbourne
| | | | - Xi Zen Yap
- Burnet Institute, Melbourne.,Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Victoria, Australia
| | | | - Philippe Boeuf
- Burnet Institute, Melbourne.,Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Victoria, Australia
| | - Gregory Fegan
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi
| | - Faith F H Osier
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi.,Burnet Institute, Melbourne.,Department of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Germany
| | - Freya J I Fowkes
- Burnet Institute, Melbourne.,Department of Epidemiology and Preventive Medicine, Monash University.,Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Victoria, Australia
| | - Marion Avril
- Centre for Infectious Disease Research, Seattle, Washington
| | - Thomas N Williams
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi.,Imperial College, London, United Kingdom
| | - Kevin Marsh
- Kenya Medical Research Institute (KEMRI), Centre for Geographic Medicine, Coast, KEMRI-Wellcome Trust Research Programme, Kilifi
| | - James G Beeson
- Burnet Institute, Melbourne.,Department of Medicine, Royal Melbourne Hospital, University of Melbourne, Victoria, Australia.,Central Clinical School and Department of Microbiology, Monash University, Melbourne, Victoria, Australia
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47
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Mogeni P, Omedo I, Nyundo C, Kamau A, Noor A, Bejon P. Effect of transmission intensity on hotspots and micro-epidemiology of malaria in sub-Saharan Africa. BMC Med 2017; 15:121. [PMID: 28662646 PMCID: PMC5492887 DOI: 10.1186/s12916-017-0887-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 06/02/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria transmission intensity is heterogeneous, complicating the implementation of malaria control interventions. We provide a description of the spatial micro-epidemiology of symptomatic malaria and asymptomatic parasitaemia in multiple sites. METHODS We assembled data from 19 studies conducted between 1996 and 2015 in seven countries of sub-Saharan Africa with homestead-level geospatial data. Data from each site were used to quantify spatial autocorrelation and examine the temporal stability of hotspots. Parameters from these analyses were examined to identify trends over varying transmission intensity. RESULTS Significant hotspots of malaria transmission were observed in most years and sites. The risk ratios of malaria within hotspots were highest at low malaria positive fractions (MPFs) and decreased with increasing MPF (p < 0.001). However, statistical significance of hotspots was lowest at extremely low and extremely high MPFs, with a peak in statistical significance at an MPF of ~0.3. In four sites with longitudinal data we noted temporal instability and variable negative correlations between MPF and average age of symptomatic malaria across all sites, suggesting varying degrees of temporal stability. CONCLUSIONS We observed geographical micro-variation in malaria transmission at sites with a variety of transmission intensities across sub-Saharan Africa. Hotspots are marked at lower transmission intensity, but it becomes difficult to show statistical significance when cases are sparse at very low transmission intensity. Given the predictability with which hotspots occur as transmission intensity falls, malaria control programmes should have a low threshold for responding to apparent clustering of cases.
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Affiliation(s)
- Polycarp Mogeni
- KEMRI-Wellcome Trust Research Programme, CGMR-Coast, Kilifi, Kenya.
| | - Irene Omedo
- KEMRI-Wellcome Trust Research Programme, CGMR-Coast, Kilifi, Kenya
| | | | - Alice Kamau
- KEMRI-Wellcome Trust Research Programme, CGMR-Coast, Kilifi, Kenya
| | - Abdisalan Noor
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, CCVTM, Oxford, UK.,Spatial Health Metrics Group, Kenya Medical Research Institute/Wellcome Trust Research Programme, Nairobi, Kenya
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, CGMR-Coast, Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, CCVTM, Oxford, UK
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48
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Ifeorah IK, Brown BJ, Sodeinde OO. A COMPARISON OF RAPID DIAGNOSTIC TESTING (BY PLASMODIUM LACTATE DEHYDROGENASE), AND QUANTITATIVE BUFFY COAT TECHNIQUE IN MALARIA DIAGNOSIS IN CHILDREN. Afr J Infect Dis 2017; 11:31-38. [PMID: 28670638 PMCID: PMC5476811 DOI: 10.21010/ajid.v11i2.5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The World Health Organization (WHO) considers early and rapid diagnosis as one of the strategies to control malaria. This study compared the performance of Quantitative Buffy Coat (QBC) test and the Plasmodium lactate dehydrogenase (pLDH) rapid diagnostic test (RDT) with microscopy as the gold standard. MATERIALS AND METHODS The study involved children ages 0-5 years who presented with a history of fever at the University College Hospital, Ibadan, Nigeria. Blood was collected