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Telfils R, Dossou AY, Djènontin A, Adimi E, Akoho R, Bailly J, Bouraïma A, Matondo D, Sissinto-Savi de Tove Y, Houinato D, Massougbodji A, Dechavanne C, Cottrell G. Dynamics of submicroscopic and microscopic asymptomatic malaria infection and associated factors: A longitudinal study in South Benin. PLoS One 2024; 19:e0311217. [PMID: 39666763 PMCID: PMC11637252 DOI: 10.1371/journal.pone.0311217] [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: 02/22/2024] [Accepted: 09/12/2024] [Indexed: 12/14/2024] Open
Abstract
INTRODUCTION Asymptomatic malaria infection is now recognized as a potential threat to malaria control. However, its prevalence and its dynamics are poorly documented especially in a perennial context of high seasonal transmission. A longitudinal study was conducted in southern Benin to investigate the dynamics of asymptomatic malaria infection and to identify factors influencing it. METHODS A cohort of 377 participants was recruited, stratified into three age groups (under 5 years, between 5 and 15 years, over 15 years). After inclusion, two visits were made one-month apart between August and November 2021. Malaria infection was diagnosed by microscopy and PCR and questionnaires were administered to the participants. The dynamics of malaria infection, both submicroscopic (positive PCR / negative blood smear) and microscopic (positive blood smear), and related factors were determined using a mixed ordinal polytomous regression model and a multistate Markov model. RESULTS The human infectious reservoir consisted primarily of asymptomatic submicroscopic infections (289/512 (56.4%)), followed by asymptomatic microscopic infections (182/512 (35.5%)) and symptomatic infections (41/512 (8%)). The prevalence of asymptomatic infection was highly related to age-group (5-15 years: OR: 4 .12 [2.55-6.67] and > 15 years OR: 2.80 [1.73-4.54] compared to the under 5 years old group). The children under 15 years with asymptomatic infection had the highest risk of becoming symptomatic. The mean duration of asymptomatic infections in 5-15-year-olds was the longest (76.7 days (53.8-109.1)). CONCLUSION This study revealed a persistent asymptomatic malaria reservoir over the follow-up period, with substantial variations between age-groups. These findings are important elements to consider for an optimal deployment of malaria control interventions.
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Affiliation(s)
| | | | - Armel Djènontin
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou (Bénin) and Centre de Recherche pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université d’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Elisée Adimi
- Centre d’Étude et de Recherche sur le Paludisme Associé à la Grossesse et à l’Enfance (CERPAGE), Faculté des Sciences de la Santé, Cotonou, Bénin
| | - Romuald Akoho
- Centre d’Étude et de Recherche sur le Paludisme Associé à la Grossesse et à l’Enfance (CERPAGE), Faculté des Sciences de la Santé, Cotonou, Bénin
| | | | - Aziz Bouraïma
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou (Bénin) and Centre de Recherche pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université d’Abomey-Calavi (UAC), Cotonou, Bénin
| | | | | | - Dismand Houinato
- Faculté des Sciences de la Santé, Université d’Abomey-Calavi, Cotonou, Bénin
| | | | - Célia Dechavanne
- IRD, MERIT, Université Paris Cité, Paris, France
- Centre d’Étude et de Recherche sur le Paludisme Associé à la Grossesse et à l’Enfance (CERPAGE), Faculté des Sciences de la Santé, Cotonou, Bénin
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Duffy PE, Gorres JP, Healy SA, Fried M. Malaria vaccines: a new era of prevention and control. Nat Rev Microbiol 2024; 22:756-772. [PMID: 39025972 DOI: 10.1038/s41579-024-01065-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/30/2024] [Indexed: 07/20/2024]
Abstract
Malaria killed over 600,000 people in 2022, a death toll that has not improved since 2015. Additionally, parasites and mosquitoes resistant to existing interventions are spreading across Africa and other regions. Vaccines offer hope to reduce the mortality burden: the first licensed malaria vaccines, RTS,S and R21, will be widely deployed in 2024 and should substantially reduce childhood deaths. In this Review, we provide an overview of the malaria problem and the Plasmodium parasite, then describe the RTS,S and R21 vaccines (the first vaccines for any human parasitic disease), summarizing their benefits and limitations. We explore next-generation vaccines designed using new knowledge of malaria pathogenesis and protective immunity, which incorporate antigens and platforms to elicit effective immune responses against different parasite stages in human or mosquito hosts. We describe a decision-making process that prioritizes malaria vaccine candidates for development in a resource-constrained environment. Future vaccines might improve upon the protective efficacy of RTS,S or R21 for children, or address the wider malaria scourge by preventing pregnancy malaria, reducing the burden of Plasmodium vivax or accelerating malaria elimination.
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Affiliation(s)
- Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
| | - J Patrick Gorres
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Sara A Healy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
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Williams LR, Emary KRW, Phillips DJ, Hay J, Larwood JPJ, Ramasamy MN, Pollard AJ, Grassly NC, Voysey M. Implementation and adherence to regular asymptomatic testing in a COVID-19 vaccine trial. Vaccine 2024; 42:126167. [PMID: 39060202 DOI: 10.1016/j.vaccine.2024.126167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 07/16/2024] [Accepted: 07/19/2024] [Indexed: 07/28/2024]
Abstract
BACKGROUND For pathogens which cause infections that present asymptomatically, evaluating vaccine efficacy (VE) against asymptomatic infection is important for understanding a vaccine's potential epidemiological impact. Regular testing for subclinical infections is a potentially valuable strategy but its success hinges on participant adherence and minimising false positives. This paper describes the implementation and adherence to weekly testing in a COVID-19 vaccine trial. METHODS COV002 was a phase 2/3 trial assessing the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2. Asymptomatic infections were detected using weekly self-administered swabs for RT-PCR testing. We analysed adherence using mixed-effects regression models and estimated the probability of true and false positive asymptomatic infections using estimates of adherence and testing characteristics. FINDINGS 356,551 tests were self-administered by 10,811 participants during the 13-month follow-up. Median adherence was 75.0% (IQR 42·6-90·9), which translated to a 74·5% (IQR 50·9-78·8) probability of detecting a positive asymptomatic infection during the swabbing period, and between 21 and 96 false positives during VE evaluation. The odds of returning a swab declined by 8% per week and further after testing positive and unblinding. Adherence was higher in older age groups, females and non-healthcare workers. INTERPRETATION The COV002 trial demonstrated the feasibility of running a long-term regular asymptomatic testing strategy. This information could be valuable for designing future phase III vaccine trials in which infection is an outcome. FUNDING UK Research and Innovation, National Institutes for Health Research (NIHR), Coalition for Epidemic Preparedness Innovations, NIHR Oxford Biomedical Research Centre, Thames Valley and South Midland's NIHR Clinical Research Network, AstraZeneca.
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Affiliation(s)
- Lucy R Williams
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, United Kingdom.
| | - Katherine R W Emary
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Daniel J Phillips
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Jodie Hay
- Paul O'Gorman Leukaemia Research Centre, University of Glasgow, Glasgow, United Kingdom
| | - Jessica P J Larwood
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Maheshi N Ramasamy
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom; Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Andrew J Pollard
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom
| | - Nicholas C Grassly
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London, United Kingdom
| | - Merryn Voysey
- Oxford Vaccine Group, Department of Paediatrics, University of Oxford, Oxford, United Kingdom; NIHR Oxford Biomedical Research Centre, Oxford, United Kingdom.
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Alemayehu A, Abossie A, Zeynudin A, Beyene J, Yewhalaw D. Asymptomatic malaria in pregnancy and associated risk factors in Majang Zone, Gambella Region, Southwest Ethiopia: a hard-to-reach malaria hotspot. Malar J 2024; 23:210. [PMID: 39010115 PMCID: PMC11250956 DOI: 10.1186/s12936-024-05041-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 07/10/2024] [Indexed: 07/17/2024] Open
Abstract
BACKGROUND Asymptomatic malaria in pregnancy (AMiP) is a daunting public health problem with multifaceted adverse outcomes for mothers, fetuses, newborns and beyond. This study aimed to assess the prevalence and risk factors of AMiP and anaemia in Majang Zone, Gambella, Southwest Ethiopia. METHODS A facility-based cross-sectional study was conducted among 425 pregnant women attending the antenatal care (ANC) clinics of five health facilities in the Majang Zone from November 2022 to February 2023. Sociodemographic, obstetric, and anti-malarial intervention data were collected using an interviewer-administered questionnaire. A capillary blood specimen was collected to diagnose malaria and anaemia as well as determine the blood group. Malaria was diagnosed by rapid diagnostic test (RDT), microscopy, and quantitative polymerase chain reaction (qPCR). Statistical analyses were done by Statistical Package for Social Science (SPSS) version 26.0. The association between dependent and independent variables was assessed by multivariable binary logistic regression, considering P < 0.05 statistically significant. The magnitude of associations was quantified with the adjusted odds ratio (AOR) along with the corresponding 95% confidence interval (CI). RESULTS The overall prevalence of AMiP was 15.3% (95% CI 12.1, 18.9). It was 11.3% (95% CI 8.4, 14.7) by RDT, 11.8% (95% CI 8.9, 15.2) by microscopy and 17.6% (95% CI 11.7, 24.9) by qPCR. Plasmodium falciparum, moderate parasitaemia and submicroscopic infection accounted for 55.4% of the AMiP prevalence, 50.8% of the parasite density, and 41.6% of the qPCR-positive AMiP, respectively. Nearly 32.3% of pregnant women with AMiP carried gametocytes. Risk factors of AMiP were: not utilizing insecticide-treated net (ITN) within the previous week (AOR: 9.43 95% CI 1.57, 56.62), having a history of malaria within the previous year (AOR: 2.26 95% CI 1.16, 4.42), lack of indoor residual spraying (IRS) within the previous year (AOR: 3.00 95% CI 1.50, 6.00), and ANC contact below two rounds (AOR: 4.28 95% CI 2.06, 8.87). The prevalence of anaemia was 27.7% (95% CI 23.6, 32.1), and it was higher among AMiP-positives (56.9%) than the negatives (22.5%) (P: 000). CONCLUSION The prevalence of AMiP and anaemia was high, and remained as a critical public health problem in the study area. Focus on the identified risk factors and introduction of more sensitive diagnostic tools should be considered to mitigate AMiP in the study area.
