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Bradley L, Yewhalaw D, Hemming-Schroeder E, Embury P, Lee MC, Zemene E, Degefa T, King C, Kazura J, Yan G, Dent A. Determination of Plasmodium vivax and Plasmodium falciparum Malaria Exposure in Two Ethiopian Communities and Its Relationship to Duffy Expression. Am J Trop Med Hyg 2023; 109:1028-1035. [PMID: 37918005 PMCID: PMC10622468 DOI: 10.4269/ajtmh.22-0644] [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: 10/07/2022] [Accepted: 07/16/2023] [Indexed: 11/04/2023] Open
Abstract
Despite historical dogma that Duffy blood group negativity of human erythrocytes confers resistance to Plasmodium vivax blood stage infection, cases of P. vivax malaria and asymptomatic blood stage infection (subclinical malaria) have recently been well documented in Duffy-negative individuals throughout Africa. However, the impact of Duffy negativity on the development of naturally acquired immunity to P. vivax remains poorly understood. We examined antibody reactivity to P. vivax and P. falciparum antigens at two field sites in Ethiopia and assessed Duffy gene expression by polymerase chain reaction amplification and sequencing of the GATA-1 transcription factor-binding site of the Duffy antigen receptor for chemokines (DARC) gene promotor region that is associated with silencing of erythroid cell transcription and absent protein expression. Antibodies to three of the four P. vivax blood stage antigens examined, RBP2b, EBP2, and DBPIISal-1, were significantly lower (P < 0.001) in Duffy-negative individuals relative to Duffy-positive individuals. In stark contrast, no clear pattern was found across Duffy-negative and Duffy-positive genotypes for P. falciparum antibodies. We conclude that lack of erythroid Duffy expression is associated with reduced serologic responses, indicative of less naturally acquired immunity and less cumulative exposure to blood stage P. vivax parasites relative to Duffy positive individuals living in the same communities.
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Affiliation(s)
- Lauren Bradley
- Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of California, Irvine, California
| | - Delenasaw Yewhalaw
- Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | | | - Paula Embury
- Center for Global Health and Disease, Case Western Reserve University, Cleveland, Ohio
| | - Ming-Chieh Lee
- Program in Public Health, College of Health Sciences, University of California, Irvine, California
| | - Endalew Zemene
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Teshome Degefa
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Christopher King
- Center for Global Health and Disease, Case Western Reserve University, Cleveland, Ohio
| | - James Kazura
- Center for Global Health and Disease, Case Western Reserve University, Cleveland, Ohio
| | - Guiyun Yan
- Department of Ecology and Evolutionary Biology, School of Biological Sciences, University of California, Irvine, California
- Program in Public Health, College of Health Sciences, University of California, Irvine, California
| | - Arlene Dent
- Center for Global Health and Disease, Case Western Reserve University, Cleveland, Ohio
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Macalinao MLM, Fornace KM, Reyes RA, Hall T, Bareng APN, Adams JH, Huon C, Chitnis CE, Luchavez JS, Tetteh KK, Yui K, Hafalla JCR, Espino FEJ, Drakeley CJ. Analytical approaches for antimalarial antibody responses to confirm historical and recent malaria transmission: an example from the Philippines. THE LANCET REGIONAL HEALTH. WESTERN PACIFIC 2023; 37:100792. [PMID: 37693871 PMCID: PMC10485684 DOI: 10.1016/j.lanwpc.2023.100792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/20/2023] [Accepted: 04/28/2023] [Indexed: 09/12/2023]
Abstract
Background Assessing the status of malaria transmission in endemic areas becomes increasingly challenging as countries approach elimination. Serology can provide robust estimates of malaria transmission intensities, and multiplex serological assays allow for simultaneous assessment of markers of recent and historical malaria exposure. Methods Here, we evaluated different statistical and machine learning methods for analyzing multiplex malaria-specific antibody response data to classify recent and historical exposure to Plasmodium falciparum and Plasmodium vivax. To assess these methods, we utilized samples from a health-facility based survey (n = 9132) in the Philippines, where we quantified antibody responses against 8 P. falciparum and 6 P. vivax-specific antigens from 3 sites with varying transmission intensity. Findings Measurements of antibody responses and seroprevalence were consistent with the 3 sites' known endemicity status. Among the models tested, a machine learning (ML) approach (Random Forest model) using 4 serological markers (PfGLURP R2, Etramp5.Ag1, GEXP18, and PfMSP119) gave better predictions for P. falciparum recent infection in Palawan (AUC: 0.9591, CI 0.9497-0.9684) than individual antigen seropositivity. Although the ML approach did not improve P. vivax infection predictions, ML classifications confirmed the absence of recent exposure to P. falciparum and P. vivax in both Occidental Mindoro and Bataan. For predicting historical P. falciparum and P. vivax transmission, seroprevalence and seroconversion rates based on cumulative exposure markers AMA1 and MSP119 showed reliable trends in the 3 sites. Interpretation Our study emphasizes the utility of serological markers in predicting recent and historical exposure in a sub-national elimination setting, and also highlights the potential use of machine learning models using multiplex antibody responses to improve assessment of the malaria transmission status of countries aiming for elimination. This work also provides baseline antibody data for monitoring risk in malaria-endemic areas in the Philippines. Funding Newton Fund, Philippine Council for Health Research and Development, UK Medical Research Council.
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Affiliation(s)
- Maria Lourdes M. Macalinao
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Kimberly M. Fornace
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Institute of Biodiversity, Animal Health & Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Ralph A. Reyes
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
| | - Tom Hall
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Alison Paolo N. Bareng
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
| | | | - Christèle Huon
- Malaria Parasite Biology and Vaccines Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Chetan E. Chitnis
- Malaria Parasite Biology and Vaccines Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Jennifer S. Luchavez
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
| | - Kevin K.A. Tetteh
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Katsuyuki Yui
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
- Shionogi Global Infectious Diseases Division, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Julius Clemence R. Hafalla
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Fe Esperanza J. Espino
- Department of Parasitology and National Reference Laboratory for Malaria and Other Parasites, Research Institute for Tropical Medicine, Department of Health, Muntinlupa City, Philippines
| | - Chris J. Drakeley
- Faculty of Infectious and Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
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3
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Bittaye SO, Jagne A, Jaiteh LE, Nadjm B, Amambua-Ngwa A, Sesay AK, Singhateh Y, Effa E, Nyan O, Njie R. Clinical manifestations and outcomes of severe malaria in adult patients admitted to a tertiary hospital in the Gambia. Malar J 2022; 21:270. [PMID: 36131306 PMCID: PMC9491657 DOI: 10.1186/s12936-022-04294-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2022] [Accepted: 09/15/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is a major public health concern in The Gambia. There is limited data on the clinical manifestation and outcome of severe malaria in adult patients in The Gambia. The study therefore assessed the clinical manifestations and outcome of severe malaria in adult patients admitted at the Edward Francis Small Teaching Hospital. METHODS The study retrospectively reviewed the records of all malaria patients admitted from 18th October 2020 to 2nd February 2022. Demographic data, clinical features, investigations, treatment, and outcomes were recorded. RESULTS A total of 131 confirmed malaria patients were recruited into the study. The median age was 21 yrs, range (15-90) and most of them were within the youth age group (15-24yrs) 85 (64.9%). The majority of the patients were also male 88 (67.2%) with a male to female ratio of 2:1. The most common symptom at presentation was fever 119 (90.8%) and the most common sign was pallor 48 (36.6%). Seventy-six patients (58.1%) and 55 (41.9%) patients met the criteria for severe malaria and uncomplicated malaria diagnosis, respectively. The most common clinical feature amongst patients with severe malaria were impaired consciousness 34 (44.7%), severe anaemia 26 (34.2%) and acute kidney injury 20 (26.3%). Patients with severe malaria were younger with mean age of 22.9 vs. 29 yrs (p = 0.004), more likely to be referred from a lower-level health facility 62 (81.6%) vs. 34 (61.8%) (p = 0.012), to have a longer duration of admission (p = 0.024) and to die 13 (17.1%) vs. 0 (0%) (p = 0.001) as compared to patients with uncomplicated malaria. The total mortality was 13 (9.9%) and all the patients who died had severe malaria. Mortality was higher in patients with impaired consciousness 9 (26.5%) and there was a significant relationship between death and impaired consciousness 9 (69.3%) vs. 25 (21.4%) p = 0.001. CONCLUSION Severe malaria still affects young adults in an endemic area with significant mortality. This suggests the need for targeted malaria prevention, surveillance, case management and control strategies in this population group in The Gambia to help reduce morbidity and mortality of malaria.
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Affiliation(s)
- Sheikh Omar Bittaye
- Department of Internal Medicine, Edward Francis Small teaching hospital, Banjul, The Gambia. .,School of Medicine and Allied Health Sciences, University of The Gambia, Banjul, The Gambia.
| | - Abubacarr Jagne
- Department of Internal Medicine, Edward Francis Small teaching hospital, Banjul, The Gambia.,School of Medicine and Allied Health Sciences, University of The Gambia, Banjul, The Gambia
| | - Lamin Es Jaiteh
- Department of Internal Medicine, Edward Francis Small teaching hospital, Banjul, The Gambia.,School of Medicine and Allied Health Sciences, University of The Gambia, Banjul, The Gambia
| | - Behzad Nadjm
- Medical Research Council, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Alfred Amambua-Ngwa
- Medical Research Council, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Abdul Karim Sesay
- Medical Research Council, London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Yankuba Singhateh
- Epidemiology and disease control unit, Ministry of Health, Banjul, The Gambia
| | - Emmanuel Effa
- Department of Internal Medicine, Edward Francis Small teaching hospital, Banjul, The Gambia.,School of Medicine and Allied Health Sciences, University of The Gambia, Banjul, The Gambia
| | - Ousman Nyan
- Department of Internal Medicine, Edward Francis Small teaching hospital, Banjul, The Gambia.,School of Medicine and Allied Health Sciences, University of The Gambia, Banjul, The Gambia
| | - Ramou Njie
- Department of Internal Medicine, Edward Francis Small teaching hospital, Banjul, The Gambia.,School of Medicine and Allied Health Sciences, University of The Gambia, Banjul, The Gambia
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4
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Druetz T, van den Hoogen L, Stresman G, Joseph V, Hamre KES, Fayette C, Monestime F, Presume J, Romilus I, Mondélus G, Elismé T, Cooper S, Impoinvil D, Ashton RA, Rogier E, Existe A, Boncy J, Chang MA, Lemoine JF, Drakeley C, Eisele TP. Etramp5 as a useful serological marker in children to assess the immediate effects of mass drug campaigns for malaria. BMC Infect Dis 2022; 22:643. [PMID: 35883064 PMCID: PMC9321307 DOI: 10.1186/s12879-022-07616-8] [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: 03/17/2022] [Accepted: 07/14/2022] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION Serological methods provide useful metrics to estimate age-specific period prevalence in settings of low malaria transmission; however, evidence on the use of seropositivity as an endpoint remains scarce in studies to evaluate combinations of malaria control measures, especially in children. This study aims to evaluate the immediate effects of a targeted mass drug administration campaign (tMDA) in Haiti by using serological markers. METHODS The tMDA was implemented in September-October 2018 using sulfadoxine-pyrimethamine and single low-dose primaquine. A natural quasi-experimental study was designed, using a pretest and posttest in a cohort of 754 randomly selected school children, among which 23% reported having received tMDA. Five antigens were selected as outcomes (MSP1-19, AMA-1, Etramp5 antigen 1, HSP40, and GLURP-R0). Posttest was conducted 2-6 weeks after the intervention. RESULTS At baseline, there was no statistical difference in seroprevalence between the groups of children that were or were not exposed during the posttest. A lower seroprevalence was observed for markers informative of recent exposure (Etramp5 antigen 1, HSP40, and GLURP-R0). Exposure to tMDA was significantly associated with a 50% reduction in the odds of seropositivity for Etramp5 antigen 1 and a 21% reduction in the odds of seropositivity for MSP119. CONCLUSION Serological markers can be used to evaluate the effects of interventions against malaria on the risk of infection in settings of low transmission. Antibody responses against Etramp5 antigen 1 in Haitian children were reduced in the 2-6 weeks following a tMDA campaign, confirming its usefulness as a short-term marker in child populations.
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Affiliation(s)
- T Druetz
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA. .,Department of Social and Preventive Medicine, School of Public Health, University of Montreal, Montreal, Canada. .,Centre de Recherche en Santé Publique, Montreal, Canada.
| | - L van den Hoogen
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA
| | - G Stresman
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - V Joseph
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA.,Department of Social and Preventive Medicine, School of Public Health, University of Montreal, Montreal, Canada
| | - K E S Hamre
- Malaria Branch, Centers for Diseases Control and Prevention, Atlanta, USA.,CDC Foundation, Atlanta, USA
| | - C Fayette
- IMA World Health, Port-au-Prince, Haiti
| | | | - J Presume
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - I Romilus
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - G Mondélus
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - T Elismé
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - S Cooper
- Department of Social and Preventive Medicine, School of Public Health, University of Montreal, Montreal, Canada
| | - D Impoinvil
- Malaria Branch, Centers for Diseases Control and Prevention, Atlanta, USA
| | - R A Ashton
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA
| | - E Rogier
- Malaria Branch, Centers for Diseases Control and Prevention, Atlanta, USA
| | - A Existe
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - J Boncy
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - M A Chang
- Malaria Branch, Centers for Diseases Control and Prevention, Atlanta, USA
| | - J F Lemoine
- Programme National de Contrôle du Paludisme, Port-au-Prince, Haiti
| | - C Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - T P Eisele
- Center for Applied Malaria Research and Evaluation, School of Public Health and Tropical Medicine, Tulane University, New Orleans, USA
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5
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Mooney JP, DonVito SM, Jahateh M, Bittaye H, Bottomley C, D'Alessandro U, Riley EM. Dry season prevalence of Plasmodium falciparum in asymptomatic gambian children, with a comparative evaluation of diagnostic methods. Malar J 2022; 21:171. [PMID: 35672850 PMCID: PMC9172138 DOI: 10.1186/s12936-022-04184-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 05/10/2022] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Subclinical infection with Plasmodium falciparum remains highly prevalent, yet diagnosing these often low-density infections remains a challenge. Infections can be subpatent, falling below the limit of detection for conventional thick-film microscopy and rapid diagnostic testing (RDT). In this study, the prevalence of subclinical P. falciparum infections in school-aged children was characterised at the start of the dry season in the Upper River Region of The Gambia in 2017/2018, with a goal to also compare the utility of different diagnostic tools. METHODS In a cross-sectional survey of children living in 29 villages on the south bank of the Gambia river (median age of 10 years), matched microscopy, rapid diagnostic test (RDT, detecting histidine-rich protein 2) and polymerase chain reaction (PCR, targeting either 18S rRNA or var gene acidic terminal sequence) were used to determine the prevalence of patent and subpatent infections and to compare the performance of the different diagnostic methods. RESULTS The prevalence of var gene acidic terminal sequence (varATS) qPCR-detectable infections was 10.2% (141/1381) with a median density of 3.12 parasites/µL. Malaria prevalence was highly heterogeneous across the region, ranging from < 1% to ~ 40% prevalence in different village clusters. Compared to varATS, 18S rRNA PCR detected fewer low-density infections, with an assay sensitivity of 50% and specificity of 98.8%. Parasite prevalence in the cohort was 2.9% by microscopy and 1.5% by RDT. Compared to varATS qPCR, microscopy and RDT had sensitivities of 11.5% and 9.2%, respectively, although both methods were highly specific (> 98%). Samples that were positive by all three tests (varATS qPCR, RDT and microscopy) had significantly higher parasite densities (median = 1705 parasites/µL) than samples that were positive by varATS qPCR only (median = 2.4 parasites/µL). CONCLUSIONS The majority of subclinical malaria infections in school-aged children were of extremely low parasite density and detectable only by ultra-sensitive PCR analysis. Understanding the duration of these low density infections, their physiological impact and their contribution to sustained parasite transmission is necessary to inform malaria elimination strategies.
