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Pepey A, Souris M, Kim S, Obadia T, Chy S, Ea M, Ouk S, Remoue F, Sovannaroth S, Mueller I, Witkowski B, Vantaux A. Comparing malaria risk exposure in rural Cambodia population using GPS tracking and questionnaires. Malar J 2024; 23:75. [PMID: 38475843 DOI: 10.1186/s12936-024-04890-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 02/23/2024] [Indexed: 03/14/2024] Open
Abstract
BACKGROUND The Great Mekong Subregion has attained a major decline in malaria cases and fatalities over the last years, but residual transmission hotspots remain, supposedly fueled by forest workers and migrant populations. This study aimed to: (i) characterize the fine-scale mobility of forest-goers and understand links between their daily movement patterns and malaria transmission, using parasites detection via real time polymerase chain reaction (RT PCR) and the individual exposure to Anopheles bites by quantification of anti-Anopheles saliva antibodies via enzyme-linked immunosorbent assay; (ii) assess the concordance of questionnaires and Global Positioning System (GPS) data loggers for measuring mobility. METHODS Two 28 day follow-ups during dry and rainy seasons, including a GPS tracking, questionnaires and health examinations, were performed on male forest goers representing the population at highest risk of infection. Their time spent in different land use categories and demographic data were analyzed in order to understand the risk factors driving malaria in the study area. RESULTS Malaria risk varied with village forest cover and at a resolution of only a few kilometers: participants from villages outside the forest had the highest malaria prevalence compared to participants from forest fringe's villages. The time spent in a specific environment did not modulate the risk of malaria, in particular the time spent in forest was not associated with a higher probability to detect malaria among forest-goers. The levels of antibody response to Anopheles salivary peptide among participants were significantly higher during the rainy season, in accordance with Anopheles mosquito density variation, but was not affected by sociodemographic and mobility factors. The agreement between GPS and self-reported data was only 61.9% in reporting each kind of visited environment. CONCLUSIONS In a context of residual malaria transmission which was mainly depicted by P. vivax asymptomatic infections, the implementation of questionnaires, GPS data-loggers and quantification of anti-saliva Anopheles antibodies on the high-risk group were not powerful enough to detect malaria risk factors associated with different mobility behaviours or time spent in various environments. The joint implementation of GPS trackers and questionnaires allowed to highlight the limitations of both methodologies and the benefits of using them together. New detection and follow-up strategies are still called for.
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Affiliation(s)
- Anaïs Pepey
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, 5 Blvd Monivong, Phnom Penh 120 210, Phnom Penh, BP983, Cambodia.
| | - Marc Souris
- UMR Unité des Virus Emergents, UVE: Aix-Marseille Univ-IRD 190-Inserm 1207-IHU 5 Méditerranée Infection, 13005, Marseille, France
| | - Saorin Kim
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, 5 Blvd Monivong, Phnom Penh 120 210, Phnom Penh, BP983, Cambodia
| | - Thomas Obadia
- Institut Pasteur, G5 Infectious Disease Epidemiology and Analytics, Université Paris Cité, 75015, Paris, France
- Institut Pasteur, Bioinformatics and Biostatistics Hub, Université Paris Cité, 75015, Paris, France
| | - Sophy Chy
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, 5 Blvd Monivong, Phnom Penh 120 210, Phnom Penh, BP983, Cambodia
| | - Malen Ea
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, 5 Blvd Monivong, Phnom Penh 120 210, Phnom Penh, BP983, Cambodia
| | - Sivkeng Ouk
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, 5 Blvd Monivong, Phnom Penh 120 210, Phnom Penh, BP983, Cambodia
| | - Franck Remoue
- UMR MIVEGEC, IRD, CNRS, University of Montpellier, Montpellier, France
| | - Siv Sovannaroth
- National Centre for Parasitology Entomology and Malaria Control (CNM), Phnom Penh 120 801, Phnom Penh, Cambodia
| | - Ivo Mueller
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC, Australia
- Department of Medical Biology, University of Melbourne, Melbourne, VIC, Australia
| | - Benoit Witkowski
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, 5 Blvd Monivong, Phnom Penh 120 210, Phnom Penh, BP983, Cambodia
- Genetic and Biology of Plasmodium Unit, Institut Pasteur de Madagascar, Antananarivo, Madagascar
| | - Amélie Vantaux
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, 5 Blvd Monivong, Phnom Penh 120 210, Phnom Penh, BP983, Cambodia
- Genetic and Biology of Plasmodium Unit, Institut Pasteur de Madagascar, Antananarivo, Madagascar
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Lupaka M, Degefa T, Eba K, Zeynudin A, Yewhalaw D. Diagnostic performance of ultrasensitive rapid diagnostic test for the detection of Plasmodium falciparum infections in asymptomatic individuals in Kisangani, Northeast Democratic Republic of Congo. Malar J 2023; 22:354. [PMID: 37981691 PMCID: PMC10658930 DOI: 10.1186/s12936-023-04790-1] [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: 07/09/2023] [Accepted: 11/13/2023] [Indexed: 11/21/2023] Open
Abstract