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Affiliation(s)
- Aklilu Alemayehu
- School of Medical Laboratory Science, Institute of Health, Jimma University, Jimma, Ethiopia.
- Department of Medical Laboratory Science, College of Medicine and Health Science, Arba Minch University, Arba Minch, Ethiopia.
| | - Ashenafi Abossie
- School of Medical Laboratory Science, Institute of Health, Jimma University, Jimma, Ethiopia
- Department of Medical Laboratory Science, College of Medicine and Health Science, Arba Minch University, Arba Minch, Ethiopia
| | - Ahmed Zeynudin
- School of Medical Laboratory Science, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Joseph Beyene
- Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, ON, Canada
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Science, Institute of Health, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Centre, Jimma University, Jimma, Ethiopia
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Amwoma JG, Kituyi S, Wakoli DM, Ochora DO, Chemwor G, Maisiba R, Okore W, Opot B, Juma D, Muok EM, Garges EC, Egbo TE, Nyabuga FN, Andagalu B, Akala HM. Comparative analysis of peripheral whole blood transcriptome from asymptomatic carriers reveals upregulation of subsets of surface proteins implicated in Plasmodium falciparum phenotypic plasticity. Biochem Biophys Rep 2024; 37:101596. [PMID: 38146350 PMCID: PMC10749222 DOI: 10.1016/j.bbrep.2023.101596] [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: 07/13/2023] [Revised: 11/17/2023] [Accepted: 11/27/2023] [Indexed: 12/27/2023] Open
Abstract
The molecular mechanism underlying Plasmodium falciparum's persistence in the asymptomatic phase of infection remains largely unknown. However, large-scale shifts in the parasites' gene expression during asymptomatic infections may enhance phenotypic plasticity, maximizing their fitness and leading to the persistence of the asymptomatic infections. To uncover these mechanisms, we aimed to identify parasite genetic factors implicated in asymptomatic infections through whole transcriptome analysis. We analyzed publicly available transcriptome datasets containing asymptomatic malaria (ASM), uncomplicated malaria (SM), and malaria-naïve (NSM) samples from 35 subjects for differentially expressed genes (DEGs) and long noncoding RNAs. Our analysis identified 755 and 1773 DEGs in ASM vs SM and NSM, respectively. These DEGs revealed sets of genes coding for proteins of unknown functions (PUFs) upregulated in ASM vs SM and ASM, suggesting their role in underlying fundamental molecular mechanisms during asymptomatic infections. Upregulated genes in ASM vs SM revealed a subset of 24 clonal variant genes (CVGs) involved in host-parasite and symbiotic interactions and modulation of the symbiont of host erythrocyte aggregation pathways. Moreover, we identified 237 differentially expressed noncoding RNAs in ASM vs SM, of which 11 were found to interact with CVGs, suggesting their possible role in regulating the expression of CVGs. Our results suggest that P. falciparum utilizes phenotypic plasticity as an adaptive mechanism during asymptomatic infections by upregulating clonal variant genes, with long noncoding RNAs possibly playing a crucial role in their regulation. Thus, our study provides insights into the parasites' genetic factors that confer a fitness advantage during asymptomatic infections.
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Affiliation(s)
- Joseph G. Amwoma
- Department of Biological Sciences, University of Embu, Kenya
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - Sarah Kituyi
- Department of Biological Sciences, University of Embu, Kenya
- Forgarty International Center of the National Institutes of Health, Bethesda, MD, USA
| | - Dancan M. Wakoli
- Department of Biochemistry and Molecular Biology, Egerton University, Kenya
| | - Douglas O. Ochora
- Department of Biological Sciences, School of Pure and Applied Sciences, Kisii University, Kenya
- DSI/NWU, Preclinical Drug Development Platform, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
| | - Gladys Chemwor
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - Risper Maisiba
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - Winnie Okore
- Department of Biomedical Sciences and Technology, Maseno University, Kenya
| | - Benjamin Opot
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - Dennis Juma
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - Eric M.O. Muok
- Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Eric C. Garges
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya
| | - Timothy E. Egbo
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya
| | | | - Ben Andagalu
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - Hoseah M. Akala
- United States Army Medical Research Directorate-Africa (USAMRD-A), Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
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Orish VN, Kyeremateng C, Appiah BP, Addei IB, Ayaba MA, Kwadzokpui PK, Marinkovic A, Prakash S, Okorie C, Izurieta R, Sanyaolu A. Knowledge and perception of asymptomatic malaria in the Volta region of Ghana. Trans R Soc Trop Med Hyg 2024; 118:33-43. [PMID: 37534813 DOI: 10.1093/trstmh/trad049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Revised: 06/19/2023] [Accepted: 07/17/2023] [Indexed: 08/04/2023] Open
Abstract
BACKGROUND The control of asymptomatic malaria is considered a key aspect of malaria control. This study aimed to assess the knowledge and perception of asymptomatic malaria among people in Ho municipality of the Volta region. METHODS A descriptive cross-sectional study involving questionnaire administration was conducted among randomly sampled residents of the Ho municipality of the Volta region of Ghana. Using SPSS version 25 statistical software, frequency distributions and proportions were computed for sociodemographic variables while knowledge and perception about asymptomatic malaria were computed into percentages and categorized into three levels based on Bloom's cut-off for further analysis. Findings with p-values <0.05 were considered statistically significant. RESULTS Among the 200 participants, 197 (98.5%) were aware of malaria. The majority (116 [58.0%]) of the study participants agreed to the possibility of asymptomatic infection, but most (133 [66.5%]) of the community members did not know that asymptomatic individuals can still transmit infections. The majority of the participants (184 [92.0%]) showed interest in getting further education on asymptomatic malaria and a significant majority (180 [90.0%]) expressed a willingness to take treatment after testing positive without showing any symptoms. CONCLUSIONS Asymptomatic malaria control can be achieved through a mass testing and treatment strategy, therefore improving the knowledge and perception about asymptomatic malaria might improve malaria control.
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Affiliation(s)
- Verner N Orish
- Department of Microbiology and Immunology, School of Medicine, University of Health and Allied Sciences, Ho, Volta Region, Ghana
| | - Caleb Kyeremateng
- School of Medicine, University of Health and Allied Sciences, Ho, Ghana
| | - Baffoe P Appiah
- Department of Medical Laboratory Sciences, School of Allied Health Sciences, University of Health and Allied Sciences, Ho, Ghana
| | - Isaac B Addei
- School of Medicine, University of Health and Allied Sciences, Ho, Ghana
| | - Moses A Ayaba
- School of Medicine, University of Health and Allied Sciences, Ho, Ghana
| | | | | | | | - Chuku Okorie
- Department of Allied Health Sciences, Union College of Union County, Plainfield Campus, NJ, USA
| | - Ricardo Izurieta
- Department of Global Communicable Diseases, College of Public Health, University of South Florida, Tampa, FL, USA
| | - Adekunle Sanyaolu
- Department of Public Health, Federal Ministry of Health, Abuja, Nigeria
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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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Duguma T, Tekalign E, Kebede SS, Bambo GM. Prevalence of asymptomatic malaria and associated factors among pregnant women in Ethiopia: systematic review and meta-analysis. FRONTIERS IN REPRODUCTIVE HEALTH 2023; 5:1258952. [PMID: 37886226 PMCID: PMC10598859 DOI: 10.3389/frph.2023.1258952] [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: 07/29/2023] [Accepted: 09/22/2023] [Indexed: 10/28/2023] Open
Abstract
The proactive identification of asymptomatic patients and the mitigation of associated problems are essential to the elimination of malaria. For asymptomatic malaria and related variables among pregnant women in Ethiopia, there are no national pooled estimates. As a result, the goal of this study is to compile thorough and compelling data from several Ethiopian investigations. Google Scholar, PubMed, Scopes, the Web of Science, the Cochrane Library, and African Journals Online were a few of the electronic resources that were accessed. The investigation included all observational studies. STATA version 15 was used to extract the data from the Microsoft Excel file and conduct the analysis. The estimated pooled prevalence of asymptomatic malaria among pregnant women was calculated using a random-effects model. An inverse variance index (I2) analysis was utilized to find heterogeneity. To assess the publication bias, funnel plots, and Egger's statistical tests were used. The study determined that the combined prevalence of asymptomatic malaria among pregnant women was 7.20 (95% confidence interval = 4.22, 10.18) and 4.69 (95% confidence interval = 2.77, 6.62) by microscopy and rapid diagnostic test, respectively. The presence of stagnant water near their home (odds ratio = 4.31; 95% confidence interval = 1.66, 11.20); not using insecticide-treated nets (odds ratio = 6.93; 95% confidence interval = 3.27, 14.71); the lack of indoor residual spray service (odds ratio = 2.68; 95% confidence interval = 1.63, 4.40); and the presence of pregnant women in their neighborhood (odds ratio = 3.14; 95% confidence interval = 1.4). This study showed that pregnant women have a high pooled prevalence of asymptomatic malaria. Women living in rural areas near stagnant water and those who never used insecticide-treated nets had a two-, four-, or six-fold higher prevalence of asymptomatic malaria, respectively. The use of advanced diagnostic techniques could produce a higher magnitude of the disease. For effective intervention toward elimination, active case detection at the community level is also advised. Systematic Review Registration https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023411385; identifier, CRD42023411385.
