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Oboh MA, Ndiaye T, Diongue K, Ndiaye YD, Sy M, Deme AB, Diallo MA, Yade MS, Volkman SK, Badiane AS, Amambua-Ngwa A, Ndiaye D. Allelic diversity of MSP1 and MSP2 repeat loci correlate with levels of malaria endemicity in Senegal and Nigerian populations. Malar J 2021; 20:38. [PMID: 33436004 PMCID: PMC7805152 DOI: 10.1186/s12936-020-03563-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Accepted: 12/20/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Characterizing the genetic diversity of malaria parasite populations in different endemic settings (from low to high) could be helpful in determining the effectiveness of malaria interventions. This study compared Plasmodium falciparum parasite population diversity from two sites with low (pre-elimination) and high transmission in Senegal and Nigeria, respectively. METHODS Parasite genomic DNA was extracted from 187 dried blood spot collected from confirmed uncomplicated P. falciparum malaria infected patients in Senegal (94) and Nigeria (93). Allelic polymorphism at merozoite surface protein 1 (msp1) and merozoite surface protein- 2 (msp2) genes were assessed by nested PCR. RESULTS The most frequent msp1 and msp2 allelic families are the K1 and IC3D7 allelotypes in both Senegal and Nigeria. Multiplicity of infection (MOI) of greater that 1 and thus complex infections was common in both study sites in Senegal (Thies:1.51/2.53; Kedougou:2.2/2.0 for msp1/2) than in Nigeria (Gbagada: 1.39/1.96; Oredo: 1.35/1.75]). The heterozygosity of msp1 gene was higher in P. falciparum isolates from Senegal (Thies: 0.62; Kedougou: 0.53) than isolates from Nigeria (Gbagada: 0.55; Oredo: 0.50). In Senegal, K1 alleles was associated with heavy than with moderate parasite density. Meanwhile, equal proportions of K1 were observed in both heavy and moderate infection types in Nigeria. The IC3D7 subtype allele of the msp2 family was the most frequent in heavily parasitaemic individuals from both countries than in the moderately infected participants. CONCLUSION The unexpectedly low genetic diversity of infections high endemic Nigerian setting compared to the low endemic settings in Senegal is suggestive of possible epidemic outbreak in Nigeria.
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Affiliation(s)
- Mary A Oboh
- Medical Research Council Unit, the Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia.
| | - Tolla Ndiaye
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal.
| | - Khadim Diongue
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Yaye D Ndiaye
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Mouhamad Sy
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Awa B Deme
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Mamadou A Diallo
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Mamadou S Yade
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Sarah K Volkman
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
| | - Aida S Badiane
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit, the Gambia at the London School of Hygiene and Tropical Medicine, Fajara, The Gambia
| | - Daouda Ndiaye
- Laboratory of Parasitology and Mycology, Aristide Le Dantec University Hospital, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
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Ndiaye T, Sy M, Gaye A, Siddle KJ, Park DJ, Bei AK, Deme AB, Mbaye A, Dieye B, Ndiaye YD, Ndiaye IM, Diallo MA, Diongue K, Volkman SK, Badiane AS, Ndiaye D. Molecular epidemiology of Plasmodium falciparum by multiplexed amplicon deep sequencing in Senegal. Malar J 2020; 19:403. [PMID: 33172455 PMCID: PMC7654156 DOI: 10.1186/s12936-020-03471-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 10/30/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Molecular epidemiology can provide important information regarding the genetic diversity and transmission of Plasmodium falciparum, which can assist in designing and monitoring elimination efforts. However, malaria molecular epidemiology including understanding the genetic diversity of the parasite and performing molecular surveillance of transmission has been poorly documented in Senegal. Next Generation Sequencing (NGS) offers a practical, fast and high-throughput approach to understand malaria population genetics. This study aims to unravel the population structure of P. falciparum and to estimate the allelic diversity, multiplicity of infection (MOI), and evolutionary patterns of the malaria parasite using the NGS platform. METHODS Multiplex amplicon deep sequencing of merozoite surface protein 1 (PfMSP1) and merozoite surface protein 2 (PfMSP2) in fifty-three P. falciparum isolates from two epidemiologically different areas in the South and North of Senegal, was carried out. RESULTS A total of 76 Pfmsp1 and 116 Pfmsp2 clones were identified and 135 different alleles were found, 56 and 79 belonged to the pfmsp1 and pfmsp2 genes, respectively. K1 and IC3D7 allelic families were most predominant in both sites. The local haplotype diversity (Hd) and nucleotide diversity (π) were higher in the South than in the North for both genes. For pfmsp1, a high positive Tajima's D (TD) value was observed in the South (D = 2.0453) while negative TD value was recorded in the North (D = - 1.46045) and F-Statistic (Fst) was 0.19505. For pfmsp2, non-directional selection was found with a highly positive TD test in both areas and Fst was 0.02111. The mean MOI for both genes was 3.07 and 1.76 for the South and the North, respectively, with a statistically significant difference between areas (p = 0.001). CONCLUSION This study revealed a high genetic diversity of pfmsp1 and pfmsp2 genes and low genetic differentiation in P. falciparum population in Senegal. The MOI means were significantly different between the Southern and Northern areas. Findings also showed that multiplexed amplicon deep sequencing is a useful technique to investigate genetic diversity and molecular epidemiology of P. falciparum infections.