BACKGROUND Ultrasensitive rapid diagnostic test (usRDT) was recently developed to improve the detection of low-density Plasmodium falciparum infections. However, its diagnostic performance has not been evaluated in the Democratic Republic of Congo (DRC). This study aims to determine the performance of the usRDT in malaria diagnosis in asymptomatic individuals under field condition in Kisangani, Northeast of DRC. METHODS A community-based cross-sectional study was carried out from June to August 2022 on 312 asymptomatic individuals residing in the city of Kisangani. Capillary blood samples were collected by finger prick for microscopic examination of thick and thin blood film, RDTs, and nested polymerase chain reaction (PCR). Alere™ Malaria Ag P.f usRDT and conventional RDT (cRDT/SD Bioline Malaria Ag P.f) kits were used for the detection of Plasmodium histidine rich protein 2 (HRP2) antigen as a proxy for the presence of P. falciparum. The diagnostic performance of the usRDT was compared with cRDT, microscopy and PCR. RESULTS The prevalence of asymptomatic P. falciparum malaria was 40.4%, 42.0%, 47.1% and 54.2% by cRDT, microscopy, usRDT and PCR, respectively. By using PCR as a reference, usRDT had sensitivity and specificity of 87.0% (95% CI 81.4-91.7) and 100.0% (95% CI 97.5-100.0), respectively, whereas the cRDT had sensitivity and specificity of 74.6% (95% CI 67.3-80.9) and 100% (95% CI 97.1-100.0), respectively. By using microscopy as a reference, usRDT had sensitivity and specificity of 96.9% (95% CI 92.4-99.2) and 89.0% (95% CI 83.5-93.1), respectively, while the cRDT had sensitivity and specificity of 96.2% (95% CI 92.3-98.7) and 100% (95% CI 97.9-100.0), respectively. CONCLUSION The usRDT showed better diagnostic performance with higher sensitivity than the cRDT which is currently in use as point-of-care test. Further research is necessary to assess the access and cost-effectiveness of the usRDTs to use for malaria surveillance.
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Affiliation(s)
- Mbumba Lupaka
- Faculty of Medicine and Pharmacy, University of Kisangani, Kisangani, Democratic Republic of the Congo
- School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Teshome Degefa
- School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia.
| | - Kasahun Eba
- Department of Environmental Health Sciences and Technology, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Ahmed Zeynudin
- School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center (TIDRC), Jimma University, Jimma, Ethiopia
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Malpartida-Cardenas K, Moser N, Ansah F, Pennisi I, Ahu Prah D, Amoah LE, Awandare G, Hafalla JCR, Cunnington A, Baum J, Rodriguez-Manzano J, Georgiou P. Sensitive Detection of Asymptomatic and Symptomatic Malaria with Seven Novel Parasite-Specific LAMP Assays and Translation for Use at Point-of-Care. Microbiol Spectr 2023; 11:e0522222. [PMID: 37158750 PMCID: PMC10269850 DOI: 10.1128/spectrum.05222-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/18/2023] [Indexed: 05/10/2023] Open
Abstract
Human malaria is a life-threatening parasitic disease with high impact in the sub-Saharan Africa region, where 95% of global cases occurred in 2021. While most malaria diagnostic tools are focused on Plasmodium falciparum, there is a current lack of testing non-P. falciparum cases, which may be underreported and, if undiagnosed or untreated, may lead to severe consequences. In this work, seven species-specific loop-mediated isothermal amplification (LAMP) assays were designed and evaluated against TaqMan quantitative PCR (qPCR), microscopy, and enzyme-linked immunosorbent assays (ELISAs). Their clinical performance was assessed with a cohort of 164 samples of symptomatic and asymptomatic patients from Ghana. All asymptomatic samples with a parasite load above 80 genomic DNA (gDNA) copies per μL of extracted sample were detected with the Plasmodium falciparum LAMP assay, reporting 95.6% (95% confidence interval [95% CI] of 89.9 to 98.5) sensitivity and 100% (95% CI of 87.2 to 100) specificity. This assay showed higher sensitivity than microscopy and ELISA, which were 52.7% (95% CI of 39.7 to 67%) and 67.3% (95% CI of 53.3 to 79.3%), respectively. Nine samples were positive for P. malariae, indicating coinfections with P. falciparum, which represented 5.5% of the tested population. No samples were detected as positive for P. vivax, P. ovale, P. knowlesi, or P. cynomolgi by any method. Furthermore, translation to the point-of-care was demonstrated with a subcohort of 18 samples tested locally in Ghana using our handheld lab-on-chip platform, Lacewing, showing comparable results to a conventional fluorescence-based instrument. The developed molecular diagnostic test could detect asymptomatic malaria cases, including submicroscopic parasitemia, and it has the potential to be used for point-of-care applications. IMPORTANCE The spread of Plasmodium falciparum parasites with Pfhrp2/3 gene deletions presents a major threat to reliable point-of-care diagnosis with current rapid diagnostic tests (RDTs). Novel molecular diagnostics based on nucleic acid amplification are needed to address this liability. In this work, we overcome this challenge by developing sensitive tools for the detection of Plasmodium falciparum and non-P. falciparum species. Furthermore, we evaluate these tools with a cohort of symptomatic and asymptomatic malaria patients and test a subcohort locally in Ghana. The findings of this work could lead to the implementation of DNA-based diagnostics to fight against the spread of malaria and provide reliable, sensitive, and specific diagnostics at the point of care.