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Affiliation(s)
- Jason P Mooney
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, Kings Buildings, Charlotte Auerbach Rd, Edinburgh, EH9 3FL, UK.
| | - Sophia M DonVito
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, Kings Buildings, Charlotte Auerbach Rd, Edinburgh, EH9 3FL, UK
| | - Maimuna Jahateh
- Medical Research Council Unit in The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Haddy Bittaye
- Medical Research Council Unit in The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Christian Bottomley
- Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Umberto D'Alessandro
- Medical Research Council Unit in The Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Eleanor M Riley
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, Kings Buildings, Charlotte Auerbach Rd, Edinburgh, EH9 3FL, UK
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Okebe J, Dabira E, Jaiteh F, Mohammed N, Bradley J, Drammeh NF, Bah A, Masunaga Y, Achan J, Muela Ribera J, Yeung S, Balen J, Peeters Grietens K, D'Alessandro U. Reactive, self-administered malaria treatment against asymptomatic malaria infection: results of a cluster randomized controlled trial in The Gambia. Malar J 2021; 20:253. [PMID: 34098984 PMCID: PMC8186162 DOI: 10.1186/s12936-021-03761-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 05/11/2021] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Selectively targeting and treating malaria-infected individuals may further decrease parasite carriage in low-burden settings. Using a trans-disciplinary approach, a reactive treatment strategy to reduce Plasmodium falciparum prevalence in participating communities was co-developed and tested. METHODS This is a 2-arm, open-label, cluster-randomized trial involving villages in Central Gambia during the 2017 and 2018 malaria transmission season. Villages were randomized in a 1:1 ratio using a minimizing algorithm. In the intervention arm, trained village health workers delivered a full course of pre-packed dihydroartemisinin-piperaquine to all residents of compounds where clinical cases were reported while in the control arm, compound residents were screened for infection at the time of the index case reporting. All index cases were treated following national guidelines. The primary endpoint was malaria prevalence, determined by molecular methods, at the end of the intervention period. RESULTS The trial was carried out in 50 villages: 34 in 2017 and 16 additional villages in 2018. At the end of the 2018 transmission season, malaria prevalence was 0.8% (16/1924, range 0-4%) and 1.1% (20/1814, range 0-17%) in the intervention and control arms, respectively. The odds of malaria infection were 29% lower in the intervention than in the control arm after adjustment for age (OR 0.71, 95% CI 0.27-1.84, p = 0.48). Adherence to treatment was high, with 98% (964/979) of those treated completing the 3-day treatment. Over the course of the study, only 37 villages, 20 in the intervention and 17 in the control arm, reported at least one clinical case. The distribution of clinical cases by month in both transmission seasons was similar and the odds of new clinical malaria cases during the trial period did not vary between arms (OR 1.04, 95% CI 0.57-1.91, p = 0.893). All adverse events were classified as mild to moderate and resolved completely. CONCLUSION The systematic and timely administration of an anti-malarial treatment to residents of compounds with confirmed malaria cases did not significantly decrease malaria prevalence and incidence in communities where malaria prevalence was already low. Treatment coverage and adherence was very high. Results were strongly influenced by the lower-than-expected malaria prevalence, and by no clinical cases in villages with asymptomatic malaria-infected individuals. TRIAL REGISTRATION This study is registered with ClinicalTrials.gov, NCT02878200. Registered 25 August 2016. https://clinicaltrials.gov/ct2/show/NCT02878200 .
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Affiliation(s)
- Joseph Okebe
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Edgard Dabira
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Fatou Jaiteh
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Amsterdam Institute of Social Science Research, Amsterdam, The Netherlands
| | - Nuredin Mohammed
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Ndey-Fatou Drammeh
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Amadou Bah
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Yoriko Masunaga
- Medical Anthropology Unit, Institute of Tropical Medicine, Antwerp, Belgium
- Amsterdam Institute of Social Science Research, Amsterdam, The Netherlands
| | - Jane Achan
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
- Malaria Consortium, Cambridge Heath, London, UK
| | | | - Shunmay Yeung
- Clinical Research Department, London School of Hygiene and Tropical Medicine, London, UK
| | - Julie Balen
- School of Health and Related Research, The University of Sheffield, Sheffield, UK
| | | | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia At the London School of Hygiene and Tropical Medicine, Fajara, The Gambia.
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7
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Wu L, Mwesigwa J, Affara M, Bah M, Correa S, Hall T, Singh SK, Beeson JG, Tetteh KKA, Kleinschmidt I, D’Alessandro U, Drakeley C. Sero-epidemiological evaluation of malaria transmission in The Gambia before and after mass drug administration. BMC Med 2020; 18:331. [PMID: 33183292 PMCID: PMC7664049 DOI: 10.1186/s12916-020-01785-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2020] [Accepted: 09/16/2020] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND As The Gambia aims to achieve malaria elimination by 2030, serological assays are a useful surveillance tool to monitor trends in malaria incidence and evaluate community-based interventions. METHODS Within a mass drug administration (MDA) study in The Gambia, where reduced malaria infection and clinical disease were observed after the intervention, a serological sub-study was conducted in four study villages. Spatio-temporal variation in transmission was measured with a panel of recombinant Pf antigens on a multiplexed bead-based assay. Village-level antibody levels were quantified as under-15 sero-prevalence, sero-conversion rates, and age-adjusted antibody acquisition rates. Antibody levels prior to MDA were assessed for association with persistent malaria infection after community chemoprophylaxis. RESULTS Seasonal changes in antibodies to Etramp5.Ag1 were observed in children under 15 years in two transmission settings-the West Coast and Upper River Regions (4.32% and 31.30% Pf prevalence, respectively). At the end of the malaria season, short-lived antibody responses to Etramp5.Ag1, GEXP18, HSP40.Ag1, EBA175 RIII-V, and Rh2.2030 were lower amongst 1-15 year olds in the West Coast compared to the Upper River, reflecting known differences in transmission. Prior to MDA, individuals in the top 50th percentile of antibody levels had two-fold higher odds of clinical malaria during the transmission season, consistent with previous findings from the Malaria Transmission Dynamics Study, where individuals infected before the implementation of MDA had two-fold higher odds of re-infection post-MDA. CONCLUSIONS Serological markers can serve dual functions as indicators of malaria exposure and incidence. By monitoring age-specific sero-prevalence, the magnitude of age-stratified antibody levels, or identifying groups of individuals with above-average antibody responses, these antigens have the potential to complement conventional malaria surveillance tools. Further studies, particularly cluster randomised trials, can help establish standardised serological protocols to reliably measure transmission across endemic settings.
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Affiliation(s)
- Lindsey Wu
- Faculty of Infectious Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT UK
| | - Julia Mwesigwa
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Muna Affara
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Arusha, Tanzania
| | - Mamadou Bah
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Simon Correa
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Tom Hall
- St. George’s University of London (SGUL), London, SW17 0RE UK
| | - Susheel K. Singh
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
- Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - James G. Beeson
- Burnet Institute, Melbourne, Victoria 3004 Australia
- Central Clinical School, Monash University, Melbourne, Victoria Australia
- Department of Medicine, University of Melbourne, Melbourne, Victoria Australia
| | - Kevin K. A. Tetteh
- Faculty of Infectious Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT UK
| | - Immo Kleinschmidt
- Faculty of Epidemiology and Population Health, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT UK
- School of Pathology, Wits Institute for Malaria Research, Faculty of Health Science, University of Witwatersrand, Johannesburg, South Africa
| | - Umberto D’Alessandro
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Chris Drakeley
- Faculty of Infectious Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT UK
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8
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Ondigo BN, Hamre KES, Frosch AEP, Ayodo G, White MT, John CC. Antibody Profiles to P. falciparum Antigens Over Time Characterize Acute and Long-Term Malaria Exposure in an Area of Low and Unstable Transmission. Am J Trop Med Hyg 2020; 103:2189-2197. [PMID: 33124539 DOI: 10.4269/ajtmh.19-0480] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Prevalence and levels of antibodies to multiple Plasmodium falciparum antigens show promise as tools for estimating malaria exposure. In a highland area of Kenya with unstable transmission, we assessed the presence and levels of antibodies to 12 pre-erythrocytic and blood-stage P. falciparum antigens by multiplex cytometric bead assay or ELISA in 604 individuals in August 2007, with follow-up testing in this cohort in April 2008, April 2009, and May 2010. Four hundred individuals were tested at all four time points. During this period, the only substantial malaria incidence occurred from April to August 2009. Antibody prevalence in adults was high at all time points (> 70%) for apical membrane antigen 1, erythrocyte-binding antigen 175, erythrocyte-binding protein-2, glutamate rich protein (GLURP)-R2, merozoite surface protein (MSP) 1 (19), MSP-1 (42), and liver-stage antigen-1; moderate (30-70%) for GLURP-R0, MSP-3, and thrombospondin-related adhesive protein; and low (< 30%) for SE and circumsporozoite protein (CSP). Changes in community-wide malaria exposure were best reflected in decreasing antibody levels overtime for highly immunogenic antigens, and in antibody seroprevalence overtime for the less-immunogenic antigens. Over the 3 years, antibody levels to all antigens except CSP and schizont extract (SE) decreased in an age-dependent manner. Prevalence and levels of antibodies to all antigens except CSP and SE increased with age. Increases in antibody prevalence and levels to CSP and SE coincided with increases in community-wide malaria incidence. Antibody levels to multiple P. falciparum antigens decrease in the absence of consistent transmission. Multiplex assays that assess both the presence and level of antibodies to multiple pre-erythrocytic and blood-stage P. falciparum antigens may provide the most useful estimates of past and recent malaria transmission in areas of unstable transmission and could be useful tools in malaria control and elimination campaigns.
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Affiliation(s)
- Bartholomew N Ondigo
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health (NIH), Bethesda, Maryland.,Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.,Department of Biochemistry and Molecular Biology, Egerton University, Nakuru, Kenya
| | - Karen E S Hamre
- CDC Foundation, Atlanta, Georgia.,Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, Minnesota.,Division of Global Pediatrics, University of Minnesota, Minneapolis, Minnesota
| | - Anne E P Frosch
- Hennepin Healthcare Research Institute, Minneapolis, Minnesota.,Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - George Ayodo
- School of Health Sciences, Jaramogi Oginga Odinga University of Science and Technology, Siaya, Kenya.,Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Michael T White
- Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France
| | - Chandy C John
- Division of Global Pediatrics, University of Minnesota, Minneapolis, Minnesota.,Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.,Ryan White Center for Pediatric Infectious Diseases and Global Health, Indiana University School of Medicine, Indianapolis, Indiana
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9
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Wu L, Mwesigwa J, Affara M, Bah M, Correa S, Hall T, Singh SK, Beeson JG, Tetteh KKA, Kleinschmidt I, D'Alessandro U, Drakeley C. Antibody responses to a suite of novel serological markers for malaria surveillance demonstrate strong correlation with clinical and parasitological infection across seasons and transmission settings in The Gambia. BMC Med 2020; 18:304. [PMID: 32972398 PMCID: PMC7517687 DOI: 10.1186/s12916-020-01724-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 07/30/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND As malaria transmission declines, sensitive diagnostics are needed to evaluate interventions and monitor transmission. Serological assays measuring malaria antibody responses offer a cost-effective detection method to supplement existing surveillance tools. METHODS A prospective cohort study was conducted from 2013 to 2015 in 12 villages across five administrative regions in The Gambia. Serological analysis included samples from the West Coast Region at the start and end of the season (July and December 2013) and from the Upper River Region in July and December 2013 and April and December 2014. Antigen-specific antibody responses to eight Plasmodium falciparum (P. falciparum) antigens-Etramp5.Ag1, GEXP18, HSP40.Ag1, Rh2.2030, EBA175 RIII-V, PfMSP119, PfAMA1, and PfGLURP.R2-were quantified using a multiplexed bead-based assay. The association between antibody responses and clinical and parasitological endpoints was estimated at the individual, household, and population level. RESULTS Strong associations were observed between clinical malaria and concurrent sero-positivity to Etramp5.Ag1 (aOR 4.60 95% CI 2.98-7.12), PfMSP119 (aOR 4.09 95% CI 2.60-6.44), PfAMA1 (aOR 2.32 95% CI 1.40-3.85), and PfGLURP.R2 (aOR 3.12, 95% CI 2.92-4.95), while asymptomatic infection was associated with sero-positivity to all antigens. Village-level sero-prevalence amongst children 2-10 years against Etramp5.Ag1, HSP40.Ag1, and PfMSP119 showed the highest correlations with clinical and P. falciparum infection incidence rates. For all antigens, there were increased odds of asymptomatic P. falciparum infection in subjects residing in a compound with greater than 50% sero-prevalence, with a 2- to 3-fold increase in odds of infection associated with Etramp5.Ag1, GEXP18, Rh2.2030, PfMSP119, and PfAMA1. For individuals residing in sero-positive compounds, the odds of clinical malaria were reduced, suggesting a protective effect. CONCLUSIONS At low transmission, long-lived antibody responses could indicate foci of malaria transmission that have been ongoing for several seasons or years. In settings where sub-patent infections are prevalent and fluctuate below the detection limit of polymerase chain reaction (PCR), the presence of short-lived antibodies may indicate recent infectivity, particularly in the dry season when clinical cases are rare. Serological responses may reflect a persistent reservoir of infection, warranting community-targeted interventions if individuals are not clinically apparent but have the potential to transmit. Therefore, serological surveillance at the individual and household level may be used to target interventions where there are foci of asymptomatically infected individuals, such as by measuring the magnitude of age-stratified antibody levels or identifying areas with clustering of above-average antibody responses across a diverse range of serological markers.
