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Lyons MR, Arantes T, Vieira BR, Furtado JM, Smith JR. Impact of gender on clinical features and outcomes of ocular toxoplasmosis. Br J Ophthalmol 2024; 108:710-714. [PMID: 37225390 DOI: 10.1136/bjo-2023-323227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 05/09/2023] [Indexed: 05/26/2023]
Abstract
AIM To investigate the effect of gender on the clinical features and outcomes of ocular toxoplasmosis. METHODS 262 patients (139 women and 123 men) presenting to a tertiary referral uveitis service in Ribeirão Preto, Brazil, with serological and clinical evidence of ocular toxoplasmosis were prospectively enrolled in an observational study. Predefined data items including demographics, descriptors of uveitis and ocular toxoplasmosis, best-corrected visual acuity and ocular complications were disaggregated by gender and compared statistically. RESULTS Approximately equal numbers of women and men had active versus inactive ocular toxoplasmosis. In both women and men, most infections were remotely acquired. Men were significantly more likely to present with primary active disease than women (24.4% vs 12.9%); conversely, women were significantly more likely to present with recurrent active disease than men (36.0% vs 28.5%). One toxoplasmic retinal lesion was observed in more eyes of men than eyes of women (50.4% vs 35.3%), while women's eyes were more likely to have multiple lesions than men's eyes (54.7% vs 39.8%). Lesions in women's eyes were significantly more likely to occur at the posterior pole compared with those in men's eyes (56.1% vs 39.8%). Measures of vision were similar for women and men. There were no significant differences in measures of visual acuity, ocular complications, and occurrence and timing of reactivations between the genders. CONCLUSION Ocular toxoplasmosis has equivalent outcomes in women and men, with clinical differences in the form and type of disease, as well as characteristics of the retinal lesion.
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Affiliation(s)
- Matilda R Lyons
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
| | - Tiago Arantes
- Sadalla Amin Ghanem Eye Hospital, Joinville, Santa Catarina, Brazil
| | - Barbara R Vieira
- Division of Ophthalmology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Joao M Furtado
- Division of Ophthalmology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Justine R Smith
- College of Medicine and Public Health, Flinders University, Adelaide, South Australia, Australia
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Jebiwott S, Gutapaka N, Sumari D, Loss G, Athuman T, Nyandele JP, Cummins H, Chemba M, Benjamin-Chung J, Gangar P, Wu X, Smith J, Chen I, Dorsey G, Fink G, Olotu A, Hsiang M. Child Health and Infection with Low Density (CHILD) malaria: a protocol for a randomised controlled trial to assess the long-term health and socioeconomic impacts of testing and treating low-density malaria infection among children in Tanzania. BMJ Open 2024; 14:e082227. [PMID: 38538037 PMCID: PMC10982758 DOI: 10.1136/bmjopen-2023-082227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/16/2023] [Accepted: 02/15/2024] [Indexed: 04/04/2024] Open
Abstract
INTRODUCTION As malaria declines, low-density malaria infections (LMIs) represent an increasing proportion of infections and may have negative impacts on child health and cognition, necessitating development of targeted and effective solutions. This trial assesses the health, cognitive and socioeconomic impact of two strategies for detecting and treating LMI in a low transmission setting. METHODS AND ANALYSIS The study is a 3-arm open-label individually randomised controlled trial enrolling 600 children aged 6 months to 10 years in Bagamoyo district, Tanzania. Children are randomised to one of three arms: active case detection with molecular (ACDm) testing by high volume quantitative PCR (qPCR), passive case detection also with molecular testing (PCDm) and a control of standard PCD using rapid diagnostics tests (RDTs). Over the 2-year trial, ACDm participants receive malaria testing using RDT and qPCR three times annually, and malaria testing by RDT only when presenting with fever. PCDm and PCD participants receive malaria testing by RDT and qPCR or RDT only, respectively, when presenting with fever. RDT or qPCR positive participants with uncomplicated malaria are treated with artemether lumefantrine. The primary outcome is cumulative incidence of all-cause sick visits. Secondary outcomes include fever episodes, clinical failure after fever episodes, adverse events, malaria, non-malarial infection, antibiotic use, anaemia, growth faltering, cognition and attention, school outcomes, immune responses, and socioeconomic effects. Outcomes are assessed through monthly clinical assessments and testing, and baseline and endline neurodevelopmental testing. The trial is expected to provide key evidence and inform policy on health, cognitive and socioeconomic impact of interventions targeting LMI in children. ETHICS AND DISSEMINATION Study is approved by Tanzania NatHREC and institutional review boards at University of California San Francisco and Ifakara Health Institute. Findings will be reported on ClinicalTrials.gov, in peer-reviewed journals and through stakeholder meetings. TRIAL REGISTRATION NUMBER NCT05567016.
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Affiliation(s)
- Sylvia Jebiwott
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | | | - Deborah Sumari
- Ifakara Health Institute, Bagamoyo, Tanzania, United Republic of
| | - Georg Loss
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Thabit Athuman
- Ifakara Health Institute, Bagamoyo, Tanzania, United Republic of
| | | | - Hannah Cummins
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Mwajuma Chemba
- Ifakara Health Institute, Bagamoyo, Tanzania, United Republic of
| | - Jade Benjamin-Chung
- Epidemiology and Population Health, Stanford University School of Medicine, Stanford, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
| | - Pamela Gangar
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Xue Wu
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Jennifer Smith
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Ingrid Chen
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, San Francisco, California, USA
| | - Günther Fink
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Ally Olotu
- Ifakara Health Institute, Bagamoyo, Tanzania, United Republic of
| | - Michelle Hsiang
- Malaria Elimination Initiative, Institute of Global Health Sciences, University of California, San Francisco, San Francisco, California, USA
- Chan Zuckerberg Biohub, San Francisco, California, USA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, California, USA
- Department of Pediatrics, University of California, San Francisco, San Francisco, California, USA
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Andolina C, Graumans W, Guelbeogo M, van Gemert GJ, Ramijth J, Harouna S, Soumanaba Z, Stoter R, Vegte-Bolmer M, Pangos M, Sinnis P, Collins K, Staedke SG, Tiono AB, Drakeley C, Lanke K, Bousema T. Quantification of sporozoite expelling by Anopheles mosquitoes infected with laboratory and naturally circulating P. falciparum gametocytes. eLife 2024; 12:RP90989. [PMID: 38517746 PMCID: PMC10959522 DOI: 10.7554/elife.90989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/24/2024] Open
Abstract
It is currently unknown whether all Plasmodium falciparum-infected mosquitoes are equally infectious. We assessed sporogonic development using cultured gametocytes in the Netherlands and naturally circulating strains in Burkina Faso. We quantified the number of sporozoites expelled into artificial skin in relation to intact oocysts, ruptured oocysts, and residual salivary gland sporozoites. In laboratory conditions, higher total sporozoite burden was associated with shorter duration of sporogony (p<0.001). Overall, 53% (116/216) of infected Anopheles stephensi mosquitoes expelled sporozoites into artificial skin with a median of 136 expelled sporozoites (interquartile range [IQR], 34-501). There was a strong positive correlation between ruptured oocyst number and salivary gland sporozoite load (ρ = 0.8; p<0.0001) and a weaker positive correlation between salivary gland sporozoite load and number of sporozoites expelled (ρ = 0.35; p=0.0002). In Burkina Faso, Anopheles coluzzii mosquitoes were infected by natural gametocyte carriers. Among salivary gland sporozoite positive mosquitoes, 89% (33/37) expelled sporozoites with a median of 1035 expelled sporozoites (IQR, 171-2969). Again, we observed a strong correlation between ruptured oocyst number and salivary gland sporozoite load (ρ = 0.9; p<0.0001) and a positive correlation between salivary gland sporozoite load and the number of sporozoites expelled (ρ = 0.7; p<0.0001). Several mosquitoes expelled multiple parasite clones during probing. Whilst sporozoite expelling was regularly observed from mosquitoes with low infection burdens, our findings indicate that mosquito infection burden is positively associated with the number of expelled sporozoites. Future work is required to determine the direct implications of these findings for transmission potential.
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Affiliation(s)
- Chiara Andolina
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Wouter Graumans
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Moussa Guelbeogo
- Centre National de Recherche et de Formation sur le PaludismeOuagadougouBurkina Faso
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Jordache Ramijth
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Soré Harouna
- Centre National de Recherche et de Formation sur le PaludismeOuagadougouBurkina Faso
| | - Zongo Soumanaba
- Centre National de Recherche et de Formation sur le PaludismeOuagadougouBurkina Faso
| | - Rianne Stoter
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Marga Vegte-Bolmer
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Martina Pangos
- Department of Plastic and Reconstructive Surgery, Azienda Ospedaliero Universitaria GiulianoIsontina TriesteTriesteItaly
| | - Photini Sinnis
- Department of Molecular Microbiology and Immunology, Johns HopkinsBloomberg School of Public HealthBaltimoreUnited States
| | - Katharine Collins
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Sarah G Staedke
- Liverpool School of Tropical MedicineLiverpoolUnited Kingdom
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le PaludismeOuagadougouBurkina Faso
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical MedicineLondonUnited Kingdom
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical CentreNijmegenNetherlands
- Department of Immunology and Infection, London School of Hygiene and Tropical MedicineLondonUnited Kingdom
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Kayiba NK, Nitahara Y, Tshibangu-Kabamba E, Mbuyi DK, Kabongo-Tshibaka A, Kalala NT, Tshiebue BM, Candray-Medina KS, Kaku N, Nakagama Y, Speybroeck N, Mumba DN, Disashi GT, Kaneko A, Kido Y. Malaria infection among adults residing in a highly endemic region from the Democratic Republic of the Congo. Malar J 2024; 23:82. [PMID: 38500094 PMCID: PMC10946143 DOI: 10.1186/s12936-024-04881-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 02/15/2024] [Indexed: 03/20/2024] Open
Abstract
BACKGROUND Adults infected with Plasmodium spp. in endemic areas need to be re-evaluated in light of global malaria elimination goals. They potentially undermine malaria interventions but remain an overlooked aspect of public health strategies. METHODS This study aimed to estimate the prevalence of Plasmodium spp. infections, to identify underlying parasite species, and to assess predicting factors among adults residing in an endemic area from the Democratic Republic of Congo (DRC). A community-based cross-sectional survey in subjects aged 18 years and above was therefore carried out. Study participants were interviewed using a standard questionnaire and tested for Plasmodium spp. using a rapid diagnostic test and a nested polymerase chain reaction assay. Logistic regression models were fitted to assess the effect of potential predictive factors for infections with different Plasmodium spp. RESULTS Overall, 420 adults with an estimated prevalence of Plasmodium spp. infections of 60.2% [95% CI 55.5; 64.8] were included. Non-falciparum species infected 26.2% [95% CI 22.2; 30.5] of the study population. Among infected participants, three parasite species were identified, including Plasmodium falciparum (88.5%), Plasmodium malariae (39.9%), and Plasmodium ovale (7.5%) but no Plasmodium vivax. Mixed species accounted for 42.3% of infections while single-species infections predominated with P. falciparum (56.5%) among infected participants. All infected participants were asymptomatic at the time of the survey. Adults belonging to the "most economically disadvantaged" households had increased risks of infections with any Plasmodium spp. (adjusted odds ratio, aOR = 2.87 [95% CI 1.66, 20.07]; p < 0.001), compared to those from the "less economically disadvantaged" households. Conversely, each 1 year increase in age reduced the risk of infections with any Plasmodium spp. (aOR = 0.99 [95% CI 0.97, 0.99]; p = 0.048). Specifically for non-falciparum spp., males had increased risks of infection than females (aOR = 1.83 [95% CI 1.13, 2.96]; p = 0.014). CONCLUSION Adults infected with malaria constitute a potentially important latent reservoir for the transmission of the disease in the study setting. They should specifically be taken into account in public health measures and translational research.
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Affiliation(s)
- Nadine Kalenda Kayiba
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Department of Public Health, Faculty of Medicine - Pharmacy and Public Health, University of Mbujimayi, Mbuji Mayi, Democratic Republic of Congo
- Research Institute of Health and Society, Université Catholique de Louvain, Brussels, Belgium
| | - Yuko Nitahara
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
| | - Evariste Tshibangu-Kabamba
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Department of Internal Medicine, Faculty of Medicine - Pharmacy and Public Health, University of Mbujimayi, Mbuji Mayi, Democratic Republic of Congo
| | - Denis Kalambayi Mbuyi
- Department of Internal Medicine, Faculty of Medicine - Pharmacy and Public Health, University of Mbujimayi, Mbuji Mayi, Democratic Republic of Congo
| | - Augustin Kabongo-Tshibaka
- Department of Internal Medicine, Faculty of Medicine - Pharmacy and Public Health, University of Mbujimayi, Mbuji Mayi, Democratic Republic of Congo
- Department of Molecular Infection Dynamics, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Nestor Tshituka Kalala
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Department of Public Health, Faculty of Medicine - Pharmacy and Public Health, University of Mbujimayi, Mbuji Mayi, Democratic Republic of Congo
| | - Barthélemy Mukenga Tshiebue
- Department of Internal Medicine, Faculty of Medicine - Pharmacy and Public Health, University of Mbujimayi, Mbuji Mayi, Democratic Republic of Congo
| | - Katherine-Sofia Candray-Medina
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
| | - Natsuko Kaku
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
| | - Yu Nakagama
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
| | - Niko Speybroeck
- Research Institute of Health and Society, Université Catholique de Louvain, Brussels, Belgium
| | - Dieudonné Ngoyi Mumba
- Department of Parasitology, Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of Congo
| | - Ghislain Tumba Disashi
- Department of Internal Medicine, Faculty of Medicine - Pharmacy and Public Health, University of Mbujimayi, Mbuji Mayi, Democratic Republic of Congo
| | - Akira Kaneko
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan
- Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Yasutoshi Kido
- Research Center for Infectious Disease Sciences, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan.