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Affiliation(s)
- Kenny Malpartida-Cardenas
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, United Kingdom
- Department of Electrical and Electronic Engineering, Faculty of Engineering, Imperial College London, London, United Kingdom
| | - Nicolas Moser
- Department of Electrical and Electronic Engineering, Faculty of Engineering, Imperial College London, London, United Kingdom
| | - Felix Ansah
- West African Centre for Cell Biology of Infectious Pathogens, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Ghana
| | - Ivana Pennisi
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Diana Ahu Prah
- West African Centre for Cell Biology of Infectious Pathogens, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Ghana
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Linda Eva Amoah
- West African Centre for Cell Biology of Infectious Pathogens, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Ghana
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Gordon Awandare
- West African Centre for Cell Biology of Infectious Pathogens, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Ghana
| | - Julius Clemence R. Hafalla
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
- Immunology Department, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Aubrey Cunnington
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Jake Baum
- Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, United Kingdom
- School of Biomedical Sciences, University of New South Wales Sydney, Sydney, Australia
| | - Jesus Rodriguez-Manzano
- Department of Infectious Disease, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Pantelis Georgiou
- Department of Electrical and Electronic Engineering, Faculty of Engineering, Imperial College London, London, United Kingdom
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Mpina M, Stabler TC, Schindler T, Raso J, Deal A, Acuche Pupu L, Nyakarungu E, Del Carmen Ovono Davis M, Urbano V, Mtoro A, Hamad A, Lopez MSA, Pasialo B, Eyang MAO, Rivas MR, Falla CC, García GA, Momo JC, Chuquiyauri R, Saverino E, Preston Church LW, Kim Lee Sim B, Manguire B, Tanner M, Maas C, Abdulla S, Billingsley PF, Hoffman SL, Jongo S, Richie TL, Daubenberger CA. Diagnostic performance and comparison of ultrasensitive and conventional rapid diagnostic test, thick blood smear and quantitative PCR for detection of low-density Plasmodium falciparum infections during a controlled human malaria infection study in Equatorial Guinea. Malar J 2022; 21:99. [PMID: 35331251 PMCID: PMC8943516 DOI: 10.1186/s12936-022-04103-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 02/23/2022] [Indexed: 12/02/2022] Open
Abstract
Background Progress towards malaria elimination has stagnated, partly because infections persisting at low parasite densities comprise a large reservoir contributing to ongoing malaria transmission and are difficult to detect. This study compared the performance of an ultrasensitive rapid diagnostic test (uRDT) designed to detect low density infections to a conventional RDT (cRDT), expert microscopy using Giemsa-stained thick blood smears (TBS), and quantitative polymerase chain reaction (qPCR) during a controlled human malaria infection (CHMI) study conducted in malaria exposed adults (NCT03590340). Methods Blood samples were collected from healthy Equatoguineans aged 18–35 years beginning on day 8 after CHMI with 3.2 × 103 cryopreserved, infectious Plasmodium falciparum sporozoites (PfSPZ Challenge, strain NF54) administered by direct venous inoculation. qPCR (18s ribosomal DNA), uRDT (Alere™ Malaria Ag P.f.), cRDT [Carestart Malaria Pf/PAN (PfHRP2/pLDH)], and TBS were performed daily until the volunteer became TBS positive and treatment was administered. qPCR was the reference for the presence of Plasmodium falciparum parasites. Results 279 samples were collected from 24 participants; 123 were positive by qPCR. TBS detected 24/123 (19.5% sensitivity [95% CI 13.1–27.8%]), uRDT 21/123 (17.1% sensitivity [95% CI 11.1–25.1%]), cRDT 10/123 (8.1% sensitivity [95% CI 4.2–14.8%]); all were 100% specific and did not detect any positive samples not detected by qPCR. TBS and uRDT were more sensitive than cRDT (TBS vs. cRDT p = 0.015; uRDT vs. cRDT p = 0.053), detecting parasitaemias as low as 3.7 parasites/µL (p/µL) (TBS and uRDT) compared to 5.6 p/µL (cRDT) based on TBS density measurements. TBS, uRDT and cRDT did not detect any of the 70/123 samples positive by qPCR below 5.86 p/µL, the qPCR density corresponding to 3.7 p/µL by TBS. The median prepatent periods in days (ranges) were 14.5 (10–20), 18.0 (15–28), 18.0 (15–20) and 18.0 (16–24) for qPCR, TBS, uRDT and cRDT, respectively; qPCR detected parasitaemia significantly earlier (3.5 days) than the other tests. Conclusions TBS and uRDT had similar sensitivities, both were more sensitive than cRDT, and neither matched qPCR for detecting low density parasitaemia. uRDT could be considered an alternative to TBS in selected applications, such as CHMI or field diagnosis, where qualitative, dichotomous results for malaria infection might be sufficient. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04103-y.