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Affiliation(s)
- Lindsey Wu
- Faculty of Infectious Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK.
| | - Julia Mwesigwa
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Muna Affara
- Bernhard Nocht Institute for Tropical Medicine (BNITM), Arusha, Tanzania
| | - Mamadou Bah
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Simon Correa
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Tom Hall
- St. George's University of London (SGUL), London, UK
| | - Susheel K Singh
- Department for Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Centre for Medical Parasitology at Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - James G Beeson
- Burnet Institute, Melbourne, Australia.,Central Clinical School, Monash University, Melbourne, Victoria, Australia.,Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - Kevin K A Tetteh
- Faculty of Infectious Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
| | - Immo Kleinschmidt
- Faculty of Epidemiology and Population Health, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK.,School of Pathology, Wits Institute for Malaria Research, Faculty of Health Science, University of Witwatersrand, Johannesburg, South Africa
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Chris Drakeley
- Faculty of Infectious Tropical Diseases, Department of Infection Biology, London School of Hygiene and Tropical Medicine (LSHTM), London, WC1E 7HT, UK
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10
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van den Hoogen LL, Bareng P, Alves J, Reyes R, Macalinao M, Rodrigues JM, Fernandes JM, Goméz LF, Hall T, Singh SK, Fornace K, Luchavez J, Kitchen A, Chiodini P, Espino F, Tetteh KKA, Stresman G, Sepúlveda N, Drakeley C. Comparison of Commercial ELISA Kits to Confirm the Absence of Transmission in Malaria Elimination Settings. Front Public Health 2020; 8:480. [PMID: 33014975 PMCID: PMC7509087 DOI: 10.3389/fpubh.2020.00480] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 07/28/2020] [Indexed: 11/13/2022] Open
Abstract
Background: Antimalarial antibody measurements are useful because they reflect historical and recent exposure to malaria. As such, they may provide additional information to assess ongoing transmission in low endemic or pre-elimination settings where cases are rare. In addition, the absence of antibody responses in certain individuals can indicate the cessation of transmission. Commercial malaria enzyme-linked immunosorbent assays (ELISA) detect antimalarial antibodies and are commonly used to screen blood donations for possible malaria infection. However, there is no standardized test to detect antimalarial antibodies for epidemiological use. Here we compared five commercially available ELISA kits (Trinity Biotech, newbio, DiaPro, Cellabs, and NovaTec) in search of a standardized tool for supporting claims of absence of malaria transmission. For comparison, a research-based (RB) ELISA protocol was performed alongside the commercial kits. Results: The commercial kits were first compared using serum samples from known malaria-unexposed individuals (n = 223) and Toxoplasma-infected individuals (n = 191) to assess specificity and cross-reactivity against non-malaria infections. In addition, 134 samples from ≥10-year-olds collected in a hyperendemic region in the Gambia in the early 1990s were used to assess sensitivity. Three out of five kits showed high sensitivity (90–92%), high specificity (98–99%), low cross-reactivity (0–3%) and were considered user-friendly (Trinity Biotech, newbio and NovaTec). Two of these kits (Trinity Biotech and NovaTec) were taken forward for epidemiological evaluation and results were compared to those using the RB-ELISA. Samples from two pre-elimination settings (Praia, Cape Verde; n = 1,396, and Bataan, the Philippines; n = 1,824) were tested. Serological results from both the Trinity Biotech kit and the RB-ELISA concurred with recent passively detected case counts in both settings. Results from the Trinity Biotech kit reflected a significant decrease in the number of reported cases in Bataan in the 1990s better than the RB-ELISA. Results from the NovaTec kit did not reflect transmission patterns in either setting. Conclusion: The Trinity Biotech commercial ELISA kit was considered reliable for epidemiological use and accurately described transmission patterns in two (previously) malaria endemic settings. The use of this simple and standardized serological tool may aid national control and elimination programs by confirming that regions are free from malaria.
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Affiliation(s)
- Lotus L van den Hoogen
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Paolo Bareng
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Joana Alves
- National Institute of Public Health, Praia, Cape Verde
| | - Ralph Reyes
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Malou Macalinao
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | | | - José M Fernandes
- Faculty of Science and Technology, University of Cape Verde, Praia, Cape Verde
| | - Lara F Goméz
- Department of Natural, Life and Environmental Sciences, Jean Piaget University of Cape Verde, Praia, Cape Verde
| | - Tom Hall
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Susheel K Singh
- Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Department of Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Kimberly Fornace
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jennifer Luchavez
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Alan Kitchen
- NHS Blood and Transplant, London, United Kingdom
| | - Peter Chiodini
- Hospital for Tropical Diseases and London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Fe Espino
- Department of Health, Research Institute for Tropical Medicine, Manila, Philippines
| | - Kevin K A Tetteh
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Gillian Stresman
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Nuno Sepúlveda
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom.,Centre of Statistics and Applications, University of Lisbon, Lisbon, Portugal
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, United Kingdom
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11
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van den Hoogen LL, Stresman G, Présumé J, Romilus I, Mondélus G, Elismé T, Existe A, Hamre KES, Ashton RA, Druetz T, Joseph V, Beeson JG, Singh SK, Boncy J, Eisele TP, Chang MA, Lemoine JF, Tetteh KKA, Rogier E, Drakeley C. Selection of Antibody Responses Associated With Plasmodium falciparum Infections in the Context of Malaria Elimination. Front Immunol 2020; 11:928. [PMID: 32499783 PMCID: PMC7243477 DOI: 10.3389/fimmu.2020.00928] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 04/21/2020] [Indexed: 12/30/2022] Open
Abstract
In our aim to eliminate malaria, more sensitive tools to detect residual transmission are quickly becoming essential. Antimalarial antibody responses persist in the blood after a malaria infection and provide a wider window to detect exposure to infection compared to parasite detection metrics. Here, we aimed to select antibody responses associated with recent and cumulative exposure to malaria using cross-sectional survey data from Haiti, an elimination setting. Using a multiplex bead assay, we generated data for antibody responses (immunoglobulin G) to 23 Plasmodium falciparum targets in 29,481 participants across three surveys. This included one community-based survey in which participants were enrolled during household visits and two sentinel group surveys in which participants were enrolled at schools and health facilities. First, we correlated continuous antibody responses with age (Spearman) to determine which showed strong age-related associations indicating accumulation over time with limited loss. AMA-1 and MSP-119 antibody levels showed the strongest correlation with age (0.47 and 0.43, p < 0.001) in the community-based survey, which was most representative of the underlying age structure of the population, thus seropositivity to either of these antibodies was considered representative of cumulative exposure to malaria. Next, in the absence of a gold standard for recent exposure, we included antibody responses to the remaining targets to predict highly sensitive rapid diagnostic test (hsRDT) status using receiver operating characteristic curves. For this, only data from the survey with the highest hsRDT prevalence was used (7.2%; 348/4,849). The performance of the top two antigens in the training dataset (two-thirds of the dataset; n = 3,204)-Etramp 5 ag 1 and GLURP-R0 (area-under-the-curve, AUC, 0.892 and 0.825, respectively)-was confirmed in the test dataset (remaining one-third of the dataset; n = 1,652, AUC 0.903 and 0.848, respectively). As no further improvement was seen by combining seropositivity to GLURP-R0 and Etramp 5 ag 1 (p = 0.266), seropositivity to Etramp 5 ag 1 alone was selected as representative of current or recent exposure to malaria. The validation of antibody responses associated with these exposure histories simplifies analyses and interpretation of antibody data and facilitates the application of results to evaluate programs.
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Affiliation(s)
- Lotus L. van den Hoogen
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
| | - Gillian Stresman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | | | | | - Gina Mondélus
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - Tamara Elismé
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | | | - Karen E. S. Hamre
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
- CDC Foundation, Atlanta, GA, United States
| | - Ruth A. Ashton
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
| | - Thomas Druetz
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
- Department of Social and Preventive Medicine, University of Montreal School of Public Health, Montreal, QC, Canada
| | - Vena Joseph
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
| | - James G. Beeson
- Burnet Institute, Melbourne, VIC, Australia
- Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia
- Central Clinical School and Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Susheel K. Singh
- Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark
- Department of Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Jacques Boncy
- Laboratoire National de Santé Publique, Port-au-Prince, Haiti
| | - Thomas P. Eisele
- Center for Applied Malaria Research and Evaluation, Tulane University School of Public Health & Tropical Medicine, New Orleans, LA, United States
| | - Michelle A. Chang
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Jean F. Lemoine
- Ministère de la Santé Publique et de la Population, Port-au-Prince, Haiti
| | - Kevin K. A. Tetteh
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, United States
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, United Kingdom
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12
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Rogier E, van den Hoogen L, Herman C, Gurrala K, Joseph V, Stresman G, Presume J, Romilus I, Mondelus G, Elisme T, Ashton R, Chang M, Lemoine JF, Druetz T, Eisele TP, Existe A, Boncy J, Drakeley C, Udhayakumar V. High-throughput malaria serosurveillance using a one-step multiplex bead assay. Malar J 2019; 18:402. [PMID: 31801556 PMCID: PMC6894145 DOI: 10.1186/s12936-019-3027-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/21/2019] [Indexed: 01/21/2023] Open
Abstract
Background Serological data indicating the presence and level of antibodies against infectious disease antigens provides indicators of exposure and transmission patterns in a population. Laboratory testing for large-scale serosurveys is often hindered by time-consuming immunoassays that employ multiple tandem steps. Some nations have recently begun using malaria serosurveillance data to make inferences about the malaria exposure in their populations, and serosurveys have grown increasingly larger as more accurate estimates are desired. Presented here is a novel approach of antibody detection using bead-based immunoassay that involves incubating all assay reagents concurrently overnight. Results A serosurvey in was performed in Haiti in early 2017 with both sera (n = 712) and dried blood spots (DBS, n = 796) collected for the same participants. The Luminex® multiplex bead-based assay (MBA) was used to detect total IgG against 8 malaria antigens: PfMSP1, PvMSP1, PmMSP1, PfCSP, PfAMA1, PfLSA1, PfGLURP-R0, PfHRP2. All sera and DBS samples were assayed by MBA using a standard immunoassay protocol with multiple steps, as well a protocol where sample and all reagents were incubated together overnight—termed here the OneStep assay. When compared to a standard multi-step assay, this OneStep assay amplified the assay signal for IgG detection for all 8 malaria antigens. The greatest increases in assay signal were seen at the low- and mid-range IgG titers and were indicative of an enhancement in the analyte detection, not simply an increase in the background signal of the assay. Seroprevalence estimates were generally similar for this sample Haitian population for all antigens regardless of serum or DBS sample type or assay protocol used. Conclusions When using the MBA for IgG detection, overnight incubation for the test sample and all assay reagents greatly minimized hands-on time for laboratory staff. Enhanced IgG signal was observed with the OneStep assay for all 8 malaria antigens employed in this study, and seroprevalence estimates for this sample population were similar regardless of assay protocol used. This overnight incubation protocol has the potential to be deployed for large-scale malaria serosurveys for the high-throughput and timely collection of antibody data, particularly for malaria seroprevalence estimates.
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Affiliation(s)
- Eric Rogier
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA.
| | - Lotus van den Hoogen
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Camelia Herman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA.,CDC Foundation, Atlanta, GA, 30308, USA
| | - Kevin Gurrala
- Georgia Institute of Technology, Atlanta, GA, 30332, USA
| | - Vena Joseph
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, 70112, USA
| | - Gillian Stresman
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Jacquelin Presume
- Laboratoire National de Santé Publique (LNSP), Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | - Ithamare Romilus
- Laboratoire National de Santé Publique (LNSP), Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | - Gina Mondelus
- Laboratoire National de Santé Publique (LNSP), Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | - Tamara Elisme
- Laboratoire National de Santé Publique (LNSP), Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | - Ruth Ashton
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, 70112, USA
| | - Michelle Chang
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
| | - Jean F Lemoine
- Programme National de Contrôle de la Malaria/MSPP, Port-au-Prince, Haiti
| | - Thomas Druetz
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, 70112, USA.,Department of Social and Preventive Medicine, University of Montreal School of Public Health, Montreal, QC, H3X 1X9, Canada
| | - Thomas P Eisele
- Center for Applied Malaria Research and Evaluation, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, 70112, USA
| | - Alexandre Existe
- Laboratoire National de Santé Publique (LNSP), Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | - Jacques Boncy
- Laboratoire National de Santé Publique (LNSP), Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, WC1E 7HT, UK
| | - Venkatachalam Udhayakumar
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, GA, 30329, USA
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13
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Surendra H, Wijayanti MA, Murhandarwati EH, Irnawati, Yuniarti T, Mardiati, Herdiana, Sumiwi ME, Hawley WA, Lobo NF, Cook J, Drakeley C, Supargiyono. Analysis of serological data to investigate heterogeneity of malaria transmission: a community-based cross-sectional study in an area conducting elimination in Indonesia. Malar J 2019; 18:227. [PMID: 31286973 PMCID: PMC6615161 DOI: 10.1186/s12936-019-2866-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 07/03/2019] [Indexed: 01/22/2023] Open
Abstract
Background Analysis of anti-malarial antibody responses has the potential to improve characterization of the variation in exposure to infection in low transmission settings, where conventional measures, such as entomological estimates and parasitaemia point prevalence become less sensitive and expensive to measure. This study evaluates the use of sero-epidemiological analysis to investigate heterogeneity of transmission in area conducting elimination in Indonesia. Methods Filter paper bloodspots and epidemiological data were collected through a community-based cross-sectional study conducted in two sub-districts in Sabang municipality, Aceh province, Indonesia in 2013. Antibody responses to merozoite surface protein 1 (MSP-119) and apical membrane antigen 1 (AMA-1) for Plasmodium falciparum and Plasmodium vivax were measured using indirect enzyme-linked immunosorbent assay (ELISA). Seroconversion rates (SCR) were estimated by fitting a simple reversible catalytic model to seroprevalence data for each antibody. Spatial analysis was performed using a Normal model (SaTScan v.9.4.2) to identify the clustering of higher values of household antibody responses. Multiple logistic regression was used to investigate factors associated with exposure. Results 1624 samples were collected from 605 households. Seroprevalence to any P. falciparum antigen was higher than to any P. vivax antigen, 6.9% (95% CI 5.8–8.2) vs 2.0% (95% CI 1.4–2.8). SCR estimates suggest that there was a significant change in P. falciparum transmission with no exposure seen in children under 5 years old. Plasmodium falciparum SCR in over 5 years old was 0.008 (95% CI 0.003–0.017) and 0.012 (95% CI 0.005–0.030) in Sukakarya and Sukajaya sub-districts, respectively. Clusters of exposure were detected for both P. falciparum and P. vivax, most of them in Sukajaya sub-district. Higher age, P. vivax seropositivity and use of long-lasting insecticide-treated bed net (LLIN) were associated with higher P. falciparum exposure. Conclusion Analysis of community-based serological data helps describe the level of transmission, heterogeneity and factors associated with malaria transmission in Sabang. This approach could be an important additional tool for malaria monitoring and surveillance in low transmission settings in Indonesia. Electronic supplementary material The online version of this article (10.1186/s12936-019-2866-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Henry Surendra
- Infection Biology Department, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK. .,Centre for Tropical Medicine, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia.