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Affiliation(s)
- Tadesse Duguma
- Department of Medical Laboratory Science, College of Health Science and Medicine, Mizan-Tepi University, Mizan-Aman, Ethiopia
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Debash H, Tesfaw G, Ebrahim H, Shibabaw A, Melese Y, Tilahun M, Alemayehu E, Mohammed O, Tesfaye M, Abate M. Symptomatic and asymptomatic malaria prevalence and its determinant factors in pastoral communities of Waghemira Zone, Northeast Ethiopia: A community-based cross-sectional study. Health Sci Rep 2023; 6:e1336. [PMID: 37305151 PMCID: PMC10248203 DOI: 10.1002/hsr2.1336] [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: 02/23/2023] [Revised: 05/25/2023] [Accepted: 05/30/2023] [Indexed: 06/13/2023] Open
Abstract
Background and Aims Malaria elimination programs have also encountered numerous challenges, such as widespread asymptomatic carriers in endemic areas, which should be taken into account in malaria-control programs for effective transmission interruption. The purpose of this research was to determine the prevalence of symptomatic and asymptomatic malaria infections and associated factors, in pastoral communities. Methods A community-based cross-sectional study was conducted among selected districts in the Waghemra Zone, Northeast Ethiopia, from September to December 2022. A structured questionnaire was employed to collect sociodemographic data and associated risk factors. Plasmodium species were detected using light microscopy and a rapid diagnostic test. Data entry and analysis were carried out using SPSS version 26 software. The association between dependent and independent variables was explored by using multivariable logistic regression analyses. A statistically significant association was declared at a p-value of <0.05. Results The overall prevalence of malaria was 21.2% (134/633), with the predominant Plasmodium falciparum infections accounting for 67.8% (87/134). Among asymptomatic participants, 7.5% (34/451) and 10.2% (46/451) were diagnosed by rapid diagnostic test and light microscopy, respectively. On the other hand, the prevalence of symptomatic malaria was 44.5% (81/182) and 48.4% (88/182) as diagnosed by rapid diagnostic test and light microscopy, respectively. The presence of stagnant water near the houses, the utilization of insecticide-treated mosquito nets, the number of insecticide-treated mosquito nets, and outdoor stays at night were all positively linked with the prevalence of malaria. Conclusions The overall prevalence estimate for symptomatic and asymptomatic malaria was high. Malaria is still a public health problem in the study area. Malaria infection was associated with the presence of stagnant water near the houses, the utilization of insecticide-treated mosquito nets, the number of insecticide-treated mosquito nets, and outdoor stays at night. Improved access to all malaria interventions is needed to interrupt the transmission at the community level.
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Affiliation(s)
- Habtu Debash
- Department of Medical Laboratory Science, College of Medicine and Health SciencesWollo UniversityDessieEthiopia
| | - Gebru Tesfaw
- Department of Internal Medicine, School of Medicine, College of Medicine and Health SciencesWollo UniversityDessieEthiopia
| | - Hussen Ebrahim
- Department of Medical Laboratory Science, College of Medicine and Health SciencesWollo UniversityDessieEthiopia
| | - Agumas Shibabaw
- Department of Medical Laboratory Science, College of Medicine and Health SciencesWollo UniversityDessieEthiopia
| | - Yimer Melese
- Department of Medical Laboratory Science, College of Medicine and Health SciencesDebre Berhan UniversityDebre BerhanEthiopia
| | - Mihret Tilahun
- Department of Medical Laboratory Science, College of Medicine and Health SciencesWollo UniversityDessieEthiopia
| | - Ermiyas Alemayehu
- Department of Medical Laboratory Science, College of Medicine and Health SciencesWollo UniversityDessieEthiopia
| | - Ousman Mohammed
- Department of Medical Laboratory Science, College of Medicine and Health SciencesWollo UniversityDessieEthiopia
| | - Melkam Tesfaye
- Department of Medical Laboratory Science, College of Medicine and Health SciencesWollo UniversityDessieEthiopia
| | - Mengistu Abate
- Department of Midwifery, School of Nursing and Midwifery College of Medicine and Health SciencesWollo UniversityDessieEthiopia
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Biruksew A, Demeke A, Birhanu Z, Kebede E, Golassa L, Mathebula EM, Yewhalaw D. Diagnostic performance of NxTek™ Eliminate Malaria-Pf test for the detection of Plasmodium falciparum in school children with asymptomatic malaria. Malar J 2023; 22:112. [PMID: 36991438 DOI: 10.1186/s12936-023-04529-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 03/13/2023] [Indexed: 03/30/2023] Open
Abstract
Abstract
Background
One of the major roadblocks to the falciparum malaria elimination programme is the presence of a portion of the population, such as school children, with asymptomatic malaria infection. Targeting such reservoirs of infections is critical to interrupting transmission and enhancing elimination efforts. The NxTek™ Eliminate Malaria Pf test is a highly sensitive rapid diagnostic test (hsRDT) for the detection of HRP-2. However, knowledge gaps exist in Ethiopia on the diagnostic performance of hsRDT for the detection of Plasmodium falciparum in school children with asymptomatic malaria.
Methods
A school-based cross-sectional study was conducted from September 2021 to January 2022 on 994 healthy school children (aged 6–15 years). Finger-pricked whole blood samples were collected for microscopy, hsRDT, conventional RDT (cRDT or SD Bioline Malaria Ag Pf/P.v), and QuantStudio™ 3 Real—Time PCR system (qPCR). The hsRDT was compared to cRDT and microscopy. qPCR and microscopy were used as reference methods.
Results
The prevalence of Plasmodium falciparum was 1.51%, 2.2%. 2.2% and 4.52%, by microscopy, hsRDT, cRDT and qPCR, respectively. Using qPCR as reference, the sensitivity of hsRDT was higher (48.89%) than the microscopy (33.3%), and showed 100% specificity and a positive predictive value (PPV). Microscopy showed similar specificity and PPV as hsRDT. Using microscopy as a reference, the diagnostic perforrmances of both hsRDT and cRDT were similar. Both RDTs demonstrated identical diagnostic performances in both comparison methods.
Conclusions
hsRDT has the same diagnostic performance as cRDT but improved diagnostic characteristics than microscopy for detection of P. falciparum in school children with asymptomatic malaria. It can be a useful tool for the national malaria elimination plan of Ethiopia.
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Mohon AN, Toppings N, Castañeda-Mogollón D, Kamaliddin C, Pillai DR. Ultrasensitive Reverse Transcriptase Loop-Mediated Isothermal Amplification (US-LAMP)-Based Detection of Malaria Infection from Dried Blood Spots. Methods Mol Biol 2023; 2621:325-337. [PMID: 37041454 DOI: 10.1007/978-1-0716-2950-5_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2023]
Abstract
Submicroscopic malaria diagnosis requires highly sensitive tools instead of the conventional microscopy and rapid diagnostic tests (RDTs). While polymerase chain reaction (PCR) is more sensitive than RDTs and microscopy, the required capital cost and technical expertise hinder implementation of PCR in low- and middle-income countries. This chapter describes an ultrasensitive reverse transcriptase loop-mediated isothermal amplification (US-LAMP) test for malaria with a high sensitivity and specificity, while also being practical to implement in low-complexity laboratory settings. The workflow combines a silica spin column-based total nucleic extraction from dried blood spots (DBS) with US-LAMP amplifying the Plasmodium (Pan-LAMP) target and subsequent identification Plasmodium falciparum (Pf-LAMP).
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Affiliation(s)
- Abu Naser Mohon
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Noah Toppings
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Daniel Castañeda-Mogollón
- Department of Microbiology and Infectious Disease, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Claire Kamaliddin
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
- Department of Microbiology and Infectious Disease, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Dylan R Pillai
- Department of Pathology and Laboratory Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
- Department of Microbiology and Infectious Disease, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
- Department of Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.
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12
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Paper functionalization for detection of Plasmodium falciparum DNA using square waves voltammetry. Talanta 2023; 252:123839. [DOI: 10.1016/j.talanta.2022.123839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 08/08/2022] [Accepted: 08/11/2022] [Indexed: 11/18/2022]
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13
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Malaria Microscopy Competency in the Subnational Verification, China: Implications for Malaria Elimination and the Prevention of Malaria Reestablishment. THE CANADIAN JOURNAL OF INFECTIOUS DISEASES & MEDICAL MICROBIOLOGY = JOURNAL CANADIEN DES MALADIES INFECTIEUSES ET DE LA MICROBIOLOGIE MEDICALE 2022; 2022:8003845. [PMID: 36349187 PMCID: PMC9637463 DOI: 10.1155/2022/8003845] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Revised: 09/15/2022] [Accepted: 10/19/2022] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Qualified microscopy competency is a key indicator for certification of malaria elimination. To better prepare the country certification and identify the priorities that need improvement to prevent malaria reestablishment, microscopy competency at different levels were assessed in subnational verification of malaria elimination in China. Methodology. Microscopist representatives from centers for disease control and prevention (CDC)/institutes of parasitic diseases (IPD) and medical institutes for malaria diagnosis at the provincial and county levels in the subnational verification were analyzed. Specifically, five provincial microscopist representatives and ten county-level representatives were assessed in each of previously endemic provinces on qualitative identification (Plasmodium positive or negative) and Plasmodium species identification using standard slides from the National Malaria Diagnosis Reference Laboratory. RESULTS A total of 100 provincial-level representatives (60 from 42 CDCs/IPDs and 40 from 34 medical institutes) and 200 county-level representatives (61 from 41 CDCs and 139 from 118 medical institutes) were included. The qualitative accuracy was higher than 90% each (P = 0.137), but slides with low parasite density were easy to be misdiagnosed as negative. Furthermore, the accuracy of species identification was 80.0% and 83.6% in medical institutes and centers for disease control and prevention (CDCs) at the provincial level (P = 0.407) with relatively high misdiagnosis of P. vivax as P. ovale in the latter (16.2%) and 82.0% and 85.0% in medical institutes and CDCs at the county level (P = 0.330) for the identification of P. falciparum and non-P. falciparum with higher false-negative in medical institutions (P < 0.001). CONCLUSIONS In conclusion, competent microscopy in subnational verification supported the quality in eliminating malaria in China, while the accurate identification of malaria parasites, especially slides with low parasite density still need to be improved through continuous diagnostic platform construction, continuous technological innovation, and targeted training to prevent reestablishment of malaria transmission.