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Affiliation(s)
- Maxmillian Mpina
- Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland. .,Ifakara Health Institute, Ifakara, Tanzania.
| | - Thomas C Stabler
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Tobias Schindler
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Jose Raso
- Medical Care Development International, Malabo, Equatorial Guinea.,Equatorial Guinea Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Anna Deal
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | | | - Elizabeth Nyakarungu
- Ifakara Health Institute, Ifakara, Tanzania.,Medical Care Development International, Malabo, Equatorial Guinea
| | | | - Vicente Urbano
- Medical Care Development International, Malabo, Equatorial Guinea.,Equatorial Guinea Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Ali Mtoro
- Ifakara Health Institute, Ifakara, Tanzania.,Medical Care Development International, Malabo, Equatorial Guinea
| | - Ali Hamad
- Ifakara Health Institute, Ifakara, Tanzania.,Medical Care Development International, Malabo, Equatorial Guinea
| | - Maria Silvia A Lopez
- Medical Care Development International, Malabo, Equatorial Guinea.,Equatorial Guinea Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Beltran Pasialo
- Medical Care Development International, Malabo, Equatorial Guinea.,Equatorial Guinea Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Marta Alene Owono Eyang
- Medical Care Development International, Malabo, Equatorial Guinea.,Equatorial Guinea Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Matilde Riloha Rivas
- Equatorial Guinea Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | | | | | - Juan Carlos Momo
- Medical Care Development International, Malabo, Equatorial Guinea.,Equatorial Guinea Ministry of Health and Social Welfare, Malabo, Equatorial Guinea
| | - Raul Chuquiyauri
- Medical Care Development International, Malabo, Equatorial Guinea.,Sanaria Inc., 9800 Medical Center Drive, Rockville, MD, 20850, USA
| | | | | | - B Kim Lee Sim
- Sanaria Inc., 9800 Medical Center Drive, Rockville, MD, 20850, USA
| | | | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Carl Maas
- Marathon EG production Ltd., Houston, USA
| | | | | | | | - Said Jongo
- Ifakara Health Institute, Ifakara, Tanzania.,Medical Care Development International, Malabo, Equatorial Guinea
| | - Thomas L Richie
- Sanaria Inc., 9800 Medical Center Drive, Rockville, MD, 20850, USA
| | - Claudia A Daubenberger
- Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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Yimam Y, Mohebali M, Abbaszadeh Afshar MJ. Comparison of diagnostic performance between conventional and ultrasensitive rapid diagnostic tests for diagnosis of malaria: A systematic review and meta-analysis. PLoS One 2022; 17:e0263770. [PMID: 35143565 PMCID: PMC8830612 DOI: 10.1371/journal.pone.0263770] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 01/26/2022] [Indexed: 11/19/2022] Open
Abstract
Background Successful malaria treatment, control and elimination programs require accurate, affordable, and field-deployable diagnostic tests. A number of studies have directly compared diagnostic performance between the new ultrasensitive rapid diagnostic test (us-RDT) and conventional rapid diagnostic test (co-RDT) for detecting malaria. Thus, we undertook this review to directly compare pooled diagnostic performance of us-RDT and co-RDT for detection of malaria. Methods PubMed, Web of Science, Scopus, Embase, and ProQuest were searched from their inception until 31 January 2021 accompanied by forward and backward citations tracking. Two authors independently assessed the quality of included studies by RevMan5 software (using the QUADAS-2 checklist). Diagnostic accuracy estimates (sensitivity and specificity and others) were pooled using a random-effect model and 95% confidence interval (CI) in Stata 15 software. Results Fifteen studies with a total of 20,236 paired co-RDT and us-RDT tests were included in the meta-analysis. Molecular methods (15 studies) and immunoassay test (one study) were used as standard methods for comparison with co-RDT and us-RDT tests. The pooled sensitivity for co-RDT and us-RDT were 42% (95%CI: 25–62%) and 61% (95%CI: 47–73%), respectively, with specificity of 99% (95%CI: 98–100%) for co-RDT, and 99% (95%CI: 96–99%) for us-RDT. In asymptomatic individuals, the pooled sensitivity and specificity of co-RDT were 27% (95%CI: 8–58%) and 100% (95%CI: 97–100%), respectively, while us-RDT had a sensitivity of 50% (95%CI: 33–68%) and specificity of 98% (95%CI: 94–100%). In low transmission settings, pooled sensitivity for co-RDT was 36% (95%CI: 9 76%) and 62% (95%CI: 44 77%) for us RDT, while in high transmission areas, pooled sensitivity for co RDT and us RDT were 62% (95%CI: 39 80%) and 75% (95%CI: 57–87%), respectively. Conclusion The us-RDT test showed better performance than co-RDT test, and this characteristic is more evident in asymptomatic individuals and low transmission areas; nonetheless, additional studies integrating a range of climate, geography, and demographics are needed to reliably understand the potential of the us-RDT.