| | - Mahardika A Wijayanti
- Centre for Tropical Medicine, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia.,Department of Parasitology, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia
| | - Elsa H Murhandarwati
- Centre for Tropical Medicine, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia.,Department of Parasitology, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia
| | - Irnawati
- Sabang Municipal Health Office, Sabang, Aceh, Indonesia
| | | | - Mardiati
- Sabang Municipal Health Office, Sabang, Aceh, Indonesia
| | - Herdiana
- Child Survival and Development Cluster, UNICEF Aceh Field Office, Jakarta, Indonesia
| | - Maria E Sumiwi
- Child Survival and Development Cluster, UNICEF Aceh Field Office, Jakarta, Indonesia
| | - William A Hawley
- Child Survival and Development Cluster, UNICEF Indonesia Country Office, Jakarta, Indonesia
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Jackie Cook
- MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Chris Drakeley
- Infection Biology Department, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Supargiyono
- Centre for Tropical Medicine, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia.,Department of Parasitology, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, 55281, Indonesia
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14
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Kobayashi T, Jain A, Liang L, Obiero JM, Hamapumbu H, Stevenson JC, Thuma PE, Lupiya J, Chaponda M, Mulenga M, Mamini E, Mharakurwa S, Gwanzura L, Munyati S, Mutambu S, Felgner P, Davies DH, Moss WJ. Distinct Antibody Signatures Associated with Different Malaria Transmission Intensities in Zambia and Zimbabwe. mSphere 2019; 4:e00061-19. [PMID: 30918058 PMCID: PMC6437277 DOI: 10.1128/mspheredirect.00061-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/30/2022] Open
Abstract
Antibodies to Plasmodium falciparum are specific biomarkers that can be used to monitor parasite exposure over broader time frames than microscopy, rapid diagnostic tests, or molecular assays. Consequently, seroprevalence surveys can assist with monitoring the impact of malaria control interventions, particularly in the final stages of elimination, when parasite incidence is low. The protein array format to measure antibodies to diverse P. falciparum antigens requires only small sample volumes and is high throughput, permitting the monitoring of malaria transmission on large spatial and temporal scales. We expanded the use of a protein microarray to assess malaria transmission in settings beyond those with a low malaria incidence. Antibody responses in children and adults were profiled, using a P. falciparum protein microarray, through community-based surveys in three areas in Zambia and Zimbabwe at different stages of malaria control and elimination. These three epidemiological settings had distinct serological profiles reflective of their malaria transmission histories. While there was little correlation between transmission intensity and antibody signals (magnitude or breadth) in adults, there was a clear correlation in children younger than 5 years of age. Antibodies in adults appeared to be durable even in the absence of significant recent transmission, whereas antibodies in children provided a more accurate picture of recent levels of transmission intensity. Seroprevalence studies in children could provide a valuable marker of progress toward malaria elimination.IMPORTANCE As malaria approaches elimination in many areas of the world, monitoring the effect of control measures becomes more important but challenging. Low-level infections may go undetected by conventional tests that depend on parasitemia, particularly in immune individuals, who typically show no symptoms of malaria. In contrast, antibodies persist after parasitemia and may provide a more accurate picture of recent exposure. Only a few parasite antigens-mainly vaccine candidates-have been evaluated in seroepidemiological studies. We examined antibody responses to 500 different malaria proteins in blood samples collected through community-based surveillance from areas with low, medium, and high malaria transmission intensities. The breadth of the antibody responses in adults was broad in all three settings and was a poor correlate of recent exposure. In contrast, children represented a better sentinel population for monitoring recent malaria transmission. These data will help inform the use of multiplex serology for malaria surveillance.
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Affiliation(s)
- Tamaki Kobayashi
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Aarti Jain
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Li Liang
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - Joshua M Obiero
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | | | - Jennifer C Stevenson
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Macha Research Trust, Choma, Zambia
| | - Philip E Thuma
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
- Macha Research Trust, Choma, Zambia
| | - James Lupiya
- Tropical Diseases Research Centre, Ndola, Zambia
| | | | | | - Edmore Mamini
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | | | | | - Shungu Munyati
- Biomedical Research and Training Institute, Harare, Zimbabwe
| | - Susan Mutambu
- National Institute of Health Research, Harare, Zimbabwe
| | - Philip Felgner
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - D Huw Davies
- Vaccine Research & Development Center, Department of Physiology & Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA
| | - William J Moss
- Johns Hopkins Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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15
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van den Hoogen LL, Walk J, Oulton T, Reuling IJ, Reiling L, Beeson JG, Coppel RL, Singh SK, Draper SJ, Bousema T, Drakeley C, Sauerwein R, Tetteh KKA. Antibody Responses to Antigenic Targets of Recent Exposure Are Associated With Low-Density Parasitemia in Controlled Human Plasmodium falciparum Infections. Front Microbiol 2019; 9:3300. [PMID: 30700984 PMCID: PMC6343524 DOI: 10.3389/fmicb.2018.03300] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 12/18/2018] [Indexed: 12/05/2022] Open
Abstract
The majority of malaria infections in low transmission settings remain undetectable by conventional diagnostics. A powerful model to identify antibody responses that allow accurate detection of recent exposure to low-density infections is controlled human malaria infection (CHMI) studies in which healthy volunteers are infected with the Plasmodium parasite. We aimed to evaluate antibody responses in malaria-naïve volunteers exposed to a single CHMI using a custom-made protein microarray. All participants developed a blood-stage infection with peak parasite densities up to 100 parasites/μl in the majority of participants (50/54), while the remaining four participants had peak densities between 100 and 200 parasites/μl. There was a strong correlation between parasite density and antibody responses associated with the most reactive blood-stage targets 1 month after CHMI (Etramp 5, GLURP-R2, MSP4 and MSP1-19; Spearman’s ρ = 0.82, p < 0.001). Most volunteers developed antibodies against a potential marker of recent exposure: Etramp 5 (37/45, 82%). Our findings justify validation in endemic populations to define a minimum set of antigens needed to detect exposure to natural low-density infections.
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Affiliation(s)
- Lotus L van den Hoogen
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Jona Walk
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Tate Oulton
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Isaie J Reuling
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | | | - James G Beeson
- Burnet Institute, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Melbourne, VIC, Australia.,Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Ross L Coppel
- Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Susheel K Singh
- Department of Congenital Disorders, Statens Serum Institut, Copenhagen, Denmark.,Department of International Health, Immunology and Microbiology, Centre for Medical Parasitology, University of Copenhagen, Copenhagen, Denmark
| | - Simon J Draper
- Jenner Institute, University of Oxford, Oxford, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands
| | - Kevin K A Tetteh
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, United Kingdom
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16
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Duffy CW, Amambua-Ngwa A, Ahouidi AD, Diakite M, Awandare GA, Ba H, Tarr SJ, Murray L, Stewart LB, D'Alessandro U, Otto TD, Kwiatkowski DP, Conway DJ. Multi-population genomic analysis of malaria parasites indicates local selection and differentiation at the gdv1 locus regulating sexual development. Sci Rep 2018; 8:15763. [PMID: 30361631 PMCID: PMC6202401 DOI: 10.1038/s41598-018-34078-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Accepted: 10/11/2018] [Indexed: 02/08/2023] Open
Abstract
Parasites infect hosts in widely varying environments, encountering diverse challenges for adaptation. To identify malaria parasite genes under locally divergent selection across a large endemic region with a wide spectrum of transmission intensity, genome sequences were obtained from 284 clinical Plasmodium falciparum infections from four newly sampled locations in Senegal, The Gambia, Mali and Guinea. Combining these with previous data from seven other sites in West Africa enabled a multi-population analysis to identify discrete loci under varying local selection. A genome-wide scan showed the most exceptional geographical divergence to be at the early gametocyte gene locus gdv1 which is essential for parasite sexual development and transmission. We identified a major structural dimorphism with alternative 1.5 kb and 1.0 kb sequence deletions at different positions of the 3'-intergenic region, in tight linkage disequilibrium with the most highly differentiated single nucleotide polymorphism, one of the alleles being very frequent in Senegal and The Gambia but rare in the other locations. Long non-coding RNA transcripts were previously shown to include the entire antisense of the gdv1 coding sequence and the portion of the intergenic region with allelic deletions, suggesting adaptive regulation of parasite sexual development and transmission in response to local conditions.
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Affiliation(s)
- Craig W Duffy
- Pathogen Molecular Biology Department, London School of Hygiene and Tropical Medicine, Keppel St, London, UK
| | | | | | - Mahamadou Diakite
- Malaria Research and Training Center, University of Bamako, Bamako, Mali
| | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP) and Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Ghana
| | - Hampate Ba
- Institut National de Recherches en Santé Publique (INRSP), Nouakchott, Mauritania
| | - Sarah J Tarr
- Pathogen Molecular Biology Department, London School of Hygiene and Tropical Medicine, Keppel St, London, UK
| | - Lee Murray
- Pathogen Molecular Biology Department, London School of Hygiene and Tropical Medicine, Keppel St, London, UK
| | - Lindsay B Stewart
- Pathogen Molecular Biology Department, London School of Hygiene and Tropical Medicine, Keppel St, London, UK
| | - Umberto D'Alessandro
- MRC Gambia Unit, Fajara, The Gambia
- Disease Control Department, London School of Hygiene and Tropical Medicine, Keppel St, London, UK
| | - Thomas D Otto
- Malaria Programme, Wellcome Trust Sanger Institute, Cambridge, UK
| | | | - David J Conway
- Pathogen Molecular Biology Department, London School of Hygiene and Tropical Medicine, Keppel St, London, UK.
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17
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Optimization of a magnetic bead-based assay (MAGPIX ®-Luminex) for immune surveillance of exposure to malaria using multiple Plasmodium antigens and sera from different endemic settings. Malar J 2018; 17:324. [PMID: 30189885 PMCID: PMC6127931 DOI: 10.1186/s12936-018-2465-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 08/27/2018] [Indexed: 01/08/2023] Open
Abstract
Background Serological markers are potentially useful tools for monitoring the progress of malaria control programs, but a better understanding of antibody response dynamics is necessary. The use of a magnetic bead-based immunoassay (MBA) is advantageous compared to ELISA, due to its multiplexing capacity, but limited information is available on the standardization and validation of this assay. Methods Several parameters for multiplex testing of antibodies to Plasmodium antigens were analysed using a set of 4 antigens and 98 sera from Senegalese rural asymptomatic and urban symptomatic individuals. The 4 antigens included Plasmodium falciparum CSP and PfAMA1 peptides, recombinant P. falciparum MSP4p20 and a Plasmodium malariae CSP (PmCSP) peptide. Comparisons with ELISA were done using MSP4p20 and whole schizont extract (SE) antigens. Results The use of fewer beads (1000 beads per well instead of 2000) and 5 µg of antigen per 106 bead were validated as lower amounts. The use of a carrier protein (BSA) was shown to be critical when using peptides and the effect of a 24 h delayed measures was evaluated (5–25% signal decrease). Analysis of Ab responses showed almost equally high levels and prevalence in all transmission settings. Clear distinctions between rural and urban malaria were noted using PmCSP and SE antigens. Conclusions This study underlines the importance of further optimization of the MBA technique and highlights the interest of using multistage/multispecies antigens for surveillance of malaria in endemic settings.
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18
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Consistent signatures of selection from genomic analysis of pairs of temporal and spatial Plasmodium falciparum populations from The Gambia. Sci Rep 2018; 8:9687. [PMID: 29946063 PMCID: PMC6018809 DOI: 10.1038/s41598-018-28017-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 06/14/2018] [Indexed: 11/16/2022] Open
Abstract
Genome sequences of 247 Plasmodium falciparum isolates collected in The Gambia in 2008 and 2014 were analysed to identify changes possibly related to the scale-up of antimalarial interventions that occurred during this period. Overall, there were 15 regions across the genomes with signatures of positive selection. Five of these were sweeps around known drug resistance and antigenic loci. Signatures at antigenic loci such as thrombospodin related adhesive protein (Pftrap) were most frequent in eastern Gambia, where parasite prevalence and transmission remain high. There was a strong temporal differentiation at a non-synonymous SNP in a cysteine desulfarase (Pfnfs) involved in iron-sulphur complex biogenesis. During the 7-year period, the frequency of the lysine variant at codon 65 (Pfnfs-Q65K) increased by 22% (10% to 32%) in the Greater Banjul area. Between 2014 and 2015, the frequency of this variant increased by 6% (20% to 26%) in eastern Gambia. IC50 for lumefantrine was significantly higher in Pfnfs-65K isolates. This is probably the first evidence of directional selection on Pfnfs or linked loci by lumefantrine. Given the declining malaria transmission, the consequent loss of population immunity, and sustained drug pressure, it is important to monitor Gambian P. falciparum populations for further signs of adaptation.
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19
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Micro-epidemiology of malaria in an elimination setting in Central Vietnam. Malar J 2018; 17:119. [PMID: 29554901 PMCID: PMC5859719 DOI: 10.1186/s12936-018-2262-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 03/08/2018] [Indexed: 11/10/2022] Open
Abstract
Background In Vietnam, malaria persists in remote forested regions where infections are spatially heterogeneous, mostly asymptomatic and with low parasite density. Previous studies in Vietnam have investigated broad behavioural concepts such as ‘engaging in forest activities’ as risk factors for malaria infection, which may not explain heterogeneity in malaria risk, especially in malaria elimination settings. Methods A mixed methods study combining ethnographic research and a cross-sectional survey was embedded in a 1-year malariometric cohort study in three ethnic minority villages in South Tra My district, Quang Nam Province in Central Vietnam. Qualitative data collection included in-depth interviews, informal conversations and participant observations over a 2-month period, and the findings were used to develop the questionnaire used in the cross-sectional survey. The latter collected data on evening activities, mobility patterns and household characteristics. The primary outcome, recent exposure to malaria, was defined using the classification and regression tree method to determine significant changes in antibody titres during the year preceding the survey. Risk factor analyses for recent exposure to malaria were conducted using logistic regression. Results 22 in-depth interviews and numerous participant observations were recorded during the ethnographic research (April to June 2015), and 160 adults (86% response rate) responded to the cross-sectional survey (November to December 2015). Recent exposure to Plasmodium falciparum malaria was estimated at 22.9 and at 17.1% for Plasmodium vivax. Ongoing malaria transmission appears to be maintained by activities that delay or disrupt sleeping in a permanent structure in which a bed net could be hung, including evening drinking gatherings, fishing, logging in the forest and outdoor TV watching. Conclusions Vector control tools for outdoor evening activities in villages as well as at farms, forest and river locations should be incorporated into current malaria elimination efforts in Central Vietnam. Micro-epidemiology studies using mixed-methods designs can provide a comprehensive understanding of the malaria risk at fine spatial scales and better inform the implementation of targeted interventions for malaria elimination. Electronic supplementary material The online version of this article (10.1186/s12936-018-2262-0) contains supplementary material, which is available to authorized users.