- Departments of Virology and Parasitology, Graduate School of Medicine, Osaka Metropolitan University, Osaka, Japan.
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Céspedes N, Donnelly EL, Hansten G, Fellows AM, Dobson M, Kaylor HL, Coles TA, Schauer J, Van de Water J, Luckhart S. Mast cell-derived IL-10 protects intestinal barrier integrity during malaria in mice and regulates parasite transmission to Anopheles stephensi with a female-biased immune response. Infect Immun 2024; 92:e0036023. [PMID: 38299826 PMCID: PMC10929420 DOI: 10.1128/iai.00360-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 01/11/2024] [Indexed: 02/02/2024] Open
Abstract
Malaria is strongly predisposed to bacteremia, which is associated with increased gastrointestinal permeability and a poor clinical prognosis. We previously identified mast cells (MCs) as mediators of intestinal permeability in malaria and described multiple cytokines that rise with parasitemia, including interleukin (IL)-10, which could protect the host from an inflammatory response and alter parasite transmission to Anopheles mosquitoes. Here, we used the Cre-loxP system and non-lethal Plasmodium yoelii yoelii 17XNL to study the roles of MC-derived IL-10 in malaria immunity and transmission. Our data suggest a sex-biased and local inflammatory response mediated by MC-derived IL-10, supported by early increased number and activation of MCs in females relative to males. Increased parasitemia in female MC IL-10 (-) mice was associated with increased ileal levels of chemokines and plasma myeloperoxidase (MPO). We also observed increased intestinal permeability in female and male MC IL-10 (-) mice relative to MC IL-10 (+) mice but no differences in blood bacterial 16S DNA levels. Transmission success of P. yoelii to A. stephensi was higher in female relative to male mice and from female and male MC IL-10 (-) mice relative to MC IL-10 (+) mice. These patterns were associated with increased plasma levels of pro-inflammatory cytokines in female MC IL-10 (-) mice and increased plasma levels of chemokines and markers of neutrophil activation in male MC IL-10 (-) mice. Overall, these data suggest that MC-derived IL-10 protects intestinal barrier integrity, regulates parasite transmission, and controls local and systemic host immune responses during malaria, with a female bias.
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Affiliation(s)
- Nora Céspedes
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, Idaho, USA
| | - Erinn L. Donnelly
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, USA
| | - Gretchen Hansten
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, Idaho, USA
| | - Abigail M. Fellows
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, Idaho, USA
| | - Megan Dobson
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, Idaho, USA
| | - Hannah L. Kaylor
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, Idaho, USA
| | - Taylor A. Coles
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, Idaho, USA
| | - Joseph Schauer
- Division of Rheumatology, Allergy and Clinical Immunology, University of California, Davis, California, USA
| | - Judy Van de Water
- Division of Rheumatology, Allergy and Clinical Immunology, University of California, Davis, California, USA
| | - Shirley Luckhart
- Department of Entomology, Plant Pathology and Nematology, University of Idaho, Moscow, Idaho, USA
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, USA
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Tebben K, Yirampo S, Coulibaly D, Koné AK, Laurens MB, Stucke EM, Dembélé A, Tolo Y, Traoré K, Niangaly A, Berry AA, Kouriba B, Plowe CV, Doumbo OK, Lyke KE, Takala-Harrison S, Thera MA, Travassos MA, Serre D. Gene expression analyses reveal differences in children's response to malaria according to their age. Nat Commun 2024; 15:2021. [PMID: 38448421 PMCID: PMC10918175 DOI: 10.1038/s41467-024-46416-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 02/26/2024] [Indexed: 03/08/2024] Open
Abstract
In Bandiagara, Mali, children experience on average two clinical malaria episodes per year. However, even in the same transmission area, the number of uncomplicated symptomatic infections, and their parasitemia, can vary dramatically among children. We simultaneously characterize host and parasite gene expression profiles from 136 Malian children with symptomatic falciparum malaria and examine differences in the relative proportion of immune cells and parasite stages, as well as in gene expression, associated with infection and or patient characteristics. Parasitemia explains much of the variation in host and parasite gene expression, and infections with higher parasitemia display proportionally more neutrophils and fewer T cells, suggesting parasitemia-dependent neutrophil recruitment and/or T cell extravasation to secondary lymphoid organs. The child's age also strongly correlates with variations in gene expression: Plasmodium falciparum genes associated with age suggest that older children carry more male gametocytes, while variations in host gene expression indicate a stronger innate response in younger children and stronger adaptive response in older children. These analyses highlight the variability in host responses and parasite regulation during P. falciparum symptomatic infections and emphasize the importance of considering the children's age when studying and treating malaria infections.
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Affiliation(s)
- Kieran Tebben
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Salif Yirampo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Drissa Coulibaly
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Abdoulaye K Koné
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Matthew B Laurens
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Emily M Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ahmadou Dembélé
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Youssouf Tolo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Karim Traoré
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Amadou Niangaly
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Andrea A Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Bourema Kouriba
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Christopher V Plowe
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ogobara K Doumbo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Kirsten E Lyke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Shannon Takala-Harrison
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Mahamadou A Thera
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies, Bamako, Mali
| | - Mark A Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - David Serre
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.
- Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore, MD, USA.
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7
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Potter GE, Callier V, Shrestha B, Joshi S, Dwivedi A, Silva JC, Laurens MB, Follmann DA, Deye GA. Can incorporating genotyping data into efficacy estimators improve efficiency of early phase malaria vaccine trials? Malar J 2023; 22:383. [PMID: 38115002 PMCID: PMC10729369 DOI: 10.1186/s12936-023-04802-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 11/22/2023] [Indexed: 12/21/2023] Open
Abstract
BACKGROUND Early phase malaria vaccine field trials typically measure malaria infection by PCR or thick blood smear microscopy performed on serially sampled blood. Vaccine efficacy (VE) is the proportion reduction in an endpoint due to vaccination and is often calculated as VEHR = 1-hazard ratio or VERR = 1-risk ratio. Genotyping information can distinguish different clones and distinguish multiple infections over time, potentially increasing statistical power. This paper investigates two alternative VE endpoints incorporating genotyping information: VEmolFOI, the vaccine-induced proportion reduction in incidence of new clones acquired over time, and VEC, the vaccine-induced proportion reduction in mean number of infecting clones per exposure. METHODS Power of VEmolFOI and VEC was compared to that of VEHR and VERR by simulations and analytic derivations, and the four VE methods were applied to three data sets: a Phase 3 trial of RTS,S malaria vaccine in 6912 African infants, a Phase 2 trial of PfSPZ Vaccine in 80 Burkina Faso adults, and a trial comparing Plasmodium vivax incidence in 466 Papua New Guinean children after receiving chloroquine + artemether lumefantrine with or without primaquine (as these VE methods can also quantify effects of other prevention measures). By destroying hibernating liver-stage P. vivax, primaquine reduces subsequent reactivations after treatment completion. RESULTS In the trial of RTS,S vaccine, a significantly reduced number of clones at first infection was observed, but this was not the case in trials of PfSPZ Vaccine or primaquine, although the PfSPZ trial lacked power to show a reduction. Resampling smaller data sets from the large RTS,S trial to simulate phase 2 trials showed modest power gains from VEC compared to VEHR for data like those from RTS,S, but VEC is less powerful than VEHR for trials in which the number of clones at first infection is not reduced. VEmolFOI was most powerful in model-based simulations, but only the primaquine trial collected enough serial samples to precisely estimate VEmolFOI. The primaquine VEmolFOI estimate decreased after most control arm liver-stage infections reactivated (which mathematically resembles a waning vaccine), preventing VEmolFOI from improving power. CONCLUSIONS The power gain from the genotyping methods depends on the context. Because input parameters for early phase power calculations are often uncertain, these estimators are not recommended as primary endpoints for small trials unless supported by targeted data analysis. TRIAL REGISTRATIONS NCT00866619, NCT02663700, NCT02143934.
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Affiliation(s)
- Gail E Potter
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
| | - Viviane Callier
- Clinical Monitoring Research Program Directorate, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Biraj Shrestha
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Sudhaunshu Joshi
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ankit Dwivedi
- Institute for Genomic Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Joana C Silva
- Institute for Genomic Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Microbiology & Immunology, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Matthew B Laurens
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Dean A Follmann
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Gregory A Deye
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
- AstraZeneca PLC, Gaithersburg, MD, USA
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8
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Emiru T, Getachew D, Murphy M, Sedda L, Ejigu LA, Bulto MG, Byrne I, Demisse M, Abdo M, Chali W, Elliott A, Vickers EN, Aranda-Díaz A, Alemayehu L, Behaksera SW, Jebessa G, Dinka H, Tsegaye T, Teka H, Chibsa S, Mumba P, Girma S, Hwang J, Yoshimizu M, Sutcliffe A, Taffese HS, Bayissa GA, Zohdy S, Tongren JE, Drakeley C, Greenhouse B, Bousema T, Tadesse FG. Evidence for a role of Anopheles stephensi in the spread of drug- and diagnosis-resistant malaria in Africa. Nat Med 2023; 29:3203-3211. [PMID: 37884028 PMCID: PMC10719088 DOI: 10.1038/s41591-023-02641-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Accepted: 10/12/2023] [Indexed: 10/28/2023]
Abstract
Anopheles stephensi, an Asian malaria vector, continues to expand across Africa. The vector is now firmly established in urban settings in the Horn of Africa. Its presence in areas where malaria resurged suggested a possible role in causing malaria outbreaks. Here, using a prospective case-control design, we investigated the role of An. stephensi in transmission following a malaria outbreak in Dire Dawa, Ethiopia in April-July 2022. Screening contacts of patients with malaria and febrile controls revealed spatial clustering of Plasmodium falciparum infections around patients with malaria in strong association with the presence of An. stephensi in the household vicinity. Plasmodium sporozoites were detected in these mosquitoes. This outbreak involved clonal propagation of parasites with molecular signatures of artemisinin and diagnostic resistance. To our knowledge, this study provides the strongest evidence so far for a role of An. stephensi in driving an urban malaria outbreak in Africa, highlighting the major public health threat posed by this fast-spreading mosquito.
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Affiliation(s)
- Tadele Emiru
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | | | - Maxwell Murphy
- EPPIcenter program, Division of HIV, ID and Global Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Luigi Sedda
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, Lancaster, UK
| | | | | | - Isabel Byrne
- London School of Hygiene and Tropical Medicine, London, UK
| | | | - Melat Abdo
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Wakweya Chali
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
- Radboudumc, Nijmegen, the Netherlands
| | - Aaron Elliott
- EPPIcenter program, Division of HIV, ID and Global Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Eric Neubauer Vickers
- EPPIcenter program, Division of HIV, ID and Global Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Andrés Aranda-Díaz
- EPPIcenter program, Division of HIV, ID and Global Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Lina Alemayehu
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | | | - Gutema Jebessa
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Hunduma Dinka
- Adama Science and Technology University, Adama, Ethiopia
| | - Tizita Tsegaye
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Hiwot Teka
- U.S. President's Malaria Initiative, USAID, Addis Ababa, Ethiopia
| | - Sheleme Chibsa
- U.S. President's Malaria Initiative, USAID, Addis Ababa, Ethiopia
| | - Peter Mumba
- U.S. President's Malaria Initiative, USAID, Addis Ababa, Ethiopia
| | - Samuel Girma
- U.S. President's Malaria Initiative, USAID, Addis Ababa, Ethiopia
| | - Jimee Hwang
- U.S. President's Malaria Initiative, Malaria Branch, US Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | - Alice Sutcliffe
- U.S. President's Malaria Initiative, Entomology Branch, US Centers for Disease Control and Prevention, Atlanta, GA, USA
| | | | | | - Sarah Zohdy
- U.S. President's Malaria Initiative, Entomology Branch, US Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Jon Eric Tongren
- U.S. President's Malaria Initiative, Malaria Branch, US Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Chris Drakeley
- London School of Hygiene and Tropical Medicine, London, UK
| | - Bryan Greenhouse
- EPPIcenter program, Division of HIV, ID and Global Medicine, University of California, San Francisco, San Francisco, CA, USA
| | | | - Fitsum G Tadesse
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia.
- London School of Hygiene and Tropical Medicine, London, UK.
- Radboudumc, Nijmegen, the Netherlands.
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9
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Tebben K, Yirampo S, Coulibaly D, Koné A, Laurens M, Stucke E, Dembélé A, Tolo Y, Traoré K, Niangaly A, Berry A, Kouriba B, Plowe C, Doumbo O, Lyke K, Takala-Harrison S, Thera M, Travassos M, Serre D. Gene expression analyses reveal differences in children's response to malaria according to their age. RESEARCH SQUARE 2023:rs.3.rs-3487114. [PMID: 37961587 PMCID: PMC10635353 DOI: 10.21203/rs.3.rs-3487114/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
In Bandiagara, Mali, children experience on average two clinical malaria episodes per season. However, even in the same transmission area, the number of uncomplicated symptomatic infections, and their parasitemia, vary dramatically among children. To examine the factors contributing to these variations, we simultaneously characterized the host and parasite gene expression profiles from 136 children with symptomatic falciparum malaria and analyzed the expression of 9,205 human and 2,484 Plasmodium genes. We used gene expression deconvolution to estimate the relative proportion of immune cells and parasite stages in each sample and to adjust the differential gene expression analyses. Parasitemia explained much of the variation in both host and parasite gene expression and revealed that infections with higher parasitemia had more neutrophils and fewer T cells, suggesting parasitemia-dependent neutrophil recruitment and/or T cell extravasation to secondary lymphoid organs. The child's age was also strongly correlated with gene expression variations. Plasmodium falciparum genes associated with age suggested that older children carried more male gametocytes, while host genes associated with age indicated a stronger innate response (through TLR and NLR signaling) in younger children and stronger adaptive immunity (through TCR and BCR signaling) in older children. These analyses highlight the variability in host responses and parasite regulation during P. falciparum symptomatic infections and emphasize the importance of considering the children's age when studying and treating malaria infections.