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Affiliation(s)
- Yonas Yimam
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Department of Biology, Faculty of Natural and Computational Sciences, Woldia University, Woldia, Ethiopia
- * E-mail:
| | - Mehdi Mohebali
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Centers for Research of Endemic Parasites of Iran (CREPI), Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Javad Abbaszadeh Afshar
- Department of Medical Parasitology and Mycology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Department of Medical Parasitology and Mycology, School of Medicine, Jiroft University of Medical Sciences, Jiroft, Iran
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Slater HC, Ding XC, Knudson S, Bridges DJ, Moonga H, Saad NJ, De Smet M, Bennett A, Dittrich S, Slutsker L, Domingo GJ. Performance and utility of more highly sensitive malaria rapid diagnostic tests. BMC Infect Dis 2022; 22:121. [PMID: 35120441 PMCID: PMC8815208 DOI: 10.1186/s12879-021-07023-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 12/30/2021] [Indexed: 12/03/2022] Open
Abstract
Background A new more highly sensitive rapid diagnostic test (HS-RDT) for Plasmodium falciparum malaria (Alere™/Abbott Malaria Ag P.f RDT [05FK140], now called NxTek™ Eliminate Malaria Ag Pf) was launched in 2017. The test has already been used in many research studies in a wide range of geographies and use cases. Methods In this study, we collate all published and available unpublished studies that use the HS-RDT and assess its performance in (i) prevalence surveys, (ii) clinical diagnosis, (iii) screening pregnant women, and (iv) active case detection. Two individual-level data sets from asymptomatic populations are used to fit logistic regression models to estimate the probability of HS-RDT positivity based on histidine-rich protein 2 (HRP2) concentration and parasite density. The performance of the HS-RDT in prevalence surveys is estimated by calculating the sensitivity and positive proportion in comparison to polymerase chain reaction (PCR) and conventional malaria RDTs. Results We find that across 18 studies, in prevalence surveys, the mean sensitivity of the HS-RDT is estimated to be 56.1% (95% confidence interval [CI] 46.9–65.4%) compared to 44.3% (95% CI 32.6–56.0%) for a conventional RDT (co-RDT) when using nucleic acid amplification techniques as the reference standard. In studies where prevalence was estimated using both the HS-RDT and a co-RDT, we found that prevalence was on average 46% higher using a HS-RDT compared to a co-RDT. For use in clinical diagnosis and screening pregnant women, the HS-RDT was not significantly more sensitive than a co-RDT. Conclusions Overall, the evidence presented here suggests that the HS-RDT is more sensitive in asymptomatic populations and could provide a marginal improvement in clinical diagnosis and screening pregnant women. Although the HS-RDT has limited temperature stability and shelf-life claims compared to co-RDTs, there is no evidence to suggest, given this test has the same cost as current RDTs, it would have any negative impacts in terms of malaria misdiagnosis if it were widely used in all four population groups explored here. Supplementary Information The online version contains supplementary material available at 10.1186/s12879-021-07023-5.
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Affiliation(s)
- Hannah C Slater
- Diagnostics Program, PATH, Seattle, WA, USA. .,Malaria and Neglected Tropical Diseases, PATH, Seattle, WA, USA.
| | - Xavier C Ding
- Foundation for Innovative New Diagnostics, Geneva, Switzerland
| | | | - Daniel J Bridges
- PATH Malaria Control and Elimination Partnership in Africa (MACEPA), Lusaka, Zambia
| | - Hawela Moonga
- National Malaria Elimination Centre, Zambia Ministry of Health, Lusaka, Zambia
| | - Neil J Saad
- Médecins Sans Frontières, Phnom Penh, Preah Vihear, Cambodia
| | | | - Adam Bennett
- Malaria and Neglected Tropical Diseases, PATH, Seattle, WA, USA.,Malaria Elimination Initiative, Global Health Group, University of California San Francisco, San Francisco, CA, USA
| | - Sabine Dittrich
- Foundation for Innovative New Diagnostics, Geneva, Switzerland
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Clustering of malaria in households in the Greater Mekong Subregion: operational implications for reactive case detection. Malar J 2021; 20:351. [PMID: 34446009 PMCID: PMC8393740 DOI: 10.1186/s12936-021-03879-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 08/15/2021] [Indexed: 11/10/2022] Open
Abstract
Background Malaria reactive case detection is the testing and, if positive, treatment of close contacts of index cases. It is included in national malaria control programmes of countries in the Greater Mekong Subregion to accelerate malaria elimination. Yet the value of reactive case detection in the control and elimination of malaria remains controversial because of the low yield, limited evidence for impact, and high demands on resources. Methods Data from the epidemiological assessments of large mass drug administration (MDA) studies in Myanmar, Vietnam, Cambodia and Laos were analysed to explore malaria infection clustering in households. The proportion of malaria positive cases among contacts screened in a hypothetical reactive case detection programme was then determined. The parasite density thresholds for rapid diagnostic test (RDT) detection was assumed to be > 50/µL (50,000/mL), for dried-blood-spot (DBS) based PCR > 5/µL (5000/mL), and for ultrasensitive PCR (uPCR) with a validated limit of detection at 0.0022/µL (22/mL). Results At baseline, before MDA, 1223 Plasmodium infections were detected by uPCR in 693 households. There was clustering of Plasmodium infections. In 637 households with asymptomatic infections 44% (278/637) had more than one member with Plasmodium infections. In the 132 households with symptomatic infections, 65% (86/132) had more than one member with Plasmodium infections. At baseline 4% of households had more than one Plasmodium falciparum infection, but three months after MDA no household had more than one P. falciparum infected member. Reactive case detection using DBS PCR would have detected ten additional cases in six households, and an RDT screen would have detected five additional cases in three households among the 169 households with at least one RDT positive case. This translates to 19 and 9 additional cases identified per 1000 people screened, respectively. Overall, assuming all febrile RDT positive patients would seek treatment and provoke reactive case detection using RDTs, then 1047 of 1052 (99.5%) Plasmodium infections in these communities would have remained undetected. Conclusion Reactive case detection in the Greater Mekong subregion is predicted to have a negligible impact on the malaria burden, but it has substantial costs in terms of human and financial resources. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03879-9.