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Affiliation(s)
- Tolla Ndiaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal.
| | - Mouhamad Sy
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Amy Gaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | | | - Daniel J Park
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Amy K Bei
- Yale School of Public Health, 60 College Street, New Haven, CT, 06510, USA
| | - Awa B Deme
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Aminata Mbaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Baba Dieye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Yaye Die Ndiaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Ibrahima Mbaye Ndiaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Mamadou Alpha Diallo
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Khadim Diongue
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Sarah K Volkman
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Department of Immunology and Infectious Diseases, Harvard University, Cambridge, MA, USA
| | - Aida Sadikh Badiane
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
| | - Daouda Ndiaye
- Laboratoire de Parasitologie-Mycologie, Université Cheikh Anta Diop de Dakar (UCAD), Hôpital Aristide Le Dantec, Dakar, Senegal
- Department of Immunology and Infectious Diseases, Harvard University, Cambridge, MA, USA
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Ehrlich HY, Jones J, Parikh S. Molecular surveillance of antimalarial partner drug resistance in sub-Saharan Africa: a spatial-temporal evidence mapping study. LANCET MICROBE 2020; 1:e209-e217. [PMID: 33089222 DOI: 10.1016/s2666-5247(20)30094-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Background Molecular markers for antimalarial drug resistance can be used to rapidly monitor the emergence and spatial distribution of resistance to artemisinin-based combination therapies (ACTs). Little has been done to analyse molecular surveillance efforts or to assess surveillance coverage. This study aimed to develop an evidence map to characterise the spatial-temporal distribution and sampling methodologies of drug resistance surveillance in sub-Saharan Africa, specifically focusing on markers associated with ACT partner drugs. Methods By use of a systematic search, we identified studies that reported data on the following mutations associated with ACT partner drug resistance: pfmdr1 Asn86Tyr, Tyr184Phe, Asp1246Tyr, and copy number variation and pfcrt Lys76Thr, with sample collection occurring in sub-Saharan Africa between Jan 1, 2004, and Dec 31, 2018, corresponding to the uptake of ACTs. For each identified study, we extracted information on its sampling and laboratory methods, author and publication affiliations, years of sampling and of publication, geographic coordinates of the study sites, and prevalence of the partner drug resistance-associated markers. We used linear models to test whether urbanicity, population density, and endemicity were predictors of drug resistance survey sites and linear regressions to identify associations between the number of resistance surveys within a given country and the at-risk malaria population in 2010, the per-capita GDP in 2010, and the mean amount of funding directed to malaria and to determine trends in marker prevalence over time. For country case studies with three or more datapoints, we assessed global spatial autocorrelation using Moran's I. Findings Our search yielded 254 studies encompassing 492 year-specific and location-specific surveys from 35 malaria-endemic countries, the most complete set of molecular partner drug surveillance data to date. We observed a median time lag of 3·1 years (95% CI 1·0-7·7) from final sample acquisition to publication. 22 (49%) of the 44 countries in the study region conducted, on average, one or fewer studies every 3 years. The locations of surveillance sites were positively associated with urbanicity (p<0·0001), and the abundance of country-level data was associated with reported donor funding in 2004-18 (p=0·0011) and local government funding in 2004-09 (p=0·014). Nearly all molecular markers displayed significant regional trends over time and global spatial autocorrelation in space. For selected countries with more widespread coverage of surveillance data, some markers also displayed spatial heterogeneity. Interpretation In most sub-Saharan countries, molecular data on antimalarial resistance might not be representative of the temporal and geographic heterogeneity of partner drug resistance, and likely do not represent the true spatially dependent distribution of partner drug resistance. Our results highlight several inefficiencies that can be improved upon to develop more accurate data landscapes, including the expansion of sentinel surveillance systems, syndemic usage of research samples, and increased participation in reporting published and unpublished data to centralised platforms.