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Affiliation(s)
| | - Salif Yirampo
- Universite des Sciences des Techniques et des Technologies de Bamako
| | - Drissa Coulibaly
- Universite des Sciences des Techniques et des Technologies de Bamako
| | - Abdoulaye Koné
- Universite des Sciences des Techniques et des Technologies de Bamako
| | | | | | - Ahmadou Dembélé
- Universite des Sciences des Techniques et des Technologies de Bamako
| | - Youssouf Tolo
- Universite des Sciences des Techniques et des Technologies de Bamako
| | - Karim Traoré
- Universite des Sciences des Techniques et des Technologies de Bamako
| | - Ahmadou Niangaly
- Universite des Sciences des Techniques et des Technologies de Bamako
| | | | - Bourema Kouriba
- Universite des Sciences des Techniques et des Technologies de Bamako
| | | | - Ogobara Doumbo
- Universite des Sciences des Techniques et des Technologies de Bamako
| | | | | | - Mahamadou Thera
- Malaria Research and Training Centre-International Center for Excellence in Research (MRTC-ICER)
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10
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Tebben K, Yirampo S, Coulibaly D, Koné AK, Laurens MB, Stucke EM, Dembélé A, Tolo Y, Traoré K, Niangaly A, Berry AA, Kouriba B, Plowe CV, Doumbo OK, Lyke KE, Takala-Harrison S, Thera MA, Travassos MA, Serre D. Gene expression analyses reveal differences in children's response to malaria according to their age. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.24.563751. [PMID: 37961701 PMCID: PMC10634788 DOI: 10.1101/2023.10.24.563751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
In Bandiagara, Mali, children experience on average two clinical malaria episodes per season. However, even in the same transmission area, the number of uncomplicated symptomatic infections, and their parasitemia, vary dramatically among children. To examine the factors contributing to these variations, we simultaneously characterized the host and parasite gene expression profiles from 136 children with symptomatic falciparum malaria and analyzed the expression of 9,205 human and 2,484 Plasmodium genes. We used gene expression deconvolution to estimate the relative proportion of immune cells and parasite stages in each sample and to adjust the differential gene expression analyses. Parasitemia explained much of the variation in both host and parasite gene expression and revealed that infections with higher parasitemia had more neutrophils and fewer T cells, suggesting parasitemia-dependent neutrophil recruitment and/or T cell extravasation to secondary lymphoid organs. The child's age was also strongly correlated with gene expression variations. Plasmodium falciparum genes associated with age suggested that older children carried more male gametocytes, while host genes associated with age indicated a stronger innate response (through TLR and NLR signaling) in younger children and stronger adaptive immunity (through TCR and BCR signaling) in older children. These analyses highlight the variability in host responses and parasite regulation during P. falciparum symptomatic infections and emphasize the importance of considering the children's age when studying and treating malaria infections.
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Affiliation(s)
- Kieran Tebben
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine; Baltimore, USA
| | - Salif Yirampo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Drissa Coulibaly
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Abdoulaye K. Koné
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Matthew B. Laurens
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine; Baltimore, USA
| | - Emily M. Stucke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine; Baltimore, USA
| | - Ahmadou Dembélé
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Youssouf Tolo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Karim Traoré
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Amadou Niangaly
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Andrea A. Berry
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine; Baltimore, USA
| | - Bourema Kouriba
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Christopher V. Plowe
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine; Baltimore, USA
| | - Ogobara K Doumbo
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Kirsten E. Lyke
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine; Baltimore, USA
| | - Shannon Takala-Harrison
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine; Baltimore, USA
| | - Mahamadou A. Thera
- Malaria Research and Training Center, University of Sciences, Techniques and Technologies; Bamako, Mali
| | - Mark A. Travassos
- Malaria Research Program, Center for Vaccine Development and Global Health, University of Maryland School of Medicine; Baltimore, USA
| | - David Serre
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine; Baltimore, USA
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11
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Biruksew A, Demeke A, Birhanu Z, Golassa L, Getnet M, Yewhalaw D. Schoolchildren with asymptomatic malaria are potential hotspot for malaria reservoir in Ethiopia: implications for malaria control and elimination efforts. Malar J 2023; 22:311. [PMID: 37845680 PMCID: PMC10580533 DOI: 10.1186/s12936-023-04736-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 09/30/2023] [Indexed: 10/18/2023] Open
Abstract
BACKGROUND Schoolchildren with asymptomatic malaria infections often go undiagnosed and untreated, serving as reservoirs for infection that hamper malaria control and elimination efforts. In this context, little is known about the magnitude of asymptomatic malaria infections in apparently healthy schoolchildren in Ethiopia. This study was aimed at determining the prevalence of asymptomatic malaria infection and its associated factors in apparently healthy schoolchildren in Ethiopia. METHODS From September 2021 to January 2022, a school-based cross-sectional study was conducted on 994 apparently healthy schoolchildren (aged 6-15 years) selected from 21 primary schools in the Gomma district, of Jimma zone, southwestern Oromia, Ethiopia. A multi-stage sampling technique was used to select schools and participants. After allocating the total sample proportionally to each school and then to each grade, participants were selected using the lottery method from a list of student records (rosters). Finger-pricked blood samples were collected for microscopy blood film preparation and malaria rapid diagnostic test (RDT) (SD Bioline Malaria Ag Pf/Pv). Moreover, dry blood spots (DBSs) were prepared onto filter papers for quantitative real time polymerase chain reaction (qPCR) analysis. RESULTS As determined by RDT and microscopy, the prevalence of asymptomatic malaria was 2.20% and 1.51%, respectively. Using qPCR, the overall prevalence was 5.03% (50/994). Of this, Plasmodium falciparum, Plasmodium vivax and mixed infections accounted for 90%, 6% and 4%, respectively. Submicroscopic asymptomatic malaria infection was also accounted for 70% (35/50) of the overall prevalence. Household head age, nighttime outdoor activities of household heads, family history of malaria, absence of insecticide-treated nets (ITN), and presence of stagnant water around the houses are all significantly associated with asymptomatic malaria infections among schoolchildren. CONCLUSIONS This study found that both RDT and microscopy underestimated the prevalence of asymptomatic malaria in schoolchildren. However, qPCR was able to detect even low levels of parasitaemia and revealed a higher prevalence of asymptomatic submicroscopic malaria infections. The findings imply that schoolchildren with asymptomatic malaria infection are potential hotspot for malaria reservoir that fuels ongoing transmission. Therefore, it is imperative to include schoolchildren and schools in malaria intervention package and equally important is the adoption of more advanced and sensitive diagnostic tools, which would be crucial for successful malaria control and elimination efforts. Targeted interventions for asymptomatic malaria-infected schoolchildren can provide invaluable support to the National Malaria Control Programme in controlling and eventually eliminating the disease.
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Affiliation(s)
- Abdissa Biruksew
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIRC), Jimma University, Jimma, Ethiopia
| | | | - Zewdie Birhanu
- Department of Health, Behavior, and Society, Faculty of Public Health, Institute of Health Jimma University, Jimma, Ethiopia
| | - Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Masrie Getnet
- Department of Biostatistics and Epidemiology, Faculty of Public Health, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Faculty of Health Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIRC), Jimma University, Jimma, Ethiopia
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12
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Potter GE, Callier V, Shrestha B, Joshi S, Dwivedi A, Silva JC, Laurens MB, Follmann DA, Deye GA. Can incorporating genotyping data into efficacy estimators improve efficiency of early phase malaria vaccine trials? RESEARCH SQUARE 2023:rs.3.rs-3370731. [PMID: 37790581 PMCID: PMC10543529 DOI: 10.21203/rs.3.rs-3370731/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Background Early phase malaria vaccine field trials typically measure malaria infection by PCR or thick blood smear microscopy performed on serially sampled blood. Vaccine efficacy (VE) is the proportion reduction in an endpoint due to vaccination and is often calculated as V E H R = 1 - hazard ratio or V E R R = 1 - risk ratio. Genotyping information can distinguish different clones and distinguish multiple infections over time, potentially increasing statistical power. This paper investigates two alternative VE endpoints incorporating genotyping information: V E m o l F O I , the vaccine-induced proportion reduction in incidence of new clones acquired over time, and V E C , the vaccine-induced proportion reduction in mean number of infecting clones per exposure. Methods We used simulations and analytic derivations to compare power of these methods to V E H R and V E R R and applied them to three data sets: a Phase 3 trial of RTS,S malaria vaccine in 6912 African infants, a Phase 2 trial of PfSPZ Vaccine in 80 Burkina Faso adults, and a trial comparing Plasmodium vivax incidence in 466 Papua New Guinean children after receiving chloroquine + artemether lumefantrine with or without primaquine (as these VE methods can also quantify effects of other prevention measures). By destroying hibernating liver-stage P. vivax, primaquine reduces subsequent reactivations after treatment completion. Results The RTS,S vaccine significantly reduced the number of clones at first infection, but PfSPZ vaccine and primaquine did not. Resampling smaller data sets from the large RTS,S trial to simulate phase 2 trials showed modest power gains from V E C compared to V E H R for data like RTS,S, but V E C is less powerful than V E H R for vaccines which do not reduce the number of clones at first infection. V E m o l F O I was most powerful in model-based simulations, but only the primaquine trial collected enough serial samples to precisely estimate V E m o l F O I . The primaquine V E m o l F O I estimate decreased after most control arm liver-stage infections reactivated (which mathematically resembles a waning vaccine), preventing V E m o l F O I from improving power. Conclusions The power gain from the genotyping methods depends on the context. Because input parameters for early phase power calculations are often uncertain, we recommend against these estimators as primary endpoints for small trials unless supported by targeted data analysis. Trial registrations NCT00866619, NCT02663700, NCT02143934.
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Affiliation(s)
- Gail E Potter
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health
| | - Viviane Callier
- Clinical Monitoring Research Program Directorate, Frederick National Laboratory for Cancer Research
| | | | | | - Ankit Dwivedi
- Institute for Genomic Sciences, University of Maryland School of Medicine
| | - Joana C Silva
- Institute for Genomic Sciences and Department of Microbiology & Immunology, University of Maryland School of Medicine
| | - Matthew B Laurens
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine
| | - Dean A Follmann
- Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health
| | - Gregory A Deye
- Division of Microbiology and Infectious Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health
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13
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Rapp T, Amagai K, Sinai C, Basham C, Loya M, Ngasala S, Said H, Muller MS, Chhetri SB, Yang G, François R, Odas M, Mathias D, Juliano JJ, Lin FC, Ngasala B, Lin JT. Micro-heterogeneity of transmission shapes the submicroscopic malaria reservoir in coastal Tanzania. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.09.06.23295089. [PMID: 37732257 PMCID: PMC10508794 DOI: 10.1101/2023.09.06.23295089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Background Asymptomatic malaria may be patent (visible by microscopy) and detectable by rapid malaria diagnostic tests (RDTs), or it may be submicroscopic and only detectable by polymerase chain reaction (PCR). Methods To characterize the submicroscopic reservoir in an area of declining malaria transmission, asymptomatic persons >5 years of age in Bagamoyo District, Tanzania, were screened using RDT, microscopy, and PCR. We investigated the size of the submicroscopic reservoir across villages, determined factors associated with submicroscopic parasitemia, and assessed the natural history of submicroscopic malaria over four weeks. Results Among 6,076 participants, Plasmodium falciparum prevalence by RDT, microscopy, and PCR was 9%, 9%, and 28%, respectively, with roughly two-thirds of PCR-positive individuals harboring submicroscopic infection. Adult status, female gender, dry season months, screened windows, and bednet use were associated with submicroscopic carriage. Among 15 villages encompassing 80% of participants, the proportion of submicroscopic carriers increased with decreasing village-level malaria prevalence. Over four weeks, 23% (61/266) of submicroscopic carriers became RDT-positive and were treated, with half exhibiting symptoms. This occurred more frequently in villages with higher malaria prevalence. Conclusions Micro-heterogeneity in transmission impacts the size of the submicroscopic reservoir and the likelihood of submicroscopic carriers developing patent malaria in coastal Tanzania.