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Savi MK, Callo-Concha D, Tonnang HEZ, Borgemeister C. Emerging properties of malaria transmission and persistence in urban Accra, Ghana: evidence from a participatory system approach. Malar J 2021; 20:321. [PMID: 34281554 PMCID: PMC8287558 DOI: 10.1186/s12936-021-03851-7] [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: 03/25/2021] [Accepted: 07/12/2021] [Indexed: 11/10/2022] Open
Abstract
Background Several studies that aim to enhance the understanding of malaria transmission and persistence in urban settings failed to address its underlining complexity. This study aims at doing that by applying qualitative and participatory-based system analysis and mapping to elicit the system’s emergent properties. Methods In two experts’ workshops, the system was sketched and refined. This system was represented through a causal loop diagram, where the identification of leverage points was done using network analysis. Results 45 determinants interplaying through 56 linkages, and three subsystems: urbanization-related transmission, infection-prone behaviour and healthcare efficiency, and Plasmodium resistance were identified. Apart from the number of breeding sites and malaria-positive cases, other determinants such as drug prescription and the awareness of householders were identified by the network analysis as leverage points and emergent properties of the system of transmission and persistence of malaria. Conclusion Based on the findings, the ongoing efforts to control malaria, such as the use of insecticide-treated bed nets and larvicide applications should continue, and new ones focusing on the public awareness and malaria literacy of city dwellers should be included. The participatory approach strengthened the legitimacy of the recommendations and the co-learning of participants. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03851-7.
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Affiliation(s)
| | - Daniel Callo-Concha
- Center for Development Research (ZEF), University of Bonn, 53113, Bonn, Germany.,Institute for Environmental Sciences (iES), University of Koblenz-Landau, 76829, Landau, Germany
| | - Henri E Z Tonnang
- International Centre for Insect Physiology and Ecology (Icipe), Nairobi, Kenya
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9
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Danwang C, Kirakoya-Samadoulougou F, Samadoulougou S. Assessing field performance of ultrasensitive rapid diagnostic tests for malaria: a systematic review and meta-analysis. Malar J 2021; 20:245. [PMID: 34082776 PMCID: PMC8176703 DOI: 10.1186/s12936-021-03783-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 05/25/2021] [Indexed: 02/01/2023] Open
Abstract
Background To overcome the limitations of conventional malaria rapid diagnostic tests (cRDTs) in diagnosing malaria in patients with low parasitaemia, ultrasensitive malaria rapid diagnostic tests (uRDTs) have recently been developed, with promising results under laboratory conditions. The current study is the first meta-analysis comparing the overall sensitivity, and specificity of newly developed ultrasensitive Plasmodium falciparum malaria RDT (Alere™ Ultra-sensitive Malaria Ag P. falciparum RDT) with the cRDT conducted in the same field conditions. Methods PubMed, EMBASE, Cochrane infectious diseases group specialized register, and African Journals Online (AJOL) were searched up to 20th April 2021. Studies with enough data to compute sensitivity and specificity of uRDT and cRDT were retrieved. A random-effect model for meta-analysis was used to obtain the pooled sensitivity and specificity. Results Overall, 15 data sets from 14 studies were included in the meta-analysis. The overall sensitivity of the Alere™ ultra-sensitive Malaria Ag P. falciparum RDT regardless of the reference test and the clinical presentation of participants, was 55.5% (95% confidence interval [CI]: 45.5; 65.0), while the sensitivity regardless of the reference test and the clinical presentation of participants, was 42.9% (95% CI: 31.5; 55.2) for the cRDT performed in the same field conditions. When PCR was used as reference test, the sensitivity of uRDT was 60.4% (95% CI: 50.8; 69.2), while the sensitivity was 49.4% (95% CI: 38.2; 60.6) for the cRDT. The pooled specificity of uRDT regardless of the reference test and the clinical presentation of participants was 98.6% (95% CI: 97.1; 99.4), and the pooled specificity of cRDT regardless of the reference test and the clinical presentation of participants was 99.3% (95% CI: 98.1; 99.7). When PCR was used as reference test the specificity of uRDT and cRDT was 97.5% (95% CI: 94.1; 98.9) and 98.2% (95% CI: 95.5; 99.3). Regardless of the reference test used, the sensitivity of Alere™ Ultra-sensitive Malaria Ag P. falciparum RDT in symptomatic patients was 72.1% (95%CI: 67.4; 76.4), while sensitivity of cRDT was 67.4% (95%CI: 57.6; 75.9). Conclusion Findings of the meta-analysis show that Alere™ Ultra-sensitive Malaria Ag P. falciparum RDT compared to cRDT performed in the same field conditions has higher sensitivity but lower specificity although the difference is not statistically significant. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03783-2.