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20
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Okebe J, Ribera JM, Balen J, Jaiteh F, Masunaga Y, Nwakanma D, Bradley J, Yeung S, Peeters Grietens K, D'Alessandro U. Reactive community-based self-administered treatment against residual malaria transmission: study protocol for a randomized controlled trial. Trials 2018; 19:126. [PMID: 29463288 PMCID: PMC5819183 DOI: 10.1186/s13063-018-2506-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 01/29/2018] [Indexed: 11/18/2022] Open
Abstract
Background Systematic treatment of all individuals living in the same compound of a clinical malaria case may clear asymptomatic infections and possibly reduce malaria transmission, where this is focal. High and sustained coverage is extremely important and requires active community engagement. This study explores a community-based approach to treating malaria case contacts. Methods/design This is a cluster-randomized trial to determine whether, in low-transmission areas, treating individuals living in the same compound of a clinical malaria case with dihydroartemisinin-piperaquine can reduce parasite carriage and thus residual malaria transmission. Treatment will be administered through the local health system with the approach of encouraging community participation designed and monitored through formative research. The trial goal is to show that this approach can reduce in intervention villages the prevalence of Plasmodium falciparum infection toward the end of the malaria transmission season. Discussion Adherence and cooperation of the local communities are critical for the success of mass treatment campaigns aimed at reducing malaria transmission. By exploring community perceptions of the changing trends in malaria burden, existing health systems, and reaction to self-administered treatment, this study will develop and adapt a model for community engagement toward malaria elimination that is cost-effective and fits within the existing health system. Trial registration Clinical trials.gov, NCT02878200. Registered on 25 August 2016. Electronic supplementary material The online version of this article (10.1186/s13063-018-2506-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joseph Okebe
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia
| | - Joan Muela Ribera
- Medial Anthropology Research Center (MARC), Universitat Rovira i Virgili, Tarragona, Spain
| | - Julie Balen
- School of Health and Related Research, The University of Sheffield, Sheffield, UK
| | - Fatou Jaiteh
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.,Medical Anthropology Unit, Department of Public health, Institute of Tropical Medicine, Antwerp, Belgium.,Amsterdam Institute of Social Science Research, University of Amsterdam, Amsterdam, The Netherlands
| | - Yoriko Masunaga
- Medical Anthropology Unit, Department of Public health, Institute of Tropical Medicine, Antwerp, Belgium.,Amsterdam Institute of Social Science Research, University of Amsterdam, Amsterdam, The Netherlands
| | - Davis Nwakanma
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Shunmay Yeung
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Koen Peeters Grietens
- Medical Anthropology Unit, Department of Public health, Institute of Tropical Medicine, Antwerp, Belgium
| | - Umberto D'Alessandro
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia. .,Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
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21
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Niang M, Diop F, Niang O, Sadio BD, Sow A, Faye O, Diallo M, Sall AA, Perraut R, Toure-Balde A. Unexpected high circulation of Plasmodium vivax in asymptomatic children from Kédougou, southeastern Senegal. Malar J 2017; 16:497. [PMID: 29284488 PMCID: PMC5747145 DOI: 10.1186/s12936-017-2146-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2017] [Accepted: 12/18/2017] [Indexed: 01/06/2023] Open
Abstract
Background Malaria in Senegal is due essentially to infections by Plasmodium falciparum and, to a lesser extent to Plasmodium malariae and Plasmodium ovale. By the use of molecular methods, detection of Plasmodium vivax has been recently reported in the region of Kedougou, raising the question of appraisal of its potential prevalence in this setting. Methods A retrospective serological study was carried out using 188 samples taken from 2010 to 2011 in a longitudinal school survey during which 48 asymptomatic children (9–11 years) were recruited. Four collections of samples collected during two successive dry and rainy seasons were analysed for antibody responses to P. vivax and P. falciparum. Recombinant P. falciparum and P. vivax MSP1 antigens and total P. falciparum schizont lysate from African 07/03 strain (adapted to culture) were used for ELISA. Nested PCR amplification was used for molecular detection of P. vivax. Results A surprising high prevalence of IgG responses against P. vivax MSP1 was evidenced with 53% of positive samples and 58% of the individuals that were found positive to this antigen. There was 77% of responders to P. falciparum outlined by 63% of positive samples. Prevalence of responders did not differ as function of seasons. Levels of antibodies to P. falciparum fluctuated with significant increasing between dry and rainy season (P < 0.05), contrary to responses to P. vivax. There was a significant reciprocal relationship (P < 10−3) between antibody responses to the different antigens, but with weak coefficient of correlation (Rho around 0.3) underlining a variable profile at the individual level. Clear molecular signature was found in positive IgG to P. vivax msp1 samples by PCR. Conclusion This cross-sectional longitudinal study highlights the unexpected high circulation of P. vivax in this endemic area. Sero-immunology and molecular methods are powerful additive tools to identify endemic sites where relevant control measures have to be settled and monitored.
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Affiliation(s)
- Makhtar Niang
- Immunology Unit, Institut Pasteur de Dakar, Dakar, Senegal
| | - Fode Diop
- Immunology Unit, Institut Pasteur de Dakar, Dakar, Senegal
| | - Oulimata Niang
- Immunology Unit, Institut Pasteur de Dakar, Dakar, Senegal
| | - Bacary D Sadio
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur de Dakar, Dakar, Senegal
| | - Abdourahmane Sow
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur de Dakar, Dakar, Senegal.,West African Health Organization, Ouagadougou, Burkina Faso
| | - Ousmane Faye
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur de Dakar, Dakar, Senegal
| | - Mawlouth Diallo
- Medical Entomology Unit, Institut Pasteur de Dakar, Dakar, Senegal
| | - Amadou A Sall
- Arbovirus and Viral Hemorrhagic Fevers Unit, Institut Pasteur de Dakar, Dakar, Senegal
| | - Ronald Perraut
- Immunology Unit, Institut Pasteur de Dakar, Dakar, Senegal
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22
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Sustained Ex Vivo Susceptibility of Plasmodium falciparum to Artemisinin Derivatives but Increasing Tolerance to Artemisinin Combination Therapy Partner Quinolines in The Gambia. Antimicrob Agents Chemother 2017; 61:AAC.00759-17. [PMID: 28971859 PMCID: PMC5700332 DOI: 10.1128/aac.00759-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 09/22/2017] [Indexed: 02/03/2023] Open
Abstract
Antimalarial interventions have yielded a significant decline in malaria prevalence in The Gambia, where artemether-lumefantrine (AL) has been used as a first-line antimalarial for a decade. Clinical Plasmodium falciparum isolates collected from 2012 to 2015 were analyzed ex vivo for antimalarial susceptibility and genotyped for drug resistance markers (pfcrt K76T, pfmdr1 codons 86, 184, and 1246, and pfk13) and microsatellite variation. Additionally, allele frequencies of single nucleotide polymorphisms (SNPs) from other drug resistance-associated genes were compared from genomic sequence data sets from 2008 (n = 79) and 2014 (n = 168). No artemisinin resistance-associated pfk13 mutation was found, and only 4% of the isolates tested in 2015 showed significant growth after exposure to dihydroartemisinin. Conversely, the 50% inhibitory concentrations (IC50s) of amodiaquine and lumefantrine increased within this period. pfcrt 76T and pfmdr1 184F mutants remained at a prevalence above 80%. pfcrt 76T was positively associated with higher IC50s to chloroquine. pfmdr1 NYD increased in frequency between 2012 and 2015 due to lumefantrine selection. The TNYD (pfcrt 76T and pfmdr1 NYD wild-type haplotype) also increased in frequency following AL implementation in 2008. These results suggest selection for pfcrt and pfmdr1 genotypes that enable tolerance to lumefantrine. Increased tolerance to lumefantrine calls for sustained chemotherapeutic monitoring in The Gambia to minimize complete artemisinin combination therapy (ACT) failure in the future.
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23
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Migchelsen SJ, Sepúlveda N, Martin DL, Cooley G, Gwyn S, Pickering H, Joof H, Makalo P, Bailey R, Burr SE, Mabey DCW, Solomon AW, Roberts CH. Serology reflects a decline in the prevalence of trachoma in two regions of The Gambia. Sci Rep 2017; 7:15040. [PMID: 29118442 PMCID: PMC5678181 DOI: 10.1038/s41598-017-15056-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 10/16/2017] [Indexed: 11/09/2022] Open
Abstract
Trachoma is caused by Chlamydia trachomatis (Ct). It is targeted for global elimination as a public health problem. In 2014, a population-based cross-sectional study was performed in two previously trachoma-endemic areas of The Gambia. Participants of all ages from Lower River Region (LRR) (N = 1028) and Upper River Region (URR) (N = 840) underwent examination for trachoma and had blood collected for detection of antibodies against the Ct antigen Pgp3, by ELISA. Overall, 30 (1.6%) individuals had active trachoma; the prevalence in children aged 1-9 years was 3.4% (25/742) with no statistically significant difference in prevalence between the regions. There was a significant difference in overall seroprevalence by region: 26.2% in LRR and 17.1% in URR (p < 0.0001). In children 1-9 years old, seroprevalence was 4.4% in LRR and 3.9% in URR. Reversible catalytic models using information on age-specific seroprevalence demonstrated a decrease in the transmission of Ct infection in both regions, possibly reflecting the impact of improved access to water, health and sanitation as well as mass drug administration campaigns. Serological testing for antibodies to Ct antigens is potentially useful for trachoma programmes, but consideration should be given to the co-endemicity of sexually transmitted Ct infections.
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Affiliation(s)
- Stephanie J Migchelsen
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom.
| | - Nuno Sepúlveda
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Centro de Estatística e Aplicações, Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Diana L Martin
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Gretchen Cooley
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Sarah Gwyn
- IHRC, Inc., Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Harry Pickering
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Hassan Joof
- Disease Control and Elimination Theme, Medical Research Council, The Gambia Unit, Fajara, The Gambia
| | - Pateh Makalo
- Disease Control and Elimination Theme, Medical Research Council, The Gambia Unit, Fajara, The Gambia
| | - Robin Bailey
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Sarah E Burr
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Disease Control and Elimination Theme, Medical Research Council, The Gambia Unit, Fajara, The Gambia
| | - David C W Mabey
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Anthony W Solomon
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Chrissy H Roberts
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
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Bridges DJ, Miller JM, Chalwe V, Moonga H, Hamainza B, Steketee R, Silumbe K, Nyangu J, Larsen DA. Community-led Responses for Elimination (CoRE): a study protocol for a community randomized controlled trial assessing the effectiveness of community-level, reactive focal drug administration for reducing Plasmodium falciparum infection prevalence and incidence in Southern Province, Zambia. Trials 2017; 18:511. [PMID: 29096671 PMCID: PMC5667476 DOI: 10.1186/s13063-017-2249-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Accepted: 10/04/2017] [Indexed: 11/10/2022] Open
Abstract
Background Zambia is pushing for, and has made great strides towards, the elimination of malaria transmission in Southern Province. Reactive focal test and treat (RFTAT) using rapid diagnostic tests and artemether-lumefantrine (AL) has been key in making this progress. Reactive focal drug administration (RFDA) using dihydroartemisinin-piperaquine (DHAP), may be superior in accelerating clearance of the parasite reservoir in humans due to the provision of enhanced chemoprophylactic protection of at-risk populations against new infections. The primary aim of this study is to quantify the relative effectiveness of RFDA with DHAP against RFTAT with AL (standard of care) for reducing Plasmodium falciparum prevalence and incidence. Methods/design The study will be conducted in four districts in Southern Province, Zambia; an area of low malaria transmission and high coverage of vector control. A community randomized controlled trial of 16 health facility catchment areas will be used to evaluate the impact of sustained year-round routine RFDA for 2 years, relative to a control of year-round routine RFTAT. Reactive case detection will be triggered by a confirmed malaria case, e.g., by microscopy or rapid diagnostic test at any government health facility. Reactive responses will be performed by community health workers (CHW) within 7 days of the index case confirmation date. Responses will be performed out to a radius of 140 m from the index case household. A subset of responses will be followed longitudinally for 90 days to examine reinfection rates. Primary outcomes include a post-intervention survey of malaria seropositivity (n = 4800 children aged 1 month to under 5 years old) and a difference-in-differences analysis of malaria parasite incidence, as measured through routine passive case detection at health facilities enrolled in the study. The study is powered to detect approximately a 65% relative reduction in these outcomes between the intervention versus the control. Discussion Strengths of this trial include a robust study design and an endline cross-sectional parasite survey as well as a longitudinal sample. Primary limitations include statistical power to detect only a 65% reduction in primary outcomes, and the potential for contamination to dilute the effects of the intervention. Trial registration ClinicalTrials.gov, ID: NCT02654912. Registered on 12 November 2015. Electronic supplementary material The online version of this article (doi:10.1186/s13063-017-2249-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Daniel J Bridges
- PATH-Malaria Control and Elimination Partnership in Africa (MACEPA), National Malaria Control Centre, Chainama Hospital College Grounds, Lusaka, Zambia.
| | - John M Miller
- PATH-Malaria Control and Elimination Partnership in Africa (MACEPA), National Malaria Control Centre, Chainama Hospital College Grounds, Lusaka, Zambia
| | - Victor Chalwe
- Zambia Ministry of Health, Provincial Medical Office, Mansa, Luapula Province, Zambia
| | - Hawela Moonga
- National Malaria Control Centre, Zambia Ministry of Health, Chainama Hospital, Lusaka, Zambia
| | - Busiku Hamainza
- National Malaria Control Centre, Zambia Ministry of Health, Chainama Hospital, Lusaka, Zambia
| | - Rick Steketee
- PATH-Malaria Control and Elimination Partnership in Africa (MACEPA), 2201 Westlake Avenue, Seattle, WA, USA
| | - Kafula Silumbe
- PATH-Malaria Control and Elimination Partnership in Africa (MACEPA), National Malaria Control Centre, Chainama Hospital College Grounds, Lusaka, Zambia
| | - Jenala Nyangu
- PATH-Malaria Control and Elimination Partnership in Africa (MACEPA), National Malaria Control Centre, Chainama Hospital College Grounds, Lusaka, Zambia
| | - David A Larsen
- Syracuse University Department of Public Health, Food Studies and Nutrition, Syracuse, NY, USA
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malERA: An updated research agenda for characterising the reservoir and measuring transmission in malaria elimination and eradication. PLoS Med 2017; 14:e1002452. [PMID: 29190279 PMCID: PMC5708619 DOI: 10.1371/journal.pmed.1002452] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
This paper summarises key advances in defining the infectious reservoir for malaria and the measurement of transmission for research and programmatic use since the Malaria Eradication Research Agenda (malERA) publication in 2011. Rapid and effective progress towards elimination requires an improved understanding of the sources of transmission as well as those at risk of infection. Characterising the transmission reservoir in different settings will enable the most appropriate choice, delivery, and evaluation of interventions. Since 2011, progress has been made in a number of areas. The extent of submicroscopic and asymptomatic infections is better understood, as are the biological parameters governing transmission of sexual stage parasites. Limitations of existing transmission measures have been documented, and proof-of-concept has been established for new innovative serological and molecular methods to better characterise transmission. Finally, there now exists a concerted effort towards the use of ensemble datasets across the spectrum of metrics, from passive and active sources, to develop more accurate risk maps of transmission. These can be used to better target interventions and effectively monitor progress toward elimination. The success of interventions depends not only on the level of endemicity but also on how rapidly or recently an area has undergone changes in transmission. Improved understanding of the biology of mosquito-human and human-mosquito transmission is needed particularly in low-endemic settings, where heterogeneity of infection is pronounced and local vector ecology is variable. New and improved measures of transmission need to be operationally feasible for the malaria programmes. Outputs from these research priorities should allow the development of a set of approaches (applicable to both research and control programmes) that address the unique challenges of measuring and monitoring transmission in near-elimination settings and defining the absence of transmission.
