601
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Bhumiratana A, Intarapuk A, Sorosjinda-Nunthawarasilp P, Maneekan P, Koyadun S. Border malaria associated with multidrug resistance on Thailand-Myanmar and Thailand-Cambodia borders: transmission dynamic, vulnerability, and surveillance. BIOMED RESEARCH INTERNATIONAL 2013; 2013:363417. [PMID: 23865048 PMCID: PMC3707221 DOI: 10.1155/2013/363417] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Accepted: 06/06/2013] [Indexed: 12/20/2022]
Abstract
This systematic review elaborates the concepts and impacts of border malaria, particularly on the emergence and spread of Plasmodium falciparum and Plasmodium vivax multidrug resistance (MDR) malaria on Thailand-Myanmar and Thailand-Cambodia borders. Border malaria encompasses any complex epidemiological settings of forest-related and forest fringe-related malaria, both regularly occurring in certain transmission areas and manifesting a trend of increased incidence in transmission prone areas along these borders, as the result of interconnections of human settlements and movement activities, cross-border population migrations, ecological changes, vector population dynamics, and multidrug resistance. For regional and global perspectives, this review analyzes and synthesizes the rationales pertaining to transmission dynamics and the vulnerabilities of border malaria that constrain surveillance and control of the world's most MDR falciparum and vivax malaria on these chaotic borders.
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Affiliation(s)
- Adisak Bhumiratana
- Department of Parasitology and Entomology, Faculty of Public Health, Mahidol University, 420/1 Rajvithi Road, Rajthewee, Bangkok 10400, Thailand.
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602
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Elixirs of death. International organizations are working towards a global solution to address the problem of falsified and substandard medicines, but progress has stagnated. EMBO Rep 2013; 14:597-600. [PMID: 23764922 DOI: 10.1038/embor.2013.82] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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603
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Dondorp AM, Ringwald P. Artemisinin resistance is a clear and present danger. Trends Parasitol 2013; 29:359-60. [PMID: 23768981 DOI: 10.1016/j.pt.2013.05.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 05/17/2013] [Indexed: 10/26/2022]
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604
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Brunner R, Ng CL, Aissaoui H, Akabas MH, Boss C, Brun R, Callaghan PS, Corminboeuf O, Fidock DA, Frame IJ, Heidmann B, Le Bihan A, Jenö P, Mattheis C, Moes S, Müller IB, Paguio M, Roepe PD, Siegrist R, Voss T, Welford RWD, Wittlin S, Binkert C. UV-triggered affinity capture identifies interactions between the Plasmodium falciparum multidrug resistance protein 1 (PfMDR1) and antimalarial agents in live parasitized cells. J Biol Chem 2013; 288:22576-83. [PMID: 23754276 DOI: 10.1074/jbc.m113.453159] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
A representative of a new class of potent antimalarials with an unknown mode of action was recently described. To identify the molecular target of this class of antimalarials, we employed a photo-reactive affinity capture method to find parasite proteins specifically interacting with the capture compound in living parasitized cells. The capture reagent retained the antimalarial properties of the parent molecule (ACT-213615) and accumulated within parasites. We identified several proteins interacting with the capture compound and established a functional interaction between ACT-213615 and PfMDR1. We surmise that PfMDR1 may play a role in the antimalarial activity of the piperazine-containing compound ACT-213615.
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Affiliation(s)
- Ralf Brunner
- Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, CH-4002 Basel, Switzerland
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605
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Progressing the global antimalarial portfolio: finding drugs which target multiple Plasmodium life stages. Parasitology 2013; 141:66-76. [PMID: 23746048 DOI: 10.1017/s0031182013000747] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The number of novel antimalarial candidates entering preclinical development has seen an increase over the last several years. Most of these drug candidates were originally identified as hits coming from screening large chemical libraries specifically targeting the asexual blood stages of Plasmodium falciparum. Indeed, a large proportion of the current antimalarial arsenal has mainly targeted the asexual blood stage which is responsible for clinical symptoms of the disease. However, as part of the eradication agenda and to address resistance, any next-generation antimalarial should have additional activity on at least one other parasite life stage, i.e. gametocytocidal and/or tissue schizonticidal activity. We have applied this approach by screening compounds with intrinsic activity on asexual blood stages in assays against sexual and liver stages and identified two new antimalarial chemotypes with activity on multiple parasite life stages. This strategy can be expanded to identify other chemical classes of molecules with similar activity profiles for the next generation antimalarials. The following review summarizes the discovery of the spiroindolones and imidazolopiperazine classes of antimalarials developed by the NGBS consortium (Novartis Institute for Tropical Diseases, Genomic Institute of the Novartis Research Foundation, Biomedical Primate Research Center, and the Swiss Tropical and Public Health Institute) currently in clinical trials.
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606
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Miotto O, Almagro-Garcia J, Manske M, MacInnis B, Campino S, Rockett KA, Amaratunga C, Lim P, Suon S, Sreng S, Anderson JM, Duong S, Nguon C, Chuor CM, Saunders D, Se Y, Lon C, Fukuda MM, Amenga-Etego L, Hodgson AVO, Asoala V, Imwong M, Takala-Harrison S, Nosten F, Su XZ, Ringwald P, Ariey F, Dolecek C, Hien TT, Boni MF, Thai CQ, Amambua-Ngwa A, Conway DJ, Djimdé AA, Doumbo OK, Zongo I, Ouedraogo JB, Alcock D, Drury E, Auburn S, Koch O, Sanders M, Hubbart C, Maslen G, Ruano-Rubio V, Jyothi D, Miles A, O’Brien J, Gamble C, Oyola SO, Rayner JC, Newbold CI, Berriman M, Spencer CCA, McVean G, Day NP, White NJ, Bethell D, Dondorp AM, Plowe CV, Fairhurst RM, Kwiatkowski DP. Multiple populations of artemisinin-resistant Plasmodium falciparum in Cambodia. Nat Genet 2013; 45:648-55. [PMID: 23624527 PMCID: PMC3807790 DOI: 10.1038/ng.2624] [Citation(s) in RCA: 345] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Accepted: 04/04/2013] [Indexed: 11/09/2022]
Abstract
We describe an analysis of genome variation in 825 P. falciparum samples from Asia and Africa that identifies an unusual pattern of parasite population structure at the epicenter of artemisinin resistance in western Cambodia. Within this relatively small geographic area, we have discovered several distinct but apparently sympatric parasite subpopulations with extremely high levels of genetic differentiation. Of particular interest are three subpopulations, all associated with clinical resistance to artemisinin, which have skewed allele frequency spectra and high levels of haplotype homozygosity, indicative of founder effects and recent population expansion. We provide a catalog of SNPs that show high levels of differentiation in the artemisinin-resistant subpopulations, including codon variants in transporter proteins and DNA mismatch repair proteins. These data provide a population-level genetic framework for investigating the biological origins of artemisinin resistance and for defining molecular markers to assist in its elimination.
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Affiliation(s)
- Olivo Miotto
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Jacob Almagro-Garcia
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Magnus Manske
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Bronwyn MacInnis
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Susana Campino
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Kirk A Rockett
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Chanaki Amaratunga
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Pharath Lim
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Seila Suon
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Sokunthea Sreng
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Jennifer M Anderson
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Socheat Duong
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Chea Nguon
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Char Meng Chuor
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - David Saunders
- Department of Immunology and Medicine, US Army Medical Component, Armed Forces Research Institute of Medical Sciences (USAMC-AFRIMS), Bangkok, Thailand
| | - Youry Se
- US Army Medical Component, Armed Forces Research Institute of Medical Sciences (USAMC-AFRIMS), Phnom Penh, Cambodia
| | - Chantap Lon
- US Army Medical Component, Armed Forces Research Institute of Medical Sciences (USAMC-AFRIMS), Phnom Penh, Cambodia
| | - Mark M Fukuda
- Department of Immunology and Medicine, US Army Medical Component, Armed Forces Research Institute of Medical Sciences (USAMC-AFRIMS), Bangkok, Thailand
- Armed Forces Health Surveillance Center, Silver Spring MD 20904, USA
| | | | | | | | - Mallika Imwong
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
| | - Shannon Takala-Harrison
- Howard Hughes Medical Institute, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Francois Nosten
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand
- Shoklo Malaria Research Unit, Mae Sot, Tak 63110, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford OX3 7LJ, UK
| | - Xin-zhuan Su
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Pascal Ringwald
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Frédéric Ariey
- Unité d’Immunologie Moléculaire des Parasites, Institut Pasteur, Paris 75015, France
| | - Christiane Dolecek
- Centre for Tropical Medicine, University of Oxford, Oxford OX3 7LJ, UK
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Tran Tinh Hien
- Centre for Tropical Medicine, University of Oxford, Oxford OX3 7LJ, UK
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Maciej F Boni
- Centre for Tropical Medicine, University of Oxford, Oxford OX3 7LJ, UK
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | - Cao Quang Thai
- Oxford University Clinical Research Unit, Wellcome Trust Major Overseas Programme, Ho Chi Minh City, Vietnam
| | | | - David J Conway
- MRC Laboratories, Fajara, The Gambia
- London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Abdoulaye A Djimdé
- Malaria Research and Training Center, Faculty of Pharmacy, University of Science, Techniques and Technologies of Bamako, Mali
| | - Ogobara K Doumbo
- Malaria Research and Training Center, Faculty of Pharmacy, University of Science, Techniques and Technologies of Bamako, Mali
| | - Issaka Zongo
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l’Ouést, Bobo-Dioulasso, Burkina Faso
| | - Jean-Bosco Ouedraogo
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l’Ouést, Bobo-Dioulasso, Burkina Faso
| | - Daniel Alcock
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Eleanor Drury
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Sarah Auburn
- Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territories 0811, Australia
| | - Oliver Koch
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
| | - Mandy Sanders
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Christina Hubbart
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Gareth Maslen
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Valentin Ruano-Rubio
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Dushyanth Jyothi
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Alistair Miles
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - John O’Brien
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Chris Gamble
- Department of Statistics, University of Oxford, Oxford, OX1 3TG, UK
| | - Samuel O Oyola
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Julian C Rayner
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Chris I Newbold
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
- Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Matthew Berriman
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Chris CA Spencer
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Gilean McVean
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
| | - Nicholas P Day
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford OX3 7LJ, UK
| | - Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford OX3 7LJ, UK
| | - Delia Bethell
- Department of Immunology and Medicine, US Army Medical Component, Armed Forces Research Institute of Medical Sciences (USAMC-AFRIMS), Bangkok, Thailand
| | - Arjen M Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford OX3 7LJ, UK
| | - Christopher V Plowe
- Howard Hughes Medical Institute, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
| | - Rick M Fairhurst
- National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Dominic P Kwiatkowski
- MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
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607
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Cruz LR, Spangenberg T, Lacerda MVG, Wells TNC. Malaria in South America: a drug discovery perspective. Malar J 2013; 12:168. [PMID: 23706107 PMCID: PMC3665683 DOI: 10.1186/1475-2875-12-168] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 05/15/2013] [Indexed: 11/17/2022] Open
Abstract
The challenge of controlling and eventually eradicating malaria means that new tools are urgently needed. South America's role in this fight spans both ends of the research and development spectrum: both as a continent capable of discovering and developing new medicines, and also as a continent with significant numbers of malaria patients. This article reviews the contribution of groups in the South American continent to the research and development of new medicines over the last decade. Therefore, the current situation of research targeting malaria control and eradication is discussed, including endemicity, geographical distribution, treatment, drug-resistance and diagnosis. This sets the scene for a review of efforts within South America to discover and optimize compounds with anti-malarial activity.