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Affiliation(s)
- Hanna Y Ehrlich
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Justin Jones
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Sunil Parikh
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
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Papa Mze N, Bogreau H, Diedhiou CK, Herdell V, Rahamatou S, Bei AK, Volkman SK, Basco L, Mboup S, Ahouidi AD. Genetic diversity of Plasmodium falciparum in Grande Comore Island. Malar J 2020; 19:320. [PMID: 32883282 PMCID: PMC7469287 DOI: 10.1186/s12936-020-03384-5] [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: 05/02/2020] [Accepted: 07/15/2020] [Indexed: 11/18/2022] Open
Abstract
Background Despite several control interventions resulting in a considerable decrease in malaria prevalence in the Union of the Comoros, the disease remains a public health problem with high transmission in Grande Comore compared to neighbouring islands. In this country, only a few studies investigating the genetic diversity of Plasmodium falciparum have been performed so far. For this reason, this study aims to examine the genetic diversity of P. falciparum by studying samples collected in Grande Comore in 2012 and 2013, using merozoite surface protein 1 (msp1), merozoite surface protein 2 (msp2) and single nucleotide polymorphism (SNP) genetic markers. Methods A total of 162 positive rapid diagnostic test (RDT) samples from Grande Comore were used to extract parasite DNA. Allelic families K1, Mad20 and RO33 of the msp1 gene as well as allelic families IC3D7 and FC37 of the msp2 gene were determined by using nested PCR. Additionally, 50 out of 151 samples were genotyped to study 24 SNPs by using high resolution melting (HRM). Results Two allelic families were predominant, the K1 family of msp1 gene (55%) and the FC27 family of msp2 gene (47.4%). Among 50 samples genotyped for 24 SNPs, 42 (84%) yielded interpretable results. Out of these isolates, 36 (85%) were genetically unique and 6 (15%) grouped into two clusters. The genetic diversity of P. falciparum calculated from msp1 and msp2 genes and SNPs was 0.82 and 0.61, respectively. Conclusion In summary, a large genetic diversity of P. falciparum was observed in Grande Comore. This may favour persistence of malaria and might be one of the reasons for the high malaria transmission compared to neighbouring islands. Further surveillance of P. falciparum isolates, mainly through environmental management and vector control, is warranted until complete elimination is attained.
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Affiliation(s)
- Nasserdine Papa Mze
- Laboratory of Bacteriology-Virology, Hospital Aristide Le Dantec, BP 7325, Dakar, Senegal. .,Institut de Recherche en Santé, de Surveillance Épidémiologique et de Formations, Arrondissement 4 Rue 2D1 Pôle Urbain de Diamniadio, Dakar, Senegal. .,Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, Marseille, France. .,IHU-Méditerranée Infection, Marseille, France. .,Laboratory of National Malaria Control Program, Moroni, Comoros.
| | - Hervé Bogreau
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, Marseille, France.,IHU-Méditerranée Infection, Marseille, France.,Département Microbiologie et Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, Unité Parasitologie et Entomologie, Marseille, France.,Centre National de Référence du Paludisme, Marseille, France
| | - Cyrille K Diedhiou
- Laboratory of Bacteriology-Virology, Hospital Aristide Le Dantec, BP 7325, Dakar, Senegal.,Institut de Recherche en Santé, de Surveillance Épidémiologique et de Formations, Arrondissement 4 Rue 2D1 Pôle Urbain de Diamniadio, Dakar, Senegal
| | - Vendela Herdell
- Karolinska Institutet, Berzelius väg 3, 17177, Stockholm, Sweden
| | - Silai Rahamatou
- Laboratory of National Malaria Control Program, Moroni, Comoros
| | - Amy K Bei
- Laboratory of Bacteriology-Virology, Hospital Aristide Le Dantec, BP 7325, Dakar, Senegal.,Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, 06510, USA
| | - Sarah K Volkman
- Broad Institute: The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Leonardo Basco
- Aix Marseille Univ, IRD, AP-HM, SSA, VITROME, Marseille, France.,IHU-Méditerranée Infection, Marseille, France
| | - Souleymane Mboup
- Laboratory of Bacteriology-Virology, Hospital Aristide Le Dantec, BP 7325, Dakar, Senegal.,Institut de Recherche en Santé, de Surveillance Épidémiologique et de Formations, Arrondissement 4 Rue 2D1 Pôle Urbain de Diamniadio, Dakar, Senegal
| | - Ambroise D Ahouidi
- Laboratory of Bacteriology-Virology, Hospital Aristide Le Dantec, BP 7325, Dakar, Senegal. .,Institut de Recherche en Santé, de Surveillance Épidémiologique et de Formations, Arrondissement 4 Rue 2D1 Pôle Urbain de Diamniadio, Dakar, Senegal.