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26
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Perraut R, Varela ML, Joos C, Diouf B, Sokhna C, Mbengue B, Tall A, Loucoubar C, Touré A, Mercereau-Puijalon O. Association of antibodies to Plasmodium falciparum merozoite surface protein-4 with protection against clinical malaria. Vaccine 2017; 35:6720-6726. [PMID: 29042203 DOI: 10.1016/j.vaccine.2017.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2017] [Revised: 09/10/2017] [Accepted: 10/05/2017] [Indexed: 11/17/2022]
Abstract
Identification of parasite antigens targeted by immune effector mechanisms that confer protection against malaria is important for the design of a multi-component malaria vaccine. Here, the association of antibodies reacting with the Plasmodium falciparum merozoite surface protein-4 (MSP4) with protection against clinical malaria was investigated in a Senegalese community living in an area of moderate, seasonal malaria transmission. Blood samples were collected at the end of an 8-month long dry season without any recorded parasite transmission from 206 residents enrolled in a prospective follow-up study. Active daily clinical monitoring was implemented during the subsequent five months. Entomologic monitoring documented parasite transmission during the first three months of follow-up. Serum IgG levels were determined by ELISA against three MSP4 baculovirus-encoded recombinant protein constructs, namely the full-length MSP4p40, MSP4p30 devoid of a highly polymorphic sequence stretch and the conserved C-terminal EGF-containing MSP4p20, as well as against a merozoite crude extract. Community seroprevalence against all three constructs was quite high, the lowest being against MSP4p30. Seroprevalence and antibody levels against the three MSP4 constructs were age-dependent. IgG1 dominated the anti-MSP4p20 responses, while both IgG1 and IgG3 were observed against MSP4p40. Anti-MSP4 antibodies were associated with the antibody-dependent respiratory burst (ADRB) activity in a functional assay of merozoite phagocytosis by polymorphonuclear cells. Importantly, high antibody levels against each of the three MSP4 constructs at the end of the dry season were associated with reduced morbidity during the subsequent transmission season in an age-adjusted Poisson regression model (IRR = 0.65 [0.50-0.83], P<0.001 for responses over the median values). These data are consistent with a protective role for the naturally acquired anti-MSP4 antibodies and support further development of MSP4 as a candidate component of malaria vaccine.
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Affiliation(s)
- Ronald Perraut
- Unité d'Immunologie, Institut Pasteur de Dakar, Senegal.
| | | | | | - Babacar Diouf
- Unité d'Immunologie, Institut Pasteur de Dakar, Senegal
| | - Cheikh Sokhna
- Institut de Recherche pour le Développement (IRD), URMITE, UMR 198, Dakar, Senegal
| | | | - Adama Tall
- Unité d'Epidémiologie, Institut Pasteur de Dakar, Senegal
| | - Cheikh Loucoubar
- Institut Pasteur de Dakar, G4 Biostatistiques Bioinformatique et Modélisation, Dakar, Senegal
| | | | - Odile Mercereau-Puijalon
- Institut Pasteur, Département Parasites et Insectes Vecteurs, 25 Rue du Dr. Roux, 75015 Paris, France
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27
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Ataíde R, Powell R, Moore K, McLean A, Phyo AP, Nair S, White M, Anderson TJ, Beeson JG, Simpson JA, Nosten F, Fowkes FJI. Declining Transmission and Immunity to Malaria and Emerging Artemisinin Resistance in Thailand: A Longitudinal Study. J Infect Dis 2017; 216:723-731. [PMID: 28934435 PMCID: PMC5853569 DOI: 10.1093/infdis/jix371] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Background Reductions in malaria transmission decrease naturally acquired immunity, which may influence the emergence of Plasmodium falciparum artemisinin-resistant phenotypes and genotypes over time. Methods Antibodies specific for P. falciparum antigens were determined in uncomplicated hyperparasitemic malaria patients over a 10-year period of declining malaria transmission and emerging artemisinin resistance in northwestern Thailand. We investigated the association between antibody levels and both parasite clearance time (PCt½) and artemisinin resistance–associated kelch13 genotypes over time. Results Immunity to P. falciparum declined prior to 2004, preceding the emergence of artemisinin resistance-associated genotypes and phenotypes (maximum mean change in antibody level per year: anti-MSP142 = −0.17; 95% confidence interval [CI] = −.31 to −.04; P = .01). In this period of declining immunity, and in the absence of kelch13 mutations, PCt½ increased. Between 2007 and 2011, levels of antibodies fluctuated, and higher antibody levels were associated with faster PCt½ (maximum yearly change in PCt½, in hours: EBA140rII = −0.39; 95% CI = −.61 to −.17; P < .001). Conclusions Understanding the impact of changing transmission and immunity on the emergence of artemisinin resistance is important particularly as increased malaria control and elimination activities may enhance immunological conditions for the expansion of artemisinin-resistant P. falciparum.
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Affiliation(s)
| | | | | | | | - Aung Pyae Phyo
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot,Thailand
| | - Shalini Nair
- Texas Biomedical Research Institute, San Antonio
| | - Marina White
- Texas Biomedical Research Institute, San Antonio
| | | | | | - Julie A Simpson
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne
| | - Francois Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research, University of Oxford, United Kingdom
| | - Freya J I Fowkes
- Disease Elimination Program, Burnet Institute.,Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne.,Department of Epidemiology and Preventive Medicine, Department of Infectious Diseases, Monash University, Melbourne, Australia
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28
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Naturally acquired antibody response to Plasmodium falciparum describes heterogeneity in transmission on islands in Lake Victoria. Sci Rep 2017; 7:9123. [PMID: 28831122 PMCID: PMC5567232 DOI: 10.1038/s41598-017-09585-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/25/2017] [Indexed: 11/09/2022] Open
Abstract
As markers of exposure anti-malaria antibody responses can help characterise heterogeneity in malaria transmission. In the present study antibody responses to Plasmodium falciparum AMA-1, MSP-119 and CSP were measured with the aim to describe transmission patterns in meso-endemic settings in Lake Victoria. Two cross-sectional surveys were conducted in Lake Victoria in January and August 2012. The study area comprised of three settings: mainland (Ungoye), large island (Mfangano) and small islands (Takawiri, Kibuogi, Ngodhe). Individuals provided a finger-blood sample to assess malaria infection by microscopy and PCR. Antibody response to P. falciparum was determined in 4,112 individuals by ELISA using eluted dried blood from filter paper. The overall seroprevalence was 64.0% for AMA-1, 39.5% for MSP-119, and 12.9% for CSP. Between settings, seroprevalences for merozoite antigens were similar between Ungoye and Mfangano, but higher when compared to the small islands. For AMA-1, the seroconversion rates (SCRs) ranged from 0.121 (Ngodhe) to 0.202 (Ungoye), and were strongly correlated to parasite prevalence. We observed heterogeneity in serological indices across study sites in Lake Victoria. These data suggest that AMA-1 and MSP-119 sero-epidemiological analysis may provide further evidence in assessing variation in malaria exposure and evaluating malaria control efforts in high endemic area.
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29
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Simmons RA, Mboera L, Miranda ML, Morris A, Stresman G, Turner EL, Kramer R, Drakeley C, O'Meara WP. A longitudinal cohort study of malaria exposure and changing serostatus in a malaria endemic area of rural Tanzania. Malar J 2017; 16:309. [PMID: 28764717 PMCID: PMC5539976 DOI: 10.1186/s12936-017-1945-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 07/18/2017] [Indexed: 01/16/2023] Open
Abstract
Background Measurements of anti-malarial antibodies are increasingly used as a proxy of transmission intensity. Most serological surveys are based on the use of cross-sectional data that, when age-stratified, approximates historical patterns of transmission within a population. Comparatively few studies leverage longitudinal data to explicitly relate individual infection events with subsequent antibody responses. Methods The occurrence of seroconversion and seroreversion events for two Plasmodium falciparum asexual stage antigens (MSP-1 and AMA-1) was examined using three annual measurements of 691 individuals from a cohort of individuals in a malaria-endemic area of rural east-central Tanzania. Mixed-effect logistic regression models were employed to determine factors associated with changes in serostatus over time. Results While the expected population-level relationship between seroprevalence and disease incidence was observed, on an individual level the relationship between individual infections and the antibody response was complex. MSP-1 antibody responses were more dynamic in response to the occurrence and resolution of infection events than AMA-1, while the latter was more correlated with consecutive infections. The MSP-1 antibody response to an observed infection seemed to decay faster over time than the corresponding AMA-1 response. Surprisingly, there was no evidence of an age effect on the occurrence of a conversion or reversion event. Conclusions While the population-level results concur with previously published sero-epidemiological surveys, the individual-level results highlight the more complex relationship between detected infections and antibody dynamics than can be analysed using cross-sectional data. The longitudinal analysis of serological data may provide a powerful tool for teasing apart the complex relationship between infection events and the corresponding immune response, thereby improving the ability to rapidly assess the success or failure of malaria control programmes.
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Affiliation(s)
- Ryan A Simmons
- Department of Biostatistics and Bioinformatics, Duke University Medical Center, 2721, Durham, NC, 27701, USA. .,Duke Global Health Institute, Duke University, 310 Trent Drive, Durham, NC, 27701, USA.
| | - Leonard Mboera
- National Institute for Medical Research, 3 Barack Obama Drive, P.O. Box 9653, 11101, Dar es Salaam, United Republic of Tanzania
| | | | - Alison Morris
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Gillian Stresman
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Elizabeth L Turner
- Department of Biostatistics and Bioinformatics, Duke University Medical Center, 2721, Durham, NC, 27701, USA.,Duke Global Health Institute, Duke University, 310 Trent Drive, Durham, NC, 27701, USA
| | - Randall Kramer
- Duke Global Health Institute, Duke University, 310 Trent Drive, Durham, NC, 27701, USA
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Wendy P O'Meara
- Duke Global Health Institute, Duke University, 310 Trent Drive, Durham, NC, 27701, USA
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30
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Perraut R, Varela ML, Loucoubar C, Niass O, Sidibé A, Tall A, Trape JF, Wotodjo AN, Mbengue B, Sokhna C, Vigan-Womas I, Touré A, Richard V, Mercereau-Puijalon O. Serological signatures of declining exposure following intensification of integrated malaria control in two rural Senegalese communities. PLoS One 2017; 12:e0179146. [PMID: 28609450 PMCID: PMC5469466 DOI: 10.1371/journal.pone.0179146] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/24/2017] [Indexed: 01/26/2023] Open
Abstract
Recent control scale-up has reduced malaria in many areas but new tools are needed to monitor further progress, including indicators of decreasing exposure to parasite infection. Although serology is considered a promising approach in this regard, the serological impact of control interventions has been so far studied using indirect quantification of exposure. Cohort surveys concomitantly recording entomological and malariometric indices have been conducted in two Senegalese settings where supervised control intensification implemented in 2006 shifted malaria from historically holoendemic in Dielmo and mesoendemic in Ndiop to hypoendemic in both settings by 2013. We analyse here serological signatures of declining transmission using archived blood samples. Responses against ten pre-erythrocytic and erythrocytic antigens from Plasmodium falciparum and P. malariae alongside an Anopheles gambiae salivary gland antigen were analysed. Cross-sectional surveys conducted before (2002) and after (2013) control intensification showed a major impact of control intensification in both settings. The age-associated prevalence, magnitude and breadth of the IgG responses to all antigens were village-specific in 2002. In 2013, remarkably similar patterns were observed in both villages, with marginal responses against all parasite antigens in the 0-5y children and reduced responses in all previously seropositive age groups. Waning of humoral responses of individuals who were immune at the time of control intensification was studied from 2006 to 2013 using yearly samplings. Longitudinal data were analysed using the Cochran-Armittage trend test and an age-related reversible catalytic conversion model. This showed that the antigen-specific antibody declines were more rapid in older children than adults. There was a strong association of antibody decline with the declining entomological inoculation rate. We thus identified serological markers of declining exposure to malaria parasites that should help future monitoring of progress towards malaria elimination.