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14
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Hergott DEB, Owalla TJ, Balkus JE, Apio B, Lema J, Cemeri B, Akileng A, Seilie AM, Chavtur C, Staubus W, Chang M, Egwang TG, Murphy SC. Feasibility of community at-home dried blood spot collection combined with pooled reverse transcription PCR as a viable and convenient method for malaria epidemiology studies. Malar J 2022; 21:221. [PMID: 35836179 PMCID: PMC9284728 DOI: 10.1186/s12936-022-04239-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 06/26/2022] [Indexed: 01/08/2023] Open
Abstract
Background Many Plasmodium infections in endemic regions exist at densities below the limit of detection of standard diagnostic tools. These infections threaten control efforts and may impact vaccine and therapeutic drug studies. Simple, cost-effective methods are needed to study the natural history of asymptomatic submicroscopic parasitaemia. Self-collected dried blood spots (DBS) analysed using pooled and individual quantitative reverse transcription polymerase chain reaction (qRT-PCR) provide such a solution. Here, the feasibility and acceptability of daily at-home DBS collections for qRT-PCR was studied to better understand low-density infections. Methods Rapid diagnostic test (RDT)-negative individuals in Katakwi District, northeastern Uganda, were recruited between April and May 2021. Venous blood samples and clinic-collected DBS were taken at enrollment and at four weekly clinic visits. Participants were trained in DBS collection and asked to collect six DBS weekly between clinic visits. Opinions about the collection process were solicited using daily Diary Cards and a Likert scale survey at the final study visit. Venous blood and DBS were analysed by Plasmodium 18S rRNA qRT-PCR. The number of participants completing the study, total DBS collected, and opinions of the process were analysed to determine compliance and acceptability. The human internal control mRNA and Plasmodium 18S rRNA were evaluated for at-home vs. clinic-collected DBS and venous blood to assess quality and accuracy of at-home collected samples. Results One-hundred two adults and 29 children were enrolled, and 95 and 26 completed the study, respectively. Three individuals withdrew due to pain or inconvenience of procedures. Overall, 96% of participants collected ≥ 16 of 24 at-home DBS, and 87% of DBS contained ≥ 40 µL of blood. The procedure was well tolerated and viewed favourably by participants. At-home collected DBS were acceptable for qRT-PCR and showed less than a one qRT-PCR cycle threshold shift in the human control mRNA compared to clinic-collected DBS. Correlation between Plasmodium falciparum 18S rRNA from paired whole blood and DBS was high (R = 0.93). Conclusions At-home DBS collection is a feasible, acceptable, and robust method to obtain blood to evaluate the natural history of low-density Plasmodium infections by qRT-PCR. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04239-x.
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Affiliation(s)
- Dianna E B Hergott
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | - Tonny J Owalla
- Med Biotech Laboratories, P.O. Box 9364, Kampala, Uganda
| | - Jennifer E Balkus
- Department of Epidemiology, School of Public Health, University of Washington, Seattle, WA, USA
| | | | - Jimmy Lema
- Med Biotech Laboratories, P.O. Box 9364, Kampala, Uganda
| | - Barbara Cemeri
- Med Biotech Laboratories, P.O. Box 9364, Kampala, Uganda
| | - Andrew Akileng
- Med Biotech Laboratories, P.O. Box 9364, Kampala, Uganda
| | - Annette M Seilie
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Chris Chavtur
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Weston Staubus
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Ming Chang
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA.,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA
| | | | - Sean C Murphy
- Department of Laboratory Medicine and Pathology, University of Washington, 750 Republican St., F870, Seattle, WA, 98109, USA. .,Center for Emerging and Re-Emerging Infectious Diseases, University of Washington, Seattle, WA, USA. .,Department of Microbiology, University of Washington, Seattle, WA, USA.
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15
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Adderley J, Boulet C, McCann K, McHugh E, Ioannidis LJ, Yeoh LM. Advances in Plasmodium research, an update: highlights from the Malaria in Melbourne 2021 conference. Mol Biochem Parasitol 2022; 250:111487. [DOI: 10.1016/j.molbiopara.2022.111487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 05/05/2022] [Accepted: 05/18/2022] [Indexed: 11/28/2022]
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Yin J, Yan H, Li M. Prompt and precise identification of various sources of infection in response to the prevention of malaria re-establishment in China. Infect Dis Poverty 2022; 11:45. [PMID: 35436964 PMCID: PMC9014402 DOI: 10.1186/s40249-022-00968-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 04/07/2022] [Indexed: 11/10/2022] Open
Abstract
Prompt and precise diagnosis of patients is an essential component of malaria control and elimination strategies, it is even more vital for the prevention of malaria re-establishment in the post elimination phase. After eliminating malaria in China, the strategy for prevention of malaria re-establishment was updated in a timely manner from the elimination strategy focusing on each case/focus to the prevention of re-establishment focusing on timely identification of the source of infection. However, there are numerous challenges, such as the persistent large number of imported malaria cases, the long-term threat of border malaria, unknown levels of asymptomatic infections and Plasmodium falciparum HRP2/3 gene deletions, and the continuous spreading of antimalarial drug resistance. Meanwhile, the detection capacity also need to be further improved to meet the timely detection of all sources of infection, otherwise it is bound to occur introduced malaria cases and malaria re-establishment in the presence of malaria vector mosquitoes. Therefore, it is necessary to continuously strengthen the malaria detection competency at all levels, promote the research and development on the malaria parasitological testing technologies, thus improving the timely detection of various sources of infection, and preventing the re-establishment of malaria.
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Affiliation(s)
- Jianhai Yin
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research), NHC Key Laboratory of Parasite and Vector Biology, WHO Collaborating Center for Tropical Diseases, National Center for International Research on Tropical Diseases, Shanghai, 200025, China.
| | - He Yan
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research), NHC Key Laboratory of Parasite and Vector Biology, WHO Collaborating Center for Tropical Diseases, National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Mei Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research), NHC Key Laboratory of Parasite and Vector Biology, WHO Collaborating Center for Tropical Diseases, National Center for International Research on Tropical Diseases, Shanghai, 200025, China
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17
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Tamiru A, Tolossa T, Regasa B, Mosisa G. Prevalence of asymptomatic malaria and associated factors in Ethiopia: Systematic review and meta-analysis. SAGE Open Med 2022; 10:20503121221088085. [PMID: 35433001 PMCID: PMC9006361 DOI: 10.1177/20503121221088085] [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: 05/11/2021] [Accepted: 02/23/2022] [Indexed: 11/15/2022] Open
Abstract
Active detection of asymptomatic malaria cases and resolution of associated factors are essential for malaria elimination. There are no nationwide estimates for asymptomatic malaria and associated factors in Ethiopia. Therefore, this study aims to generate comprehensive and conclusive evidence from various studies conducted in Ethiopia. Published articles from various electronic databases such as PubMed, Google Scholar, CINAHL, Scopes, Cochrane Library, the Web of Science, and African Journals Online were accessed. Also, unpublished studies from Addis Ababa digital library were identified. All observational study designs were included in the search. Data were extracted on the Microsoft Excel spreadsheet and analyzed using STATA version 14.1. A random-effects model was fitted to estimate the pooled prevalence of asymptomatic malaria. A meta-regression and subgroup analysis was computed to see heterogeneity. The publication bias was assessed by the funnel plots and Egger's statistical tests. The analysis found that the pooled burden of asymptomatic malaria was 6.7 (95% confidence interval = 4.60, 8.79). The pooled prevalence of Plasmodium falciparum was 3.75 (95% confidence interval = 2.25, 5.18), and that of Plasmodium vivax was 2.22 (95% confidence interval = 1.46, 2.99). Factors such indoor residual spray service (odds ratio = 0.46; 95% confidence interval = 0.26, 0.81), never used insecticide-treated nets (odds ratio = 6.36; 95% confidence interval = 4.01, 10.09), and presence of stagnant water in the vicinity (odds ratio = 3.24; 95% confidence interval = 1.20, 8.71) were found to have a significant association with asymptomatic malaria. This study highlighted that pooled prevalence of asymptomatic malaria is high and varied by population groups. Prevalence of asymptomatic malaria was increased among those who never used insecticide-treated nets and were living near stagnant water by six and three times, respectively. The use of more sensitive diagnostic methods could yield a higher burden of the disease. Furthermore, active case detection is recommended for effective intervention toward elimination.
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Affiliation(s)
- Afework Tamiru
- Department of Public Health, Institute of Health Sciences, Wollega University, Nekemte, Ethiopia
| | - Tadesse Tolossa
- Department of Public Health, Institute of Health Sciences, Wollega University, Nekemte, Ethiopia
| | - Bikila Regasa
- Department of Public Health, Institute of Health Sciences, Wollega University, Nekemte, Ethiopia
| | - Getu Mosisa
- School of Nursing and Midwifery, Institute of Health Sciences, Wollega University, Nekemte, Ethiopia
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Yin J, Li M, Yan H, Zhou S, Xia Z. Laboratory diagnosis for malaria in the elimination phase in China: efforts and challenges. Front Med 2022; 16:10-16. [PMID: 35226298 PMCID: PMC8883009 DOI: 10.1007/s11684-021-0889-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 08/10/2021] [Indexed: 01/19/2023]
Abstract
Malaria remains a global health challenge, although an increasing number of countries will enter pre-elimination and elimination stages. The prompt and precise diagnosis of symptomatic and asymptomatic carriers of Plasmodium parasites is the key aspect of malaria elimination. Since the launch of the China Malaria Elimination Action Plan in 2010, China has formulated clear goals for malaria diagnosis and has established a network of malaria diagnostic laboratories within medical and health institutions at all levels. Various external quality assessments were implemented, and a national malaria diagnosis reference laboratory network was established to strengthen the quality assurance in malaria diagnosis. Notably, no indigenous malaria cases have been reported since 2017, but the risk of re-establishment of malaria transmission cannot be ignored. This review summarizes the lessons about malaria diagnosis in the elimination phase, primarily including the establishments of laboratory networks and quality control in China, to better improve malaria diagnosis and maintain a malaria-free status. A reference is also provided for countries experiencing malaria elimination.