from each patient and used for RDT, QBC and Giemsa-stained blood films for malaria parasites (MP). Results of QBC and RDT were compared with microscopy results for the diagnosis of malaria. RESULTS A total of 370 cases (194 boys and 176 girls) were studied giving a male: female ratio of 1.1:1. Of the 370 cases tested using Giemsa-stained thick blood films for MP, 78 (21 %) were positive. For the QBC test, 78 (21%) of the cases were positive with sensitivity, specificity, positive and negative predictive values of 70.5 %, 92.1%, 70.5 % and 92.1 % respectively. Seventy-six (20%) of the cases were positive by RDT with sensitivity, specificity, positive and negative predictive values of 84.2 %, 95.2 %, 82.1 %, and 95.9 % respectively. There was no significant difference in the sensitivity of QBC compared with the RDT. CONCLUSION Both the QBC and the pfLDH (RDT) performed reasonably well in this study Malaria rapid diagnostic tests are recommended in malaria endemic clinical settings to avoid unnecessary antimalarial treatment. List of Abbreviations: AO: Acridine orange, AIDS: Acquired immunodeficiency syndrome, ACT: Artemisinin-based combination therapy, CM:Cerebral malaria, BCP:Benzothiocarboxypurine, DDT:Dichloro-diphenyl-trichloroethane, DNA:DeoxyriboNucleic Acid, ELAM-1: Endothelial leukocyte adhesion molecule, G6PD: Glucose-6-Phosphate Dehydrogenase, HIV: Human immuno deficiency virus, HRP 2: Histidine Rich Protein 2, ICAM -1: Inter cellular adhesion molecule1, ICER: Incremental cost effectiveness ratio, IL-1: Interleukin -1, IFN-g: Interferon-gamma, IgG: Immunoglobulin G, MP: Malaria parasite, NADP: Oxidised Nicotinamide Adenine Dinucleotide Phosphate, NADPH: Reduced Nicotinamide Adenine Dinucleotide Phosphate, PCV: Packed Cell Volume (haematocrit), P. falciparum: Plasmodium falciparum, PLDH: Plasmodium lactate dehydrogenase, PCR: Polymerase Chain Reaction, PPV: Positive predictive value, QBC: Quantitative Buffy Coat examination, TNF: Tumour necrosis factor, NPV: Negative predictive value, RDT: Rapid diagnostic test, SP: Sulphadoxine -Pyrimethamine, SMA: Severe malarial anaemia, UM: Uncomplicated malaria, USA:United States of America, VCAM-1: Vascular cell adhesion molecule, WBC: White Blood Cell, WHO: World Health Organization.
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Affiliation(s)
| | | | - Olugbemiro O Sodeinde
- Adjunct Professor, Department of Paediatrics, College of Medicine, University of Ibadan, University College Hospital, Ibadan
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49
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Offeddu V, Olotu A, Osier F, Marsh K, Matuschewski K, Thathy V. High Sporozoite Antibody Titers in Conjunction with Microscopically Detectable Blood Infection Display Signatures of Protection from Clinical Malaria. Front Immunol 2017; 8:488. [PMID: 28533773 PMCID: PMC5421148 DOI: 10.3389/fimmu.2017.00488] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 04/07/2017] [Indexed: 11/18/2022] Open
Abstract
Immunoepidemiological studies typically reveal slow, age-dependent acquisition of immune responses against Plasmodium falciparum sporozoites. Naturally acquired immunity against preerythrocytic stages is considered inadequate to confer protection against clinical malaria. To explore previously unrecognized antisporozoite responses, we measured serum levels of naturally acquired antibodies to whole Plasmodium falciparum sporozoites (Pfspz) and the immunodominant (NANP)5 repeats of the major sporozoite surface protein, circumsporozoite protein, in a well-characterized Kenyan cohort. Sera were sampled at the start of the malaria transmission season, and all subjects were prospectively monitored for uncomplicated clinical malaria in the ensuing 6 months. We used Kaplan–Meier analysis and multivariable regression to investigate the association of antisporozoite immunity with incidence of clinical malaria. Although naturally acquired humoral responses against Pfspz and (NANP)5 were strongly correlated (p < 0.0001), 37% of Pfspz responders did not recognize (NANP)5. The prevalence and magnitude of antisporozoite responses increased with age, although some high Pfspz responders were identified among children. Survival analysis revealed a reduced risk of and increased time to first or only episode of clinical malaria among Pfspz or (NANP)5 responders carrying microscopically detectable Plasmodium falciparum (Pf) parasitemia at the start of the transmission season (p < 0.03). Our Cox regression interaction models indicated a potentially protective interaction between high anti-Pfspz (p = 0.002) or anti-(NANP)5 (p = 0.001) antibody levels and microscopically detectable Pf parasitemia on the risk of subsequent clinical malaria. Our findings indicate that robust antisporozoite immune responses can be naturally acquired already at an early age. A potentially protective role of high levels of anti-Pfspz antibodies against clinical episodes of uncomplicated malaria was detected, suggesting that antibody-mediated preerythrocytic immunity might indeed contribute to protection in nature.