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Guirou EA, Schindler T, Hosch S, Donfack OT, Yoboue CA, Krähenbühl S, Deal A, Cosi G, Gondwe L, Mwangoka G, Masuki H, Salim N, Mpina M, Said J, Abdulla S, Hoffman SL, Nlavo BM, Maas C, Falla CC, Phiri WP, Garcia GA, Tanner M, Daubenberger C. Molecular malaria surveillance using a novel protocol for extraction and analysis of nucleic acids retained on used rapid diagnostic tests. Sci Rep 2020; 10:12305. [PMID: 32703999 PMCID: PMC7378824 DOI: 10.1038/s41598-020-69268-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 07/10/2020] [Indexed: 11/09/2022] Open
Abstract
The use of malaria rapid diagnostic tests (RDTs) as a source for nucleic acids that can be analyzed via nucleic acid amplification techniques has several advantages, including minimal amounts of blood, sample collection, simplified storage and shipping conditions at room temperature. We have systematically developed and extensively evaluated a procedure to extract total nucleic acids from used malaria RDTs. The co-extraction of DNA and RNA molecules from small volumes of dried blood retained on the RDTs allows detection and quantification of P. falciparum parasites from asymptomatic patients with parasite densities as low as 1 Pf/µL blood using reverse transcription quantitative PCR. Based on the extraction protocol we have developed the ENAR (Extraction of Nucleic Acids from RDTs) approach; a complete workflow for large-scale molecular malaria surveillance. Using RDTs collected during a malaria indicator survey we demonstrated that ENAR provides a powerful tool to analyze nucleic acids from thousands of RDTs in a standardized and high-throughput manner. We found several, known and new, non-synonymous single nucleotide polymorphisms in the propeller region of the kelch 13 gene among isolates circulating on Bioko Island, Equatorial Guinea.
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Affiliation(s)
- Etienne A Guirou
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Tobias Schindler
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
| | - Salome Hosch
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | | | - Charlene Aya Yoboue
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Silvan Krähenbühl
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Anna Deal
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Glenda Cosi
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Linda Gondwe
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | - Grace Mwangoka
- Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | - Heavenlight Masuki
- Department of Paediatrics and Child Health, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania
| | - Nahya Salim
- Department of Paediatrics and Child Health, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania
| | - Maxmillian Mpina
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland.,Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | - Jongo Said
- Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | - Salim Abdulla
- Ifakara Health Institute, Bagamoyo Branch, United Republic of Tanzania
| | | | | | - Carl Maas
- Marathon EG Production Ltd, Malabo, Equatorial Guinea
| | | | - Wonder P Phiri
- Medical Care Development International, Malabo, Equatorial Guinea
| | | | - Marcel Tanner
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Claudia Daubenberger
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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DNA recovery from archived RDTs for genetic characterization of Plasmodium falciparum in a routine setting in Lambaréné, Gabon. Malar J 2019; 18:336. [PMID: 31578142 PMCID: PMC6775649 DOI: 10.1186/s12936-019-2972-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/24/2019] [Indexed: 11/15/2022] Open
Abstract
Background Rapid diagnostic tests (RDTs) have been described as a source of genetic material to analyse malaria parasites in proof-of-concept studies. The increasing use of RDTs (e.g., in focal or mass screening and treatment campaigns) makes this approach particularly attractive for large-scale investigations of parasite populations. In this study, the complexity of Plasmodium falciparum infections, parasite load and chloroquine resistance transporter gene mutations were investigated in DNA samples extracted from positive RDTs, obtained in a routine setting and archived at ambient temperature. Methods A total of 669 archived RDTs collected from malaria cases in urban, semi-urban and rural areas of central Gabon were used for P. falciparum DNA extraction. Performance of RDTs as a source of DNA for PCR was determined using: (i) amplification of a single copy merozoite surface protein 1 (msp1) gene followed by highly sensitive and automated capillary electrophoresis; (ii) genotyping of the pfcrt gene locus 72–76 using haplotype-specific-probe-based real-time PCR to characterize chloroquine resistance; and, (iii) real-time PCR targeting 18S genes to detect and quantify Plasmodium parasites. Results Out of the 669 archived RDTs, amplification of P. falciparum nucleic materials had a success rate of 97% for 18S real-time PCR, and 88% for the msp1 gene. The multiplicity of infections (MOI) of the whole population was 2.6 (95% CI 2.5–2.8). The highest number of alleles detected in one infection was 11. The MOI decreased with increasing age (β = − 0.0046, p = 0.02) and residence in Lambaréné was associated with smaller MOIs (p < 0.001). The overall prevalence of mutations associated with chloroquine resistance was 78.5% and was not associated with age. In Lambaréné, prevalence of chloroquine resistance was lower compared to rural Moyen-Ogooué (β = − 0.809, p-value = 0.011). Conclusion RDT is a reliable source of DNA for P. falciparum detection and genotyping assays. Furthermore, the increasing use of RDTs allows them to be an alternative source of DNA for large-scale genetic epidemiological studies. Parasite populations in the study area are highly diverse and prevalence of chloroquine-resistant P. falciparum remains high, especially in rural areas.