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Affiliation(s)
- Jianhai Yin
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); NHC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Center for Tropical Diseases, National Center for International Research on Tropical Diseases, Shanghai, 200025, China.
| | - Mei Li
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); NHC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Center for Tropical Diseases, National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - He Yan
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); NHC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Center for Tropical Diseases, National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Shuisen Zhou
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); NHC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Center for Tropical Diseases, National Center for International Research on Tropical Diseases, Shanghai, 200025, China
| | - Zhigui Xia
- National Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention (Chinese Center for Tropical Diseases Research); NHC Key Laboratory of Parasite and Vector Biology; WHO Collaborating Center for Tropical Diseases, National Center for International Research on Tropical Diseases, Shanghai, 200025, China.
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Kotepui KU, Masangkay FR, De Jesus Milanez G, Kotepui M. Prevalence and outcomes of malaria as co-infection among patients with human African trypanosomiasis: a systematic review and meta-analysis. Sci Rep 2021; 11:23777. [PMID: 34893680 PMCID: PMC8664815 DOI: 10.1038/s41598-021-03295-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 12/01/2021] [Indexed: 12/01/2022] Open
Abstract
Human African trypanosomiasis (HAT) is endemic in Africa; hence, the possibility of co-infection with malaria among patients with HAT exists. The present study investigated co-infection with malaria among patients with HAT to provide current evidence and characteristics to support further studies. Potentially relevant studies that reported Plasmodium spp. infection in patients with HAT was searched in PubMed, Web of Science, and Scopus. The risk of bias among the included studies was assessed using the checklist for analytical cross-sectional studies developed by the Joanna Briggs Institute. The pooled prevalence of Plasmodium spp. infection in patients with HAT was quantitatively synthesized using a random-effects model. Subgroup analyses of study sites and stages of HAT were performed to identify heterogeneity regarding prevalence among the included studies. The heterogeneity of the outcome among the included studies was assessed using Cochran’s Q and I2 statistics for consistency. Publication bias was assessed if the number of included studies was 10 or more. For qualitative synthesis, a narrative synthesis of the impact of Plasmodium spp. infection on the clinical and outcome characteristics of HAT was performed when the included studies provided qualitative data. Among 327 studies identified from three databases, nine studies were included in the systematic review and meta-analysis. The prevalence of Plasmodium spp. co-infection (692 cases) among patients with HAT (1523 cases) was 50% (95% confidence interval [CI] = 28–72%, I2 = 98.1%, seven studies). Subgroup analysis by type of HAT (gambiense or rhodesiense HAT) revealed that among patients with gambiense HAT, the pooled prevalence of Plasmodium spp. infection was 46% (95% CI = 14–78%, I2 = 96.62%, four studies), whereas that among patients with rhodesiense HAT was 44% (95% CI = 40–49%, I2 = 98.3%, three studies). Qualitative syntheses demonstrated that Plasmodium spp. infection in individuals with HAT might influence the risk of encephalopathy syndrome, drug toxicity, and significantly longer corrected QT time. Moreover, longer hospital stays and higher treatment costs were recorded among co-infected individuals. Because of the high prevalence of malaria among patients with HAT, some patients were positive for malaria parasites despite being asymptomatic. Therefore, it is suggested to test every patient with HAT for malaria before HAT treatment. If malaria is present, then antimalarial treatment is recommended before HAT treatment. Antimalarial treatment in patients with HAT might decrease the probability of poor clinical outcomes and case fatality in HAT.
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Affiliation(s)
- Kwuntida Uthaisar Kotepui
- Medical Technology, School of Allied Health Sciences, Walailak University, Tha Sala, Nakhon Si Thammarat, Thailand
| | - Frederick Ramirez Masangkay
- Department of Medical Technology, Institute of Arts and Sciences, Far Eastern University-Manila, Manila, Philippines
| | - Giovanni De Jesus Milanez
- Department of Medical Technology, Faculty of Pharmacy, Royal and Pontifical University of Santo Tomas, Manila, Philippines
| | - Manas Kotepui
- Medical Technology, School of Allied Health Sciences, Walailak University, Tha Sala, Nakhon Si Thammarat, Thailand.
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20
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Barazorda KA, Salas CJ, Braga G, Ricopa L, Ampuero JS, Siles C, Sanchez JF, Montano S, Lizewski SE, Joya CA, Bishop DK, Valdivia HO. Validation study of Boil & Spin Malachite Green Loop Mediated Isothermal Amplification (B&S MG-LAMP) versus microscopy for malaria detection in the Peruvian Amazon. PLoS One 2021; 16:e0258722. [PMID: 34695122 PMCID: PMC8544869 DOI: 10.1371/journal.pone.0258722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 10/04/2021] [Indexed: 11/19/2022] Open
Abstract
Malaria elimination efforts in Peru have dramatically reduced the incidence of cases in the Amazon Basin. To achieve the elimination, the detection of asymptomatic and submicroscopic carriers becomes a priority. Therefore, efforts should focus on tests sensitive enough to detect low-density parasitemia, deployable to resource-limited areas and affordable for large screening purposes. In this study, we assessed the performance of the Malachite–Green LAMP (MG-LAMP) using heat-treated DNA extraction (Boil & Spin; B&S MG-LAMP) on 283 whole blood samples collected from 9 different sites in Loreto, Peru and compared its performance to expert and field microscopy. A real-time PCR assay was used to quantify the parasite density. In addition, we explored a modified version of the B&S MG-LAMP for detection of submicroscopic infection in 500 samples and compared the turnaround time and cost of the MG-LAMP with microscopy. Compared to expert microscopy, the genus B&S MG-LAMP had a sensitivity of 99.4% (95%CI: 96.9%– 100%) and specificity of 97.1% (95%CI: 91.9%– 99.4%). The P. vivax specific B&S MG-LAMP had a sensitivity of 99.4% (96.6%– 100%) and specificity of 99.2% (95.5%– 100%) and the P. falciparum assay had a sensitivity of 100% (95%CI: 78.2%– 100%) and specificity of 99.3% (95%CI: 97.3%– 99.8%). The modified genus B&S MG-LAMP assay detected eight submicroscopic malaria cases (1.6%) which the species-specific assays did not identify. The turnaround time of B&S MG-LAMP was faster than expert microscopy with as many as 60 samples being processed per day by field technicians with limited training and utilizing a simple heat-block. The modified B&S MG-LAMP offers a simple and sensitive molecular test of choice for the detection of submicroscopic infections that can be used for mass screening in resources limited facilities in endemic settings nearing elimination and where a deployable test is required.
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Affiliation(s)
| | - Carola J. Salas
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Greys Braga
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Leonila Ricopa
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Julia S. Ampuero
- Department of Virology and Emerging infections, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Crystyan Siles
- Department of Virology and Emerging infections, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Juan F. Sanchez
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Silvia Montano
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Stephen E. Lizewski
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Christie A. Joya
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Danett K. Bishop
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
| | - Hugo O. Valdivia
- Department of Parasitology, U.S. Naval Medical Research Unit N°6 (NAMRU-6), Lima, Peru
- * E-mail:
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21
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Sayre D, Steinhardt LC, Irinantenaina J, Dentinger C, Rasoanaivo TF, Kapesa L, Razafindrakoto J, Legrand A, Prada N, Gutman J, Lewis L, Mangahasimbola RT, Andriamananjara M, Ravaoarinosy AV, Ralemary N, Garchitorena A, Harimanana A. Baseline malaria prevalence and care-seeking behaviours in rural Madagascar prior to a trial to expand malaria community case management to all ages. Malar J 2021; 20:422. [PMID: 34702255 PMCID: PMC8549293 DOI: 10.1186/s12936-021-03956-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 10/16/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Integrated community case management of malaria, pneumonia, and diarrhoea can reduce mortality in children under five years (CU5) in resource-poor countries. There is growing interest in expanding malaria community case management (mCCM) to older individuals, but limited empirical evidence exists to guide this expansion. As part of a two-year cluster-randomized trial of mCCM expansion to all ages in southeastern Madagascar, a cross-sectional survey was conducted to assess baseline malaria prevalence and healthcare-seeking behaviours. METHODS Two enumeration areas (EAs) were randomly chosen from each catchment area of the 30 health facilities (HFs) in Farafangana district designated for the mCCM age expansion trial; 28 households were randomly selected from each EA for the survey. All household members were asked about recent illness and care-seeking, and malaria prevalence was assessed by rapid diagnostic test (RDT) among children < 15 years of age. Weighted population estimates and Rao-Scott chi-squared tests were used to examine illness, care-seeking, malaria case management, and malaria prevalence patterns. RESULTS Illness in the two weeks prior to the survey was reported by 459 (6.7%) of 8050 respondents in 334 of 1458 households surveyed. Most individuals noting illness (375/459; 82.3%) reported fever. Of those reporting fever, 28.7% (112/375) sought care; this did not vary by participant age (p = 0.66). Most participants seeking care for fever visited public HFs (48/112, 46.8%), or community healthcare volunteers (CHVs) (40/112, 31.0%). Of those presenting with fever at HFs or to CHVs, 87.0% and 71.0%, respectively, reported being tested for malaria. RDT positivity among 3,316 tested children < 15 years was 25.4% (CI: 21.5-29.4%) and increased with age: 16.9% in CU5 versus 31.8% in 5-14-year-olds (p < 0.0001). Among RDT-positive individuals, 28.4% of CU5 and 18.5% of 5-14-year-olds reported fever in the two weeks prior to survey (p = 0.044). CONCLUSIONS The higher prevalence of malaria among older individuals coupled with high rates of malaria testing for those who sought care at CHVs suggest that expanding mCCM to older individuals may substantially increase the number of infected individuals with improved access to care, which could have additional favorable effects on malaria transmission.