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Affiliation(s)
- Luiza R Cruz
- Medicines for Malaria Venture, 20 route de Pré-Bois, Geneva, CH 1215, Switzerland
| | - Thomas Spangenberg
- Medicines for Malaria Venture, 20 route de Pré-Bois, Geneva, CH 1215, Switzerland
| | - Marcus VG Lacerda
- Fundação de Medicina Tropical Dr Heitor Vieira Dourado, Av Pedro Teixeira, 25, Manaus, Amazonas, 69040-000, Brazil
| | - Timothy NC Wells
- Medicines for Malaria Venture, 20 route de Pré-Bois, Geneva, CH 1215, Switzerland
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608
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Guler JL, Freeman DL, Ahyong V, Patrapuvich R, White J, Gujjar R, Phillips MA, DeRisi J, Rathod PK. Asexual populations of the human malaria parasite, Plasmodium falciparum, use a two-step genomic strategy to acquire accurate, beneficial DNA amplifications. PLoS Pathog 2013; 9:e1003375. [PMID: 23717205 PMCID: PMC3662640 DOI: 10.1371/journal.ppat.1003375] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/05/2013] [Indexed: 11/18/2022] Open
Abstract
Malaria drug resistance contributes to up to a million annual deaths. Judicious deployment of new antimalarials and vaccines could benefit from an understanding of early molecular events that promote the evolution of parasites. Continuous in vitro challenge of Plasmodium falciparum parasites with a novel dihydroorotate dehydrogenase (DHODH) inhibitor reproducibly selected for resistant parasites. Genome-wide analysis of independently-derived resistant clones revealed a two-step strategy to evolutionary success. Some haploid blood-stage parasites first survive antimalarial pressure through fortuitous DNA duplications that always included the DHODH gene. Independently-selected parasites had different sized amplification units but they were always flanked by distant A/T tracks. Higher level amplification and resistance was attained using a second, more efficient and more accurate, mechanism for head-to-tail expansion of the founder unit. This second homology-based process could faithfully tune DNA copy numbers in either direction, always retaining the unique DNA amplification sequence from the original A/T-mediated duplication for that parasite line. Pseudo-polyploidy at relevant genomic loci sets the stage for gaining additional mutations at the locus of interest. Overall, we reveal a population-based genomic strategy for mutagenesis that operates in human stages of P. falciparum to efficiently yield resistance-causing genetic changes at the correct locus in a successful parasite. Importantly, these founding events arise with precision; no other new amplifications are seen in the resistant haploid blood stage parasite. This minimizes the need for meiotic genetic cleansing that can only occur in sexual stage development of the parasite in mosquitoes. Malaria parasites kill up to a million people around the world every year. Emergence of resistance to drugs remains a key obstacle against elimination of malaria. In the laboratory, parasites can efficiently acquire resistance to experimental antimalarials by changing DNA at the target locus. This happens efficiently even for an antimalarial that the parasite has never encountered in a clinical setting. In this study, we formally demonstrate how parasites achieve this feat: first, individual parasites in a population of millions randomly amplify large regions of DNA between short sequence repeats of adenines (A) or thymines (T) that are peppered throughout the malaria parasite genome. The rare lucky parasite that amplifies DNA coding for the target of the antimalarial, along with dozens of its neighboring genes, gains an evolutionary advantage and survives. In a second step, to withstand increasing drug pressure and to achieve higher levels of resistance, each parasite line makes additional copies of this region. This second expansion does not rely on the random A/T-based DNA rearrangements but, instead, a more precise amplification mechanism that retains the unique signature of co-amplified genes created earlier in each parasite. Generation of multiple copies of the target genes in the parasite genome may be the beginning of other beneficial changes for the parasite, including the future acquisition of mutations.
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Affiliation(s)
- Jennifer L. Guler
- Departments of Chemistry and Global Health, University of Washington, Seattle, Washington, United States of America
| | - Daniel L. Freeman
- Departments of Chemistry and Global Health, University of Washington, Seattle, Washington, United States of America
| | - Vida Ahyong
- Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Rapatbhorn Patrapuvich
- Departments of Chemistry and Global Health, University of Washington, Seattle, Washington, United States of America
| | - John White
- Departments of Chemistry and Global Health, University of Washington, Seattle, Washington, United States of America
| | - Ramesh Gujjar
- Departments of Chemistry and Global Health, University of Washington, Seattle, Washington, United States of America
| | - Margaret A. Phillips
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, United States of America
| | - Joseph DeRisi
- Howard Hughes Medical Institute, University of California San Francisco, San Francisco, California, United States of America
| | - Pradipsinh K. Rathod
- Departments of Chemistry and Global Health, University of Washington, Seattle, Washington, United States of America
- * E-mail:
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609
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Nacher M, Guérin PJ, Demar-Pierre M, Djossou F, Nosten F, Carme B. Made in Europe: will artemisinin resistance emerge in French Guiana? Malar J 2013; 12:152. [PMID: 23641802 PMCID: PMC3649934 DOI: 10.1186/1475-2875-12-152] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2013] [Accepted: 04/29/2013] [Indexed: 11/10/2022] Open
Abstract
Resistance to artemisinin casts a shadow on the fight against malaria. The importance of illegal gold miners and of malaria in isolated regions of French Guiana constitutes a threat that endangers the fight against malaria in the Amazon. The hurdles of French laws and the remoteness of the territory from France make it impossible for the system to adapt to the problem of total inaccessibility of an important part of the malaria problem. Transmission is high in these areas and gold miners self-medicate with erratic regimens of artemisinin combinations, thus creating perfect conditions for the emergence of resistance. What needs to be done is being done, but within the limits of national law, with some results. However, facing the same difficult problem, Suriname shows more flexibility and is doing much better than French Guiana despite having lower resources. Local authorities in French Guiana cannot overrule the laws that block appropriate malaria care from reaching a third of malaria-exposed persons. Thus the health authorities in France should take immediate calibrated legislative and financial measures to avoid a predictable disaster.
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Affiliation(s)
- Mathieu Nacher
- Centre d'Investigation Clinique Epidémiologie Clinique Antilles Guyane CIC-EC CIE 802, Cayenne General Hospital, Cayenne, French Guiana.
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610
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Labadie-Bracho M, Adhin MR. Increased pfmdr1 copy number in Plasmodium falciparum isolates from Suriname. Trop Med Int Health 2013; 18:796-9. [PMID: 23621761 DOI: 10.1111/tmi.12118] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amplification of the pfmdr1 gene is associated with clinical failures and reduced in vivo and in vitro sensitivity to both mefloquine and artemether-lumefantrine in South-East Asia. Several African countries have reported the absence or very low prevalence of increased copy number, whilst South American reports are limited to Peru without and Venezuela with increased pfmdr1 multiplication. The relative pfmdr1 copy numbers were assessed in 68 isolates from Suriname collected from different endemic villages (2005) and from mining areas (2009). 11% of the isolates harbour multiple copies of the pfmdr1 gene. Isolates originating from mining areas do not yet display a higher tendency for increased copy number and no significant differences could be registered within a time span of 4 years, but the mere presence of increased copy number warrants caution and should be considered as an early warning sign for emerging drug resistance in Suriname and South America.
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611
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Krishna S, Kremsner PG. Antidogmatic approaches to artemisinin resistance: reappraisal as treatment failure with artemisinin combination therapy. Trends Parasitol 2013; 29:313-7. [PMID: 23623760 DOI: 10.1016/j.pt.2013.04.001] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 03/29/2013] [Accepted: 04/01/2013] [Indexed: 11/17/2022]
Abstract
The definition of artemisinin resistance is becoming one of a prolonged parasite clearance phenotype, although this variable is a complex function of both host and parasite characteristics. We discuss some of the limitations of this definition of artemisinin resistance, particularly because of its potential global impact. This opinion article reviews the mechanisms underlying parasite clearance after artemisinin treatment and how these might relate to in vitro methods to assay for resistance. It revisits criteria for defining artemisinin resistance that are not currently being applied and suggests the term 'treatment failure of artemisinin combination therapy' (TFACT) as a more accurate description of most cases of 'artemisinin resistance'.
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Affiliation(s)
- Sanjeev Krishna
- Centre for Infection and Immunity, Division of Clinical Sciences, St George's, University of London, Cranmer Terrace, London SW17 0RE, UK.
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612
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High-throughput analysis of antimalarial susceptibility data by the WorldWide Antimalarial Resistance Network (WWARN) in vitro analysis and reporting tool. Antimicrob Agents Chemother 2013; 57:3121-30. [PMID: 23612201 DOI: 10.1128/aac.02350-12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Assessment of in vitro susceptibility is a fundamental component of antimalarial surveillance studies, but wide variations in the measurement of parasite growth and the calculation of inhibitory constants make comparisons of data from different laboratories difficult. Here we describe a Web-based, high-throughput in vitro analysis and reporting tool (IVART) generating inhibitory constants for large data sets. Fourteen primary data sets examining laboratory-determined susceptibility to artemisinin derivatives and artemisinin combination therapy partner drugs were collated from 11 laboratories. Drug concentrations associated with half-maximal inhibition of growth (IC50s) were determined by a modified sigmoid Emax model-fitting algorithm, allowing standardized analysis of 7,350 concentration-inhibition assays involving 1,592 isolates. Examination of concentration-inhibition data revealed evidence of apparent paradoxical growth at high concentrations of nonartemisinin drugs, supporting amendment of the method for calculating the maximal drug effect in each assay. Criteria for defining more-reliable IC50s based on estimated confidence intervals and growth ratios improved correlation coefficients for the drug pairs mefloquine-quinine and chloroquine-desethylamodiaquine in 9 of 11 and 8 of 8 data sets, respectively. Further analysis showed that maximal drug inhibition was higher for artemisinins than for other drugs, particularly in ELISA (enzyme-linked immunosorbent assay)-based assays, a finding consistent with the earlier onset of action of these drugs in the parasite life cycle. This is the first high-throughput analytical approach to apply consistent constraints and reliability criteria to large, diverse antimalarial susceptibility data sets. The data also illustrate the distinct biological properties of artemisinins and underline the need to apply more sensitive approaches to assessing in vitro susceptibility to these drugs.
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613
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Ex vivo responses of Plasmodium falciparum clinical isolates to conventional and new antimalarial drugs in Niger. Antimicrob Agents Chemother 2013; 57:3415-9. [PMID: 23612203 DOI: 10.1128/aac.02383-12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Little is known about resistance of Plasmodium falciparum to antimalarials in Sahelian countries. Here we investigated the drug susceptibilities of fresh isolates collected in Niger post-deployment of artemisinin-based combination therapies (ACTs). We found that the parasites remained highly susceptible to new (dihydroartemisinin, lumefantrine, pyronaridine, and piperaquine) and conventional (amodiaquine and chloroquine) antimalarial drugs. The introduction of ACTs in 2005 and their further deployment nationwide have therefore not resulted in a decrease in P. falciparum susceptibilities to these antimalarials.