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Affiliation(s)
- Tyler Rapp
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Kano Amagai
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Cyrus Sinai
- Department of Geography, University of North Carolina, Chapel Hill, NC USA
| | - Christopher Basham
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Mwajabu Loya
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Sifa Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Hamza Said
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Meredith S Muller
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Srijana B Chhetri
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Guozheng Yang
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Ruthly François
- Gillings School of Global Public Health, University of North Carolina, Chapel Hill, NC USA
| | - Melic Odas
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Derrick Mathias
- Florida Medical Entomology Laboratory, Institute of Food & Agricultural Sciences, University of Florida, Vero Beach, FL USA
| | - Jonathan J Juliano
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
| | - Feng-Chang Lin
- Department of Geography, University of North Carolina, Chapel Hill, NC USA
| | - Billy Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Jessica T Lin
- Institute of Global Health and Infectious Diseases, University of North Carolina School of Medicine, Chapel Hill, NC USA
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14
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de Oliveira Rekowsky LL, de Oliveira DT, Cazzaniga RA, Magalhães LS, Albuquerque LF, Araujo JMS, Tenório MDL, Machado TC, Lipscomb MW, Dos Santos PL, Ribeiro de Jesus A, Bezerra-Santos M, da Silva RLL. Influence of Testosterone in Neglected Tropical Diseases: Clinical Aspects in Leprosy and In Vitro Experiments in Leishmaniasis. Trop Med Infect Dis 2023; 8:357. [PMID: 37505653 PMCID: PMC10385189 DOI: 10.3390/tropicalmed8070357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/02/2023] [Accepted: 07/05/2023] [Indexed: 07/29/2023] Open
Abstract
Neglected tropical diseases encompass a group of chronic and debilitating infectious diseases that primarily affect marginalized populations. Among these diseases, leprosy and leishmaniasis are endemic in numerous countries and can result in severe and disfiguring manifestations. Although there have been reports indicating a higher incidence of leprosy and leishmaniasis in males, the underlying factors contributing to this observation remain unclear. Therefore, the objective of this study was to examine both clinical and experimental evidence regarding the role of testosterone in leprosy and leishmaniasis. A prospective clinical study was conducted to compare the clinical forms of leprosy and assess circulating testosterone levels. Additionally, the impact of testosterone on Leishmania amazonensis-infected macrophages was evaluated in vitro. The findings demonstrated that serum testosterone levels were higher in women with leprosy than in the control group, irrespective of the multi- or pauci-bacillary form of the disease. However, no differences in testosterone levels were observed in men when comparing leprosy patients and controls. Interestingly, increasing doses of testosterone in macrophages infected with L. amazonensis resulted in a higher proportion of infected cells, decreased CD40 expression on the cell surface, elevated expression of SOCS1, and decreased expression of IRF5. These findings provide biological evidence to support the influence of testosterone on intracellular infections, though the interpretation of clinical evidence remains limited.
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Affiliation(s)
- Laís Lima de Oliveira Rekowsky
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Posgraduate Program of Health Science, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Daniela Teles de Oliveira
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Rodrigo Anselmo Cazzaniga
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Lucas Sousa Magalhães
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Posgraduate Program of Health Science, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Lenise Franco Albuquerque
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Dermatology Division of Medical Hospital, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Jonnia Maria Sherlock Araujo
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Dermatology Division of Medical Hospital, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Martha Débora Lira Tenório
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Dermatology Division of Medical Hospital, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Tiziane Cotta Machado
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Michael W Lipscomb
- Department of Pharmacology, Center for Immunology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Priscila Lima Dos Santos
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Posgraduate Program of Health Science, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Amelia Ribeiro de Jesus
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Posgraduate Program of Health Science, Federal University of Sergipe, Aracaju 49060676, Brazil
- Instituto de Investigação em Imunologia (iii), Institutos Nacionais de Ciência e Tecnologia (INCT), CNPq, São Paulo 05403-900, Brazil
| | - Márcio Bezerra-Santos
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Posgraduate Program of Health Science, Federal University of Sergipe, Aracaju 49060676, Brazil
| | - Ricardo Luís Louzada da Silva
- Laboratory of Immunology and Molecular Biology, Federal University of Sergipe, Aracaju 49060676, Brazil
- Health Education Department, Federal University of Sergipe, Lagarto 49400000, Brazil
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15
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Ali MH, Kitau J, Ali AS, Al-Mafazy AW, Tegegne SG, Ussi O, Musanhu C, Shija SJ, Khatib BO, Mkali H, Mkude S, Makenga G, Kasagama E, Molteni F, Kisoka N, Kitojo C, Serbantez N, Reaves E, Yoti Z. Malaria elimination in Zanzibar: where next? Pan Afr Med J 2023; 45:7. [PMID: 37538363 PMCID: PMC10395111 DOI: 10.11604/pamj.supp.2023.45.1.39804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Accepted: 06/12/2023] [Indexed: 08/05/2023] Open
Abstract
In 2018, Zanzibar developed a national malaria strategic plan IV (2018-2023) to guide elimination of malaria by 2023. We assessed progress in the implementation of malaria activities as part of the end-term review of the strategic plan. The review was done between August and October 2022 following the WHO guideline to assess progress made towards malaria elimination, effectiveness of the health systems in delivering malaria case management; and malaria financing. A desk review examined available malaria data, annual work plans and implementation reports for evidence of implemented malaria activities. This was complemented by field visits to selected health facilities and communities by external experts, and interviews with health management teams and inhabitants to authenticate desk review findings. A steady increase in the annual parasite incidence (API) was observed in Zanzibar, from 2.7 (2017) to 3.6 (2021) cases per 1,000 population with marked heterogeneity between areas. However, about 68% of the detected malaria cases were imported into Zanzibar. Malaria case follow-up and investigation increased from <70% in 2017 to 94% and 96% respectively, in 2021. The review noted a 3.7-fold increase of the health allocation in the country's budget, from 31.7 million USD (2017/18) to 117.3 million USD (2022/23) but malaria allocation remained low (<1%). The varying transmission levels in the islands suggest a need for strategic re-orientation of the elimination attempts from a national-wide to a sub-national agenda. We recommend increasing malaria allocation from the health budget to ensure sustainability of malaria elimination interventions.
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Affiliation(s)
- Mohamed Haji Ali
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, Tanzania
| | - Jovin Kitau
- World Health Organization, Country office, Dar-es-Salaam, Tanzania
| | | | - Abdul-wahid Al-Mafazy
- Second Vice President Office-Zanzibar Country Coordinating Mechanism, Zanzibar, Tanzania
| | | | - Omar Ussi
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, Tanzania
| | | | - Shija Joseph Shija
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, Tanzania
| | - Bakari Omar Khatib
- Zanzibar Malaria Elimination Programme, Ministry of Health, Zanzibar, Tanzania
| | - Humphrey Mkali
- Population Services International, Dar-es-Salaam, Tanzania
| | - Sigsbert Mkude
- Population Services International, Dar-es-Salaam, Tanzania
| | | | | | - Fabrizio Molteni
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
| | - Noela Kisoka
- Swiss Tropical and Public Health Institute, Allschwil, Switzerland
| | - Chonge Kitojo
- US President´s Malaria Initiative, United States Agency for International Development, Dar-es-Salaam, United Republic of Tanzania
| | - Naomi Serbantez
- US President´s Malaria Initiative, United States Agency for International Development, Dar-es-Salaam, United Republic of Tanzania
| | - Erik Reaves
- United States Centers for Disease Control, Dar-es-Salaam, Tanzania
| | - Zabulon Yoti
- World Health Organization, Country office, Dar-es-Salaam, Tanzania
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16
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Patel RK, Pirozzi NT, Hoefler TG, Connolly MG, Singleton LG, Kohman RA. Sex-dependent deficits in associative learning across multiple LPS doses. Physiol Behav 2023; 268:114249. [PMID: 37210020 DOI: 10.1016/j.physbeh.2023.114249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/15/2023] [Accepted: 05/16/2023] [Indexed: 05/22/2023]
Abstract
Activation of the immune system by administration of the bacterial endotoxin lipopolysaccharide (LPS) impairs cognitive and neural plasticity processes. For instance, acute LPS exposure has been reported to impair memory consolidation, spatial learning and memory, and associative learning. However, the inclusion of both males and females in basic research is limited. Whether LPS-induced cognitive deficits are comparable in males and females is currently unclear. Therefore, the present study evaluated sex differences in associative learning following administration of LPS at a dose (i.e., 0.25 mg/kg) that impairs learning in males and higher LPS doses (i.e., 0.325 - 1 mg/kg) across multiple experiments. Adult male and female C57BL/6J mice were trained in a two-way active avoidance conditioning task following their respective treatments. Results showed that LPS had sex-dependent effects on associative learning. The 0.25 mg/kg LPS dose impaired learning in males, consistent with prior work. However, LPS, at any of the doses employed across three experiments, did not disrupt associative learning in females. Female mice were resistant to learning deficits despite showing heightened levels of select proinflammatory cytokines in response to LPS. Collectively, these findings demonstrate that the learning impairments resulting from acute LPS exposure are sex-dependent.
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Affiliation(s)
- Reeva K Patel
- University of North Carolina Wilmington, Department of Psychology, Wilmington, NC, USA.
| | - Nicolas T Pirozzi
- University of North Carolina Wilmington, Department of Psychology, Wilmington, NC, USA.
| | - Tiffany G Hoefler
- University of North Carolina Wilmington, Department of Psychology, Wilmington, NC, USA.
| | - Meghan G Connolly
- University of Illinois Urbana-Champaign, Department of Psychology, Champaign, IL, USA.
| | - Lauren G Singleton
- University of North Carolina Wilmington, Department of Psychology, Wilmington, NC, USA.
| | - Rachel A Kohman
- University of North Carolina Wilmington, Department of Psychology, Wilmington, NC, USA.
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17
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Andolina C, Ramjith J, Rek J, Lanke K, Okoth J, Grignard L, Arinaitwe E, Briggs J, Bailey J, Aydemir O, Kamya MR, Greenhouse B, Dorsey G, Staedke SG, Drakeley C, Jonker M, Bousema T. Plasmodium falciparum gametocyte carriage in longitudinally monitored incident infections is associated with duration of infection and human host factors. Sci Rep 2023; 13:7072. [PMID: 37127688 PMCID: PMC10150352 DOI: 10.1038/s41598-023-33657-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 04/17/2023] [Indexed: 05/03/2023] Open
Abstract
Malaria transmission depends on the presence of Plasmodium gametocytes that are the only parasite life stage that can infect mosquitoes. Gametocyte production varies between infections and over the course of infections. Infection duration is highly important for gametocyte production but poorly quantified. Between 2017 and 2019 an all-age cohort of individuals from Tororo, eastern Uganda was followed by continuous passive and routine assessments. We longitudinally monitored 104 incident infections from 98 individuals who were sampled once every 28 days and on any day of symptoms. Among infections that lasted ≥ 3 months, gametocyte appearance was near-universal with 96% of infections having detectable gametocytes prior to clearance. However, most infections were of much shorter duration; 55.7% of asymptomatic infections were detected only once. When considering all asymptomatic infections, regardless of their duration, only 36.3% had detectable gametocytes on at least one time-point prior to parasite clearance. Infections in individuals with sickle-cell trait (HbAS) were more likely to have gametocytes detected (Hazard Rate (HR) = 2.68, 95% CI 1.12, 6.38; p = 0.0231) and had gametocytes detected at higher densities (Density Ratio (DR) = 9.19, 95% CI 2.79, 30.23; p = 0.0002) compared to infections in wildtype (HbAA) individuals. Our findings suggest that a large proportion of incident infections is too short in duration and of too low density to contribute to onward transmission.
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Affiliation(s)
- Chiara Andolina
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Jordache Ramjith
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- Department for Health Evidence, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Joseph Okoth
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Lynn Grignard
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | | | - Jessica Briggs
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA
| | - Jeffrey Bailey
- Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, USA
| | - Ozkan Aydemir
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Bryan Greenhouse
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA
| | - Grant Dorsey
- Department of Medicine, San Francisco General Hospital, University of California, San Francisco, USA
| | - Sarah G Staedke
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Marianne Jonker
- Department for Health Evidence, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK.
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18
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The influence of the host sex on parasitemia of parasite lineages belonging to Haemoproteus majoris in a natural bird community. Parasitol Res 2023; 122:895-901. [PMID: 36781472 DOI: 10.1007/s00436-023-07793-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 02/07/2023] [Indexed: 02/15/2023]
Abstract
Immunological capability shows a sexual dimorphism in diverse animal species. Females are generally more immunocompetent than males, leading to the higher susceptibility of males to infection compared to females and thus greater infection-related pathology in males. These sex-differences in immunity remain understudied in birds. Here, we compared the percentage of parasitemia of three different parasite lineages belonging to the morphological species Haemoproteus majoris (namely, PARUS1, PHSIB1 and WW2) in terms of the sex of birds living in a natural community. We found that parasitemia (percentage of erythrocytes infected with parasites) of WW2 lineage, but not of the other two lineages of H. majoris, is higher in male birds compared to female birds. Similarly, we showed that the total parasitemia of these three H. majoris lineages is higher in male birds compared to female birds. Our study points out that male birds at the community level may be more susceptible to infection by certain parasites than female birds. We propose that sexual dimorphism in parasitemia of certain parasites in host birds might be more common than previously thought, similar to what is observed in other species, influencing host population dynamics in a sex-specific manner. Therefore, it can be speculated that infection by certain parasites might differentially affect male and female birds, possibly resulting in a bias in survival rates between sexes due to infections, in certain contexts.
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19
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Oduma CO, Ombok M, Zhao X, Huwe T, Ondigo BN, Kazura JW, Grieco J, Achee N, Liu F, Ochomo E, Koepfli C. Altitude, not potential larval habitat availability, explains pronounced variation in Plasmodium falciparum infection prevalence in the western Kenya highlands. PLOS GLOBAL PUBLIC HEALTH 2023; 3:e0001505. [PMID: 37068071 PMCID: PMC10109483 DOI: 10.1371/journal.pgph.0001505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Accepted: 03/03/2023] [Indexed: 04/18/2023]
Abstract
Progress in malaria control has stalled over the recent years. Knowledge on main drivers of transmission explaining small-scale variation in prevalence can inform targeted control measures. We collected finger-prick blood samples from 3061 individuals irrespective of clinical symptoms in 20 clusters in Busia in western Kenya and screened for Plasmodium falciparum parasites using qPCR and microscopy. Clusters spanned an altitude range of 207 meters (1077-1284 m). We mapped potential mosquito larval habitats and determined their number within 250 m of a household and distances to households using ArcMap. Across all clusters, P. falciparum parasites were detected in 49.8% (1524/3061) of individuals by qPCR and 19.5% (596/3061) by microscopy. Across the clusters, prevalence ranged from 26% to 70% by qPCR. Three to 34 larval habitats per cluster and 0-17 habitats within a 250m radius around households were observed. Using a generalized linear mixed effect model (GLMM), a 5% decrease in the odds of getting infected per each 10m increase in altitude was observed, while the number of larval habitats and their proximity to households were not statistically significant predictors for prevalence. Kitchen located indoors, open eaves, a lower level of education of the household head, older age, and being male were significantly associated with higher prevalence. Pronounced variation in prevalence at small scales was observed and needs to be taken into account for malaria surveillance and control. Potential larval habitat frequency had no direct impact on prevalence.