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Affiliation(s)
- Dean Sayre
- Epidemic Intelligence Service, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA. .,Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, CDC Atlanta, 1600 Clifton Rd, Atlanta, GA, USA.
| | - Laura C Steinhardt
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, CDC Atlanta, 1600 Clifton Rd, Atlanta, GA, USA
| | | | - Catherine Dentinger
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, CDC Atlanta, 1600 Clifton Rd, Atlanta, GA, USA.,U.S. President's Malaria Initiative, Centers for Disease Control and Prevention, Lot 207A, Point Liberty, Andranoro, Antehiroka, 105, Antananarivo, Madagascar
| | | | - Laurent Kapesa
- U.S. President's Malaria Initiative, USAID, Lot 207A, Point Liberty, Andranoro, Antehiroka, 105, Antananarivo, Madagascar
| | - Jocelyn Razafindrakoto
- U.S. President's Malaria Initiative, USAID, Lot 207A, Point Liberty, Andranoro, Antehiroka, 105, Antananarivo, Madagascar
| | - Agathe Legrand
- Institut Pasteur de Madagascar , BP 1274 Ambatofotsikely, 101, Antananarivo, Madagascar
| | - Nicole Prada
- Institut Pasteur de Madagascar , BP 1274 Ambatofotsikely, 101, Antananarivo, Madagascar
| | - Julie Gutman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, CDC Atlanta, 1600 Clifton Rd, Atlanta, GA, USA
| | - Lauren Lewis
- U.S. President's Malaria Initiative, Centers for Disease Control and Prevention, 1600 Clifton Rd, Atlanta, GA, USA.,Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, CDC Atlanta, 1600 Clifton Rd, Atlanta, GA, USA
| | | | | | | | - Nicolas Ralemary
- Ministry of Public Health, Farafangana District Office, Farafangana, Madagascar
| | - Andres Garchitorena
- Institut Pasteur de Madagascar , BP 1274 Ambatofotsikely, 101, Antananarivo, Madagascar.,MIVEGEC, Univ. Montpellier, CNRS, IRD, 911 Av Agropolis, Montpellier, France
| | - Aina Harimanana
- Institut Pasteur de Madagascar , BP 1274 Ambatofotsikely, 101, Antananarivo, Madagascar
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22
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Quang HH, Chavchich M, Trinh NTM, Manh ND, Edstein MD, Martin NJ, Edgel KA. Cross-sectional survey of asymptomatic malaria in Dak Nong province in the Central Highlands of Vietnam for the malaria elimination roadmap. PLoS One 2021; 16:e0258580. [PMID: 34669697 PMCID: PMC8528296 DOI: 10.1371/journal.pone.0258580] [Citation(s) in RCA: 4] [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: 01/07/2021] [Accepted: 09/30/2021] [Indexed: 12/25/2022] Open
Abstract
Asymptomatic parasite carriers represent a "silent" infective reservoir for malaria transmission and contributes to malaria persistence. However, limited data are available on asymptomatic malaria in Vietnam. Between November 2018 and March 2019, we conducted a malaria epidemiological survey of asymptomatic people (children ≥ 10 years old and adults ≥18 years old, n = 2,809) residing in three communes in Tuy Duc district, Dak Nong province in the Central Highlands of Vietnam. Based on the national stratification of malaria risk, Dak Buk So, Dak Ngo and Quang Truc communes were classified by the National Malaria Control Programme as low, moderate and high malaria endemic areas, respectively. Using participants' finger prick blood samples, malaria parasites were detected by one-step reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The median age (Interquartile Range) for adults and children were 35 years (26-50) and 12 years (11-14), respectively. The prevalence of asymptomatic malaria was 1.7% (22/1,328), 3.5% (31/890) and 12.2% (72/591) for participants from Dak Buk So, Dak Ngo and Quang Truc, respectively. The prevalence of asymptomatic malaria was lower in children compared to adults: 2.6% (9/352) versus 4.7% (116/2,457) (Odds Ratio 0.53, 95% Confidence Interval 0.28 to1.02). Ownership of long-lasting insecticide-treated bed nets and hammocks was 97.1%, 99.0% and 94.7% for participants in Dak Buk So, Dak Ngo and Quang Truc, respectively, however, only 66.0%, 57.3% and 42.8% of the participants reported using bed nets every night. Of the several risk factors examined, going to the forest two weeks prior to enrolment into the study and sleeping in the forest had a significant association with participants being infected with asymptomatic malaria in Quang Truc, but not in the other two communes. Knowledge of the prevalence and distribution of asymptomatic malaria will help design and evaluate future intervention strategies for malaria elimination in Vietnam.
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Affiliation(s)
- Huynh Hong Quang
- Institute of Malariology, Parasitology and Entomology, Quy Nhon, Vietnam
| | - Marina Chavchich
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
| | | | | | - Michael D. Edstein
- Australian Defence Force Malaria and Infectious Disease Institute, Brisbane, Australia
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23
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Carrasco-Escobar G, Qquellon J, Villa D, Cava R, Llanos-Cuentas A, Benmarhnia T. Time-Varying Effects of Meteorological Variables on Malaria Epidemiology in the Context of Interrupted Control Efforts in the Amazon Rainforest, 2000-2017. Front Med (Lausanne) 2021; 8:721515. [PMID: 34660633 PMCID: PMC8511324 DOI: 10.3389/fmed.2021.721515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Accepted: 08/27/2021] [Indexed: 11/25/2022] Open
Abstract
Successful malaria control interventions, mostly based on the training of health workers, distribution of insecticide-treated nets, and spraying, decrease malaria incidence; however, when these interventions are interrupted, a resurgence may occur. In the Peruvian Amazon, after discontinuing the control activities implemented by the PAMAFRO project (2006–2010)-a Global Fund-sponsored project for the strengthening of malaria control and surveillance in multiple countries in Latin America– malaria cases re-emerged dramatically. In parallel, meteorological factors determine the conditions suitable for the development, reproduction, and survival of mosquito vectors and parasites. This study hypothesized that interruption of malaria interventions may have modified the meteorological-malaria relationships over time (i.e., temporal changes in the dose-response between meteorological variables and malaria incidence). In this panel data analysis, we assessed the extent that relationships between meteorological variables and malaria changed temporally using data of monthly malaria incidence due to Plasmodium vivax or P. falciparum in Loreto, Peru (2000–2017). Generalized additive models were used to explore how the effects of meteorological variables changed in magnitude before, during, and after the PAMAFRO intervention. We found that once the PAMAFRO intervention had been interrupted, the estimated effects (dose-response) of meteorological variables on incidence rates decreased for both malaria parasite species. However, these fitted effect estimates did not reach their baseline levels (before the PAMAFRO period); variations of time-varying slopes between 0.45 and 2.07 times were observed after the PAMAFRO intervention. We also reported significant heterogeneity in the geographical distributions of malaria, parasite species, and meteorological variables. High malaria transmission occurred consistently in the northwestern provinces of Loreto Department. Since the end of the PAMAFRO period, a higher effect of precipitation and actual evapotranspiration was described on P. falciparum compared to P. vivax. The effect of temperature on malaria was greater over a shorter time (1-month lag or less), compared with precipitation and actual evapotranspiration (12-month lag). These findings demonstrate the importance of sustained malaria control efforts since interruption may enhance the links between meteorological factors and malaria. Our results also emphasize the importance of considering the time-varying effect of meteorological factors on malaria incidence to tailor control interventions, especially to better manage the current and future climate change crisis.
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Affiliation(s)
- Gabriel Carrasco-Escobar
- Health Innovation Laboratory, Institute of Tropical Medicine "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru.,Herbert Wertheim School of Public Health and Human Longevity Science, University of California, San Diego, La Jolla, CA, United States
| | - Jazmin Qquellon
- Health Innovation Laboratory, Institute of Tropical Medicine "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Diego Villa
- Health Innovation Laboratory, Institute of Tropical Medicine "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Renato Cava
- Health Innovation Laboratory, Institute of Tropical Medicine "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Alejandro Llanos-Cuentas
- Facultad de Salud Pública y Administración, Universidad Peruana Cayetano Heredia, Lima, Peru.,Instituto de Medicina Tropical "Alexander von Humboldt", Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Tarik Benmarhnia
- Herbert Wertheim School of Public Health and Human Longevity Science, University of California, San Diego, La Jolla, CA, United States.,Scripps Institution of Oceanography, University of California, San Diego, San Diego, CA, United States
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24
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Monteiro EF, Fernandez-Becerra C, Curado I, Wunderlich G, Hiyane MI, Kirchgatter K. Antibody Profile Comparison against MSP1 Antigens of Multiple Plasmodium Species in Human Serum Samples from Two Different Brazilian Populations Using a Multiplex Serological Assay. Pathogens 2021; 10:1138. [PMID: 34578170 PMCID: PMC8470980 DOI: 10.3390/pathogens10091138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 11/16/2022] Open
Abstract
Plasmodium malariae has a wide geographic distribution, but mainly at very low parasitemias and in co-infections, leading to an underestimated prevalence of this species. Studies for the detection of antibodies against Plasmodium recombinant proteins are increasingly used to map geographical distributions, seroprevalence and transmission intensities of malaria infection. However, no seroepidemiological survey using recombinant P. malariae proteins has been conducted in Brazil. This work evaluated the antibody response in serum samples of individuals from endemic regions of Brazil (the Amazon region and Atlantic Forest) against five recombinant proteins of P. malariae merozoite surface protein 1 (MSP1), and the MSP1 C-terminal portions of P. vivax and P. falciparum, in a multiplex assay. The positivity was 69.5% of samples recognizing at least one MSP1 recombinant protein. The mean of the Reactivity Index for the C-terminal portion of the P. falciparum was significantly higher compared to the other recombinant proteins, followed by the C-terminal of P. vivax and the N-terminal of P. malariae. Among the recombinant P. malariae proteins, the N-terminal of P. malariae showed the highest Reactivity Index alone. This study validates the use of the multiplex assay to measure naturally acquired IgG antibodies against Plasmodium MSP1 proteins and demonstrate that these proteins are important tools for seroepidemiological surveys and could be used in malaria surveillance.