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Ndiaye T, Sy M, Gaye A, Ndiaye D. Genetic polymorphism of Merozoite Surface Protein 1 (msp1) and 2 (msp2) genes and multiplicity of Plasmodium falciparum infection across various endemic areas in Senegal. Afr Health Sci 2019; 19:2446-2456. [PMID: 32127816 PMCID: PMC7040301 DOI: 10.4314/ahs.v19i3.19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
INTRODUCTION Despite a significant decline in Senegal, malaria remains a burden in various parts of the country. Assessment of multiplicity of Plasmodium falciparum infection and genetic diversity of parasites population could help in monitoring of malaria control. OBJECTIVE To assess genetic diversity and multiplicity of infection in P. falciparum isolates from three areas in Senegal with different malaria transmissions. METHODS 136 blood samples were collected from patients with uncomplicated P. falciparum malaria in Pikine, Kedougou and Thies. Polymorphic loci of msp1 and 2 (Merozoite surface protein-1 and 2) genes were amplified by nested PCR. RESULTS For msp1gene, K1 allelic family was predominant with frequency of 71%. Concerning msp2 gene, IC3D7 allelic family was the most represented with frequency of 83%. Multiclonal isolates found were 36% and 31% for msp1et msp2 genes respectively. The MOI found in all areas was 2.56 and was statistically different between areas (P=0.024). Low to intermediate genetic diversity were found with heterozygosity range (He=0,394-0,637) and low genetic differentiation (Fst msp1= 0.011; Fst msp2=0.017) were observed between P. falciparum population within the country. CONCLUSION Low to moderate genetic diversity of P.falciparum strains and MOI disparities were found in Senegal.
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Affiliation(s)
- Tolla Ndiaye
- Laboratory of Parasitology/Mycology HALD, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Mouhamad Sy
- Laboratory of Parasitology/Mycology HALD, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Amy Gaye
- Laboratory of Parasitology/Mycology HALD, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
| | - Daouda Ndiaye
- Laboratory of Parasitology/Mycology HALD, Cheikh Anta Diop University of Dakar, PO Box 5005, Dakar, Senegal
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA, USA
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Raman J, Kagoro FM, Mabuza A, Malatje G, Reid A, Frean J, Barnes KI. Absence of kelch13 artemisinin resistance markers but strong selection for lumefantrine-tolerance molecular markers following 18 years of artemisinin-based combination therapy use in Mpumalanga Province, South Africa (2001-2018). Malar J 2019; 18:280. [PMID: 31438951 PMCID: PMC6704579 DOI: 10.1186/s12936-019-2911-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 08/13/2019] [Indexed: 11/28/2022] Open
Abstract
Background The ability of Plasmodium falciparum parasites to develop resistance to widely used anti-malarials threatens malaria control and elimination efforts. Regular drug efficacy monitoring is essential for ensuring effective treatment policies. In low transmission settings where therapeutic efficacy studies are often not feasible, routine surveillance for molecular markers associated with anti-malarial resistance provides an alternative for the early detection of emerging resistance. Such a longitudinal survey of changes in the prevalence of selected molecular markers of resistance was conducted in the malaria-endemic regions of Mpumalanga Province, South Africa, where malaria elimination at a district-level is being pursued. Methods Molecular analyses to determine the prevalence of alleles associated with resistance to lumefantrine (mdr86N, crt76K and mdr1 copy number variation) and sulfadoxine–pyrimethamine (dhfr triple, dhps double, SP quintuple) were conducted between 2001 and 2018, while artemisinin resistance markers (kelch13 mutations) were assessed only in 2018. Results Parasite DNA was successfully amplified from 1667/2393 (70%) of malaria-positive rapid diagnostic tests routinely collected at primary health care facilities. No artemisinin resistance-associated kelch13 mutations nor amplification of the mdr1 gene copy number associated with lumefantrine resistance were observed. However, prevalence of both the mdr86N and crt76K alleles increased markedly over the study period, with all isolates collected in 2018 carrying these markers. SP quintuple mutation prevalence increased steadily from 14% in 2001 to 96% in 2018. Mixed alleles at any of the codons assessed were rare by 2018. Conclusion No kelch13 mutations confirmed or suspected to be associated with artemisinin resistance were identified in 2018. Although parasites carrying the mdr86N and crt76K alleles associated with reduced lumefantrine susceptibility were strongly selected for over the study period, nearing fixation by 2018, the marker for lumefantrine resistance, namely increased mdr1 copy number, was not observed in this study. The increase in mdr86N and crt76K allele prevalence together with intense regional artemether–lumefantrine drug pressure, raises concern regarding the sustained artemether–lumefantrine efficacy. Regular, rigorous anti-malarial resistance marker surveillance across all three South African malaria-endemic provinces to inform case management is recommended.