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Affiliation(s)
- Colins O Oduma
- Department of Biochemistry and Molecular Biology, Egerton University, Nakuru, Kenya
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Maurice Ombok
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Xingyuan Zhao
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN, United States of America
| | - Tiffany Huwe
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
| | - Bartholomew N Ondigo
- Department of Biochemistry and Molecular Biology, Egerton University, Nakuru, Kenya
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - James W Kazura
- Case Western Reserve University, Center for Global Health and Diseases, Cleveland, OH, United States of America
| | - John Grieco
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
| | - Nicole Achee
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
| | - Fang Liu
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, IN, United States of America
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
| | - Eric Ochomo
- Kenya Medical Research Institute, Centre for Global Health Research, Kisumu, Kenya
| | - Cristian Koepfli
- Department of Biological Sciences and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, United States of America
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20
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Briggs J, Murray M, Nideffer J, Jagannathan P. Sex-Linked Differences in Malaria Risk Across the Lifespan. Curr Top Microbiol Immunol 2023; 441:185-208. [PMID: 37695429 DOI: 10.1007/978-3-031-35139-6_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Despite the high burden of malaria worldwide, there is surprisingly scarce research on sex-based differences in malaria outside of pregnancy. A more thorough understanding of sexual dimorphism in malaria, and what underlies these sex-based differences, could elucidate the underlying mechanisms driving malaria pathogenesis and has the potential to inform malaria control efforts, including new vaccines. This review summarizes our current understanding of sex-based differences in the epidemiology of malaria across the lifespan, potential sex- or gender-based mechanisms driving these differences, and the knowledge gaps that need to be addressed.
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Affiliation(s)
- Jessica Briggs
- Department of Medicine, University of California, San Francisco, California, United States
| | - Margaret Murray
- Department of Medicine, University of California, San Francisco, California, United States
| | - Jason Nideffer
- Department of Medicine, Stanford University, Stanford, California, United States
| | - Prasanna Jagannathan
- Department of Medicine, Stanford University, Stanford, California, United States.
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21
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Zowonoo F, Iverson G, Doyle M, Richards SL. Retrospective spatiotemporal analysis of malaria cases reported between 2000 and 2020 in North Carolina, USA. Travel Med Infect Dis 2023; 51:102505. [PMID: 36427707 DOI: 10.1016/j.tmaid.2022.102505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/27/2022] [Accepted: 11/15/2022] [Indexed: 11/25/2022]
Abstract
BACKGROUND There are 1,000-2,000 cases of malaria diagnosed in the United States annually and most are imported. METHODS Malaria cases reported between 2000 and 2020 in North Carolina (NC) were analyzed (NC Department of Health and Human Services, Division of Public Health). Differences in numbers of NC malaria cases were further analyzed by year, month, county, gender, age, and country of origin. RESULTS Most cases originated from travelers visiting Africa and returning to NC (i.e., Mecklenburg [N = 162 cases], Wake [N = 153], Guilford [N = 103], Durham [N = 74], and Cumberland [N = 41] Counties). Per capita analysis (i.e., per 100,000 population) was used to correct for differences in NC county population sizes and Durham (N = 22.8), Guilford (N = 19.0), Onslow (N = 14.7), Mecklenburg (N = 14.5), Wake (N = 13.5), Orange (N = 12.8) and Cumberland (N = 12.2) Counties showed the highest cases. Malaria was more prevalent among males (N = 532) relative to females (N = 245), and this difference was statistically significant. CONCLUSIONS Travelers visiting malaria-endemic regions should be educated on malaria prevention measures (e.g., chemoprophylaxis, mosquito repellent). These measures should be readily available to travelers. The malaria registry in NC should be improved by requiring additional data related to imported malaria cases.
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Affiliation(s)
- Felix Zowonoo
- Environmental Health Sciences Program, Department of Health Education and Promotion, College of Health and Human Performance, East Carolina University, Greenville, NC, USA
| | - Guy Iverson
- Environmental Health Sciences Program, Department of Health Education and Promotion, College of Health and Human Performance, East Carolina University, Greenville, NC, USA
| | - Michael Doyle
- North Carolina Department of Health and Human Services, Division of Public Health, Communicable Disease Branch, Raleigh, NC, USA
| | - Stephanie L Richards
- Environmental Health Sciences Program, Department of Health Education and Promotion, College of Health and Human Performance, East Carolina University, Greenville, NC, USA.
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22
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Ondeto BM, Wang X, Atieli H, Zhong D, Zhou G, Lee MC, Orondo PW, Ochwedo KO, Omondi CJ, Muriu SM, Odongo DO, Ochanda H, Kazura J, Githeko AK, Yan G. A prospective cohort study of Plasmodium falciparum malaria in three sites of Western Kenya. Parasit Vectors 2022; 15:416. [PMID: 36352453 PMCID: PMC9647947 DOI: 10.1186/s13071-022-05503-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 09/14/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Malaria in western Kenya is currently characterized by sustained high Plasmodial transmission and infection resurgence, despite positive responses in some areas following intensified malaria control interventions since 2006. This study aimed to evaluate long-term changes in malaria transmission profiles and to assess patterns of asymptomatic malaria infections in school children aged 5-15 years at three sites in western Kenya with heterogeneous malaria transmission and simultaneous malaria control interventions. METHODS The study was conducted from 2018 to 2019 and is based on data taken every third year from 2005 to 2014 during a longitudinal parasitological and mosquito adult surveillance and malaria control programme that was initiated in 2002 in the villages of Kombewa, Iguhu, and Marani. Plasmodium spp. infections were determined using microscopy. Mosquito samples were identified to species and host blood meal source and sporozoite infections were assayed using polymerase chain reaction. RESULTS Plasmodium falciparum was the only malaria parasite evaluated during this study (2018-2019). Asymptomatic malaria parasite prevalence in school children decreased in all sites from 2005 to 2008. However, since 2011, parasite prevalence has resurged by > 40% in Kombewa and Marani. Malaria vector densities showed similar reductions from 2005 to 2008 in all sites, rose steadily until 2014, and decreased again. Overall, Kombewa had a higher risk of infection compared to Iguhu (χ2 = 552.52, df = 1, P < 0.0001) and Marani (χ2 = 1127.99, df = 1, P < 0.0001). There was a significant difference in probability of non-infection during malaria episodes (log-rank test, χ2 = 617.59, df = 2, P < 0.0001) in the study sites, with Kombewa having the least median time of non-infection during malaria episodes. Gender bias toward males in infection was observed (χ2 = 27.17, df = 1, P < 0.0001). The annual entomological inoculation rates were 5.12, 3.65, and 0.50 infective bites/person/year at Kombewa, Iguhu, and Marani, respectively, during 2018 to 2019. CONCLUSIONS Malaria prevalence in western Kenya remains high and has resurged in some sites despite continuous intervention efforts. Targeting malaria interventions to those with asymptomatic infections who serve as human reservoirs might decrease malaria transmission and prevent resurgences. Longitudinal monitoring enables detection of changes in parasitological and entomological profiles and provides core baseline data for the evaluation of vector interventions and guidance for future planning of malaria control.
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Affiliation(s)
- Benyl M. Ondeto
- grid.10604.330000 0001 2019 0495Department of Biology, University of Nairobi, Nairobi, 00100 Kenya ,Sub-Saharan Africa International Center of Excellence for Malaria Research, Tom Mboya University, Homa Bay, 40300 Kenya
| | - Xiaoming Wang
- grid.266093.80000 0001 0668 7243Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA 92697 USA
| | - Harrysone Atieli
- Sub-Saharan Africa International Center of Excellence for Malaria Research, Tom Mboya University, Homa Bay, 40300 Kenya
| | - Daibin Zhong
- grid.266093.80000 0001 0668 7243Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA 92697 USA
| | - Guofa Zhou
- grid.266093.80000 0001 0668 7243Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA 92697 USA
| | - Ming-Chieh Lee
- grid.266093.80000 0001 0668 7243Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA 92697 USA
| | - Pauline Winnie Orondo
- Sub-Saharan Africa International Center of Excellence for Malaria Research, Tom Mboya University, Homa Bay, 40300 Kenya ,grid.411943.a0000 0000 9146 7108Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, 00200 Kenya
| | - Kevin O. Ochwedo
- grid.10604.330000 0001 2019 0495Department of Biology, University of Nairobi, Nairobi, 00100 Kenya ,Sub-Saharan Africa International Center of Excellence for Malaria Research, Tom Mboya University, Homa Bay, 40300 Kenya
| | - Collince J. Omondi
- grid.10604.330000 0001 2019 0495Department of Biology, University of Nairobi, Nairobi, 00100 Kenya ,Sub-Saharan Africa International Center of Excellence for Malaria Research, Tom Mboya University, Homa Bay, 40300 Kenya
| | - Simon M. Muriu
- grid.449370.d0000 0004 1780 4347Department of Biological Sciences, Pwani University, Kilifi, 80108 Kenya
| | - David O. Odongo
- grid.10604.330000 0001 2019 0495Department of Biology, University of Nairobi, Nairobi, 00100 Kenya
| | - Horace Ochanda
- grid.10604.330000 0001 2019 0495Department of Biology, University of Nairobi, Nairobi, 00100 Kenya
| | - James Kazura
- grid.67105.350000 0001 2164 3847Center for Global Health and Disease, Case Western Reserve University, Cleveland, OH 44106 USA
| | - Andrew K. Githeko
- Sub-Saharan Africa International Center of Excellence for Malaria Research, Tom Mboya University, Homa Bay, 40300 Kenya ,grid.33058.3d0000 0001 0155 5938Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, 40100 Kenya
| | - Guiyun Yan
- grid.266093.80000 0001 0668 7243Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA 92697 USA
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23
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Masserey T, Penny MA, Lee TE. Patient variability in the blood-stage dynamics of Plasmodium falciparum captured by clustering historical data. Malar J 2022; 21:300. [PMID: 36289505 PMCID: PMC9608883 DOI: 10.1186/s12936-022-04317-0] [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: 02/24/2022] [Accepted: 10/11/2022] [Indexed: 11/15/2022] Open
Abstract
Background Mathematical models provide an understanding of the dynamics of a Plasmodium falciparum blood-stage infection (within-host models), and can predict the impact of control strategies that affect the blood-stage of malaria. However, the dynamics of P. falciparum blood-stage infections are highly variable between individuals. Within-host models use different techniques to capture this inter-individual variation. This struggle may be unnecessary because patients can be clustered according to similar key within-host dynamics. This study aimed to identify clusters of patients with similar parasitaemia profiles so that future mathematical models can include an improved understanding of within-host variation. Methods Patients’ parasitaemia data were analyzed to identify (i) clusters of patients (from 35 patients) that have a similar overall parasitaemia profile and (ii) clusters of patients (from 100 patients) that have a similar first wave of parasitaemia. For each cluster analysis, patients were clustered based on key features which previous models used to summarize parasitaemia dynamics. The clustering analyses were performed using a finite mixture model. The centroid values of the clusters were used to parameterize two established within-host models to generate parasitaemia profiles. These profiles (that used the novel centroid parameterization) were compared with profiles that used individual-specific parameterization (as in the original models), as well as profiles that ignored individual variation (using overall means for parameterization). Results To capture the variation of within-host dynamics, when studying the overall parasitaemia profile, two clusters efficiently grouped patients based on their infection length and the height of the first parasitaemia peak. When studying the first wave of parasitaemia, five clusters efficiently grouped patients based on the height of the peak and the speed of the clearance following the peak of parasitaemia. The clusters were based on features that summarize the strength of patient innate and adaptive immune responses. Parameterizing previous within host-models based on cluster centroid values accurately predict individual patient parasitaemia profiles. Conclusion This study confirms that patients have personalized immune responses, which explains the variation of parasitaemia dynamics. Clustering can guide the optimal inclusion of within-host variation in future studies, and inform the design and parameterization of population-based models. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04317-0.