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Affiliation(s)
- Vittoria Offeddu
- Parasitology Unit, Max Planck Institute for Infection Biology, Berlin, Germany
| | - Ally Olotu
- Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kenya Medical Research Institute (KEMRI), Kilifi, Kenya
| | - Faith Osier
- Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kenya Medical Research Institute (KEMRI), Kilifi, Kenya
| | - Kevin Marsh
- Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kenya Medical Research Institute (KEMRI), Kilifi, Kenya.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Kai Matuschewski
- Parasitology Unit, Max Planck Institute for Infection Biology, Berlin, Germany.,Molecular Parasitology, Institute of Biology, Humboldt University, Berlin, Germany
| | - Vandana Thathy
- Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kenya Medical Research Institute (KEMRI), Kilifi, Kenya
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50
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McCallum FJ, Persson KEM, Fowkes FJI, Reiling L, Mugyenyi CK, Richards JS, Simpson JA, Williams TN, Gilson PR, Hodder AN, Sanders PR, Anders RF, Narum DL, Chitnis C, Crabb BS, Marsh K, Beeson JG. Differing rates of antibody acquisition to merozoite antigens in malaria: implications for immunity and surveillance. J Leukoc Biol 2016; 101:913-925. [PMID: 27837017 DOI: 10.1189/jlb.5ma0716-294r] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 09/28/2016] [Accepted: 10/19/2016] [Indexed: 12/18/2022] Open
Abstract
Antibodies play a key role in acquired human immunity to Plasmodium falciparum (Pf) malaria and target merozoites to reduce or prevent blood-stage replication and the development of disease. Merozoites present a complex array of antigens to the immune system, and currently, there is only a partial understanding of the targets of protective antibodies and how responses to different antigens are acquired and boosted. We hypothesized that there would be differences in the rate of acquisition of antibodies to different antigens and how well they are boosted by infection, which impacts the acquisition of immunity. We examined responses to a range of merozoite antigens in 2 different cohorts of children and adults with different age structures and levels of malaria exposure. Overall, antibodies were associated with age, exposure, and active infection, and the repertoire of responses increased with age and active infection. However, rates of antibody acquisition varied between antigens and different regions within an antigen following exposure to malaria, supporting our hypothesis. Antigen-specific responses could be broadly classified into early response types in which antibodies were acquired early in childhood exposure and late response types that appear to require substantially more exposure for the development of substantial levels. We identified antigen-specific responses that were effectively boosted after recent infection, whereas other responses were not. These findings advance our understanding of the acquisition of human immunity to malaria and are relevant to the development of malaria vaccines targeting merozoite antigens and the selection of antigens for use in malaria surveillance.
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Affiliation(s)
- Fiona J McCallum
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Australia.,Department of Drug Evaluation, Australian Army Malaria Institute, Brisbane, Australia
| | - Kristina E M Persson
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden.,Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Freya J I Fowkes
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia.,Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Victoria, Australia.,Departments of Epidemiology and Preventive Medicine and Infectious Diseases, Monash University, Melbourne, Australia
| | - Linda Reiling
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Cleopatra K Mugyenyi
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia.,Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jack S Richards
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia.,Department of Microbiology, Monash University, Melbourne, Australia.,Department of Medicine, University of Melbourne, Parkville, Australia
| | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Victoria, Australia
| | - Thomas N Williams
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.,Department of Medicine, Imperial College of Science, Technology and Medicine, London, United Kingdom
| | - Paul R Gilson
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Anthony N Hodder
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia.,Department of Medical Biology, University of Melbourne, Melbourne, Australia
| | - Paul R Sanders
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Robin F Anders
- Department of Biochemistry and Genetics, La Trobe Institute for Molecular Science, Latrobe University, Melbourne, Australia
| | - David L Narum
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Brendan S Crabb
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia
| | - Kevin Marsh
- Kenya Medical Research Institute-Wellcome Trust Research Programme, Kilifi, Kenya.,Nuffield Department of Medicine, Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - James G Beeson
- Burnet Institute for Medical Research and Public Health, Melbourne, Australia; .,Department of Microbiology, Monash University, Melbourne, Australia.,Department of Medicine, University of Melbourne, Parkville, Australia
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