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614
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Das D, Price RN, Bethell D, Guerin PJ, Stepniewska K. Early parasitological response following artemisinin-containing regimens: a critical review of the literature. Malar J 2013; 12:125. [PMID: 23602021 PMCID: PMC3649884 DOI: 10.1186/1475-2875-12-125] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 02/08/2013] [Indexed: 11/23/2022] Open
Abstract
Background Parasitaemia on Day 3 has been proposed as a useful alert of potential artemisinin resistance, however, the normal variation of parasite clearance observed in artemisinin-based combination therapy clinical trials is poorly documented. Methods The trends in early parasitological response following treatment with an artemisinin anti-malarial regimen were reviewed. A PubMed literature search identified all studies using an artemisinin regimen for uncomplicated falciparum malaria published between January 2000 and December 2011. Data from clinical studies were extracted for analysis using a standardized questionnaire. Results In total 65,078 patients were enrolled into 213 clinical trials with 413 treatment arms containing either an artemisinin derivative alone (n=26) or in combination with a partner drug (n=387). The proportion of patients remaining parasitaemic at 24, 48 and 72 hours was documented in 115 (28%), 167 (40%) and 153 (37%) treatment arms, respectively. Excluding resistance studies in Cambodia, the median proportion of patients still parasitaemic was 53.8% [range 3–95, IQR=30.5-69.2] on Day 1, 6% [range 0–65.9, IQR=2-11.5] on Day 2 and 0 [range 0–12.6, IQR=0-2] on Day 3. Comparing studies from 2000 to 2005 and 2006 to 2011, the median proportion of patients reported to remain parasitaemic at 72 hours decreased in Africa (1.2% vs 0%, p=0.007), but increased in Asia (0.4% vs 3.9%, p=0.076). In 95% of studies the proportion of patients with peripheral parasitaemia was less than 6% at 72 hours. Conclusions These results highlight the normal distribution of early parasitological responses following ACT, and the influence that heterogeneity in study design, host and parasite factors have in confounding a surveillance system based on Day 3 parasite positivity. Greater understanding of factors influencing parasite clearance is crucial, but will require analysis of pooled data from individual patient records.
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Affiliation(s)
- Debashish Das
- WorldWide Antimalarial Resistance Network, Oxford, UK
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615
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Pulcini S, Staines HM, Pittman JK, Slavic K, Doerig C, Halbert J, Tewari R, Shah F, Avery MA, Haynes RK, Krishna S. Expression in yeast links field polymorphisms in PfATP6 to in vitro artemisinin resistance and identifies new inhibitor classes. J Infect Dis 2013; 208:468-78. [PMID: 23599312 DOI: 10.1093/infdis/jit171] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND The mechanism of action of artemisinins against malaria is unclear, despite their widespread use in combination therapies and the emergence of resistance. RESULTS Here, we report expression of PfATP6 (a SERCA pump) in yeast and demonstrate its inhibition by artemisinins. Mutations in PfATP6 identified in field isolates (such as S769N) and in laboratory clones (such as L263E) decrease susceptibility to artemisinins, whereas they increase susceptibility to unrelated inhibitors such as cyclopiazonic acid. As predicted from the yeast model, Plasmodium falciparum with the L263E mutation is also more susceptible to cyclopiazonic acid. An inability to knockout parasite SERCA pumps provides genetic evidence that they are essential in asexual stages of development. Thaperoxides are a new class of potent antimalarial designed to act by inhibiting PfATP6. Results in yeast confirm this inhibition. CONCLUSIONS The identification of inhibitors effective against mutated PfATP6 suggests ways in which artemisinin resistance may be overcome.
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Affiliation(s)
- Serena Pulcini
- Division of Clinical Sciences, St. George's, University of London, UK
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616
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Weiss KM, Parker DM. Will you stop bugging me?: Malaria and the evolutionary challenge that won't go away. Evol Anthropol 2013; 22:46-51. [PMID: 23585377 DOI: 10.1002/evan.21340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Indexed: 11/06/2022]
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617
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Nkhoma SC, Stepniewska K, Nair S, Phyo AP, McGready R, Nosten F, Anderson TJC. Genetic evaluation of the performance of malaria parasite clearance rate metrics. J Infect Dis 2013; 208:346-50. [PMID: 23592863 PMCID: PMC3685230 DOI: 10.1093/infdis/jit165] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Accurate measurement of malaria parasite clearance rates (CRs) following artemisinin (ART) treatment is critical for resistance surveillance and research, and various CR metrics are currently used. We measured 13 CR metrics in 1472 ART-treated hyperparasitemia infections for which 6-hour parasite counts and parasite genotypes (93 single nucleotide polymorphisms [SNPs]) were available. We used heritability to evaluate the performance of each metric. Heritability ranged from 0.06 ± 0.06 (SD) for 50% parasite clearance times to 0.67 ± 0.04 (SD) for clearance half-lives estimated from 6-hour parasite counts. These results identify the measures that should be avoided and show that reliable clearance measures can be obtained with abbreviated monitoring protocols.
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618
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Sana TR, Gordon DB, Fischer SM, Tichy SE, Kitagawa N, Lai C, Gosnell WL, Chang SP. Global mass spectrometry based metabolomics profiling of erythrocytes infected with Plasmodium falciparum. PLoS One 2013; 8:e60840. [PMID: 23593322 PMCID: PMC3621881 DOI: 10.1371/journal.pone.0060840] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2012] [Accepted: 03/05/2013] [Indexed: 12/20/2022] Open
Abstract
Malaria is a global infectious disease that threatens the lives of millions of people. Transcriptomics, proteomics and functional genomics studies, as well as sequencing of the Plasmodium falciparum and Homo sapiens genomes, have shed new light on this host-parasite relationship. Recent advances in accurate mass measurement mass spectrometry, sophisticated data analysis software, and availability of biological pathway databases, have converged to facilitate our global, untargeted biochemical profiling study of in vitro P. falciparum-infected (IRBC) and uninfected (NRBC) erythrocytes. In order to expand the number of detectable metabolites, several key analytical steps in our workflows were optimized. Untargeted and targeted data mining resulted in detection of over one thousand features or chemical entities. Untargeted features were annotated via matching to the METLIN metabolite database. For targeted data mining, we queried the data using a compound database derived from a metabolic reconstruction of the P. falciparum genome. In total, over one hundred and fifty differential annotated metabolites were observed. To corroborate the representation of known biochemical pathways from our data, an inferential pathway analysis strategy was used to map annotated metabolites onto the BioCyc pathway collection. This hypothesis-generating approach resulted in over-representation of many metabolites onto several IRBC pathways, most prominently glycolysis. In addition, components of the “branched” TCA cycle, partial urea cycle, and nucleotide, amino acid, chorismate, sphingolipid and fatty acid metabolism were found to be altered in IRBCs. Interestingly, we detected and confirmed elevated levels for cyclic ADP ribose and phosphoribosyl AMP in IRBCs, a novel observation. These metabolites may play a role in regulating the release of intracellular Ca2+ during P. falciparum infection. Our results support a strategy of global metabolite profiling by untargeted data acquisition. Untargeted and targeted data mining workflows, when used together to perform pathway-inferred metabolomics, have the benefit of obviating MS/MS confirmation for every detected compound.
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Affiliation(s)
- Theodore R. Sana
- Life Sciences Group, Agilent Technologies, Santa Clara, California, United States of America
| | - D. Benjamin Gordon
- Life Sciences Group, Agilent Technologies, Santa Clara, California, United States of America
| | - Steven M. Fischer
- Life Sciences Group, Agilent Technologies, Santa Clara, California, United States of America
| | - Shane E. Tichy
- Life Sciences Group, Agilent Technologies, Santa Clara, California, United States of America
| | - Norton Kitagawa
- Life Sciences Group, Agilent Technologies, Santa Clara, California, United States of America
| | - Cindy Lai
- Life Sciences Group, Agilent Technologies, Santa Clara, California, United States of America
| | - William L. Gosnell
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
| | - Sandra P. Chang
- Department of Tropical Medicine, Medical Microbiology and Pharmacology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, Hawaii, United States of America
- * E-mail:
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Henriques G, Martinelli A, Rodrigues L, Modrzynska K, Fawcett R, Houston DR, Borges ST, d'Alessandro U, Tinto H, Karema C, Hunt P, Cravo P. Artemisinin resistance in rodent malaria--mutation in the AP2 adaptor μ-chain suggests involvement of endocytosis and membrane protein trafficking. Malar J 2013; 12:118. [PMID: 23561245 PMCID: PMC3655824 DOI: 10.1186/1475-2875-12-118] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 02/26/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The control of malaria, caused by Plasmodium falciparum, is hampered by the relentless evolution of drug resistance. Because artemisinin derivatives are now used in the most effective anti-malarial therapy, resistance to artemisinin would be catastrophic. Indeed, studies suggest that artemisinin resistance has already appeared in natural infections. Understanding the mechanisms of resistance would help to prolong the effective lifetime of these drugs. Genetic markers of resistance are therefore required urgently. Previously, a mutation in a de-ubiquitinating enzyme was shown to confer artemisinin resistance in the rodent malaria parasite Plasmodium chabaudi. METHODS Here, for a mutant P. chabaudi malaria parasite and its immediate progenitor, the in vivo artemisinin resistance phenotypes and the mutations arising using Illumina whole-genome re-sequencing were compared. RESULTS An increased artemisinin resistance phenotype is accompanied by one non-synonymous substitution. The mutated gene encodes the μ-chain of the AP2 adaptor complex, a component of the endocytic machinery. Homology models indicate that the mutated residue interacts with a cargo recognition sequence. In natural infections of the human malaria parasite P. falciparum, 12 polymorphisms (nine SNPs and three indels) were identified in the orthologous gene. CONCLUSION An increased artemisinin-resistant phenotype occurs along with a mutation in a functional element of the AP2 adaptor protein complex. This suggests that endocytosis and trafficking of membrane proteins may be involved, generating new insights into possible mechanisms of resistance. The genotypes of this adaptor protein can be evaluated for its role in artemisinin responses in human infections of P. falciparum.
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Affiliation(s)
- Gisela Henriques
- Centro de Malaria & Doenças Tropicais,LA/IHMT/Universidade Nova de Lisboa, Lisbon, Portugal.
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620
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Arora N, Gogna A, Kumar D, Puri K. Peripheral gangrene in Plasmodium vivax malaria: a rare manifestation. Trop Doct 2013; 43:23-4. [PMID: 23550200 DOI: 10.1177/0049475512472440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Symmetrical peripheral gangrene (SPG) is an extremely rare complication of malaria that has been well described in multiple case reports of Plasmodium falciparum and mixed infection. We present a case of malaria with isolated Pl. vivax infection complicated by SPG. This index case is the first reported case of peripheral gangrene involving bilateral hands and feet in Pl. vivax infection in an adult.
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Affiliation(s)
- Neha Arora
- Safdarjang Hospital and Vardhman Mahavir Medical College, New Delhi, India
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621
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Gatton ML, Chitnis N, Churcher T, Donnelly MJ, Ghani AC, Godfray HCJ, Gould F, Hastings I, Marshall J, Ranson H, Rowland M, Shaman J, Lindsay SW. The importance of mosquito behavioural adaptations to malaria control in Africa. Evolution 2013; 67:1218-30. [PMID: 23550770 PMCID: PMC3655544 DOI: 10.1111/evo.12063] [Citation(s) in RCA: 199] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Accepted: 01/12/2013] [Indexed: 01/25/2023]
Abstract
Over the past decade the use of long-lasting insecticidal nets (LLINs), in combination with improved drug therapies, indoor residual spraying (IRS), and better health infrastructure, has helped reduce malaria in many African countries for the first time in a generation. However, insecticide resistance in the vector is an evolving threat to these gains. We review emerging and historical data on behavioral resistance in response to LLINs and IRS. Overall the current literature suggests behavioral and species changes may be emerging, but the data are sparse and, at times unconvincing. However, preliminary modeling has demonstrated that behavioral resistance could have significant impacts on the effectiveness of malaria control. We propose seven recommendations to improve understanding of resistance in malaria vectors. Determining the public health impact of physiological and behavioral insecticide resistance is an urgent priority if we are to maintain the significant gains made in reducing malaria morbidity and mortality.