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Affiliation(s)
- Ronald Perraut
- Institut Pasteur de Dakar, Unité d’Immunologie, Dakar, Sénégal
- * E-mail:
| | - Marie-Louise Varela
- Institut Pasteur de Dakar, G4 Biostatistiques Bioinformatique et Modélisation, Dakar, Sénégal
| | - Cheikh Loucoubar
- Institut Pasteur de Dakar, G4 Biostatistiques Bioinformatique et Modélisation, Dakar, Sénégal
| | - Oumy Niass
- Institut Pasteur de Dakar, Unité d’Immunologie, Dakar, Sénégal
| | - Awa Sidibé
- Institut Pasteur de Dakar, Unité d’Immunologie, Dakar, Sénégal
| | - Adama Tall
- Institut Pasteur de Dakar, Unité d’Epidémiologie, Dakar, Sénégal
| | | | | | - Babacar Mbengue
- Institut Pasteur de Dakar, Unité d’Immunogénétique, Dakar, Sénégal
| | - Cheikh Sokhna
- Institut de Recherche pour le Développement (IRD), URMITE, Dakar, Sénégal
| | - Inès Vigan-Womas
- Institut Pasteur de Madagascar, Unité d’Immunologie des Maladies Infectieuses, Antanarivo, Madagascar
- Institut Pasteur, Department of Parasitology and Insect Vectors, 25 Rue du Dr Roux, Paris, France
| | - Aissatou Touré
- Institut Pasteur de Dakar, Unité d’Immunologie, Dakar, Sénégal
| | - Vincent Richard
- Institut Pasteur de Dakar, Unité d’Epidémiologie, Dakar, Sénégal
| | - Odile Mercereau-Puijalon
- Institut Pasteur, Department of Parasitology and Insect Vectors, 25 Rue du Dr Roux, Paris, France
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31
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Idris ZM, Chan CW, Mohammed M, Kalkoa M, Taleo G, Junker K, Arcà B, Drakeley C, Kaneko A. Serological measures to assess the efficacy of malaria control programme on Ambae Island, Vanuatu. Parasit Vectors 2017; 10:204. [PMID: 28441959 PMCID: PMC5405492 DOI: 10.1186/s13071-017-2139-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/13/2017] [Indexed: 01/10/2023] Open
Abstract
Background Seroepidemiology can provide evidence for temporal changes in malaria transmission and is an important tool to evaluate the effectiveness of control interventions. During the early 2000s, Vanuatu experienced an acute increase in malaria incidence due to a lapse in funding for vector control. After the distribution of subsidised insecticide-treated nets (ITNs) resumed in 2003, malaria incidence decreased in the subsequent years. This study was conducted to find the serological evidence supporting the impact of ITN on exposure to Anopheles vector bites and parasite prevalence. Methods On Ambae Island, blood samples were collected from 231 and 282 individuals in 2003 and 2007, respectively. Parasite prevalence was determined by microscopy. Antibodies to three Plasmodium falciparum (PfSE, PfMSP-119, and PfAMA-1) and three Plasmodium vivax (PvSE, PvMSP-119, and PvAMA-1) antigens, as well as the Anopheles-specific salivary antigen gSG6, were detected by ELISA. Age-specific seroprevalence was analysed using a reverse catalytic modelling approach to estimate seroconversion rates (SCRs). Results Parasite rate decreased significantly (P < 0.001) from 19.0% in 2003 to 3.2% in 2007, with a shift from P. falciparum predominance to P. falciparum-P. vivax co-dominance. Significant (P < 0.001) decreases were observed in seroprevalence to all three P. falciparum antigens but only two of three P. vivax antigens (except PvAMA-1; P = 0.153), consistent with the more pronounced decrease in P. falciparum prevalence. Seroprevalence to gSG6 also decreased significantly (P < 0.001), suggesting that reduced exposure to vector bites was important to the decrease in parasite prevalence between 2003 and 2007. Analyses of age-specific seroprevalence showed a three-fold decrease in P. falciparum transmission, but the evidence for the decrease in P. vivax transmission was less clear. Conclusions Serological markers pointed to the effectiveness of ITNs in reducing malaria prevalence on Ambae Island between 2003 and 2007. The recombinant gSG6 antigen originally developed to indicate exposure to the Afrotropical vector An. gambiae may be used in the Pacific to complement the traditional measure of entomological inoculation rate (EIR).
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Affiliation(s)
- Zulkarnain Md Idris
- Island Malaria Group, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden. .,Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia Medical Centre, Kuala Lumpur, Malaysia.
| | - Chim W Chan
- Island Malaria Group, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Mubasher Mohammed
- Island Malaria Group, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | | | | | - Klara Junker
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK.,Yeast and Fermentation, Carlsberg Research Laboratory, Copenhagen, Denmark
| | - Bruno Arcà
- Department of Public Health and Infectious Diseases, Parasitology Section, Sapienza University of Rome, Rome, Italy
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Akira Kaneko
- Island Malaria Group, Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden.,Department of Parasitology and Research Centre for Infectious Disease Sciences, Graduate School of Medicine, Osaka City University, Osaka, Japan.,Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
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32
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Koffi D, Varela ML, Loucoubar C, Beourou S, Vigan-Womas I, Touré A, Djaman JA, Touré AO, Perraut R. Longitudinal analysis of antibody responses in symptomatic malaria cases do not mirror parasite transmission in peri-urban area of Cote d'Ivoire between 2010 and 2013. PLoS One 2017; 12:e0172899. [PMID: 28245264 PMCID: PMC5330500 DOI: 10.1371/journal.pone.0172899] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 02/10/2017] [Indexed: 11/19/2022] Open
Abstract
Background In the agenda towards malaria eradication, assessment of both malaria exposure and efficacy of anti-vectorial and therapeutic strategies is a key component of management and the follow-up of field interventions. The simultaneous use of several antigens (Ags) as serological markers has the potential for accurate evaluation of malaria exposure. Here we aimed to measure the longitudinal evolution of the background levels of immunity in an urban setting in confirmed clinical cases of malaria. Methods A retrospective serological cross-sectional study on was carried out using 234 samples taken from 2010 to 2013 in peri-urban sentinel facility of Cote d’Ivoire. Antibody responses to recombinant proteins or BSA-peptides, 8 Plasmodium falciparum (PfAMA1, PfMSP4, PfMSP1, PfEMP1-DBL1α1-PF13, PfLSA1-41, PfLSA3-NR2, PfGLURP and PfCSP), one P. malariae (PmCSP) and one Anopheles gambiae salivary (gSG6-P1) antigens were measured using magnetic bead-based multiplex immunoassay (MBA). Total anti- P. falciparum IgG responses against schizont lysate from african 07/03 strain (adapted to culture) and 3D7 strain was measured by ELISA. Results High prevalence (7–93%) and levels of antibody responses to most of the antigens were evidenced. However, analysis showed only marginal decreasing trend of Ab responses from 2010 to 2013 that did not parallel the reduction of clinical malaria prevalence following the implementation of intervention in this area. There was a significant inverse correlation between Ab responses and parasitaemia (P<10−3, rho = 0.3). The particular recruitment of asymptomatic individuals in 2011 underlined a high background level of immunity almost equivalent to symptomatic patients, possibly obscuring observable yearly variations. Conclusion The use of cross-sectional clinical malaria surveys and MBA can help to identify endemic sites where control measures have unequal impact providing relevant information about population immunity and possible decrease of transmission. However, when immunity is substantially boosted despite observable clinical decline, a larger cohort including asymptomatic recruitment is needed to monitor the impact of control measures on level of immunity.
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Affiliation(s)
- David Koffi
- Institut Pasteur de Côte d’Ivoire, Unité de Paludologie, Abidjan, Côte d’Ivoire
- Université Félix Houphouet Boigny, UFR Biosciences, Abidjan, Côte d’Ivoire
| | | | - Cheikh Loucoubar
- Institut Pasteur de Dakar, G4 Biostatistiques Bioinformatique et Modélisation, Dakar, Sénégal
| | - Sylvain Beourou
- Institut Pasteur de Côte d’Ivoire, Unité de Paludologie, Abidjan, Côte d’Ivoire
| | - Inès Vigan-Womas
- Institut Pasteur, Unité d’Immunologie Moléculaire des Parasites, Paris, France
- Institut Pasteur de Madagascar, Unité d’Immunologie, Antanarivo, Madagascar
| | - Aissatou Touré
- Institut Pasteur de Dakar, Unité d’Immunologie, Dakar, Sénégal
| | | | | | - Ronald Perraut
- Institut Pasteur de Dakar, Unité d’Immunologie, Dakar, Sénégal
- * E-mail:
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Biggs J, Raman J, Cook J, Hlongwana K, Drakeley C, Morris N, Serocharan I, Agubuzo E, Kruger P, Mabuza A, Zitha A, Machaba E, Coetzee M, Kleinschmidt I. Serology reveals heterogeneity of Plasmodium falciparum transmission in northeastern South Africa: implications for malaria elimination. Malar J 2017; 16:48. [PMID: 28126001 PMCID: PMC5270351 DOI: 10.1186/s12936-017-1701-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 01/18/2017] [Indexed: 12/22/2022] Open
Abstract
Background It is widely acknowledged that modifications to existing control interventions are required if South Africa is to achieve malaria elimination. Targeting indoor residual spraying (IRS) to areas where cases have been detected is one strategy currently under investigation in northeastern South Africa. This seroprevalence baseline study, nested within a targeted IRS trial, was undertaken to provide insights into malaria transmission dynamics in South Africa and evaluate whether sero-epidemiological practices have the potential to be routinely incorporated into elimination programmes. Methods Filter-paper blood spots, demographic and household survey data were collected from 2710 randomly selected households in 56 study wards located in the municipalities of Ba-Phalaborwa and Bushbuckridge. Blood spots were assayed for Plasmodium falciparum apical membrane antigen-1 and merozoite surface protein-119 blood-stage antigens using an enzyme linked immunosorbent assay. Seroprevalence data were analysed using a reverse catalytic model to determine malaria seroconversion rates (SCR). Geospatial cluster analysis was used to investigate transmission heterogeneity while random effects logistic regression identified risk factors associated with malaria exposure. Results The overall SCR across the entire study site was 0.012 (95% CI 0.008–0.017) per year. Contrasting SCRs, corresponding to distinct geographical regions across the study site, ranging from <0.001 (95% CI <0.001–0.005) to 0.022 (95% CI 0.008–0.062) per annum revealed prominent transmission heterogeneity. Geospatial cluster analysis of household seroprevalence and age-adjusted antibody responses detected statistically significant (p < 0.05) spatial clusters of P. falciparum exposure. Formal secondary education was associated with lower malaria exposure in the sampled population (AOR 0.72, 95% CI 0.56–0.95, p = 0.018). Conclusions Although overall transmission intensity and exposure to malaria was low across both study sites, malaria transmission intensity was highly heterogeneous and associated with low socio-economic status in the region. Findings suggest focal targeting of interventions has the potential to be an appropriate strategy to deploy in South Africa. Furthermore, routinely incorporating sero-epidemiological practices into elimination programmes may prove useful in monitoring malaria transmission intensity in South Africa, and other countries striving for malaria elimination. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1701-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joseph Biggs
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Jaishree Raman
- Centre for Opportunistic Tropical and Hospital Infections, National Institute for Communicable Diseases, Johannesburg, South Africa. .,Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. .,Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa.
| | - Jackie Cook
- Tropical Epidemiology Group, Department of Infectious Diseases Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
| | - Khumbulani Hlongwana
- School of Nursing and Public Health, University of KwaZulu-Natal, Durban, South Africa
| | - Chris Drakeley
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Natashia Morris
- Health GIS Centre, South Africa Medical Research Council, Durban, South Africa
| | - Ishen Serocharan
- Health GIS Centre, South Africa Medical Research Council, Durban, South Africa
| | - Eunice Agubuzo
- Centre for Opportunistic Tropical and Hospital Infections, National Institute for Communicable Diseases, Johannesburg, South Africa.,Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Philip Kruger
- Limpopo Provincial Malaria Control Programme, Polokwane, South Africa
| | - Aaron Mabuza
- Mpumalanga Provincial Malaria Control Programme, Nelspruit, South Africa
| | - Alpheus Zitha
- Mpumalanga Provincial Malaria Control Programme, Nelspruit, South Africa
| | - Elliot Machaba
- Limpopo Provincial Malaria Control Programme, Polokwane, South Africa
| | - Maureen Coetzee
- Centre for Opportunistic Tropical and Hospital Infections, National Institute for Communicable Diseases, Johannesburg, South Africa.,Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Immo Kleinschmidt
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa.,Tropical Epidemiology Group, Department of Infectious Diseases Epidemiology, London School of Hygiene and Tropical Medicine, London, UK
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Migchelsen SJ, Martin DL, Southisombath K, Turyaguma P, Heggen A, Rubangakene PP, Joof H, Makalo P, Cooley G, Gwyn S, Solomon AW, Holland MJ, Courtright P, Willis R, Alexander NDE, Mabey DCW, Roberts CH. Defining Seropositivity Thresholds for Use in Trachoma Elimination Studies. PLoS Negl Trop Dis 2017; 11:e0005230. [PMID: 28099433 PMCID: PMC5242428 DOI: 10.1371/journal.pntd.0005230] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 12/05/2016] [Indexed: 11/13/2022] Open
Abstract
Background Efforts are underway to eliminate trachoma as a public health problem by 2020. Programmatic guidelines are based on clinical signs that correlate poorly with Chlamydia trachomatis (Ct) infection in post-treatment and low-endemicity settings. Age-specific seroprevalence of anti Ct Pgp3 antibodies has been proposed as an alternative indicator of the need for intervention. To standardise the use of these tools, it is necessary to develop an analytical approach that performs reproducibly both within and between studies. Methodology Dried blood spots were collected in 2014 from children aged 1–9 years in Laos (n = 952) and Uganda (n = 2700) and from people aged 1–90 years in The Gambia (n = 1868). Anti-Pgp3 antibodies were detected by ELISA. A number of visual and statistical analytical approaches for defining serological status were compared. Principal Findings Seroprevalence was estimated at 11.3% (Laos), 13.4% (Uganda) and 29.3% (The Gambia) by visual inspection of the inflection point. The expectation-maximisation algorithm estimated seroprevalence at 10.4% (Laos), 24.3% (Uganda) and 29.3% (The Gambia). Finite mixture model estimates were 15.6% (Laos), 17.1% (Uganda) and 26.2% (The Gambia). Receiver operating characteristic (ROC) curve analysis using a threshold calibrated against external reference specimens estimated the seroprevalence at 6.7% (Laos), 6.8% (Uganda) and 20.9% (The Gambia) when the threshold was set to optimise Youden’s J index. The ROC curve analysis was found to estimate seroprevalence at lower levels than estimates based on thresholds established using internal reference data. Thresholds defined using internal reference threshold methods did not vary substantially between population samples. Conclusions Internally calibrated approaches to threshold specification are reproducible and consistent and thus have advantages over methods that require external calibrators. We propose that future serological analyses in trachoma use a finite mixture model or expectation-maximisation algorithm as a means of setting the threshold for ELISA data. This will facilitate standardisation and harmonisation between studies and eliminate the need to establish and maintain a global calibration standard. Trachoma is caused by the bacterium Chlamydia trachomatis (Ct). Individuals who have previously been infected with Ct carry specific antibodies in their blood. Recent studies have suggested that these antibodies may be a good way to estimate the intensity of transmission of this bacterium in a population. Among people who do have antibodies (seropositives) there is variation in the amount that is detectable in their blood. Some people have such low levels that differentiating them from those who don’t have antibodies (seronegatives) is challenging. We used a new test for Ct antibodies on blood specimens from three countries. Our test worked extremely well, giving reproducible results when we tested the same samples multiple times. We compared four different methods for setting the position of the threshold line between seronegatives and seropositives. The estimated transmission intensity in each country varied depending on the threshold method used, but two methods that used statistical modelling algorithms to define the two groups performed consistently across all three countries’ samples. We recommend that future studies should consider adopting the statistical modelling approaches, as they are objective tests that require no reference material and allow for standardisation between studies.