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Affiliation(s)
- Eliana Ferreira Monteiro
- Instituto de Medicina Tropical, Faculdade de Medicina, Universidade de São Paulo, São Paulo 05403-000, Brazil; (E.F.M.); (I.C.)
| | - Carmen Fernandez-Becerra
- ISGlobal, Hospital Clínic—Universitat de Barcelona, 08036 Barcelona, Spain;
- Germans Trias i Pujol Health Science Research Institute (IGTP), 08916 Badalona, Spain
| | - Izilda Curado
- Instituto de Medicina Tropical, Faculdade de Medicina, Universidade de São Paulo, São Paulo 05403-000, Brazil; (E.F.M.); (I.C.)
- Departamento de Laboratórios Especializados, Superintendência de Controle de Endemias, São Paulo 01027-000, Brazil
| | - Gerhard Wunderlich
- Departamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508-000, Brazil;
| | - Meire Ioshie Hiyane
- Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo 05508-900, Brazil;
| | - Karin Kirchgatter
- Instituto de Medicina Tropical, Faculdade de Medicina, Universidade de São Paulo, São Paulo 05403-000, Brazil; (E.F.M.); (I.C.)
- Departamento de Laboratórios Especializados, Superintendência de Controle de Endemias, São Paulo 01027-000, Brazil
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25
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van Bergen K, Stuitje T, Akkers R, Vermeer E, Castel R, Mank T. Evaluation of a novel real-time PCR assay for the detection, identification and quantification of Plasmodium species causing malaria in humans. Malar J 2021; 20:314. [PMID: 34247622 PMCID: PMC8274047 DOI: 10.1186/s12936-021-03842-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/03/2021] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND The entry of PCR-based techniques into malaria diagnostics has improved the sensitivity and specificity of the detection of Plasmodium infections. It has been shown that humans are regularly infected by at least six different Plasmodium species. The MC004 real-time PCR assay for malaria diagnosis is a novel single-tube assay that has been developed for the purpose of simultaneously detecting all Plasmodium species known to infect humans, and discrimination between Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae, Plasmodium ovale wallikeri, Plasmodium ovale curtisi, Plasmodium knowlesi (including differentiation of three strains) and Plasmodium cynomolgi (including differentiation of three strains). Detection and identification of Plasmodium species relies on molecular beacon probe-based melting curve analysis. In addition, this assay might be used to quantify the parasitaemia of at least P. falciparum by calculating the level of parasitaemia directly from the Cq-value. METHODS The samples used in this study comprised reference samples, patient samples, and synthetic controls. The following analytical performance characteristics of the MC004 assay were determined: analytical specificity, limit of detection, the ability to detect mixed infections, and the potential to determine the level of parasitaemia of P. falciparum, including assessment of within-run and between-run precisions. RESULTS No false positive or false negative results were observed. The limit of detection of P. falciparum was 1 × 10-3 IU/mL (WHO standard). Mixed infections with P. falciparum and non-falciparum species were correctly identified. A calibration curve could be established to quantify the parasitaemia of at least P. falciparum. The within-run and between-run precisions were less than 20% CV at the tested parasitaemia levels of 0.09%, 0.16%, 2.15% and 27.27%. CONCLUSION Based upon the analytical performance characteristics that were determined, the MC004 assay showed performance suitable for use in clinical settings, as well as epidemiological studies.
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Affiliation(s)
- Kim van Bergen
- Result Laboratorium, Albert Schweitzer Hospital, Albert Schweitzerplaats 25, 3300 AK, Dordrecht, The Netherlands
| | - Toon Stuitje
- MRC Holland, Willem Schoutenstraat 1, 1057 DL, Amsterdam, The Netherlands
| | - Robert Akkers
- Result Laboratorium, Albert Schweitzer Hospital, Albert Schweitzerplaats 25, 3300 AK, Dordrecht, The Netherlands
| | - Eric Vermeer
- Result Laboratorium, Albert Schweitzer Hospital, Albert Schweitzerplaats 25, 3300 AK, Dordrecht, The Netherlands
| | - Rob Castel
- Result Laboratorium, Albert Schweitzer Hospital, Albert Schweitzerplaats 25, 3300 AK, Dordrecht, The Netherlands.
| | - Theo Mank
- Streeklaboratorium Voor de Volksgezondheid Kennemerland, Boerhaavelaan 26, 2035 RC, Haarlem, The Netherlands
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26
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Abstract
India observed a significant reduction in malaria cases in the previous year, reaffirming our trust and efficiency of the existing tools to achieve malaria elimination. On 25 April, 2019, countries around the world marked World Malaria Day under the theme “Zero malaria starts with me”. This provides an opportunity to rejoice the success and re-evaluate ongoing challenges in the fight against this preventable and treatable parasitic disease. We highlight the potential gaps in the malaria elimination program, and underscore potential solutions and strategies to implement, improve and intensify the success of the national goal of malaria elimination by 2030.
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27
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Prusty D, Gupta N, Upadhyay A, Dar A, Naik B, Kumar N, Prajapati VK. Asymptomatic malaria infection prevailing risks for human health and malaria elimination. INFECTION GENETICS AND EVOLUTION 2021; 93:104987. [PMID: 34216796 DOI: 10.1016/j.meegid.2021.104987] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 06/23/2021] [Accepted: 06/27/2021] [Indexed: 01/09/2023]
Abstract
There has been a consistent rise in malaria cases in the last few years. The existing malaria control measures are challenged by insecticide resistance in the mosquito vector, drug résistance in parasite populations, and asymptomatic malaria (ASM) in healthy individuals. The absence of apparent malaria symptoms and the presence of low parasitemia makes ASM a hidden reservoir for malaria transmission and an impediment in malaria elimination efforts. This review focuses on ASM in malaria-endemic countries and the past and present research trends from those geographical locations. The harmful impacts of asymptomatic malaria on human health and its contribution to disease transmission are highlighted. We discuss certain crucial genetic changes in the parasite and host immune response necessary for maintaining low parasitemia leading to long-term parasite survival in the host. Since the chronic health effects and the potential roles for disease transmission of ASM remain mostly unknown to significant populations, we offer proposals for developing general awareness. We also suggest advanced technology-based diagnostic methods, and treatment strategies to eliminate ASM.
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Affiliation(s)
- Dhaneswar Prusty
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, 305817, Rajasthan, India.
| | - Nidhi Gupta
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, 305817, Rajasthan, India
| | - Arun Upadhyay
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, 305817, Rajasthan, India
| | - Ashraf Dar
- Department of Biochemistry, University of Kashmir, Hazaratbal, Srinagar 190006, Jammu and Kashmir, India
| | - Biswajit Naik
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, 305817, Rajasthan, India
| | - Navin Kumar
- School of Biotechnology, Gautam Buddha University, Greater Noida, 201308, UP, India
| | - Vijay Kumar Prajapati
- Department of Biochemistry, School of Life Sciences, Central University of Rajasthan, Bandarsindri, Kishangarh, Ajmer, 305817, Rajasthan, India
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28
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Kosasih A, Koepfli C, Dahlan MS, Hawley WA, Baird JK, Mueller I, Lobo NF, Sutanto I. Gametocyte carriage of Plasmodium falciparum (pfs25) and Plasmodium vivax (pvs25) during mass screening and treatment in West Timor, Indonesia: a longitudinal prospective study. Malar J 2021; 20:177. [PMID: 33836772 PMCID: PMC8034167 DOI: 10.1186/s12936-021-03709-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 03/23/2021] [Indexed: 11/21/2022] Open
Abstract
Background A goal of malaria epidemiological interventions is the detection and treatment of parasite reservoirs in endemic areas—an activity that is expected to reduce local transmission. Since the gametocyte is the only transmissible stage from human host to mosquito vector, this study evaluated the pre and post presence of gametocytes during a mass screening and treatment (MST) intervention conducted during 2013 in East Nusa Tenggara, Indonesia. Methods RT-qPCR targeting pfs25 and pvs25 transcripts—gametocyte molecular markers for Plasmodium falciparum and Plasmodium vivax, respectively, was performed to detect and quantify gametocytes in blood samples of P. falciparum and P. vivax-infected subjects over the course of the MST study. The presence of both asexual and sexual parasites in microscopic and submicroscopic infections was compared from the start and end of the MST, using proportion tests as well as parametric and non-parametric tests. Results Parasite prevalence remained unchanged for P. falciparum (6% = 52/811 versus 7% = 50/740, p = 0.838), and decreased slightly for P. vivax (24% = 192/811 versus 19% = 142/740, p = 0.035) between the MST baseline and endpoint. No significant difference was observed in gametocyte prevalence for either P. falciparum (2% = 19/803 versus 3% = 23/729, p = 0.353, OR = 1.34, 95%CI = 0.69–2.63), or P. vivax (7% = 49/744 versus 5% = 39/704, p = 0.442, OR = 0.83, 95%CI = 0.52–1.31). Even though there was an insignificant difference between the two time points, the majority of parasite positive subjects at the endpoint had been negative at baseline (P. falciparum: 66% = 29/44, P. vivax: 60% = 80/134). This was similarly demonstrated for the transmissible stage—where the majority of gametocyte positive subjects at the endpoint were negative at baseline (P. falciparum: 95% = 20/21, P. vivax: 94% = 30/32). These results were independent of treatment provided during MST activities. No difference was demonstrated in parasite and gametocyte density between both time points either in P. falciparum or P. vivax. Conclusion In this study area, similar prevalence rates of P. falciparum and P. vivax parasites and gametocytes before and after MST, although in different individuals, points to a negligible impact on the parasite reservoir. Treatment administration based on parasite positivity as implemented in the MST should be reevaluated for the elimination strategy in the community. Trial registration Clinical trials registration NCT01878357. Registered 14 June 2013, https://www.clinicaltrials.gov/ct2/show/NCT01878357. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03709-y.