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Affiliation(s)
- Michelle L Gatton
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland 20892-2220, USA.
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622
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Abstract
A mathematical model which predicts the intraerythrocytic stages of Plasmodium falciparum infection was developed using data from malaria-infected mice. Variables selected accounted for levels of healthy red blood cells, merozoite (Plasmodium asexual phase) infected red blood cells, gametocyte (Plasmodium sexual phase) infected red blood cells and a phenomenological variable which accounts for the mean activity of the immune system of the host. The model built was able to reproduce the behavior of three different scenarios of malaria. It predicts the later dynamics of malaria-infected humans well after the first peak of parasitemia, the qualitative response of malaria-infected monkeys to vaccination and the changes observed in malaria-infected mice when they are treated with antimalarial drugs. The mathematical model was used to identify new targets to be focused on drug design. Optimization methodologies were applied to identify five targets for minimizing the parasite load; four of the targets thus identified have never before been taken into account in drug design. The potential targets include: 1) increasing the death rate of the gametocytes, 2) decreasing the invasion rate of the red blood cells by the merozoites, 3) increasing the transformation of merozoites into gametocytes, 4) decreasing the activation of the immune system by the gametocytes, and finally 5) a combination of the previous target with decreasing the recycling rate of the red blood cells. The first target is already used in current therapies, whereas the remainders are proposals for potential new targets. Furthermore, the combined target (the simultaneous decrease of the activation of IS by gRBC and the decrease of the influence of IS on the recycling of hRBC) is interesting, since this combination does not affect the parasite directly. Thus, it is not expected to generate selective pressure on the parasites, which means that it would not produce resistance in Plasmodium.
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Affiliation(s)
- Guido Santos
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, San Cristóbal de La Laguna, Tenerife, Spain
| | - Néstor V. Torres
- Departamento de Bioquímica y Biología Molecular, Universidad de La Laguna, San Cristóbal de La Laguna, Tenerife, Spain
- Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Universidad de La Laguna, San Cristóbal de La Laguna. Tenerife, Spain
- * E-mail:
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623
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von Seidlein L, Auburn S, Espino F, Shanks D, Cheng Q, McCarthy J, Baird K, Moyes C, Howes R, Ménard D, Bancone G, Winasti-Satyahraha A, Vestergaard LS, Green J, Domingo G, Yeung S, Price R. Review of key knowledge gaps in glucose-6-phosphate dehydrogenase deficiency detection with regard to the safe clinical deployment of 8-aminoquinoline treatment regimens: a workshop report. Malar J 2013; 12:112. [PMID: 23537118 PMCID: PMC3616837 DOI: 10.1186/1475-2875-12-112] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/14/2013] [Indexed: 01/24/2023] Open
Abstract
The diagnosis and management of glucose-6-phosphate dehydrogenase (G6PD) deficiency is a crucial aspect in the current phases of malaria control and elimination, which will require the wider use of 8-aminoquinolines for both reducing Plasmodium falciparum transmission and achieving the radical cure of Plasmodium vivax. 8-aminoquinolines, such as primaquine, can induce severe haemolysis in G6PD-deficient individuals, potentially creating significant morbidity and undermining confidence in 8-aminoquinoline prescription. On the other hand, erring on the side of safety and excluding large numbers of people with unconfirmed G6PD deficiency from treatment with 8-aminoquinolines will diminish the impact of these drugs. Estimating the remaining G6PD enzyme activity is the most direct, accessible, and reliable assessment of the phenotype and remains the gold standard for the diagnosis of patients who could be harmed by the administration of primaquine. Genotyping seems an unambiguous technique, but its use is limited by cost and the large range of recognized G6PD genotypes. A number of enzyme activity assays diagnose G6PD deficiency, but they require a cold chain, specialized equipment, and laboratory skills. These assays are impractical for care delivery where most patients with malaria live. Improvements to the diagnosis of G6PD deficiency are required for the broader and safer use of 8-aminoquinolines to kill hypnozoites, while lower doses of primaquine may be safely used to kill gametocytes without testing. The discussions and conclusions of a workshop conducted in Incheon, Korea in May 2012 to review key knowledge gaps in G6PD deficiency are reported here.
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Affiliation(s)
- Lorenz von Seidlein
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia.
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624
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Nilsen A, LaCrue AN, White KL, Forquer IP, Cross RM, Marfurt J, Mather MW, Delves MJ, Shackleford DM, Saenz FE, Morrisey JM, Steuten J, Mutka T, Li Y, Wirjanata G, Ryan E, Duffy S, Kelly JX, Sebayang BF, Zeeman AM, Noviyanti R, Sinden RE, Kocken CHM, Price RN, Avery VM, Angulo-Barturen I, Jiménez-Díaz MB, Ferrer S, Herreros E, Sanz LM, Gamo FJ, Bathurst I, Burrows JN, Siegl P, Guy RK, Winter RW, Vaidya AB, Charman SA, Kyle DE, Manetsch R, Riscoe MK. Quinolone-3-diarylethers: a new class of antimalarial drug. Sci Transl Med 2013; 5:177ra37. [PMID: 23515079 PMCID: PMC4227885 DOI: 10.1126/scitranslmed.3005029] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The goal for developing new antimalarial drugs is to find a molecule that can target multiple stages of the parasite's life cycle, thus impacting prevention, treatment, and transmission of the disease. The 4(1H)-quinolone-3-diarylethers are selective potent inhibitors of the parasite's mitochondrial cytochrome bc1 complex. These compounds are highly active against the human malaria parasites Plasmodium falciparum and Plasmodium vivax. They target both the liver and blood stages of the parasite as well as the forms that are crucial for disease transmission, that is, the gametocytes, the zygote, the ookinete, and the oocyst. Selected as a preclinical candidate, ELQ-300 has good oral bioavailability at efficacious doses in mice, is metabolically stable, and is highly active in blocking transmission in rodent models of malaria. Given its predicted low dose in patients and its predicted long half-life, ELQ-300 has potential as a new drug for the treatment, prevention, and, ultimately, eradication of human malaria.
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Affiliation(s)
- Aaron Nilsen
- VA Medical Center, 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, USA
| | - Alexis N. LaCrue
- Department of Global Health, College of Public Health, 3720 Spectrum Blvd. (Ste 304), Tampa, FL 33612, USA
| | - Karen L. White
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Isaac P. Forquer
- VA Medical Center, 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, USA
| | - Richard M. Cross
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620-5250, USA
| | - Jutta Marfurt
- Global Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Michael W. Mather
- Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
| | - Michael J. Delves
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - David M. Shackleford
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Fabian E. Saenz
- Department of Global Health, College of Public Health, 3720 Spectrum Blvd. (Ste 304), Tampa, FL 33612, USA
| | - Joanne M. Morrisey
- Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
| | - Jessica Steuten
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Tina Mutka
- Department of Global Health, College of Public Health, 3720 Spectrum Blvd. (Ste 304), Tampa, FL 33612, USA
| | - Yuexin Li
- VA Medical Center, 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, USA
| | - Grennady Wirjanata
- Global Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
| | - Eileen Ryan
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Sandra Duffy
- Eskitis Institute for Cell & Molecular Therapies, Brisbane Innovation Park, Nathan campus, Griffith University, QLD 4111, Australia
| | - Jane Xu Kelly
- VA Medical Center, 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, USA
| | - Boni F. Sebayang
- Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta 10430, Indonesia
| | - Anne-Marie Zeeman
- Department of Parasitology, Biomedical Primate Research Centre, P.O. Box 3306, 2280 GH Rijswijk, The Netherlands
| | - Rintis Noviyanti
- Eijkman Institute for Molecular Biology, Jl. Diponegoro 69, Jakarta 10430, Indonesia
| | - Robert E. Sinden
- Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom
| | - Clemens H. M. Kocken
- Department of Parasitology, Biomedical Primate Research Centre, P.O. Box 3306, 2280 GH Rijswijk, The Netherlands
| | - Ric N. Price
- Global Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7LJ, UK
| | - Vicky M. Avery
- Eskitis Institute for Cell & Molecular Therapies, Brisbane Innovation Park, Nathan campus, Griffith University, QLD 4111, Australia
| | - Iñigo Angulo-Barturen
- GlaxoSmithKline, Medicines Development Campus, Diseases of the Developing World, Severo Ochoa 2, Tres Cantos 28760, Madrid, Spain
| | - María Belén Jiménez-Díaz
- GlaxoSmithKline, Medicines Development Campus, Diseases of the Developing World, Severo Ochoa 2, Tres Cantos 28760, Madrid, Spain
| | - Santiago Ferrer
- GlaxoSmithKline, Medicines Development Campus, Diseases of the Developing World, Severo Ochoa 2, Tres Cantos 28760, Madrid, Spain
| | - Esperanza Herreros
- GlaxoSmithKline, Medicines Development Campus, Diseases of the Developing World, Severo Ochoa 2, Tres Cantos 28760, Madrid, Spain
| | - Laura M. Sanz
- GlaxoSmithKline, Medicines Development Campus, Diseases of the Developing World, Severo Ochoa 2, Tres Cantos 28760, Madrid, Spain
| | - Francisco-Javier Gamo
- GlaxoSmithKline, Medicines Development Campus, Diseases of the Developing World, Severo Ochoa 2, Tres Cantos 28760, Madrid, Spain
| | - Ian Bathurst
- Medicines for Malaria Venture, 20, route de Pré-Bois, PO Box 1826, 1215 Geneva 15, Switzerland
| | - Jeremy N. Burrows
- Medicines for Malaria Venture, 20, route de Pré-Bois, PO Box 1826, 1215 Geneva 15, Switzerland
| | - Peter Siegl
- Siegl Pharma Consulting LLC, Blue Bell, PA, USA
| | - R. Kiplin Guy
- Chemical Biology & Therapeutics, St. Jude Children’s Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105-3678 USA
| | - Rolf W. Winter
- VA Medical Center, 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, USA
| | - Akhil B. Vaidya
- Department of Microbiology and Immunology, Drexel University College of Medicine, 2900 Queen Lane, Philadelphia, PA 19129, USA
| | - Susan A. Charman
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Dennis E. Kyle
- Department of Global Health, College of Public Health, 3720 Spectrum Blvd. (Ste 304), Tampa, FL 33612, USA
| | - Roman Manetsch
- Department of Chemistry, University of South Florida, 4202 E. Fowler Avenue, Tampa, FL 33620-5250, USA