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Affiliation(s)
- Thiery Masserey
- grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Basel-Land Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, Basel, Switzerland
| | - Melissa A. Penny
- grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Basel-Land Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, Basel, Switzerland
| | - Tamsin E. Lee
- grid.416786.a0000 0004 0587 0574Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123 Allschwil, Basel-Land Switzerland ,grid.6612.30000 0004 1937 0642University of Basel, Basel, Switzerland
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24
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Kayange M, M'baya B, Hwandih T, Saker J, Coetzer TL, Münster M. Automated measurement of malaria parasitaemia among asymptomatic blood donors in Malawi using the Sysmex XN-31 analyser: could such data be used to complement national malaria surveillance in real time? Malar J 2022; 21:299. [PMID: 36284305 DOI: 10.1186/s12936-022-04314-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 10/05/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The recent worldwide increase in malaria cases highlights the need for renewed efforts to eliminate malaria. The World Health Organization advocates that malaria surveillance becomes a core intervention. Current methods to estimate the malaria burden rely on clinical malaria case reports and surveys of asymptomatic parasite infection mainly from children < 5 years. In this study the hypothesis was that screening blood donors for malaria parasites would provide real-time information on the asymptomatic reservoir of parasites in the adult population and mirror other surveillance data. METHODS This study was conducted in Malawi, a high malaria burden country, at the Malawi Blood Transfusion Service, which collects blood units at donation sites countrywide. A secondary analysis was conducted on data obtained from a prior Sysmex XN-31 analyser malaria diagnostic evaluation study utilizing residual donor blood samples. XN-31 malaria results, donor age, sex, geographical location, and collection date, were analysed using standard statistical methods. RESULTS The malaria parasite prevalence in blood donors was 11.6% (614/5281 samples) increasing seasonally from December (8.6%) to April (18.3%). The median age was 21 years and 45.9% of donors were from urban areas, which showed a lower prevalence compared to non-urban regions. The Central administrative region had the highest and the Northern region the lowest malaria parasite prevalence. The donors were predominantly male (80.2%), 13.1% of whom had malaria parasites, which was significantly higher (p < 0.0001) than for female donors (7.4%). Multivariable logistic regression analysis showed that age, location, and collection month were significant predictors of malaria positivity in males, whereas in females only location was significant. There was no gender difference in parasite density nor gametocyte carriage. CONCLUSIONS This study demonstrates the powerful utility of screening blood donors for malaria parasites using the XN-31, which not only improves the safety of blood transfusion, but provides valuable complementary surveillance data for malaria control, especially targeting males, who are generally excluded from periodic household surveys. Blood donations are sourced countrywide, year-round, and thus provide dynamic, real-time information on the malaria burden. Furthermore, the XN-31 identifies the asymptomatic human reservoir of infectious gametocytes, which must be targeted to eliminate malaria.
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Affiliation(s)
- Michael Kayange
- National Malaria Control Programme, Ministry of Health, Lilongwe, Malawi
| | | | - Talent Hwandih
- Sysmex Europe SE, Bornbarch 1, 22848, Norderstedt, Germany
| | - Jarob Saker
- Sysmex Europe SE, Bornbarch 1, 22848, Norderstedt, Germany
| | - Thérèsa L Coetzer
- Sysmex Europe SE, Bornbarch 1, 22848, Norderstedt, Germany.,Faculty of Health Sciences, Wits Research Institute for Malaria, University of the Witwatersrand, Johannesburg, South Africa
| | - Marion Münster
- Sysmex Europe SE, Bornbarch 1, 22848, Norderstedt, Germany.
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25
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Chan JA, Loughland JR, de la Parte L, Okano S, Ssewanyana I, Nalubega M, Nankya F, Musinguzi K, Rek J, Arinaitwe E, Tipping P, Bourke P, Andrew D, Dooley N, SheelaNair A, Wines BD, Hogarth PM, Beeson JG, Greenhouse B, Dorsey G, Kamya M, Hartel G, Minigo G, Feeney M, Jagannathan P, Boyle MJ. Age-dependent changes in circulating Tfh cells influence development of functional malaria antibodies in children. Nat Commun 2022; 13:4159. [PMID: 35851033 PMCID: PMC9293980 DOI: 10.1038/s41467-022-31880-6] [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: 12/12/2021] [Accepted: 07/08/2022] [Indexed: 01/29/2023] Open
Abstract
T-follicular helper (Tfh) cells are key drivers of antibodies that protect from malaria. However, little is known regarding the host and parasite factors that influence Tfh and functional antibody development. Here, we use samples from a large cross-sectional study of children residing in an area of high malaria transmission in Uganda to characterize Tfh cells and functional antibodies to multiple parasites stages. We identify a dramatic re-distribution of the Tfh cell compartment with age that is independent of malaria exposure, with Th2-Tfh cells predominating in early childhood, while Th1-Tfh cell gradually increase to adult levels over the first decade of life. Functional antibody acquisition is age-dependent and hierarchical acquired based on parasite stage, with merozoite responses followed by sporozoite and gametocyte antibodies. Antibodies are boosted in children with current infection, and are higher in females. The children with the very highest antibody levels have increased Tfh cell activation and proliferation, consistent with a key role of Tfh cells in antibody development. Together, these data reveal a complex relationship between the circulating Tfh compartment, antibody development and protection from malaria.
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Affiliation(s)
- Jo-Anne Chan
- Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia
| | - Jessica R Loughland
- QIMR-Berghofer Medical Research Institute, Herston, QLD, Australia.,Global and Tropical Health Division, Menzies School of Health Research, Tiwi, Australia
| | | | - Satomi Okano
- QIMR-Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Isaac Ssewanyana
- Infectious Diseases Research Collaboration, Kampala, Uganda.,London School of Hygiene and Tropical Medicine, London, UK
| | - Mayimuna Nalubega
- QIMR-Berghofer Medical Research Institute, Herston, QLD, Australia.,Infectious Diseases Research Collaboration, Kampala, Uganda.,Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia
| | | | | | - John Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Peta Tipping
- Global and Tropical Health Division, Menzies School of Health Research, Tiwi, Australia
| | - Peter Bourke
- Division of Medicine, Cairns Hospital, Manunda, QLD, Australia
| | - Dean Andrew
- QIMR-Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Nicholas Dooley
- QIMR-Berghofer Medical Research Institute, Herston, QLD, Australia.,Griffith University, Brisbane, QLD, Australia
| | - Arya SheelaNair
- QIMR-Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Bruce D Wines
- Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, Australia
| | - P Mark Hogarth
- Burnet Institute, Melbourne, VIC, Australia.,Department of Immunology, Central Clinical School, Monash University, Melbourne, VIC, Australia.,Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, Australia
| | - James G Beeson
- Burnet Institute, Melbourne, VIC, Australia.,Department of Medicine, The University of Melbourne, Parkville, VIC, Australia.,Department of Microbiology, Central Clinical School, Monash University, Melbourne, VIC, Australia
| | | | - Grant Dorsey
- University of California San Francisco, San Francisco, CA, USA
| | - Moses Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Gunter Hartel
- QIMR-Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Gabriela Minigo
- Global and Tropical Health Division, Menzies School of Health Research, Tiwi, Australia.,College of Health and Human Sciences, Charles Darwin University, Darwin, NT, Australia
| | - Margaret Feeney
- University of California San Francisco, San Francisco, CA, USA
| | | | - Michelle J Boyle
- Burnet Institute, Melbourne, VIC, Australia. .,QIMR-Berghofer Medical Research Institute, Herston, QLD, Australia. .,Global and Tropical Health Division, Menzies School of Health Research, Tiwi, Australia. .,Faculty of Medicine, University of Queensland, Brisbane, QLD, Australia. .,Griffith University, Brisbane, QLD, Australia.
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26
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Sedda L, McCann RS, Kabaghe AN, Gowelo S, Mburu MM, Tizifa TA, Chipeta MG, van den Berg H, Takken W, van Vugt M, Phiri KS, Cain R, Tangena JAA, Jones CM. Hotspots and super-spreaders: Modelling fine-scale malaria parasite transmission using mosquito flight behaviour. PLoS Pathog 2022; 18:e1010622. [PMID: 35793345 PMCID: PMC9292116 DOI: 10.1371/journal.ppat.1010622] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2022] [Revised: 07/18/2022] [Accepted: 05/27/2022] [Indexed: 11/19/2022] Open
Abstract
Malaria hotspots have been the focus of public health managers for several years due to the potential elimination gains that can be obtained from targeting them. The identification of hotspots must be accompanied by the description of the overall network of stable and unstable hotspots of malaria, especially in medium and low transmission settings where malaria elimination is targeted. Targeting hotspots with malaria control interventions has, so far, not produced expected benefits. In this work we have employed a mechanistic-stochastic algorithm to identify clusters of super-spreader houses and their related stable hotspots by accounting for mosquito flight capabilities and the spatial configuration of malaria infections at the house level. Our results show that the number of super-spreading houses and hotspots is dependent on the spatial configuration of the villages. In addition, super-spreaders are also associated to house characteristics such as livestock and family composition. We found that most of the transmission is associated with winds between 6pm and 10pm although later hours are also important. Mixed mosquito flight (downwind and upwind both with random components) were the most likely movements causing the spread of malaria in two out of the three study areas. Finally, our algorithm (named MALSWOTS) provided an estimate of the speed of malaria infection progression from house to house which was around 200-400 meters per day, a figure coherent with mark-release-recapture studies of Anopheles dispersion. Cross validation using an out-of-sample procedure showed accurate identification of hotspots. Our findings provide a significant contribution towards the identification and development of optimal tools for efficient and effective spatio-temporal targeted malaria interventions over potential hotspot areas.
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Affiliation(s)
- Luigi Sedda
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, United Kingdom
| | - Robert S. McCann
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Alinune N. Kabaghe
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Steven Gowelo
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- MAC Communicable Diseases Action Centre, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Monicah M. Mburu
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Tinashe A. Tizifa
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Center for Tropical Medicine and Travel Medicine, University of Amsterdam, The Netherlands
| | - Michael G. Chipeta
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | - Henk van den Berg
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Willem Takken
- Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands
| | - Michèle van Vugt
- Center for Tropical Medicine and Travel Medicine, University of Amsterdam, The Netherlands
| | - Kamija S. Phiri
- School of Global and Public Health, Kamuzu University of Health Sciences, Blantyre, Malawi
| | - Russell Cain
- Lancaster Ecology and Epidemiology Group, Lancaster Medical School, Lancaster University, United Kingdom
| | - Julie-Anne A. Tangena
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Christopher M. Jones
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
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27
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Lautenbach MJ, Yman V, Silva CS, Kadri N, Broumou I, Chan S, Angenendt S, Sondén K, Plaza DF, Färnert A, Sundling C. Systems analysis shows a role of cytophilic antibodies in shaping innate tolerance to malaria. Cell Rep 2022; 39:110709. [PMID: 35443186 DOI: 10.1016/j.celrep.2022.110709] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 03/01/2022] [Accepted: 03/29/2022] [Indexed: 12/15/2022] Open
Abstract
Natural immunity to malaria develops over time with repeated malaria episodes, but protection against severe malaria and immune regulation limiting immunopathology, called tolerance, develops more rapidly. Here, we comprehensively profile the blood immune system in patients, with or without prior malaria exposure, over 1 year after acute symptomatic Plasmodium falciparum malaria. Using a data-driven analysis approach to describe the immune landscape over time, we show that a dampened inflammatory response is associated with reduced γδ T cell expansion, early expansion of CD16+ monocytes, and parasite-specific antibodies of IgG1 and IgG3 isotypes. This also coincided with reduced parasitemia and duration of hospitalization. Our data indicate that antibody-mediated phagocytosis during the blood stage infection leads to lower parasitemia and less inflammatory response with reduced γδ T cell expansion. This enhanced control and reduced inflammation points to a potential mechanism on how tolerance is established following repeated malaria exposure.
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Affiliation(s)
- Maximilian Julius Lautenbach
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Victor Yman
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, South Stockholm Hospital, Stockholm, Sweden
| | - Carolina Sousa Silva
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden; Life and Health Sciences Research Institute, School of Medicine, University of Minho, Braga, Portugal; ICVS/3B's, PT Government Associate Laboratory, Braga, Portugal
| | - Nadir Kadri
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden; Department of Medicine Solna, Science for Life Laboratory, Karolinska Institute, Stockholm, Sweden
| | - Ioanna Broumou
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Sherwin Chan
- Department of Oncology-Pathology, Science for Life Laboratories, Karolinska Institutet, Stockholm, Sweden
| | - Sina Angenendt
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Klara Sondén
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - David Fernando Plaza
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Anna Färnert
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
| | - Christopher Sundling
- Division of Infectious Diseases, Department of Medicine Solna and Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden.
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28
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Collins KA, Ceesay S, Drammeh S, Jaiteh FK, Guery MA, Lanke K, Grignard L, Stone W, Conway DJ, D'Alessandro U, Bousema T, Claessens A. A cohort study on the duration of Plasmodium falciparum infections during the dry season in The Gambia. J Infect Dis 2022; 226:128-137. [PMID: 35380684 PMCID: PMC9373158 DOI: 10.1093/infdis/jiac116] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 04/11/2022] [Indexed: 12/03/2022] Open
Abstract
Background In areas where Plasmodium falciparum malaria is seasonal, a dry season reservoir of blood-stage infection is essential for initiating transmission during the following wet season. Methods In The Gambia, a cohort of 42 individuals with quantitative polymerase chain reaction-positive P falciparum infections at the end of the transmission season (December) were followed monthly until the end of the dry season (May) to evaluate infection persistence. The influence of human host and parasitological factors was investigated. Results A large proportion of individuals infected at the end of the wet season had detectable infections until the end of the dry season (40.0%; 16 of 40). At the start of the dry season, the majority of these persistent infections (82%) had parasite densities >10 p/µL compared to only 5.9% of short-lived infections. Persistent infections (59%) were also more likely to be multiclonal than short-lived infections (5.9%) and were associated with individuals having higher levels of P falciparum-specific antibodies (P = .02). Conclusions Asymptomatic persistent infections were multiclonal with higher parasite densities at the beginning of the dry season. Screening and treating asymptomatic infections during the dry season may reduce the human reservoir of malaria responsible for initiating transmission in the wet season.