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Affiliation(s)
- Celestin Danwang
- Department of Surgery and Specialties, Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon. .,Epidemiology and Biostatistics Unit, Institut de Recherche Expérimentale Et Clinique, Université Catholique de Louvain, Brussels, Belgium.
| | - Fati Kirakoya-Samadoulougou
- Centre for Research in Epidemiology, Biostatistics and Clinical Research, School of Public Health, Université Libre de Bruxelles (ULB), Route de Lennik, 808, 1070, Bruxelles, Brussels, Belgium
| | - Sekou Samadoulougou
- Centre for Research On Planning and Development (CRAD), Laval University, Quebec, G1V 0A6, Canada.,Evaluation Platform On Obesity Prevention, Quebec Heart and Lung Institute, Quebec, G1V 4G5, Canada
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10
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Ultrasensitive Diagnostics for Low-Density Asymptomatic Plasmodium falciparum Infections in Low-Transmission Settings. J Clin Microbiol 2021; 59:JCM.01508-20. [PMID: 33148707 DOI: 10.1128/jcm.01508-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The emergence of multidrug-resistant Plasmodium falciparum malaria in Southeast Asia (SEA) has accelerated regional malaria elimination efforts. Most malaria in this and other low-transmission settings exists in asymptomatic individuals, which conventional diagnostic tests lack the sensitivity to detect. This has led to the development of new ultrasensitive diagnostics that are capable of detecting these low-parasitemia infections. This review summarizes the current status of ultrasensitive technologies, including PCR and loop-mediated isothermal amplification (LAMP)-based methods, as well as a newly developed ultrasensitive rapid diagnostic test (uRDT). The sensitivity, specificity, and field performance of these platforms will be examined, as well as their suitability for use in resource-limited settings to aid in malaria elimination efforts. uRDTs, with their improved sensitivity, are now able to detect approximately half of asymptomatic infections, providing a useful point-of-contact tool for malaria surveillance. The increased sensitivity and high-throughput nature of PCR-based tests make them ideal for screening large populations in places where laboratory capacity exists, and the recent commercialization of malaria LAMP kits should facilitate their adoption as a public health tool in places where such infrastructure is lacking. Finally, recent advances with dried blood spots may enable utilization of the extensive laboratory infrastructure of higher-income countries to assist with molecular surveillance in support of malaria elimination. If malaria is to be eliminated in SEA and other low-endemicity regions, then ultrasensitive diagnostics will likely play a key role in identifying and clearing the vast asymptomatic pool of infections that are common to these regions.
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11
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Choosing interventions to eliminate forest malaria: preliminary results of two operational research studies inside Cambodian forests. Malar J 2021; 20:51. [PMID: 33472630 PMCID: PMC7818569 DOI: 10.1186/s12936-020-03572-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 12/24/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Rapid elimination of Plasmodium falciparum malaria in Cambodia is a goal with both national and international significance. Transmission of malaria in Cambodia is limited to forest environments, and the main population at risk consists of forest-goers who rely on forest products for income or sustenance. The ideal interventions to eliminate malaria from this population are unknown. METHODS In two forested regions of Cambodia, forest-goers were trained to become forest malaria workers (FMWs). In one region, FMWs performed mass screening and treatment, focal screening and treatment, and passive case detection inside the forest. In the other region, FMWs played an observational role for the first year, to inform the choice of intervention for the second year. In both forests, FMWs collected blood samples and questionnaire data from all forest-goers they encountered. Mosquito collections were performed in each forest. RESULTS Malaria prevalence by PCR was high in the forest, with 2.3-5.0% positive for P. falciparum and 14.6-25.0% positive for Plasmodium vivax among forest-goers in each study site. In vectors, malaria prevalence ranged from 2.1% to 9.6%, but no P. falciparum was observed. Results showed poor performance of mass screening and treatment, with sensitivity of rapid diagnostic tests equal to 9.1% (95% CI 1.1%, 29.2%) for P. falciparum and 4.4% (95% CI 1.6%, 9.2%) for P. vivax. Malaria infections were observed in all demographics and throughout the studied forests, with no clear risk factors emerging. CONCLUSIONS Malaria prevalence remains high among Cambodian forest-goers, but performance of rapid diagnostic tests is poor. More adapted strategies to this population, such as intermittent preventive treatment of forest goers, should be considered.