| | - Michael K. Riscoe
- VA Medical Center, 3710 SW US Veterans Hospital Road, Portland, Oregon 97239, USA
- Department of Molecular Microbiology and Immunology, 3181 Sam Jackson Blvd., Portland, Oregon 97239, USA
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625
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Kyaw MP, Nyunt MH, Chit K, Aye MM, Aye KH, Aye MM, Lindegardh N, Tarning J, Imwong M, Jacob CG, Rasmussen C, Perin J, Ringwald P, Nyunt MM. Reduced susceptibility of Plasmodium falciparum to artesunate in southern Myanmar. PLoS One 2013; 8:e57689. [PMID: 23520478 PMCID: PMC3592920 DOI: 10.1371/journal.pone.0057689] [Citation(s) in RCA: 168] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Accepted: 01/24/2013] [Indexed: 12/01/2022] Open
Abstract
Background Plasmodium falciparum resistance to artemisinins, the first line treatment for malaria worldwide, has been reported in western Cambodia. Resistance is characterized by significantly delayed clearance of parasites following artemisinin treatment. Artemisinin resistance has not previously been reported in Myanmar, which has the highest falciparum malaria burden among Southeast Asian countries. Methods A non-randomized, single-arm, open-label clinical trial of artesunate monotherapy (4 mg/kg daily for seven days) was conducted in adults with acute blood-smear positive P. falciparum malaria in Kawthaung, southern Myanmar. Parasite density was measured every 12 hours until two consecutive negative smears were obtained. Participants were followed weekly at the study clinic for three additional weeks. Co-primary endpoints included parasite clearance time (the time required for complete clearance of initial parasitemia), parasite clearance half-life (the time required for parasitemia to decrease by 50% based on the linear portion of the parasite clearance slope), and detectable parasitemia 72 hours after commencement of artesunate treatment. Drug pharmacokinetics were measured to rule out delayed clearance due to suboptimal drug levels. Results The median (range) parasite clearance half-life and time were 4.8 (2.1–9.7) and 60 (24–96) hours, respectively. The frequency distributions of parasite clearance half-life and time were bimodal, with very slow parasite clearance characteristic of the slowest-clearing Cambodian parasites (half-life longer than 6.2 hours) in approximately 1/3 of infections. Fourteen of 52 participants (26.9%) had a measurable parasitemia 72 hours after initiating artesunate treatment. Parasite clearance was not associated with drug pharmacokinetics. Conclusions A subset of P. falciparum infections in southern Myanmar displayed markedly delayed clearance following artemisinin treatment, suggesting either emergence of artemisinin resistance in southern Myanmar or spread to this location from its site of origin in western Cambodia. Resistance containment efforts are underway in Myanmar. Trial Registration Australian New Zealand Clinical Trials Registry ACTRN12610000896077
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Affiliation(s)
- Myat P. Kyaw
- Department of Medical Research (Lower Myanmar), Yangon, The Republic of the Union of Myanmar
| | - Myat H. Nyunt
- Department of Medical Research (Lower Myanmar), Yangon, The Republic of the Union of Myanmar
| | - Khin Chit
- Department of Medical Research (Lower Myanmar), Yangon, The Republic of the Union of Myanmar
| | - Moe M. Aye
- Department of Medical Research (Lower Myanmar), Yangon, The Republic of the Union of Myanmar
| | - Kyin H. Aye
- Department of Medical Research (Lower Myanmar), Yangon, The Republic of the Union of Myanmar
| | - Moe M. Aye
- Department of Medical Research (Lower Myanmar), Yangon, The Republic of the Union of Myanmar
| | - Niklas Lindegardh
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Joel Tarning
- Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok, Thailand
- Center for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Mahidol University, Bangkok, Thailand
| | - Christopher G. Jacob
- Malaria Group, Howard Hughes Medical Institute/Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Charlotte Rasmussen
- Drug Resistance and Containment Unit, Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Jamie Perin
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Pascal Ringwald
- Drug Resistance and Containment Unit, Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Myaing M. Nyunt
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, United States of America
- Division of Clinical Pharmacology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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626
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Sawa P, Shekalaghe SA, Drakeley CJ, Sutherland CJ, Mweresa CK, Baidjoe AY, Manjurano A, Kavishe RA, Beshir KB, Yussuf RU, Omar SA, Hermsen CC, Okell L, Schallig HDFH, Sauerwein RW, Hallett RL, Bousema T. Malaria transmission after artemether-lumefantrine and dihydroartemisinin-piperaquine: a randomized trial. J Infect Dis 2013; 207:1637-45. [PMID: 23468056 DOI: 10.1093/infdis/jit077] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Artemisinin-based combination therapy (ACT) reduces the potential for malaria transmission, compared with non-ACTs. It is unclear whether this effect differs between ACTs. METHODS A total of 298 children (age, 6 months to 10 years) with uncomplicated falciparum malaria were randomized to artemether-lumefantrine (AL; n = 153) or dihydroartemisinin-piperaquine (DP; n = 145) in Mbita, a community in western Kenya. Gametocyte carriage was determined by molecular methods on days 0, 1, 2, 3, 7, 14, 28, and 42 after treatment initiation. The gametocyte infectiousness to mosquitoes was determined by mosquito-feeding assays on day 7 after beginning therapy. RESULTS The cumulative risk of recurrent parasitemia on day 42 after initiation of treatment, unadjusted by polymerase chain reaction findings, was 20.7% (95% confidence interval [CI], 14.4-28.2) for AL, compared with 3.7% (95% CI, 1.2-8.5) for DP (P < .001). The mean duration of gametocyte carriage was 5.5 days (95% CI, 3.6-8.5) for AL and 15.3 days (95% CI, 9.7-24.2) for DP (P = .001). The proportion of mosquitoes that became infected after feeding on blood from AL-treated children was 1.88% (43 of 2293), compared with 3.50% (83 of 2371) for those that fed on blood from DP-treated children (P = .06); the oocyst burden among mosquitoes was lower among those that fed on blood from AL-treated children (P = .005) CONCLUSIONS: While DP was associated with a longer prophylactic time after treatment, gametocyte carriage and malaria transmission to mosquitoes was lower after AL treatment. CLINICAL TRIALS REGISTRATION NCT00868465.
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Affiliation(s)
- Patrick Sawa
- Human Health Division, International Centre for Insect Physiology and Ecology, Mbita Point, Nairobi, Kenya
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627
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628
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Lopera-Mesa TM, Doumbia S, Chiang S, Zeituni AE, Konate DS, Doumbouya M, Keita AS, Stepniewska K, Traore K, Diakite SAS, Ndiaye D, Sa JM, Anderson JM, Fay MP, Long CA, Diakite M, Fairhurst RM. Plasmodium falciparum clearance rates in response to artesunate in Malian children with malaria: effect of acquired immunity. J Infect Dis 2013; 207:1655-63. [PMID: 23448727 PMCID: PMC3636783 DOI: 10.1093/infdis/jit082] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Background. Artemisinin resistance, a long parasite clearance half-life in response to artemisinin, has been described in patients with Plasmodium falciparum malaria in southeast Asia. Few baseline half-lives have been reported from Africa, where artemisinins were recently introduced. Methods. We treated P. falciparum malaria in 215 Malian children aged 0.5–15 years with artesunate (0, 24, 48 hours) and amodiaquine (72, 96, 120 hours). We estimated half-life by measuring parasite density every 6 hours until undetectable and evaluated the effects of age, sex, ethnicity, and red blood cell (RBC) polymorphisms on half-life. We quantified the proportion of parasitized RBCs recognized by autologous immunoglobulin G (IgG). Results. The geometric mean half-life was 1.9 hours (95% confidence interval, 1.8–2.0) and did not correlate with parasite ex vivo susceptibility to artemisinins. In a linear model accounting for host factors, half-life decreased by 4.1 minutes for every 1-year increase in age. The proportion of parasitized RBCs recognized by IgG correlated inversely with half-life (r = −0.475; P = .0006). Conclusions. Parasite clearance in response to artesunate is faster in Mali than in southeast Asia. IgG responses to parasitized RBCs shorten half-life and may influence this parameter in areas where age is not an adequate surrogate of immunity and correlates of parasite-clearing immunity have not been identified. Clinical Trials Registration. NCT00669084.
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Affiliation(s)
- Tatiana M Lopera-Mesa
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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629
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Lombard MC, N’Da DD, Tran Van Ba C, Wein S, Norman J, Wiesner L, Vial H. Potent in vivo anti-malarial activity and representative snapshot pharmacokinetic evaluation of artemisinin-quinoline hybrids. Malar J 2013; 12:71. [PMID: 23433124 PMCID: PMC3598976 DOI: 10.1186/1475-2875-12-71] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 02/12/2013] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Because Plasmodium falciparum displays increase tolerance against the recommended artemisinin combination therapies (ACT), new classes of anti-malarial drugs are urgently required. Previously synthesized artemisinin-aminoquinoline hybrids were evaluated to ascertain whether the potent low nanomolar in vitro anti-plasmodial activity would carry over in vivo against Plasmodium vinckei. A snapshot pharmacokinetic analysis was carried out on one of the hybrids to obtain an indication of the pharmacokinetic properties of this class of anti-malarial drugs. METHODS In vitro activity of hybrids 2 and 3 were determined against the 3D7 strain of P. falciparum. Plasmodium vinckei-infected mice were treated with hybrids 1 - 3 for four days at a dosage of 0.8 mg/kg, 2.5 mg/kg, 7.5 mg/kg or 15 mg/kg intraperitoneally (ip), or orally (per os) with 2.7 mg/kg, 8.3 mg/kg, 25 mg/kg or 50 mg/kg. Artesunate was used as reference drug. A snapshot oral and IV pharmacokinetic study was performed on hybrid 2. RESULTS Hybrids 1 - 3 displayed potent in vivo anti-malarial activity with ED50 of 1.1, 1.4 and <0.8 mg/kg by the ip route and 12, 16 and 13 mg/kg per os, respectively. Long-term monitoring of parasitaemia showed a complete cure of mice (without recrudescence) at 15 mg/kg via ip route and at 50 mg/kg by oral route for hybrid 1 and 2, whereas artesunate was only able to provide a complete cure at 30 mg/kg ip and 80 mg/kg per os. CONCLUSIONS These compounds provide a new class of desperately needed anti-malarial drug. Despite a short half-life and moderate oral bioavailability, this class of compounds was able to cure malaria in mice at very low dosages. The optimum linker length for anti-malarial activity was found to be a diaminoalkyl chain consisting of two carbon atoms either methylated or unmethylated.