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Affiliation(s)
- Jaishree Raman
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, A Division of the National Health Laboratory Service, Sandringham, Johannesburg, Gauteng, South Africa. .,Wits Research Institute for Malaria, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa. .,UP Institute for Sustainable Malaria Control, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.
| | - Frank M Kagoro
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa.,Mahidol-Oxford Tropical Medicine Research Unit, Bangkok, Thailand
| | - Aaron Mabuza
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Gillian Malatje
- Mpumalanga Provincial Malaria Elimination Programme, Nelspruit, Mpumalanga, South Africa
| | - Anthony Reid
- Operational Research Unit, Médecins Sans Frontières, Operational Centre, Brussels, Luxembourg
| | - John Frean
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, A Division of the National Health Laboratory Service, Sandringham, Johannesburg, Gauteng, South Africa.,Wits Research Institute for Malaria, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Karen I Barnes
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
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9
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Proof of concept: used malaria rapid diagnostic tests applied for parallel sequencing for surveillance of molecular markers of anti-malarial resistance in Bissau, Guinea-Bissau during 2014-2017. Malar J 2019; 18:252. [PMID: 31349834 PMCID: PMC6660714 DOI: 10.1186/s12936-019-2894-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 07/23/2019] [Indexed: 01/17/2023] Open
Abstract
Background Large-scale surveillance of molecular markers of anti-malarial drug resistance is an attractive method of resistance monitoring, to complement therapeutic efficacy studies in settings where the latter are logistically challenging. Methods Between 2014 and 2017, this study sampled malaria rapid diagnostic tests (RDTs), used in routine clinical care, from two health centres in Bissau, Guinea-Bissau. In order to obtain epidemiological insights, RDTs were collected together with patient data on age and sex. A subset of positive RDTs from one of the two sites (n = 2184) were tested for Plasmodium DNA content. Those testing positive for Plasmodium DNA by PCR (n = 1390) were used for library preparation, custom designed dual indexing and next generation Miseq targeted sequencing of Plasmodium falciparum genes pfcrt, pfmdr1, pfdhfr, pfdhps and pfk13. Results The study found a high frequency of the pfmdr1 codon 86N at 88–97%, a significant decrease of the pfcrt wildtype CVMNK haplotype and elevated levels of the pfdhfr/pfdhps quadruple mutant ranging from 33 to 51% between 2014 and 2017. No polymorphisms indicating artemisinin tolerance were discovered. The demographic data indicate a large proportion of young adults (66%, interquartile range 11–28 years) presenting with P. falciparum infections. While a total of 5532 gene fragments were successfully analysed on a single Illumina Miseq flow cell, PCR-positivity from the library preparation varied considerably from 13 to 87% for different amplicons. Furthermore, pre-screening of samples for Plasmodium DNA content proved necessary prior to library preparation. Conclusions This study serves as a proof of concept for using leftover clinical material (used RDTs) for large-scale molecular surveillance, encompassing the inherent complications regarding to methodology and analysis when doing so. Factors such as RDT storage prior to DNA extraction and parasitaemia of the infection are likely to have an effect on whether or not parasite DNA can be successfully analysed, and are considered part of the reason the data yield is suboptimal. However, given the necessity of molecular surveillance of anti-malarial resistance in settings where poor infrastructure, poor economy, lack of educated staff and even surges of political instability remain major obstacles to performing clinical studies, obtaining the necessary data from used RDTs, despite suboptimal output, becomes a feasible, affordable and hence a justifiable method. Electronic supplementary material The online version of this article (10.1186/s12936-019-2894-8) contains supplementary material, which is available to authorized users.
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10
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Molecular quantification of Plasmodium parasite density from the blood retained in used RDTs. Sci Rep 2019; 9:5107. [PMID: 30911048 PMCID: PMC6434039 DOI: 10.1038/s41598-019-41438-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Accepted: 03/05/2019] [Indexed: 12/27/2022] Open
Abstract
Most malaria-endemic countries are heavily reliant upon rapid diagnostic tests (RDT) for malaria case identification and treatment. RDT previously used for malaria diagnosis can subsequently be used for molecular assays, including qualitative assessment of parasite species present or the carriage of resistance markers, because parasite DNA can be extracted from the blood inside the RDT which remains preserved on the internal components. However, the quantification of parasite density has not previously been possible from used RDT. In this study, blood samples were collected from school-age children in Western Kenya, in the form of both dried blood spots on Whatman filter paper, and the blood spot that is dropped into rapid diagnostic tests during use. Having first validated a robotic DNA extraction method, the parasite density was determined from both types of sample by duplex qPCR, and across a range of densities. The methods showed good agreement. The preservation of both parasite and human DNA on the nitrocellulose membrane inside the RDT was stable even after more than one year's storage. This presents a useful opportunity for researchers or clinicians wishing to gain greater information about the parasite populations that are being studied, without significant investment of resources.