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Affiliation(s)
- Katharine A Collins
- Radboud university medical center, Radboud Institute for Health Sciences, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Sukai Ceesay
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Sainabou Drammeh
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Fatou K Jaiteh
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Marc-Antoine Guery
- LPHI, MIVEGEC, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Kjerstin Lanke
- Radboud university medical center, Radboud Institute for Health Sciences, Department of Medical Microbiology, Nijmegen, The Netherlands
| | - Lynn Grignard
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Will Stone
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - David J Conway
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Teun Bousema
- Radboud university medical center, Radboud Institute for Health Sciences, Department of Medical Microbiology, Nijmegen, The Netherlands.,Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Antoine Claessens
- Medical Research Council Unit The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia.,LPHI, MIVEGEC, Université de Montpellier, CNRS, INSERM, Montpellier, France
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29
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Fang F, Hazegh K, Mast AE, Triulzi DJ, Spencer BR, Gladwin MT, Busch MP, Kanias T, Page GP. Sex-specific genetic modifiers identified susceptibility of cold stored red blood cells to osmotic hemolysis. BMC Genomics 2022; 23:227. [PMID: 35321643 PMCID: PMC8941732 DOI: 10.1186/s12864-022-08461-4] [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: 12/09/2021] [Accepted: 03/04/2022] [Indexed: 11/19/2022] Open
Abstract
Background Genetic variants have been found to influence red blood cell (RBC) susceptibility to hemolytic stress and affect transfusion outcomes and the severity of blood diseases. Males have a higher susceptibility to hemolysis than females, but little is known about the genetic mechanism contributing to the difference. Results To investigate the sex differences in RBC susceptibility to hemolysis, we conducted a sex-stratified genome-wide association study and a genome-wide gene-by-sex interaction scan in a multi-ethnic dataset with 12,231 blood donors who have in vitro osmotic hemolysis measurements during routine blood storage. The estimated SNP-based heritability for osmotic hemolysis was found to be significantly higher in males than in females (0.46 vs. 0.41). We identified SNPs associated with sex-specific susceptibility to osmotic hemolysis in five loci (SPTA1, KCNA6, SLC4A1, SUMO1P1, and PAX8) that impact RBC function and hemolysis. Conclusion Our study established a best practice to identify sex-specific genetic modifiers for sexually dimorphic traits in datasets with mixed ancestries, providing evidence of different genetic regulations of RBC susceptibility to hemolysis between sexes. These and other variants may help explain observed sex differences in the severity of hemolytic diseases, such as sickle cell and malaria, as well as the viability of red cell storage and recovery. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08461-4.
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Affiliation(s)
- Fang Fang
- GenOmics, Bioinformatics, and Translational Research Center, RTI International, Research Triangle Park, Durham, NC, USA.
| | | | - Alan E Mast
- Versiti Blood Research Institute, Blood Center of Wisconsin, Milwaukee, WI, USA.,Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Darrell J Triulzi
- Department of Pathology, University of Pittsburgh, Pittsburgh, PA, USA
| | | | - Mark T Gladwin
- Pittsburgh Heart, Lung, and Blood Vascular Medicine Institute, University of Pittsburgh, Pittsburgh, PA, USA.,Division of Pulmonary, Allergy and Critical Care Medicine, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Michael P Busch
- Vitalant Research Institute, San Francisco, CA, USA.,Department of Laboratory Medicine, UCSF, San Francisco, CA, USA
| | - Tamir Kanias
- Vitalant Research Institute, Denver, CO, USA.,Department of Pathology, University of Colorado Denver Anschutz Medical Campus, Aurora, CO, USA
| | - Grier P Page
- GenOmics, Bioinformatics, and Translational Research Center, RTI International, Research Triangle Park, Durham, NC, USA.,Division of Biostatistics and Epidemiology, RTI International, GA, Atlanta, USA
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30
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Roe MS, O’Flaherty K, Fowkes FJ. Can malaria parasites be spontaneously cleared? Trends Parasitol 2022; 38:356-364. [DOI: 10.1016/j.pt.2022.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Revised: 02/07/2022] [Accepted: 02/08/2022] [Indexed: 12/25/2022]
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31
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Harding AT, Heaton NS. The Impact of Estrogens and Their Receptors on Immunity and Inflammation during Infection. Cancers (Basel) 2022; 14:cancers14040909. [PMID: 35205657 PMCID: PMC8870346 DOI: 10.3390/cancers14040909] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/31/2022] [Accepted: 02/04/2022] [Indexed: 02/07/2023] Open
Abstract
Simple Summary Human health is significantly affected by microbial infections. One of the largest determinants of the outcomes of such infections is the host immune response. Too weak of a response can lead to enhanced spread by the pathogen, while an overstimulated response can lead to immune-induced tissue damage. Thus, to effectively treat infected individuals, it is critical to understand the regulators that control inflammatory responses. Recently, it has become widely accepted that estrogens, a class of sex hormones, are capable of dramatically altering the responses of host cells to microbes. In this review, we discuss how estrogens change the host immune response, as well as how these changes can alter the outcome of the infection for the individual. Abstract Sex hormones, such as estrogen and testosterone, are steroid compounds with well-characterized effects on the coordination and development of vertebrate reproductive systems. Since their discovery, however, it has become clear that these “sex hormones” also regulate/influence a broad range of biological functions. In this review, we will summarize some current findings on how estrogens interact with and regulate inflammation and immunity. Specifically, we will focus on describing the mechanisms by which estrogens alter immune pathway activation, the impact of these changes during infection and the development of long-term immunity, and how different types of estrogens and their respective concentrations mediate these outcomes.
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Affiliation(s)
- Alfred T. Harding
- Institute for Medical Engineering and Sciences, Massachusetts Institute of Technology, Cambridge, MA 02142, USA;
| | - Nicholas S. Heaton
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC 27710, USA
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC 27710, USA
- Correspondence: ; Tel.: +1-919-684-1351; Fax: +1-919-684-2790
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32
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Abate A, Assefa M, Golassa L. Five-Year Trend of Malaria Prevalence in Mojo Town, Central Ethiopia: Shifting Burden of the Disease and Its Implication for Malaria Elimination: A Retrospective Study. Infect Drug Resist 2022; 15:455-464. [PMID: 35177912 PMCID: PMC8846561 DOI: 10.2147/idr.s348203] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 02/05/2022] [Indexed: 12/16/2022] Open
Abstract
Introduction Malaria continues to strike hardest against the health and economic development in Ethiopia. The peak of malaria incidence follows the main rainfall season in each year; however, its transmission tends to be highly heterogeneous within or between years and from area to area. Thus, this study was aimed to determine the trend prevalence of malaria in Mojo town, central Ethiopia. Methods A retrospective study was conducted in Mojo town, East Shoa zone, Ethiopia from February to March 2021. Malaria cases and related data documented between 2016 and 2020 were carefully reviewed from laboratory registration logbooks. The collected data were analyzed using descriptive statistics. Results A total of 19,106 blood films were examined from malaria-suspected patients. The overall microscopically confirmed prevalence of malaria was 4.2% (793/19,106). Plasmodium vivax was the predominant species accounting for 76.2% (604/793) of positive samples. Malaria cases declined from 259 in 2016 to 77 in 2020. The proportion of malaria was higher among males (64.8%, 514/793) than females (35.2%, 279/793) (P < 0.0001). Higher malaria cases were observed from the age group 15–24 years followed by the age group of 25–34 (P < 0.0001). The number of malaria cases was at a high level from September to November and lowest from December to February. Conclusion Despite a declining trend of malaria prevalence, it remains a public health burden in the area. P. vivax, the predominant species, should get attention during prevention and control strategies for the successful progress of the malaria elimination program.
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Affiliation(s)
- Andargie Abate
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar, Ethiopia
- Correspondence: Andargie Abate, Email
| | - Mesfin Assefa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
- College of Medicine and Health Sciences, Wachamo University, Hossaena, Ethiopia
| | - Lemu Golassa
- Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia
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33
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Okiring J, Epstein A, Namuganga JF, Kamya EV, Nabende I, Nassali M, Sserwanga A, Gonahasa S, Muwema M, Kiwuwa SM, Staedke SG, Kamya MR, Nankabirwa JI, Briggs J, Jagannathan P, Dorsey G. Gender difference in the incidence of malaria diagnosed at public health facilities in Uganda. Malar J 2022; 21:22. [PMID: 35062952 PMCID: PMC8778495 DOI: 10.1186/s12936-022-04046-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 01/11/2022] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Routine malaria surveillance data in Africa primarily come from public health facilities reporting to national health management information systems. Although information on gender is routinely collected from patients presenting to these health facilities, stratification of malaria surveillance data by gender is rarely done. This study evaluated gender difference among patients diagnosed with parasitological confirmed malaria at public health facilities in Uganda. METHODS This study utilized individual level patient data collected from January 2020 through April 2021 at 12 public health facilities in Uganda and cross-sectional surveys conducted in target areas around these facilities in April 2021. Associations between gender and the incidence of malaria and non-malarial visits captured at the health facilities from patients residing within the target areas were estimated using poisson regression models controlling for seasonality. Associations between gender and data on health-seeking behaviour from the cross-sectional surveys were estimated using poisson regression models controlling for seasonality. RESULTS Overall, incidence of malaria diagnosed per 1000 person years was 735 among females and 449 among males (IRR = 1.72, 95% CI 1.68-1.77, p < 0.001), with larger differences among those 15-39 years (IRR = 2.46, 95% CI 2.34-2.58, p < 0.001) and over 39 years (IRR = 2.26, 95% CI 2.05-2.50, p < 0.001) compared to those under 15 years (IRR = 1.46, 95% CI 1.41-1.50, p < 0.001). Female gender was also associated with a higher incidence of visits where malaria was not suspected (IRR = 1.77, 95% CI 1.71-1.83, p < 0.001), with a similar pattern across age strata. These associations were consistent across the 12 individual health centres. From the cross-sectional surveys, females were more likely than males to report fever in the past 2 weeks and seek care at the local health centre (7.5% vs. 4.7%, p = 0.001) with these associations significant for those 15-39 years (RR = 2.49, 95% CI 1.17-5.31, p = 0.018) and over 39 years (RR = 2.56, 95% CI 1.00-6.54, p = 0.049). CONCLUSIONS Females disproportionately contribute to the burden of malaria diagnosed at public health facilities in Uganda, especially once they reach childbearing age. Contributing factors included more frequent visits to these facilities independent of malaria and a higher reported risk of seeking care at these facilities for febrile illnesses.
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Affiliation(s)
- Jaffer Okiring
- Clinical Epidemiology Unit, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda. .,Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda.
| | - Adrienne Epstein
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, USA
| | - Jane F Namuganga
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Emmanuel V Kamya
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Isaiah Nabende
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Martha Nassali
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Asadu Sserwanga
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Samuel Gonahasa
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Mercy Muwema
- Clinical Epidemiology Unit, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Steven M Kiwuwa
- Department of Child Health and Development Centre, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Sarah G Staedke
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda.,School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Joaniter I Nankabirwa
- Clinical Epidemiology Unit, School of Medicine, Makerere University College of Health Sciences, Kampala, Uganda.,Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Jessica Briggs
- Department of Medicine, University of California San Francisco, San Francisco, USA
| | - Prasanna Jagannathan
- Division of Infectious Diseases and Geographic Medicine, Stanford University, Stanford, USA
| | - Grant Dorsey
- Department of Medicine, University of California San Francisco, San Francisco, USA
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Ochwedo KO, Omondi CJ, Magomere EO, Olumeh JO, Debrah I, Onyango SA, Orondo PW, Ondeto BM, Atieli HE, Ogolla SO, Githure J, Otieno ACA, Githeko AK, Kazura JW, Mukabana WR, Guiyan Y. Hyper-prevalence of submicroscopic Plasmodium falciparum infections in a rural area of western Kenya with declining malaria cases. Malar J 2021; 20:472. [PMID: 34930283 PMCID: PMC8685826 DOI: 10.1186/s12936-021-04012-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 12/07/2021] [Indexed: 11/22/2022] Open
Abstract
BACKGROUND The gold standard for diagnosing Plasmodium falciparum infection is microscopic examination of Giemsa-stained peripheral blood smears. The effectiveness of this procedure for infection surveillance and malaria control may be limited by a relatively high parasitaemia detection threshold. Persons with microscopically undetectable infections may go untreated, contributing to ongoing transmission to mosquito vectors. The purpose of this study was to determine the magnitude and determinants of undiagnosed submicroscopic P. falciparum infections in a rural area of western Kenya. METHODS A health facility-based survey was conducted, and 367 patients seeking treatment for symptoms consistent with uncomplicated malaria in Homa Bay County were enrolled. The frequency of submicroscopic P. falciparum infection was measured by comparing the prevalence of infection based on light microscopic inspection of thick blood smears versus real-time polymerase chain reaction (RT-PCR) targeting P. falciparum 18S rRNA gene. Long-lasting insecticidal net (LLIN) use, participation in nocturnal outdoor activities, and gender were considered as potential determinants of submicroscopic infections. RESULTS Microscopic inspection of blood smears was positive for asexual P. falciparum parasites in 14.7% (54/367) of cases. All of these samples were confirmed by RT-PCR. 35.8% (112/313) of blood smear negative cases were positive by RT-PCR, i.e., submicroscopic infection, resulting in an overall prevalence by RT-PCR alone of 45.2% compared to 14.7% for blood smear alone. Females had a higher prevalence of submicroscopic infections (35.6% or 72 out of 202 individuals, 95% CI 28.9-42.3) compared to males (24.2%, 40 of 165 individuals, 95% CI 17.6-30.8). The risk of submicroscopic infections in LLIN users was about half that of non-LLIN users (OR = 0.59). There was no difference in the prevalence of submicroscopic infections of study participants who were active in nocturnal outdoor activities versus those who were not active (OR = 0.91). Patients who participated in nocturnal outdoor activities and use LLINs while indoors had a slightly higher risk of submicroscopic infection than those who did not use LLINs (OR = 1.48). CONCLUSION Microscopic inspection of blood smears from persons with malaria symptoms for asexual stage P. falciparum should be supplemented by more sensitive diagnostic tests in order to reduce ongoing transmission of P. falciparum parasites to local mosquito vectors.