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Affiliation(s)
- Marli C Lombard
- Pharmaceutical Chemistry, North-West University, Potchefstroom 2531, South Africa
| | - David D N’Da
- Pharmaceutical Chemistry, North-West University, Potchefstroom 2531, South Africa
| | - Christophe Tran Van Ba
- Centre National de la Recherche Scientifique, Université Montpellier 2, 34095, Montpellier Cedex 05, France
| | - Sharon Wein
- Centre National de la Recherche Scientifique, Université Montpellier 2, 34095, Montpellier Cedex 05, France
| | - Jennifer Norman
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town 7925, South Africa
| | - Lubbe Wiesner
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town 7925, South Africa
| | - Henri Vial
- Centre National de la Recherche Scientifique, Université Montpellier 2, 34095, Montpellier Cedex 05, France
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630
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Duparc S, Borghini-Fuhrer I, Craft CJ, Arbe-Barnes S, Miller RM, Shin CS, Fleckenstein L. Safety and efficacy of pyronaridine-artesunate in uncomplicated acute malaria: an integrated analysis of individual patient data from six randomized clinical trials. Malar J 2013; 12:70. [PMID: 23433102 PMCID: PMC3598551 DOI: 10.1186/1475-2875-12-70] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2012] [Accepted: 02/18/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Pyronaridine-artesunate (PA) is indicated for the treatment of acute uncomplicated Plasmodium falciparum and Plasmodium vivax malaria. METHODS Individual patient data on safety outcomes were integrated from six randomized clinical trials conducted in Africa and Asia in patients with microscopically confirmed P. falciparum (five studies) or P. vivax (one study) malaria. Efficacy against P. falciparum was evaluated across three Phase III clinical trials. RESULTS The safety population included 2,815 patients randomized to PA, 1,254 to comparators: mefloquine + artesunate (MQ + AS), artemether-lumefantrine (AL), or chloroquine. All treatments were generally well tolerated. Adverse events occurred in 57.2% (1,611/2,815) of patients with PA versus 51.5% (646/1,254) for comparators, most commonly (PA; comparators): headache (10.6%; 9.9%), cough (5.9%; 5.6%) and anaemia (4.5%; 2.9%). Serious averse events were uncommon for all treatments (0-0.7%). Transient increases in alanine aminotransferase and aspartate aminotransferase were observed with PA but did not lead to any clinical sequelae. For P. falciparum malaria, day-28 PCR-corrected adequate clinical and parasitological response with PA was 93.6% ([1,921/2,052] 95% CI 92.6, 94.7) in the intent-to-treat population and 98.5% ([1,852/1,880] 95% CI 98.0, 99.1) in the per-protocol population. Median parasite clearance time was 24.1 h with PA, 31.9 h with MQ + AS, and 24.0 h with AL. Median fever clearance time was 15.5 h with PA, 15.8 h with MQ + AS, and 14.0 h with AL. By day 42, P. falciparum gametocytes had declined to near zero for all treatments. CONCLUSIONS Pyronaridine-artesunate was well tolerated with no safety concerns with the exception of mostly mild transient rises in transaminases. Efficacy was high and met the requirements for use as first-line therapy. Pyronaridine-artesunate should be considered for inclusion in malaria treatment programmes. TRIAL REGISTRATION Clinicaltrials.gov: NCT00331136; NCT00403260; NCT00422084; NCT00440999; NCT00541385; NCT01594931.
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Affiliation(s)
- Stephan Duparc
- Medicines for Malaria Venture (MMV), International Center Cointrin, Route de Pré-Bois 20, PO Box 1826, CH-1215, Geneva 15, Switzerland.
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631
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Altered temporal response of malaria parasites determines differential sensitivity to artemisinin. Proc Natl Acad Sci U S A 2013; 110:5157-62. [PMID: 23431146 DOI: 10.1073/pnas.1217452110] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Reports of emerging resistance to first-line artemisinin antimalarials make it critical to define resistance mechanisms and identify in vitro correlates of resistance. Here we combine unique in vitro experimental and analytical approaches to mimic in vivo drug exposure in an effort to provide insight into mechanisms of drug resistance. Tightly synchronized parasites exposed to short drug pulses exhibit large stage-dependent differences in their drug response that correlate with hemoglobin digestion throughout most of the asexual cycle. As a result, ring-stage parasites can exhibit >100-fold lower sensitivity to short drug pulses than trophozoites, although we identify a subpopulation of rings (2-4 h postinvasion) that exhibits hypersensitivity. We find that laboratory strains that show little differences in drug sensitivity in standard in vitro assays exhibit substantial (>95-fold) difference in sensitivity when exposed to short drug pulses. These stage- and strain-dependent differences in drug sensitivity reflect differential response lag times with rings exhibiting lag times of up to 4 h. A simple model that assumes that the parasite experiences a saturable effective drug dose describes the complex dependence of parasite viability on both drug concentration and exposure time and is used to demonstrate that small changes in the parasite's drug response profile can dramatically alter the sensitivity to artemisinins. This work demonstrates that effective resistance can arise from the interplay between the short in vivo half-life of the drug and the stage-specific lag time and provides the framework for understanding the mechanisms of drug action and parasite resistance.
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632
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Antimalarial drug resistance: a review of the biology and strategies to delay emergence and spread. Int J Antimicrob Agents 2013; 41:311-7. [PMID: 23394809 DOI: 10.1016/j.ijantimicag.2012.12.007] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/12/2012] [Accepted: 12/13/2012] [Indexed: 11/21/2022]
Abstract
The emergence of resistance to former first-line antimalarial drugs has been an unmitigated disaster. In recent years, artemisinin class drugs have become standard and they are considered an essential tool for helping to eradicate the disease. However, their ability to reduce morbidity and mortality and to slow transmission requires the maintenance of effectiveness. Recently, an artemisinin delayed-clearance phenotype was described. This is believed to be the precursor to resistance and threatens local elimination and global eradication plans. Understanding how resistance emerges and spreads is important for developing strategies to contain its spread. Resistance is the result of two processes: (i) drug selection of resistant parasites; and (ii) the spread of resistance. In this review, we examine the factors that lead to both drug selection and the spread of resistance. We then examine strategies for controlling the spread of resistance, pointing out the complexities and deficiencies in predicting how resistance will spread.
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633
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Pathogen-host-environment interplay and disease emergence. Emerg Microbes Infect 2013; 2:e5. [PMID: 26038452 PMCID: PMC3630490 DOI: 10.1038/emi.2013.5] [Citation(s) in RCA: 148] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/07/2012] [Accepted: 01/07/2013] [Indexed: 12/13/2022]
Abstract
Gaining insight in likely disease emergence scenarios is critical to preventing such events from happening. Recent focus has been on emerging zoonoses and on identifying common patterns and drivers of emerging diseases. However, no overarching framework exists to integrate knowledge on all emerging infectious disease events. Here, we propose such a conceptual framework based on changes in the interplay of pathogens, hosts and environment that lead to the formation of novel disease patterns and pathogen genetic adjustment. We categorize infectious disease emergence events into three groups: (i) pathogens showing up in a novel host, ranging from spill-over, including zoonoses, to complete species jumps; (ii) mutant pathogens displaying novel traits in the same host, including an increase in virulence, antimicrobial resistance and host immune escape; and (iii) disease complexes emerging in a new geographic area, either through range expansion or through long distance jumps. Each of these categories is characterized by a typical set of drivers of emergence, matching pathogen trait profiles, disease ecology and transmission dynamics. Our framework may assist in disentangling and structuring the rapidly growing amount of available information on infectious diseases. Moreover, it may contribute to a better understanding of how human action changes disease landscapes globally.
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634
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Thomsen TT, Madsen LB, Hansson HH, Tomás EVE, Charlwood D, Bygbjerg IC, Alifrangis M. Rapid selection of Plasmodium falciparum chloroquine resistance transporter gene and multidrug resistance gene-1 haplotypes associated with past chloroquine and present artemether-lumefantrine use in Inhambane District, southern Mozambique. Am J Trop Med Hyg 2013; 88:536-41. [PMID: 23382159 DOI: 10.4269/ajtmh.12-0525] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Chloroquine (CQ) use in Mozambique was stopped in 2002 and artemether-lumefantrine (AL) was implemented in 2008. In light of no use of CQ and extensive use of AL, we determined the frequency of molecular markers of Plasmodium falciparum drug resistance/tolerance to CQ and AL in persons living in Linga-Linga, an isolated peninsula and in Furvela village, which is located 8 km inland. The P. falciparum chloroquine resistance transporter gene CVMNK wild type increased in frequency from 43.9% in 2009 to 66.4% in 2010 (P ≤ 0.001), and combined P. falciparum multidrug resistance gene 1 N86-184F-D1246 haplotype increased significantly between years (P = 0.039). The combination of P. falciparum chloroquine resistance transporter gene CVMNK and P. falciparum multidrug resistance gene NFD increased from 24.3% (2009) to 45.3% in (2010, P = 0.017). The rapid changes observed may largely be caused by decreased use of CQ and large-scale use of AL. In the absence of a clear AL-resistance marker and the (almost) continent-wide use of AL in sub-Saharan Africa, and when considering CQ reintroduction, continued monitoring of these markers is needed.
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Affiliation(s)
- Thomas T Thomsen
- Section for Functional Genomics, Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen N, Denmark.
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635
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Lwin KM, Peto TJ, White NJ, Day NP, Nosten F, Parker M, Cheah PY. The practicality and sustainability of a community advisory board at a large medical research unit on the Thai-Myanmar border. Health (London) 2013; 5:229-236. [PMID: 36860549 PMCID: PMC7614254 DOI: 10.4236/health.2013.52031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Community engagement is increasingly promoted to strengthen the ethics of medical research in low-income countries. One strategy is to use community advisory boards (CABs): semi-independent groups that can potentially safeguard the rights of study participants and help improve research. However, there is little published on the experience of operating and sustaining CABs. The Shoklo Malaria Research Unit (SMRU) has been conducting research and providing healthcare in a population of refugees, migrant workers, and displaced people on the Thai-Myanmar border for over 25 years. In 2009 SMRU facilitated the establishment of the Tak Province Community Ethics Advisory Board (T-CAB) in an effort to formally engage with the local communities to both to obtain advice and to establish a participatory framework within which studies and the provision of health care take place. In this paper, we draw on our experience of community engagement in this unique setting, and our interactions with the past and present CAB members to critically reflect upon the CAB's goals, structure and operations with a focus on the practicalities, what worked, what did not, and its future directions.