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11
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Molecular assays for antimalarial drug resistance surveillance: A target product profile. PLoS One 2018; 13:e0204347. [PMID: 30235327 PMCID: PMC6147503 DOI: 10.1371/journal.pone.0204347] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 09/05/2018] [Indexed: 11/25/2022] Open
Abstract
Antimalarial drug resistance is a major constraint for malaria control and elimination efforts. Artemisinin-based combination therapy is now the mainstay for malaria treatment. However, delayed parasite clearance following treatment with artemisinin derivatives has now spread in the Greater Mekong Sub region and may emerge or spread to other malaria endemic regions. This spread is of great concern for malaria control programmes, as no alternatives to artemisinin-based combination therapies are expected to be available in the near future. There is a need to strengthen surveillance systems for early detection and response to the antimalarial drug resistance threat. Current surveillance is mainly done through therapeutic efficacy studies; however these studies are complex and both time- and resource-intensive. For multiple common antimalarials, parasite drug resistance has been correlated with specific genetic mutations, and the molecular markers associated with antimalarial drug resistance offer a simple and powerful tool to monitor the emergence and spread of resistant parasites. Different techniques to analyse molecular markers associated with antimalarial drug resistance are available, each with advantages and disadvantages. However, procedures are not adequately harmonized to facilitate comparisons between sites. Here we describe the target product profiles for tests to analyse molecular markers associated with antimalarial drug resistance, discuss how use of current techniques can be standardised, and identify the requirements for an ideal product that would allow malaria endemic countries to provide useful spatial and temporal information on the spread of resistance.
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12
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Ndiaye YD, Diédhiou CK, Bei AK, Dieye B, Mbaye A, Mze NP, Daniels RF, Ndiaye IM, Déme AB, Gaye A, Sy M, Ndiaye T, Badiane AS, Ndiaye M, Premji Z, Wirth DF, Mboup S, Krogstad D, Volkman SK, Ahouidi AD, Ndiaye D. High resolution melting: a useful field-deployable method to measure dhfr and dhps drug resistance in both highly and lowly endemic Plasmodium populations. Malar J 2017; 16:153. [PMID: 28420422 PMCID: PMC5395743 DOI: 10.1186/s12936-017-1811-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 04/08/2017] [Indexed: 11/18/2022] Open
Abstract
Background Emergence and spread of drug resistance to every anti-malarial used to date, creates an urgent need for development of sensitive, specific and field-deployable molecular tools for detection and surveillance of validated drug resistance markers. Such tools would allow early detection of mutations in resistance loci. The aim of this study was to compare common population signatures and drug resistance marker frequencies between two populations with different levels of malaria endemicity and history of anti-malarial drug use: Tanzania and Sénégal. This was accomplished by implementing a high resolution melting assay to study molecular markers of drug resistance as compared to polymerase chain reaction–restriction fragment length polymorphism (PCR/RFLP) methodology. Methods Fifty blood samples were collected each from a lowly malaria endemic site (Sénégal), and a highly malaria endemic site (Tanzania) from patients presenting with uncomplicated Plasmodium falciparum malaria at clinic. Data representing the DHFR were derived using both PCR–RFLP and HRM assay; while genotyping data representing the DHPS were evaluated in Senegal and Tanzania using HRM. Msp genotyping analysis was used to characterize the multiplicity of infection in both countries. Results A high prevalence of samples harbouring mutant DHFR alleles was observed in both population using both genotyping techniques. HRM was better able to detect mixed alleles compared to PCR/RFLP for DHFR codon 51 in Tanzania; and only HRM was able to detect mixed infections from Senegal. A high prevalence of mutant alleles in DHFR (codons 51, 59, 108) and DHPS (codon 437) were found among samples from Sénégal while no mutations were observed at DHPS codons 540 and 581, from both countries. Overall, the frequency of samples harbouring either a single DHFR mutation (S108N) or double mutation in DHFR (C59R/S108N) was greater in Sénégal compared to Tanzania. Conclusion Here the results demonstrate that HRM is a rapid, sensitive, and field-deployable alternative technique to PCR–RFLP genotyping that is useful in populations harbouring more than one parasite genome (polygenomic infections). In this study, a high levels of resistance polymorphisms was observed in both dhfr and dhps, among samples from Tanzania and Sénégal. A routine monitoring by molecular markers can be a way to detect emergence of resistance involving a change in the treatment policy.