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Affiliation(s)
- Kevin O. Ochwedo
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Collince J. Omondi
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Edwin O. Magomere
- Department of Biochemistry and Molecular Biology, Egerton University, Njoro, Kenya
| | - Julius O. Olumeh
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Isaiah Debrah
- West Africa Centre for Cell Biology of Infectious Pathogen, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Accra, Ghana
| | - Shirley A. Onyango
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Pauline W. Orondo
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Benyl M. Ondeto
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Harrysone E. Atieli
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Sidney O. Ogolla
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - John Githure
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Antony C. A. Otieno
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
| | - Andrew K. Githeko
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - James W. Kazura
- Centre for Global Health and Diseases, Case Western Reserve University, Cleveland, OH USA
| | - Wolfgang R. Mukabana
- Department of Biology, Faculty of Science and Technology, University of Nairobi, Nairobi, Kenya
- Sub-Saharan Africa International Centre for Excellence in Malaria Research, Homa Bay, Kenya
| | - Yan Guiyan
- Program in Public Health, College of Health Sciences, University of California, Irvine, USA
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Andolina C, Rek JC, Briggs J, Okoth J, Musiime A, Ramjith J, Teyssier N, Conrad M, Nankabirwa JI, Lanke K, Rodriguez-Barraquer I, Meerstein-Kessel L, Arinaitwe E, Olwoch P, Rosenthal PJ, Kamya MR, Dorsey G, Greenhouse B, Drakeley C, Staedke SG, Bousema T. Sources of persistent malaria transmission in a setting with effective malaria control in eastern Uganda: a longitudinal, observational cohort study. THE LANCET. INFECTIOUS DISEASES 2021; 21:1568-1578. [PMID: 34146476 PMCID: PMC8554388 DOI: 10.1016/s1473-3099(21)00072-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/27/2020] [Accepted: 02/03/2021] [Indexed: 01/14/2023]
Abstract
BACKGROUND Symptomatic malaria cases reflect only a small proportion of all Plasmodium spp infections. Many infected individuals are asymptomatic, and persistent asymptomatic Plasmodium falciparum infections are common in endemic settings. We aimed to quantify the contribution of symptomatic and asymptomatic infections to P falciparum transmission in Tororo, Uganda. METHODS We did a longitudinal, observational cohort study in Tororo district, Uganda. We recruited participants of all ages from randomly selected households within this district. Participants were eligible if the selected household had no more than nine permanent residents and at least two members younger than 10 years, and the household was their primary residence, and they agreed to come to the study clinic for any fever episode and avoid antimalarial medications outside the study. Participants were followed-up by continuous passive surveillance for the incidence of symptomatic infections; routine assessments (ie, standardised clinical evaluation and blood samples) were done at baseline and at routine visits every 4 weeks for 2 years. P falciparum parasite density, gametocyte density, and genetic composition were determined molecularly using quantitative PCR (qPCR), quantitative reverse transcriptase PCR (qRT-PCR), and amplicon deep sequencing, respectively. Membrane feeding assays were also done to assess infectivity to mosquitoes. The contribution of different populations to the infectious reservoir was estimated for symptomatic infections, asymptomatic but microscopically detected infections, and asymptomatic but qPCR-detected infections; and for age groups younger than 5 years, 5-15 years, and 16 years or older. FINDINGS Between Oct 4, 2017, and Oct 31, 2019, 531 individuals were enrolled from 80 randomly selected households and were followed-up for 2 years. At baseline, P falciparum was detected in 28 (5·3%) of 531 participants by microscopy and an additional 64 (12·1%) by qPCR and declined thereafter. In 538 mosquito feeding experiments on 107 individuals, 446 (1·2%) of 37 404 mosquitoes became infected, with mosquito infection rates being strongly associated with gametocyte densities (β=2·11, 95% CI 1·62-2·67; p<0·0001). Considering both transmissibility of infections and their relative frequency, the estimated human infectious reservoir consisted primarily of asymptomatic microscopy-detected infections (83·8%), followed by asymptomatic submicroscopic infections (15·6%), and symptomatic infections (0·6%). Children aged 5-15 years accounted for more than half of the infectious reservoir (58·7%); individuals younger than 5 years (25·8%) and those 16 years or older (15·6%) contributed less. Samples from four children contribued to 279 (62·6%) of 446 infected mosquitoes after multiple mosquito-feeding assays. INTERPRETATION Individuals with asymptomatic infections were important drivers of malaria transmission. School-aged children contributed to more than half of all mosquito infections, with a small minority of asymptomatic children being highly infectious. Demographically targeted interventions, aimed at school-aged children, could further reduce transmission in areas under effective vector control. FUNDING US National Institutes of Health, Bill & Melinda Gates Foundation, and the European Research Council.
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Affiliation(s)
- Chiara Andolina
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - John C Rek
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Jessica Briggs
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Joseph Okoth
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Alex Musiime
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Jordache Ramjith
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands; Department for Health Evidence, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Noam Teyssier
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Melissa Conrad
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda; Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands
| | | | | | | | - Peter Olwoch
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Philip J Rosenthal
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda; Department of Medicine, Makerere University College of Health Sciences, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, CA, USA
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Sarah G Staedke
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London, UK
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Centre, Nijmegen, Netherlands.
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Saidi AM, Guenther G, Izem R, Chen X, Seydel K, Postels D. Plasmodium falciparum clearance time in Malawian children with cerebral malaria: a retrospective cohort study. Malar J 2021; 20:408. [PMID: 34663346 PMCID: PMC8524966 DOI: 10.1186/s12936-021-03947-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Accepted: 10/07/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Standard treatment for both uncomplicated and severe malaria is artemisinin derivatives. Delayed parasite clearance times preceded the appearance of artemisinin treatment failures in Southeast Asia. Most worldwide malaria cases are in sub-Saharan Africa (SSA), where clinically significant artemisinin resistance or treatment failure has not yet been detected. The recent emergence of a resistance-conferring genetic mutation in the Plasmodium falciparum parasite in Africa warrants continued monitoring throughout the continent. METHODS An analysis was performed on data from a retrospective cohort study of Malawian children with cerebral malaria admitted between 2010 and 2019 to a public referral hospital, ascertaining parasite clearance times across years. Data were collected from patients treated for severe malaria with quinine or artesunate, an artemisinin derivative. Parasite density was determined at admission and every subsequent 6 h until parasitaemia was below 1000 parasites/µl.The mean parasite clearance time in all children admitted in any one year was compared to the parasite clearance time in 2014, the first year of artesunate use in Malawi. RESULTS The median population parasite clearance time was slower from 2010 to 2013 (quinine-treated patients) compared to 2014, the first year of artesunate use in Malawi (30 h (95% CI: 30-30) vs 18 h (95% CI: 18-24)). After adjustment for admission parasite count, there was no statistically significant difference in the median population parasite clearance time when comparing 2014 with any subsequent year. CONCLUSION Malaria parasite clearance times in Malawian children with cerebral malaria remained constant between 2014 and 2019, arguing against evolving artemisinin resistance in parasites in this region.
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Affiliation(s)
- Alexuse M Saidi
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi.
| | - Geoffrey Guenther
- Department of Pediatrics, Children's National Medical Center, Washington, DC, USA
| | - Rima Izem
- Division of Biostatistics and Study Methodology, Children's National Research Institute, Washington, DC, USA
- Department of Epidemiology, The George Washington University School of Public Health, Washington, DC, USA
- Statistical Methods and Consulting, Novartis, Basel, Switzerland
| | - Xiaojun Chen
- Department of Biostatistics and Bioinformatics, The George Washington University, Washington, DC, USA
| | - Karl Seydel
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
- Department of Osteopathic Medical Specialties, College of Osteopathic Medicine, Michigan State University, East Lansing, MI, USA
| | - Douglas Postels
- Blantyre Malaria Project, University of Malawi College of Medicine, Blantyre, Malawi
- Division of Neurology, The George Washington University/Children's National Medical Center, Washington, DC, USA
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Sumner KM, Mangeni JN, Obala AA, Freedman E, Abel L, Meshnick SR, Edwards JK, Pence BW, Prudhomme-O'Meara W, Taylor SM. Impact of asymptomatic Plasmodium falciparum infection on the risk of subsequent symptomatic malaria in a longitudinal cohort in Kenya. eLife 2021; 10:e68812. [PMID: 34296998 PMCID: PMC8337072 DOI: 10.7554/elife.68812] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 07/20/2021] [Indexed: 11/13/2022] Open
Abstract
Background Asymptomatic Plasmodium falciparum infections are common in sub-Saharan Africa, but their effect on subsequent symptomaticity is incompletely understood. Methods In a 29-month cohort of 268 people in Western Kenya, we investigated the association between asymptomatic P. falciparum and subsequent symptomatic malaria with frailty Cox models. Results Compared to being uninfected, asymptomatic infections were associated with an increased 1 month likelihood of symptomatic malaria (adjusted hazard ratio [aHR]: 2.61, 95% CI: 2.05 to 3.33), and this association was modified by sex, with females (aHR: 3.71, 95% CI: 2.62 to 5.24) at higher risk for symptomaticity than males (aHR: 1.76, 95% CI: 1.24 to 2.50). This increased symptomatic malaria risk was observed for asymptomatic infections of all densities and in people of all ages. Long-term risk was attenuated but still present in children under age 5 (29-month aHR: 1.38, 95% CI: 1.05 to 1.81). Conclusions In this high-transmission setting, asymptomatic P. falciparum can be quickly followed by symptoms and may be targeted to reduce the incidence of symptomatic illness. Funding This work was supported by the National Institute of Allergy and Infectious Diseases (R21AI126024 to WPO, R01AI146849 to WPO and SMT).
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Affiliation(s)
- Kelsey M Sumner
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
- Division of Infectious Diseases, School of Medicine, Duke UniversityDurhamUnited States
| | - Judith N Mangeni
- School of Public Health, College of Health Sciences, Moi UniversityEldoretKenya
| | - Andrew A Obala
- School of Medicine, College of Health Sciences, Moi UniversityEldoretKenya
| | - Elizabeth Freedman
- Division of Infectious Diseases, School of Medicine, Duke UniversityDurhamUnited States
| | - Lucy Abel
- Academic Model Providing Access to Healthcare, Moi Teaching and Referral HospitalEldoretKenya
| | - Steven R Meshnick
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
| | - Jessie K Edwards
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
| | - Brian W Pence
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
| | - Wendy Prudhomme-O'Meara
- Division of Infectious Diseases, School of Medicine, Duke UniversityDurhamUnited States
- School of Public Health, College of Health Sciences, Moi UniversityEldoretKenya
- Duke Global Health Institute, Duke UniversityDurhamUnited States
| | - Steve M Taylor
- Department of Epidemiology, Gillings School of Global Public Health, University of North CarolinaChapel HillUnited States
- Division of Infectious Diseases, School of Medicine, Duke UniversityDurhamUnited States
- Duke Global Health Institute, Duke UniversityDurhamUnited States
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Clustering of subpatent infections in households with asymptomatic rapid diagnostic test-positive cases in Bioko Island, Equatorial Guinea independent of travel to regions of higher malaria endemicity: a cross-sectional study. Malar J 2021; 20:313. [PMID: 34247643 PMCID: PMC8274032 DOI: 10.1186/s12936-021-03844-6] [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: 04/15/2021] [Accepted: 07/03/2021] [Indexed: 11/27/2022] Open
Abstract
Background Prevalence of falciparum malaria on Bioko Island remains high despite sustained, intensive control. Progress may be hindered by high proportions of subpatent infections that are not detected by rapid diagnostic tests (RDT) but contribute to onward transmission, and by imported infections. Better understanding of the relationship between subpatent infections and RDT-detected infections, and whether this relationship is different from imported versus locally acquired infections, is imperative to better understand the sources of infection and mechanisms of transmission to tailor more effective interventions. Methods Quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) was performed on a sub-set of samples from the 2015 Malaria Indicator Survey to identify subpatent infections. Households with RDT(+) individuals were matched 1:4 with households with no RDT(+) individuals. The association between living in a household with an RDT(+) individual and having a subpatent infection was evaluated using multivariate hierarchical logistic regression models with inverse probability weights for selection. To evaluate possible modification of the association by potential importation of the RDT(+) case, the analysis was repeated among strata of matched sets based on the reported eight-week travel history of the RDT(+) individual(s). Results There were 142 subpatent infections detected in 1,400 individuals (10.0%). The prevalence of subpatent infections was higher in households with versus without an RDT(+) individual (15.0 vs 9.1%). The adjusted prevalence odds of subpatent infection were 2.59-fold greater (95% CI: 1.31, 5.09) for those in a household with an RDT(+) individual compared to individuals in a household without RDT(+) individuals. When stratifying by travel history of the RDT(+) individual, the association between subpatent infections and RDT(+) infections was stronger in the strata in which the RDT(+) individual(s) had not recently travelled (adjusted prevalence odds ratio (aPOR) 2.95; 95% CI:1.17, 7.41), and attenuated in the strata in which recent travel was reported (aPOR 1.76; 95% CI: 0.54, 5.67). Conclusions There is clustering of subpatent infections around RDT(+) individual(s) when both imported and local infection are suspected. Future control strategies that aim to treat whole households in which an RDT(+) individual is found may target a substantial portion of infections that would otherwise not be detected. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03844-6.
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