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Affiliation(s)
- Khin Maung Lwin
- Shoklo Malaria Research Unit, Mae Sot, Thailand,Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Thomas J Peto
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas P.J. Day
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Francois Nosten
- Shoklo Malaria Research Unit, Mae Sot, Thailand,Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Michael Parker
- The Ethox Centre, Department of Public Health and Primary Care, University of Oxford, Oxford, United Kingdom
| | - Phaik Yeong Cheah
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
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636
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Gharbi M, Flegg JA, Hubert V, Kendjo E, Metcalf JE, Bertaux L, Guérin PJ, Le Bras J, Aboubaca A, Agnamey P, Angoulvant A, Barbut P, Basset D, Belkadi G, Bellanger AP, Bemba D, Benoit-Vica F, Berry A, Bigel ML, Bonhomme J, Botterel F, Bouchaud O, Bougnoux ME, Bourée P, Bourgeois N, Branger C, Bret L, Buret B, Casalino E, Chevrier S, Conquere de Monbrison F, Cuisenier B, Danis M, Darde ML, De Gentile L, Delarbre JM, Delaunay P, Delaval A, Desoubeaux G, Develoux M, Dunand J, Durand R, Eloy O, Fauchet N, Faugere B, Faye A, Fenneteau O, Flori P, Fontrouge M, Garabedian C, Gayandrieu F, Godineau N, Houzé P, Houzé S, Hurst JP, Ichou H, Lachaud L, Lebuisson A, Lefevre M, LeGuern AS, Le Moal G, Lusina D, Machouart MC, Malvy D, Matheron S, Maubon D, Mechali D, Megarbane B, Menard G, Millon L, Aiach MM, Minodier P, Morelle C, Nevez G, Parola P, Parzy D, Patey O, Patoz P, Penn P, Perignon A, Picot S, Pilo JE, Poilane I, Pons D, Poupart M, Pradines B, Raffenot D, Rapp C, Receveur MC, Sarfati C, Senghor Y, Simon F, Siriez JY, Taudon N, Thellier M, Thouvenin M, Toubas D. Longitudinal study assessing the return of chloroquine susceptibility of Plasmodium falciparum in isolates from travellers returning from West and Central Africa, 2000-2011. Malar J 2013; 12:35. [PMID: 23351608 PMCID: PMC3583707 DOI: 10.1186/1475-2875-12-35] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 01/19/2013] [Indexed: 11/10/2022] Open
Abstract
Background Chloroquine (CQ) was the main malaria therapy worldwide from the 1940s until the 1990s. Following the emergence of CQ-resistant Plasmodium falciparum, most African countries discontinued the use of CQ, and now promote artemisinin-based combination therapy as the first-line treatment. This change was generally initiated during the last decade in West and Central Africa. The aim of this study is to describe the changes in CQ susceptibility in this African region, using travellers returning from this region as a sentinel system. Methods The study was conducted by the Malaria National Reference Centre, France. The database collated the pfcrtK76T molecular marker for CQ susceptibility and the in vitro response to CQ of parasites from travellers’ isolates returning from Senegal, Mali, Ivory Coast or Cameroon. As a proxy of drug pressure, data regarding CQ intake in febrile children were collated for the study period. Logistic regression models were used to detect trends in the proportions of CQ resistant isolates. Results A total of 2874 parasite isolates were genotyped between 2000–2011. The prevalence of the pfcrt76T mutant genotype significantly decreased for Senegal (from 78% to 47%), Ivory Coast (from 63% to 37%), Cameroon (from 90% to 59%) and remained stable for Mali. The geometric mean of the 50% inhibitory concentration (IC50) of CQ in vitro susceptibility and the proportion of resistant isolates (defining resistance as an IC50 value > 100 nM) significantly decreased for Senegal (from 86 nM (59%) to 39 nM (25%)), Mali (from 84 nM (50%) to 51 nM (31%)), Ivory Coast (from 75 nM (59%) to 29 nM (16%)) and Cameroon (from 181 nM (75%) to 51 nM (37%)). Both analyses (molecular and in vitro susceptibility) were performed for the 2004–2011 period, after the four countries had officially discontinued CQ and showed an accelerated decline of the resistant isolates for the four countries. Meanwhile, CQ use among children significantly deceased in this region (fixed effects slope = −0.3, p < 10-3). Conclusions An increase in CQ susceptibility following official withdrawal of the drug was observed in travellers returning from West and Central African countries. The same trends were observed for molecular and in vitro analysis between 2004-2011and they correlated to the decrease of the drug pressure.
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Affiliation(s)
- Myriam Gharbi
- Mère et enfant face aux infections tropicales, IRD unité mixte de recherche 216, Université Paris Descartes-Paris V, 4 avenue de l'Observatoire, Paris Cedex 06 75270, France.
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637
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Yeka A, Tibenderana J, Achan J, D'Alessandro U, Talisuna AO. Efficacy of quinine, artemether-lumefantrine and dihydroartemisinin-piperaquine as rescue treatment for uncomplicated malaria in Ugandan children. PLoS One 2013; 8:e53772. [PMID: 23349741 PMCID: PMC3551967 DOI: 10.1371/journal.pone.0053772] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Accepted: 12/05/2012] [Indexed: 01/09/2023] Open
Abstract
Background The treatment of falciparum malaria poses unique challenges in settings where malaria transmission intensity is high because recurrent infections are common. These could be new infections, recrudescences, or a combination of the two. Though several African countries continue to use quinine as the second line treatment for patients with recurrent infections, there is little information on its efficacy when used for rescue therapy. Moreover, such practice goes against the World Health Organisation (WHO) recommendation to use combination therapy for uncomplicated malaria. Methods We conducted a nested, randomized, open label, three-arm clinical trial of rescue therapy in children 6–59 months old with recurrent malaria infection during 28 days post treatment with artemisinin combination treatment (ACT). Patients were randomly assigned to receive either quinine, artemether-lumefantrine (AL) or dihydroartemisinin-piperaquine (DHAPQ), and actively followed up for 28 days. Findings Among 220 patients enrolled, 217 (98.6 %) were assigned an efficacy outcome and 218 (99.1 %) were assessed for safety. The risk of recurrent infection was significantly higher in patients treated with quinine (70 %, 74/110, HR = 3.9; 95 % CI: 2.4–6.7, p<0.0001) and AL (60%, 21/35, HR = 3.3; 95 % CI: 1.8–6.3, p<0.0002), compared to DHAPQ (25%, 18/72). Recrudescence tended to be lower in the DHAPQ (1%, 1/72) than in the quinine (7%, 8/110) or AL (6 %, 2/35) group, though it was not statistically significant. No serious adverse events were reported. Conclusion Recurrent infections observed after the administration of an ACT can be successfully treated with an alternative ACT rather than with quinine. Trial Registration Current Controlled Trials ISRCTN99046537
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Affiliation(s)
- Adoke Yeka
- Uganda Malaria Surveillance Project, Kampala, Uganda.
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638
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Talisuna AO, Karema C, Ogutu B, Juma E, Logedi J, Nyandigisi A, Mulenga M, Mbacham WF, Roper C, Guerin PJ, D'Alessandro U, Snow RW. Mitigating the threat of artemisinin resistance in Africa: improvement of drug-resistance surveillance and response systems. THE LANCET. INFECTIOUS DISEASES 2013; 12:888-96. [PMID: 23099083 DOI: 10.1016/s1473-3099(12)70241-4] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Artemisinin-resistant Plasmodium falciparum malaria has emerged in western Cambodia and has been detected in western Thailand. The situation is ominously reminiscent of the emergence of resistance to chloroquine and to sulfadoxine-pyrimethamine several decades ago. Artemisinin resistance is a major threat to global public health, with the most severe potential effects in sub-Saharan Africa, where the disease burden is highest and systems for monitoring and containment of resistance are inadequate. The mechanisms that underlie artemisinin resistance are not fully understood. The main phenotypic trait associated with resistance is a substantial delay in parasite clearance, so far reported in southeast Asia but not in Africa. One of the pillars of the WHO global plan for artemisinin resistance containment is to increase monitoring and surveillance. In this Personal View, we propose strategies that should be adopted by malaria-endemic countries in Africa: resource mobilisation to reactivate regional surveillance networks, establishment of baseline parasite clearance profiles to serve as benchmarks to track emerging artemisinin resistance, improved data sharing to allow pooled analyses to identify rare events, modelling of risk factors for drug resistance, and development and validation of new approaches to monitor resistance.
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Affiliation(s)
- Ambrose O Talisuna
- Malaria Public Health and Epidemiology Group, University of Oxford and KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya.
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639
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MDR1-associated resistance to artesunate+mefloquine does not impair blood-stage parasite fitness in a rodent malaria model. INFECTION GENETICS AND EVOLUTION 2013; 14:340-6. [PMID: 23318648 DOI: 10.1016/j.meegid.2012.12.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2012] [Revised: 12/05/2012] [Accepted: 12/07/2012] [Indexed: 11/20/2022]
Abstract
If drug-resistant malaria mutants are less fit than sensitive forms, they will wane over time when active drug pressure is removed and the overall sensitivity to the drug may be restored. However, most studies addressing this issue have been largely retrospective. Here, we undertook a predictive study, using mutant rodent malaria parasites resistant to the Artemisinin combination treatment (ACT) version of artesunate+mefloquine (ATN+MF) to gain insights about their ability to compete with ATN+MF-sensitive forms in untreated hosts. Previously, Plasmodium chabaudi parasites resistant to ATN+MF were selected in vivo through prolonged passaging in mice under increasing doses of the two drugs, and shown to harbour duplication of the mdr1 gene. Here, the resistant parasite, AS-ATNMF1, was mixed with its progenitor AS-ATN in different proportions and each mixture was injected into mice that were left untreated. Absolute percentage parasitaemias and the proportion of each parasite were then monitored by microscopy and proportional sequencing, respectively, every two days for a period of 14days. AS-ATNMF1 outperformed its progenitor AS-ATN over the whole sampling period regardless of the relative starting proportion of each parasite clone. In order to assess if consecutive sub-inoculations could have been responsible for the apparent fitness gain of the resistant parasite, its growth was compared to that of AS-ATN27P, a parasite which was passaged the same number of times as AS-ATNMF1, but left untreated. Although small fluctuations in the proportion of each parasite were observed through time, the relative abundance of each on the last day of sampling (Day 14) was virtually identical to that of the starting inoculum. We conclude that there is no fitness cost associated with MDR1-associated ATN+MF resistance in vivo. These observations offer the first insights about the within-host dynamics between ACT-resistant and -sensitive parasites in absence of drug pressure.
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640
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Affiliation(s)
- Steve Meshnick
- *Address correspondence to Steve Meshnick, CB#7435, Chapel Hill, NC 27599. E-mail:
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641
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Zheng W. Sirtuins as emerging anti-parasitic targets. Eur J Med Chem 2013; 59:132-40. [DOI: 10.1016/j.ejmech.2012.11.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 10/16/2012] [Accepted: 11/12/2012] [Indexed: 10/27/2022]
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642
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Arancibia R, Biot C, Delaney G, Roussel P, Pascual A, Pradines B, Klahn AH. Cyrhetrenyl chalcones: Synthesis, characterization and antimalarial evaluation. J Organomet Chem 2013. [DOI: 10.1016/j.jorganchem.2012.08.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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643
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Postels DG, Chimalizeni YF, Mallewa M, Boivin MJ, Seydel KB. Pediatric cerebral malaria: a scourge of Africa. FUTURE NEUROLOGY 2013. [DOI: 10.2217/fnl.12.84] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cerebral malaria, defined as an otherwise unexplained coma in a patient with Plasmodium falciparum parasitemia, affects up to 1 million people per year, the vast majority of them being children living in sub-Saharan Africa. Despite optimal treatment, this condition kills 15% of those affected and leaves 30% of survivors with neurologic sequelae. The clinical diagnosis is hampered by its poor specificity, but the presence or absence of a malarial retinopathy in cerebral malaria has proven to be important in the differentiation of underlying coma etiology. Both antimalarials and intense supportive care are necessary for optimal treatment. As of yet, clinical trials of adjunctive therapies have not improved the high rates of mortality and morbidity. Survivors are at high risk of neurologic sequelae including epilepsy, neurodisabilities and cognitive–behavioral problems. The neuroanatomic and functional bases of these sequelae are being elucidated. Although adjunctive therapy trials continue, the best hope for African children may lie in disease prevention. Strategies include bednets, chemoprophylaxis and vaccine development.