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Affiliation(s)
- Yaye Dié Ndiaye
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal. .,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal.
| | - Cyrille K Diédhiou
- Laboratory of Bacteriology and Virology, Hospital Aristide Le Dantec, 7325, Dakar, Senegal
| | - Amy K Bei
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal.,Laboratory of Bacteriology and Virology, Hospital Aristide Le Dantec, 7325, Dakar, Senegal.,Department of Parasitology and Medical Entomology, Muhimbili University College of Health Sciences, Dar-es-Salaam, Tanzania.,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal.,Department of Immunology and Infectious Diseases, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA
| | - Baba Dieye
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal.,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal
| | - Aminata Mbaye
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal
| | - Nasserdine Papa Mze
- Laboratory of Bacteriology and Virology, Hospital Aristide Le Dantec, 7325, Dakar, Senegal
| | - Rachel F Daniels
- Department of Immunology and Infectious Diseases, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA.,Infectious Disease Initiative, The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Ibrahima M Ndiaye
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal
| | - Awa B Déme
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal.,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal
| | - Amy Gaye
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal
| | - Mouhamad Sy
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal
| | - Tolla Ndiaye
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal
| | - Aida S Badiane
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal.,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal
| | - Mouhamadou Ndiaye
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal.,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal
| | - Zul Premji
- Department of Parasitology and Medical Entomology, Muhimbili University College of Health Sciences, Dar-es-Salaam, Tanzania.,Department of Pathology, Aga Khan University Hospital, Nairobi, Kenya
| | - Dyann F Wirth
- Department of Immunology and Infectious Diseases, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA.,Infectious Disease Initiative, The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA
| | - Souleymane Mboup
- Laboratory of Bacteriology and Virology, Hospital Aristide Le Dantec, 7325, Dakar, Senegal
| | - Donald Krogstad
- Tulane University, New Orleans, LA, USA.,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal
| | - Sarah K Volkman
- The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal.,Department of Immunology and Infectious Diseases, Harvard TH Chan School of Public Health, Boston, MA, 02115, USA.,Infectious Disease Initiative, The Broad Institute of MIT and Harvard, Cambridge, MA, 02142, USA.,School of Nursing and Health Sciences, Simmons College, Boston, MA, 02115, USA
| | - Ambroise D Ahouidi
- Laboratory of Bacteriology and Virology, Hospital Aristide Le Dantec, 7325, Dakar, Senegal.,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal
| | - Daouda Ndiaye
- Laboratory of Parasitology Mycology, Aristide le Dantec Hospital, Faculty of Medicine and Pharmacy, Cheikh Anta Diop University, 5005, Dakar, Senegal.,The International Centers of Excellence for Malaria Research (ICEMR) Program, Dakar, Senegal
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13
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Abdul-Ghani R, Mahdy MAK, Beier JC, Basco LK. Hidden reservoir of resistant parasites: the missing link in the elimination of falciparum malaria. Infect Dis Poverty 2017; 6:12. [PMID: 28166813 PMCID: PMC5294824 DOI: 10.1186/s40249-016-0227-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 12/20/2016] [Indexed: 11/29/2022] Open
Abstract
Background To successfully eliminate malaria, an integrated system that includes a number of approaches and interventions—aimed at overcoming the threat of antimalarial drug resistance—is required. Significant progress has been made in reducing malaria incidence through large-scale use of artemisinin-based combination therapies and insecticide-treated nets. To consolidate these gains, attention should be paid to the missing links in the elimination of malaria. One of these gaps is the residual reservoir of submicroscopic resistant parasites, which remains after case management or other control measures have been carried out. Therefore, the present opinion piece highlights the importance of exploring the role that submicroscopic resistant parasites could play in hindering malaria elimination by allowing the persistence of transmission, particularly in areas of low transmission or in the pre-elimination and/or elimination phase. Discussion If malaria elimination interventions are to be effective, the relative role of the hidden reservoir of resistant parasites needs to be assessed, particularly in regions that are low-transmission settings and/or in pre-elimination and/or elimination phases. Various ongoing studies are focusing on the role of submicroscopic malaria infections in malaria transmission but overlook the possible build-up of resistance to antimalarial drugs among submicroscopic parasite populations. This is an important factor as it may eventually limit the effectiveness of malaria elimination strategies. Conclusions An evidence-based estimation of the “true” reservoir of resistant parasites can help target the existing and emerging foci of resistant parasites before they spread. Emergence and spread of artemisinin-resistant Plasmodium falciparum malaria in Southeast Asia underline the need to contain drug resistance. Electronic supplementary material The online version of this article (doi:10.1186/s40249-016-0227-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rashad Abdul-Ghani
- Department of Parasitology, Faculty of Medicine and Health Sciences, Sana'a University, Sana'a, Yemen. .,Tropical Disease Research Center, University of Science and Technology, Sana'a, Yemen.
| | - Mohammed A K Mahdy
- Department of Parasitology, Faculty of Medicine and Health Sciences, Sana'a University, Sana'a, Yemen.,Tropical Disease Research Center, University of Science and Technology, Sana'a, Yemen
| | - John C Beier
- Department of Public Health Sciences, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Leonardo K Basco
- Unité de Recherche 198, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, Institut de Recherche pour le Développement, Faculté de Médecine La Timone, Aix-Marseille Université, Marseille, France
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