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Affiliation(s)
- Ayleen Kosasih
- PhD Programme in Biomedical Sciences, Medical Faculty, Universitas Indonesia, Jakarta, Indonesia.,Eijkman-Oxford Clinical Research Unit, Jakarta, Indonesia.,Indonesian Medical Education and Research Institute, Jakarta, Indonesia
| | - Cristian Koepfli
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.,Infection & Immunity Division, Walter & Eliza Hall Institute, Melbourne, Australia
| | | | | | - J Kevin Baird
- Center for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Ivo Mueller
- Infection & Immunity Division, Walter & Eliza Hall Institute, Melbourne, Australia
| | - Neil F Lobo
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA
| | - Inge Sutanto
- Indonesian Medical Education and Research Institute, Jakarta, Indonesia. .,Department of Parasitology, Medical Faculty, Universitas Indonesia, Jakarta, Indonesia.
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29
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Lamsfus Calle C, Fendel R, Singh A, Richie TL, Hoffman SL, Kremsner PG, Mordmüller B. Expansion of Functional Myeloid-Derived Suppressor Cells in Controlled Human Malaria Infection. Front Immunol 2021; 12:625712. [PMID: 33815377 PMCID: PMC8017236 DOI: 10.3389/fimmu.2021.625712] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Accepted: 02/22/2021] [Indexed: 12/12/2022] Open
Abstract
Malaria can cause life-threatening complications which are often associated with inflammatory reactions. More subtle, but also contributing to the burden of disease are chronic, often subclinical infections, which result in conditions like anemia and immunologic hyporesponsiveness. Although very frequent, such infections are difficult to study in endemic regions because of interaction with concurrent infections and immune responses. In particular, knowledge about mechanisms of malaria-induced immunosuppression is scarce. We measured circulating immune cells by cytometry in healthy, malaria-naïve, adult volunteers undergoing controlled human malaria infection (CHMI) with a focus on potentially immunosuppressive cells. Infectious Plasmodium falciparum (Pf) sporozoites (SPZ) (PfSPZ Challenge) were inoculated during two independent studies to assess malaria vaccine efficacy. Volunteers were followed daily until parasites were detected in the circulation by RT-qPCR. This allowed us to analyze immune responses during pre-patency and at very low parasite densities in malaria-naïve healthy adults. We observed a consistent increase in circulating polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) in volunteers who developed P. falciparum blood stage parasitemia. The increase was independent of preceding vaccination with a pre-erythrocytic malaria vaccine. PMN-MDSC were functional, they suppressed CD4+ and CD8+ T cell proliferation as shown by ex-vivo co-cultivation with stimulated T cells. PMN-MDSC reduced T cell proliferation upon stimulation by about 50%. Interestingly, high circulating PMN-MDSC numbers were associated with lymphocytopenia. The number of circulating regulatory T cells (Treg) and monocytic MDSC (M-MDSC) showed no significant parasitemia-dependent variation. These results highlight PMN-MDSC in the peripheral circulation as an early indicator of infection during malaria. They suppress CD4+ and CD8+ T cell proliferation in vitro. Their contribution to immunosuppression in vivo in subclinical and uncomplicated malaria will be the subject of further research. Pre-emptive antimalarial pre-treatment of vaccinees to reverse malaria-associated PMN-MDSC immunosuppression could improve vaccine response in exposed individuals.
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Affiliation(s)
| | - Rolf Fendel
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
| | - Anurag Singh
- Department of Pediatrics 1, University Children's Hospital Tübingen, Tübingen, Germany.,Institute for Clinical and Experimental Transfusion Medicine, University Hospital Tübingen, Tübingen, Germany
| | | | | | - Peter G Kremsner
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
| | - Benjamin Mordmüller
- Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.,German Center for Infection Research (DZIF), Partner Site Tübingen, Tübingen, Germany.,Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon
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30
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Hailemeskel E, Tebeje SK, Behaksra SW, Shumie G, Shitaye G, Keffale M, Chali W, Gashaw A, Ashine T, Drakeley C, Bousema T, Gadisa E, Tadesse FG. The epidemiology and detectability of asymptomatic plasmodium vivax and plasmodium falciparum infections in low, moderate and high transmission settings in Ethiopia. Malar J 2021; 20:59. [PMID: 33482841 PMCID: PMC7821398 DOI: 10.1186/s12936-021-03587-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2020] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND As countries move to malaria elimination, detecting and targeting asymptomatic malaria infections might be needed. Here, the epidemiology and detectability of asymptomatic Plasmodium falciparum and Plasmodium vivax infections were investigated in different transmission settings in Ethiopia. METHOD A total of 1093 dried blood spot (DBS) samples were collected from afebrile and apparently healthy individuals across ten study sites in Ethiopia from 2016 to 2020. Of these, 862 were from community and 231 from school based cross-sectional surveys. Malaria infection status was determined by microscopy or rapid diagnostics tests (RDT) and 18S rRNA-based nested PCR (nPCR). The annual parasite index (API) was used to classify endemicity as low (API > 0 and < 5), moderate (API ≥ 5 and < 100) and high transmission (API ≥ 100) and detectability of infections was assessed in these settings. RESULTS In community surveys, the overall prevalence of asymptomatic Plasmodium infections by microscopy/RDT, nPCR and all methods combined was 12.2% (105/860), 21.6% (183/846) and 24.1% (208/862), respectively. The proportion of nPCR positive infections that was detectable by microscopy/RDT was 48.7% (73/150) for P. falciparum and 4.6% (2/44) for P. vivax. Compared to low transmission settings, the likelihood of detecting infections by microscopy/RDT was increased in moderate (Adjusted odds ratio [AOR]: 3.4; 95% confidence interval [95% CI] 1.6-7.2, P = 0.002) and high endemic settings (AOR = 5.1; 95% CI 2.6-9.9, P < 0.001). After adjustment for site and correlation between observations from the same survey, the likelihood of detecting asymptomatic infections by microscopy/RDT (AOR per year increase = 0.95, 95% CI 0.9-1.0, P = 0.013) declined with age. CONCLUSIONS Conventional diagnostics missed nearly half of the asymptomatic Plasmodium reservoir detected by nPCR. The detectability of infections was particularly low in older age groups and low transmission settings. These findings highlight the need for sensitive diagnostic tools to detect the entire parasite reservoir and potential infection transmitters.
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Affiliation(s)
- Elifaged Hailemeskel
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
- Department of Biomedical Sciences, College of Natural and Computational Sciences, Addis Ababa University, PO Box 1176, Addis Ababa, Ethiopia
- Department of Biology, College of Natural and Computational Sciences, Wollo University, PO Box, 1145, Dessie, Ethiopia
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Surafel K Tebeje
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
| | - Sinknesh W Behaksra
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Girma Shumie
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Getasew Shitaye
- Department of Biomedical Sciences, School of Medical Sciences, Bahir Dar University, Bahir Dar, Ethiopia
| | - Migbaru Keffale
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Wakweya Chali
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Abrham Gashaw
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Temesgen Ashine
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, WC1E 7HT, London, UK
| | - Endalamaw Gadisa
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia
| | - Fitsum G Tadesse
- Malaria and Neglected Tropical Diseases Directorate, Armauer Hansen Research Institute, PO Box 1005, Addis Ababa, Ethiopia.
- Department of Medical Microbiology, Radboud University Medical Center, 6525 GA, Nijmegen, The Netherlands.
- Institute of Biotechnology, Addis Ababa University, PO Box, 1176, Addis Ababa, Ethiopia.
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Highly Sensitive and Rapid Quantitative Detection of Plasmodium falciparum Using an Image Cytometer. Microorganisms 2020; 8:microorganisms8111769. [PMID: 33187123 PMCID: PMC7696876 DOI: 10.3390/microorganisms8111769] [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: 10/16/2020] [Revised: 11/10/2020] [Accepted: 11/10/2020] [Indexed: 11/16/2022] Open
Abstract
The gold standard for malaria diagnosis is microscopic examination of blood films by expert microscopists. It is important to detect submicroscopic and asymptomatic Plasmodium infections in people, therefore the development of highly sensitive devices for diagnosing malaria is required. In the present study, we investigated whether an imaging cytometer was useful for the highly sensitive quantitative detection of parasites. Whole blood samples were prepared from uninfected individuals spiked with Plasmodium falciparum-infected erythrocytes. Thereafter, erythrocytes were purified using a push column comprising of a syringe filter unit with SiO2-nanofiber filters. After adding the erythrocytes, stained with nuclear stain, to a six-well plate, quantitative detection of the parasites was performed using an image cytometer, CQ1. Imaging of 2.6 × 106 erythrocytes was completed in 3 min, and the limit of detection indicated parasitemia of 0.00010% (≈5 parasites/μL of blood). In addition to rapid, highly sensitive, and quantitative detection, the ease of application and economic costs, image cytometry could be efficiently applied to diagnose submicroscopic parasites in infected people from endemic countries.
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