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Affiliation(s)
| | - Yamikani F Chimalizeni
- Department of Pediatrics, University of Malawi College of Medicine, Private Bag 360, Blantyre 3, Malawi
| | - Macpherson Mallewa
- Department of Pediatrics, University of Malawi College of Medicine, Private Bag 360, Blantyre 3, Malawi
| | | | - Karl B Seydel
- Michigan State University, East Lansing, MI 48824, USA
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644
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Carrara VI, Lwin KM, Phyo AP, Ashley E, Wiladphaingern J, Sriprawat K, Rijken M, Boel M, McGready R, Proux S, Chu C, Singhasivanon P, White N, Nosten F. Malaria burden and artemisinin resistance in the mobile and migrant population on the Thai-Myanmar border, 1999-2011: an observational study. PLoS Med 2013; 10:e1001398. [PMID: 23472056 PMCID: PMC3589269 DOI: 10.1371/journal.pmed.1001398] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 01/24/2013] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The Shoklo Malaria Research Unit has been working on the Thai-Myanmar border for 25 y providing early diagnosis and treatment (EDT) of malaria. Transmission of Plasmodium falciparum has declined, but resistance to artesunate has emerged. We expanded malaria activities through EDT and evaluated the impact over a 12-y period. METHODS AND FINDINGS Between 1 October 1999 and 30 September 2011, the Shoklo Malaria Research Unit increased the number of cross-border (Myanmar side) health facilities from two to 11 and recorded the number of malaria consultations. Changes in malaria incidence were estimated from a cohort of pregnant women, and prevalence from cross-sectional surveys. In vivo and in vitro antimalarial drug efficacy were monitored. Over this period, the number of malaria cases detected increased initially, but then declined rapidly. In children under 5 y, the percentage of consultations due to malaria declined from 78% (95% CI 76-80) (1,048/1,344 consultations) to 7% (95% CI 6.2-7.1) (767/11,542 consultations), p<0.001. The ratio of P. falciparum/P. vivax declined from 1.4 (95% CI 1.3-1.4) to 0.7 (95% CI 0.7-0.8). The case fatality rate was low (39/75,126; 0.05% [95% CI 0.04-0.07]). The incidence of malaria declined from 1.1 to 0.1 episodes per pregnant women-year. The cumulative proportion of P. falciparum decreased significantly from 24.3% (95% CI 21.0-28.0) (143/588 pregnant women) to 3.4% (95% CI 2.8-4.3) (76/2,207 pregnant women), p<0.001. The in vivo efficacy of mefloquine-artesunate declined steadily, with a sharp drop in 2011 (day-42 PCR-adjusted cure rate 42% [95% CI 20-62]). The proportion of patients still slide positive for malaria at day 3 rose from 0% in 2000 to reach 28% (95% CI 13-45) (8/29 patients) in 2011. CONCLUSIONS Despite the emergence of resistance to artesunate in P. falciparum, the strategy of EDT with artemisinin-based combination treatments has been associated with a reduction in malaria in the migrant population living on the Thai-Myanmar border. Although limited by its observational nature, this study provides useful data on malaria burden in a strategically crucial geographical area. Alternative fixed combination treatments are needed urgently to replace the failing first-line regimen of mefloquine and artesunate. Please see later in the article for the Editors' Summary.
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Affiliation(s)
- Verena I. Carrara
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Mahidol Oxford University Research Unit, Bangkok, Thailand
| | - Khin Maung Lwin
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Mahidol Oxford University Research Unit, Bangkok, Thailand
| | - Aung Pyae Phyo
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Mahidol Oxford University Research Unit, Bangkok, Thailand
| | - Elizabeth Ashley
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Mahidol Oxford University Research Unit, Bangkok, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | | | | | - Marcus Rijken
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Department of Obstetrics, University Medical Center Utrecht, Utrecht, The Netherlands
| | - Machteld Boel
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Academic Medical Center, Amsterdam, The Netherlands
| | - Rose McGready
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Mahidol Oxford University Research Unit, Bangkok, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Cindy Chu
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Mahidol Oxford University Research Unit, Bangkok, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | | | - Nicholas White
- Mahidol Oxford University Research Unit, Bangkok, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford, United Kingdom
| | - François Nosten
- Shoklo Malaria Research Unit, Mae Sot, Thailand
- Mahidol Oxford University Research Unit, Bangkok, Thailand
- Centre for Tropical Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
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645
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Fairhurst RM, Nayyar GML, Breman JG, Hallett R, Vennerstrom JL, Duong S, Ringwald P, Wellems TE, Plowe CV, Dondorp AM. Artemisinin-resistant malaria: research challenges, opportunities, and public health implications. Am J Trop Med Hyg 2012; 87:231-241. [PMID: 22855752 PMCID: PMC3414557 DOI: 10.4269/ajtmh.2012.12-0025] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Artemisinin-based combination therapies are the most effective drugs to treat Plasmodium falciparum malaria. Reduced sensitivity to artemisinin monotherapy, coupled with the emergence of parasite resistance to all partner drugs, threaten to place millions of patients at risk of inadequate treatment of malaria. Recognizing the significance and immediacy of this possibility, the Fogarty International Center and the National Institute of Allergy and Infectious Diseases of the U.S. National Institutes of Health convened a conference in November 2010 to bring together the diverse array of stakeholders responding to the growing threat of artemisinin resistance, including scientists from malarious countries in peril. This conference encouraged and enabled experts to share their recent unpublished data from studies that may improve our understanding of artemisinin resistance. Conference sessions addressed research priorities to forestall artemisinin resistance and fostered collaborations between field- and laboratory-based researchers and international programs, with the aim of translating new scientific evidence into public health solutions. Inspired by this conference, this review summarizes novel findings and perspectives on artemisinin resistance, approaches for translating research data into relevant public health information, and opportunities for interdisciplinary collaboration to combat artemisinin resistance.
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Affiliation(s)
- Rick M. Fairhurst
- *Address correspondence to Rick M. Fairhurst, Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 12735 Twinbrook Parkway, Room 3E-10A, Rockville, MD 20852. E-mail:
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646
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White NJ, Qiao LG, Qi G, Luzzatto L. Rationale for recommending a lower dose of primaquine as a Plasmodium falciparum gametocytocide in populations where G6PD deficiency is common. Malar J 2012; 11:418. [PMID: 23237606 PMCID: PMC3546849 DOI: 10.1186/1475-2875-11-418] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Accepted: 11/28/2012] [Indexed: 12/28/2022] Open
Abstract
In areas of low malaria transmission, it is currently recommended that a single dose of primaquine (0.75 mg base/kg; 45 mg adult dose) be added to artemisinin combination treatment (ACT) in acute falciparum malaria to block malaria transmission. Review of studies of transmission-blocking activity based on the infectivity of patients or volunteers to anopheline mosquitoes, and of haemolytic toxicity in glucose 6-dehydrogenase (G6PD) deficient subjects, suggests that a lower primaquine dose (0.25 mg base/kg) would be safer and equally effective. This lower dose could be deployed together with ACTs without G6PD testing wherever use of a specific gametocytocide is indicated.
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Affiliation(s)
- Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
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647
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Reduced artemisinin susceptibility of Plasmodium falciparum ring stages in western Cambodia. Antimicrob Agents Chemother 2012. [PMID: 23208708 DOI: 10.1128/aac.01868-12] [Citation(s) in RCA: 200] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The declining efficacy of artemisinin derivatives against Plasmodium falciparum in western Cambodia is a major concern. The knowledge gap in the understanding of the mechanisms involved hampers designing monitoring tools. Here, we culture-adapted 20 isolates from Pailin and Ratanakiri (areas of artemisinin resistance and susceptibility in western and eastern Cambodia, respectively) and studied their in vitro response to dihydroartemisinin. No significant difference between the two sets of isolates was observed in the classical isotopic test. However, a 6-h pulse exposure to 700 nM dihydroartemisinin (ring-stage survival assay -RSA]) revealed a clear-cut geographic dichotomy. The survival rate of exposed ring-stage parasites (ring stages) was 17-fold higher in isolates from Pailin (median, 13.5%) than in those from Ratanakiri (median, 0.8%), while exposed mature stages were equally and highly susceptible (0.6% and 0.7%, respectively). Ring stages survived drug exposure by cell cycle arrest and resumed growth upon drug withdrawal. The reduced susceptibility to artemisinin in Pailin appears to be associated with an altered in vitro phenotype of ring stages from Pailin in the RSA.
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648
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Arrow KJ, Danzon PM, Gelband H, Jamison D, Laxminarayan R, Mills A, Mwabu G, Panosian C, Peto R, White NJ. The Affordable Medicines Facility--malaria: killing it slowly. Lancet 2012; 380:1889-90. [PMID: 23122218 DOI: 10.1016/s0140-6736(12)61843-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Kenneth J Arrow
- Department of Economics, Stanford University, Stanford, CA, USA
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649
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Abstract
Falciparum malaria is transmitted by anopheline mosquitoes that have fed on blood containing gametocytes of Plasmodium falciparum. In areas of low malaria transmission, where symptomatic infections contribute substantially to malaria transmission, the use of gametocytocidal drugs reduces the incidence of malaria. Artemisinin-based combination therapies provide high cure rates and substantially reduce gametocyte carriage. Artemisinin resistance in P falciparum lessens overall gametocytocidal activity, which provides a selective pressure to the spread of these resistant parasites. The 8-aminoquinoline compounds possess unique gametocytocidal properties and rapidly sterilise the mature transmissible stages of P falciparum. The addition of one dose of primaquine to artemisinin-based combination regimens could help to counter the spread of artemisinin resistance. Although primaquine is commonly recommended for falciparum and vivax malaria, concerns about drug-related haemolysis frequently prevent its administration. The limited available evidence on transmission-blocking effects of primaquine and its forerunner plasmoquine suggests that doses lower than currently recommended (0.50-0.75 mg base per kg), which would be safer, might still be very effective.
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Affiliation(s)
- Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
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650
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Das D, Tripura R, Phyo AP, Lwin KM, Tarning J, Lee SJ, Hanpithakpong W, Stepniewska K, Menard D, Ringwald P, Silamut K, Imwong M, Chotivanich K, Yi P, Day NPJ, Lindegardh N, Socheat D, Nguon C, White NJ, Nosten F, Dondorp AM. Effect of high-dose or split-dose artesunate on parasite clearance in artemisinin-resistant falciparum malaria. Clin Infect Dis 2012; 56:e48-58. [PMID: 23175556 PMCID: PMC3563392 DOI: 10.1093/cid/cis958] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
New treatment strategies are needed for artemisinin-resistant falciparum malaria. This randomized trial shows that neither increasing nor splitting the standard once-daily artesunate dose reverses the markedly reduced parasite clearance rate in patients with artemisinin-resistant falciparum malaria. Background. The emergence of Plasmodium falciparum resistance to artemisinins on the Cambodian and Myanmar-Thai borders poses severe threats to malaria control. We investigated whether increasing or splitting the dose of the short-half-life drug artesunate improves parasite clearance in falciparum malaria in the 2 regions. Methods. In Pailin, western Cambodia (from 2008 to 2010), and Wang Pha, northwestern Thailand (2009–2010), patients with uncomplicated falciparum malaria were randomized to oral artesunate 6 mg/kg/d as a once-daily or twice-daily dose for 7 days, or artesunate 8 mg/kg/d as a once-daily or twice-daily dose for 3 days, followed by mefloquine. Parasite clearance and recrudescence for up to 63 days of follow-up were assessed. Results. A total of 159 patients were enrolled. Overall median (interquartile range [IQR]) parasitemia half-life (half-life) was 6.03 (4.89–7.28) hours in Pailin versus 3.42 (2.20–4.85) hours in Wang Pha (P = .0001). Splitting or increasing the artesunate dose did not shorten half-life in either site. Pharmacokinetic profiles of artesunate and dihydroartemisinin were similar between sites and did not correlate with half-life. Recrudescent infections occurred in 4 of 79 patients in Pailin and 5 of 80 in Wang Pha and was not different between treatment arms (P = .68). Conclusions. Increasing the artesunate treatment dose up to 8 mg/kg/d or splitting the dose does not improve parasite clearance in either artemisinin resistant or more sensitive infections with P. falciparum. Clinical Trials Registration. ISRCTN15351875.
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Affiliation(s)
- Debashish Das
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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