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Affiliation(s)
- Stephanie J. Migchelsen
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
- * E-mail:
| | - Diana L. Martin
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | | | - Patrick Turyaguma
- Trachoma Control Programme, Ugandan Ministry of Health, Kampala, Uganda
| | - Anne Heggen
- NTD Support Centre, Decatur, Georgia, United States of America
| | | | - Hassan Joof
- Medical Research Council Unit The Gambia, Fajara, The Gambia
| | - Pateh Makalo
- Medical Research Council Unit The Gambia, Fajara, The Gambia
| | - Gretchen Cooley
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Sarah Gwyn
- IHRC, Inc., Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Anthony W. Solomon
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
| | - Martin J. Holland
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Paul Courtright
- Kilimanjaro Centre for Community Ophthalmology, University Cape Town, Cape Town, South Africa
| | - Rebecca Willis
- International Trachoma Initiative, The Task Force for Global Health, Decatur, Georgia, United States of America
| | - Neal D. E. Alexander
- MRC Tropical Epidemiology Group, Infectious Disease Epidemiology Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - David C. W. Mabey
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Chrissy h. Roberts
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
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Kerkhof K, Sluydts V, Willen L, Kim S, Canier L, Heng S, Tsuboi T, Sochantha T, Sovannaroth S, Ménard D, Coosemans M, Durnez L. Serological markers to measure recent changes in malaria at population level in Cambodia. Malar J 2016; 15:529. [PMID: 27809852 PMCID: PMC5096337 DOI: 10.1186/s12936-016-1576-z] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2016] [Accepted: 10/27/2016] [Indexed: 11/10/2022] Open
Abstract
Background Serological markers for exposure to different Plasmodium species have recently been used in multiplex immunoassays based on the Luminex technology. However, interpretation of the assay results requires consideration of the half-life of specific antibodies against these markers. Therefore, the aim of the present study was to document the half-life of malaria specific serological makers, as well as assessing the sensitivity of these markers to pick up recent changes in malaria exposure. Methods A recently developed multiplex immunoassay was used to measure the intensity of antibody (Ab) responses against 19 different Plasmodium specific antigens, covering different human malaria parasites and two vector saliva antigens. Therefore, 8439 blood samples from five cross-sectional surveys in Ratanakiri, Cambodia, were analysed. These involve a random selection from two selected surveys, and an additional set of blood samples of individuals that were randomly re-sampled three, four or five times. A generalized estimating equation model and linear regression models were fitted on log transformed antibody intensity data. Results Results showed that most (17/21) Ab-responses are higher in PCR positive than PCR negative individuals. Furthermore, these antibody-responses follow the same upward trend within each age group. Estimation of the half-lives showed differences between serological markers that reflect short- (seasonal) and long-term (year round) transmission trends. Ab levels declined significantly together with a decrease of PCR prevalence in a group of malaria endemic villages. Conclusion For Plasmodium falciparum, antibodies against LSA3.RE, GLURP and Pf.GLURP.R2 are most likely to be a reflexion of recent (range from 6 to 8 months) exposure in the Mekong Subregion. PvEBP is the only Plasmodium vivax Ag responding reasonably well, in spite of an estimated Ab half-life of more than 1 year. The use of Ab intensity data rather dichotomizing the continuous Ab-titre data (positive vs negative) will lead to an improved approach for serological surveillance. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1576-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Karen Kerkhof
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. .,Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium.
| | - Vincent Sluydts
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.,Department of Biology, University of Antwerp, Antwerp, Belgium
| | - Laura Willen
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.,Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Saorin Kim
- Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Lydie Canier
- Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Somony Heng
- National Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Takafumi Tsuboi
- Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Japan
| | - Tho Sochantha
- National Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Siv Sovannaroth
- National Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Didier Ménard
- Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Marc Coosemans
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.,Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Lies Durnez
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium.
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36
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Zakeri S, van den Hoogen LL, Mehrizi AA, Karimi F, Raeisi A, Drakeley C. Anti-malarial seroprevalence assessment during an elimination programme in Chabahar District, south-eastern Iran. Malar J 2016; 15:382. [PMID: 27448606 PMCID: PMC4957887 DOI: 10.1186/s12936-016-1432-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 07/06/2016] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Iran has achieved a substantial decline in malaria incidence over the past decades. A common feature of malaria-endemic settings is the requirement for more sensitive techniques to describe levels of low transmission. In this study, serological and parasitological methods were used to measure transmission levels of Plasmodium falciparum and Plasmodium vivax during an elimination programme (2012) in Chabahar District, Sistan and Baluchistan Province, south-eastern Iran. METHODS Participants were randomly selected from 64 different geographical clusters in Chabahar city and surrounding villages. Antibody responses to P. falciparum and P. vivax blood-stage antigens were assessed by ELISA, while microscopy and molecular testing were used to determine parasite carriage by species. Age-adjusted antibody responses were analysed using a reversible catalytic model to calculate seroconversion rates (SCR). RESULTS There was no evidence of recent transmission in the study areas, indicated by an absence of parasite infections in all ages and low or absent serological responses to either species in young children. The best model for age P. falciparum seroconversion was one with a change in exposure 21 years before sampling was done in Chabahar city (P = 0.018) and 4 years in the villages (P = 0.039). There was a higher level of recent P. vivax transmission compared to P. falciparum, based on the SCRs, in both the city and village settings. CONCLUSION Serological analysis identified a decline in P. falciparum transmission in the urban areas of Chabahar, consistent with a previously described decrease in malaria in the early 1990s, demonstrating the utility of this approach to reconstruct exposure history. At present, it remains unclear whether the P. vivax antibody responses reflect active transmission due to new infections or relapse infections. The absence of parasitological and serological evidence of recent malaria transmission in Chabahar District is viable evidence for certification of elimination.
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MESH Headings
- Adolescent
- Adult
- Aged
- Antibodies, Protozoan/blood
- Child
- Child, Preschool
- Cross-Sectional Studies
- DNA, Protozoan/analysis
- DNA, Protozoan/genetics
- Disease Eradication
- Enzyme-Linked Immunosorbent Assay
- Female
- Humans
- Iran/epidemiology
- Malaria, Falciparum/epidemiology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Vivax/epidemiology
- Malaria, Vivax/immunology
- Malaria, Vivax/parasitology
- Male
- Microscopy
- Middle Aged
- Plasmodium falciparum/immunology
- Plasmodium falciparum/isolation & purification
- Plasmodium vivax/immunology
- Plasmodium vivax/isolation & purification
- Polymerase Chain Reaction
- Seroepidemiologic Studies
- Urban Population
- Young Adult
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Affiliation(s)
- Sedigheh Zakeri
- />Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BCR), Pasteur Institute, P.O. Box: 1316943551, Tehran, Iran
| | | | - Akram Abouie Mehrizi
- />Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BCR), Pasteur Institute, P.O. Box: 1316943551, Tehran, Iran
| | - Fatemh Karimi
- />Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BCR), Pasteur Institute, P.O. Box: 1316943551, Tehran, Iran
| | - Ahmad Raeisi
- />National Programme Manager for Malaria Control, Ministry of Health and Medical Education, Tehran, Iran
- />School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Chris Drakeley
- />Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
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Golden A, Faulx D, Kalnoky M, Stevens E, Yokobe L, Peck R, Karabou P, Banla M, Rao R, Adade K, Gantin RG, Komlan K, Soboslay PT, de Los Santos T, Domingo GJ. Analysis of age-dependent trends in Ov16 IgG4 seroprevalence to onchocerciasis. Parasit Vectors 2016; 9:338. [PMID: 27296630 PMCID: PMC4907250 DOI: 10.1186/s13071-016-1623-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 06/02/2016] [Indexed: 11/30/2022] Open
Abstract
Background Diagnostics provide a means to measure progress toward disease elimination. Many countries in Africa are approaching elimination of onchocerciasis after successful implementation of mass drug administration programs as well as vector control. An understanding of how markers for infection such as skin snip microfilaria and Onchocerca volvulus-specific seroconversion perform in near-elimination settings informs how to best use these markers. Methods All-age participants from 35 villages in Togo were surveyed in 2013 and 2014 for skin snip Onchocerca volvulus microfilaria and IgG4 antibody response by enzyme-linked immunosorbent assay (ELISA) to the Onchocerca volvulus-specific antigen Ov16. A Gaussian mixture model applying the expectation-maximization (EM) algorithm was used to determine seropositivity from Ov16 ELISA data. For a subset of participants (n = 434), polymerase chain reaction (PCR) was performed on the skin snips taken during surveillance. Results Within the 2,005 participants for which there was Ov16 ELISA data, O. volvulus microfilaremia prevalence and Ov16 seroprevalence were, 2.5 and 19.7 %, respectively, in the total population, and 1.6 and 3.6 % in children under 11. In the subset of 434 specimens for which ELISA, PCR, and microscopy data were generated, it was found that in children under 11 years of age, the anti-Ov16 IgG4 antibody response demonstrate a sensitivity and specificity of 80 and 97 %, respectively, against active infections as determined by combined PCR and microscopy on skin snips. Further analysis was performed in 34 of the 35 villages surveyed. These villages were stratified by all-age seroprevalence into three clusters: < 15 %; 15–20 %; and > 20 %. Age-dependence of seroprevalence for each cluster was best reflected by a two-phase force-of-infection (FOI) catalytic model. In all clusters, the lower of the two phases of FOI was associated with a younger age group, as reflected by the seroconversion rates for each phase. The age at which transition from lower to higher seroconversion, between the two phases of FOI, was found to be highest (older) for the cluster of villages with < 15 % seroprevalence and lowest (younger) for the cluster with the highest all-age seroprevalence. Conclusions The anti-Ov16 IgG4 antibody response is an accurate marker for active infection in children under 11 years of age in this population. Applying Ov16 surveillance to a broader age range provides additional valuable information for understanding progression toward elimination and can inform where targeted augmented interventions may be needed. Clustering of villages by all-age sero-surveillance allowed application of a biphasic FOI model to differentiate seroconversion rates for different age groups within the village cluster categories. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1623-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Dunia Faulx
- Diagnostics Global Program, PATH, Seattle, WA, USA
| | | | - Eric Stevens
- Diagnostics Global Program, PATH, Seattle, WA, USA
| | | | - Roger Peck
- Diagnostics Global Program, PATH, Seattle, WA, USA
| | | | - Méba Banla
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
| | | | - Kangi Adade
- National Onchocerciasis Control Programme, Kara, Togo
| | - Richard G Gantin
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
| | - Kossi Komlan
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
| | - Peter T Soboslay
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo.,Institute of Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
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Ampah KA, Nickel B, Asare P, Ross A, De-Graft D, Kerber S, Spallek R, Singh M, Pluschke G, Yeboah-Manu D, Röltgen K. A Sero-epidemiological Approach to Explore Transmission of Mycobacterium ulcerans. PLoS Negl Trop Dis 2016; 10:e0004387. [PMID: 26808978 PMCID: PMC4726553 DOI: 10.1371/journal.pntd.0004387] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 12/22/2015] [Indexed: 01/30/2023] Open
Abstract
The debilitating skin disease Buruli ulcer (BU) is caused by infection with Mycobacterium ulcerans. While various hypotheses on potential reservoirs and vectors of M. ulcerans exist, the mode of transmission has remained unclear. Epidemiological studies have indicated that children below the age of four are less exposed to the pathogen and at lower risk of developing BU than older children. In the present study we compared the age at which children begin to develop antibody responses against M. ulcerans with the age pattern of responses to other pathogens transmitted by various mechanisms. A total of 1,352 sera from individuals living in the BU endemic Offin river valley of Ghana were included in the study. While first serological responses to the mosquito transmitted malaria parasite Plasmodium falciparum and to soil transmitted Strongyloides helminths emerged around the age of one and two years, sero-conversion for M. ulcerans and for the water transmitted trematode Schistosoma mansoni occurred at around four and five years, respectively. Our data suggest that exposure to M. ulcerans intensifies strongly at the age when children start to have more intense contact with the environment, outside the small movement range of young children. Further results from our serological investigations in the Offin river valley also indicate ongoing transmission of Treponema pallidum, the causative agent of yaws.
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Affiliation(s)
- Kobina Assan Ampah
- Swiss Tropical and Public Health Institute, Molecular Immunology, Basel, Switzerland
- University of Basel, Basel, Switzerland
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Beatrice Nickel
- Swiss Tropical and Public Health Institute, Molecular Immunology, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Prince Asare
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Amanda Ross
- Swiss Tropical and Public Health Institute, Molecular Immunology, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Daniel De-Graft
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Sarah Kerber
- Swiss Tropical and Public Health Institute, Molecular Immunology, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Ralf Spallek
- LIONEX Diagnostics & Therapeutics, Braunschweig, Germany
| | - Mahavir Singh
- LIONEX Diagnostics & Therapeutics, Braunschweig, Germany
| | - Gerd Pluschke
- Swiss Tropical and Public Health Institute, Molecular Immunology, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Dorothy Yeboah-Manu
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Katharina Röltgen
- Swiss Tropical and Public Health Institute, Molecular Immunology, Basel, Switzerland
- University of Basel, Basel, Switzerland
- * E-mail:
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39
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Sepúlveda N, Paulino CD, Drakeley C. Sample size and power calculations for detecting changes in malaria transmission using antibody seroconversion rate. Malar J 2015; 14:529. [PMID: 26715538 PMCID: PMC4696297 DOI: 10.1186/s12936-015-1050-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2015] [Accepted: 12/12/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Several studies have highlighted the use of serological data in detecting a reduction in malaria transmission intensity. These studies have typically used serology as an adjunct measure and no formal examination of sample size calculations for this approach has been conducted. METHODS A sample size calculator is proposed for cross-sectional surveys using data simulation from a reverse catalytic model assuming a reduction in seroconversion rate (SCR) at a given change point before sampling. This calculator is based on logistic approximations for the underlying power curves to detect a reduction in SCR in relation to the hypothesis of a stable SCR for the same data. Sample sizes are illustrated for a hypothetical cross-sectional survey from an African population assuming a known or unknown change point. RESULTS Overall, data simulation demonstrates that power is strongly affected by assuming a known or unknown change point. Small sample sizes are sufficient to detect strong reductions in SCR, but invariantly lead to poor precision of estimates for current SCR. In this situation, sample size is better determined by controlling the precision of SCR estimates. Conversely larger sample sizes are required for detecting more subtle reductions in malaria transmission but those invariantly increase precision whilst reducing putative estimation bias. CONCLUSIONS The proposed sample size calculator, although based on data simulation, shows promise of being easily applicable to a range of populations and survey types. Since the change point is a major source of uncertainty, obtaining or assuming prior information about this parameter might reduce both the sample size and the chance of generating biased SCR estimates.
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Affiliation(s)
- Nuno Sepúlveda
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK. .,Center of Statistics and Applications of University of Lisbon, Faculdade de Ciências da Universidade de Lisboa, Bloco C6-Piso 4, 1749-1016, Lisbon, Portugal.
| | - Carlos Daniel Paulino
- Center of Statistics and Applications of University of Lisbon, Faculdade de Ciências da Universidade de Lisboa, Bloco C6-Piso 4, 1749-1016, Lisbon, Portugal. .,Instituto Superior Técnico, Universidade Técnica de Lisboa, Avenida Rovisco Pais, 1049-001, Lisbonn, Portugal.
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK.
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