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12
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Galatas B, Mayor A, Gupta H, Balanza N, Jang IK, Nhamussua L, Simone W, Cisteró P, Chidimatembue A, Munguambe H, Saúte F, Aide P, Bassat Q. Field performance of ultrasensitive and conventional malaria rapid diagnostic tests in southern Mozambique. Malar J 2020; 19:451. [PMID: 33287822 PMCID: PMC7720469 DOI: 10.1186/s12936-020-03526-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 11/26/2020] [Indexed: 01/01/2023] Open
Abstract
Background An ultrasensitive malaria rapid diagnostic test (RDT) was recently developed for the improved detection of low-density Plasmodium falciparum infections. This study aimed to compare the diagnostic performance of the PfHRP2-based Abbott Malaria Ag P. falciparum ultrasensitive RDT (uRDT) to that of the conventional SD-Bioline Malaria Ag P. falciparum RDT (cRDT) when performed under field conditions. Methods Finger-prick blood samples were collected from adults and children in two cross-sectional surveys in May of 2017 in southern Mozambique. Using real-time quantitative PCR (RT-qPCR) as the reference method, the age-specific diagnostic performance indicators of the cRDT and uRDT were compared. The presence of histidine-rich protein 2 (HRP2) and Plasmodium lactate dehydrogenase (pLDH) antigens was evaluated in a subset from dried blood spots by a quantitative antigen assay. pfhrp2 and pfhrp3 gene deletions were assessed in samples positive by RT-qPCR and negative by both RDTs. Results Among the 4,396 participants with complete test results, the sensitivity of uRDTs (68.2; 95% CI 60.8 to 74.9) was marginally better than that of cRDTs (61.5; 95% CI 53.9 to 68.6) (p-value = 0.004), while the specificities were similar (uRDT: 99.0 [95% CI 98.6 to 99.2], cRDT: 99.2 [95% CI 98.9 to 99.4], p-value = 0.02). While the performance of both RDTs was lowest in ≥ 15-year-olds, driven by the higher prevalence of low parasite density infections in this group, the sensitivity of uRDTs was significantly higher in this age group (54.9, 95% CI 40.3 to 68.9) compared to the sensitivity of cRDTs (39.2, 95% CI 25.8 to 53.9) (p-value = 0.008). Both RDTs detected P. falciparum infections at similar geometric mean parasite densities (112.9 parasites/μL for uRDTs and 145.5 parasites/μL for cRDTs). The presence of HRP2 antigen was similar among false positive (FP) samples of both tests (80.5% among uRDT-FPs and 84.4% among cRDT-FPs). Only one false negative sample was detected with a partial pfhrp2 deletion. Conclusion This study showed that the uRDTs developed by Abbott do not substantially outperform SD-Bioline Pf malaria RDTs in the community and are still not comparable to molecular methods to detect P. falciparum infections in this study setting.
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Affiliation(s)
- Beatriz Galatas
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain. .,Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique.
| | - Alfredo Mayor
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique.,CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain
| | - Himanshu Gupta
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Núria Balanza
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | | | - Lidia Nhamussua
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
| | - Wilson Simone
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
| | - Pau Cisteró
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | | | | | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
| | - Pedro Aide
- Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique.,National Institute of Health, Ministry of Health, Maputo, Mozambique
| | - Quique Bassat
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique.,CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain.,ICREA, Pg. Lluís Companys 23, 08010, Barcelona, Spain.,Pediatric Infectious Diseases Unit, Pediatrics Department, Hospital Sant Joan de Déu (University of Barcelona), Barcelona, Spain
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Lek D, Callery JJ, Nguon C, Debackere M, Sovannaroth S, Tripura R, Wojnarski M, Piola P, Khean ST, Manion K, Nguon S, Kunkel A, Vernaeve L, Peto TJ, Dantzer E, Davoeung C, Etienne W, Dondorp AM, Tuseo L, von Seidlein L, Guintran JO. Tools to accelerate falciparum malaria elimination in Cambodia: a meeting report. Malar J 2020; 19:151. [PMID: 32293452 PMCID: PMC7161105 DOI: 10.1186/s12936-020-03197-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Accepted: 03/20/2020] [Indexed: 02/06/2023] Open
Abstract
Cambodia targets malaria elimination by 2025. Rapid elimination will depend on successfully identifying and clearing malaria foci linked to forests. Expanding and maintaining universal access to early diagnosis and effective treatment remains the key to malaria control and ultimately malaria elimination in the Greater Mekong Subregion (GMS) in the foreseeable future. Mass Drug Administration (MDA) holds some promise in the rapid reduction of Plasmodium falciparum infections, but requires considerable investment of resources and time to mobilize the target communities. Furthermore, the most practical drug regimen for MDA in the GMS—three rounds of DHA/piperaquine—has lost some of its efficacy. Mass screening and treatment benefits asymptomatic P. falciparum carriers by clearing chronic infections, but in its current form holds little promise for malaria elimination. Hopes that “highly sensitive” diagnostic tests would provide substantial advances in screen and treat programmes have been shown to be misplaced. To reduce the burden on P. falciparum and Plasmodium vivax infections in people working in forested areas novel approaches to the use of malaria prophylaxis in forest workers should be explored. During an October 2019 workshop in Phnom Penh researchers and policymakers reviewed evidence of acceptability, feasibility and effectiveness of interventions to target malaria foci and interrupt P. falciparum transmission and discussed operational requirements and conditions for programmatic implementation.
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Affiliation(s)
- Dysoley Lek
- Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - James J Callery
- Mahidol-Oxford University Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
| | - Chea Nguon
- Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | | | - Siv Sovannaroth
- Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Rupam Tripura
- Mahidol-Oxford University Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Marius Wojnarski
- Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
| | | | - Soy Ty Khean
- University Research Company Ltd., Phnom Penh, Cambodia.,London School of Hygiene and Tropical Medicine, London, UK
| | | | - Sokomar Nguon
- University Research Company Ltd., Phnom Penh, Cambodia
| | - Amber Kunkel
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia.,Emerging Diseases Epidemiology Unit, Institut Pasteur, Paris, France
| | | | - Thomas J Peto
- Mahidol-Oxford University Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Emily Dantzer
- University of California at San Francisco, San Francisco, USA
| | | | | | - Arjen M Dondorp
- Mahidol-Oxford University Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | | | - Lorenz von Seidlein
- Mahidol-Oxford University Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK.
| | - Jean-Olivier Guintran
- Centre for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia. .,Mahidol-Oxford University Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand.
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