151
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Affiliation(s)
- Nicholas J White
- Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand.
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152
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Pollitt LC, Huijben S, Sim DG, Salathé RM, Jones MJ, Read AF. Rapid response to selection, competitive release and increased transmission potential of artesunate-selected Plasmodium chabaudi malaria parasites. PLoS Pathog 2014; 10:e1004019. [PMID: 24763470 PMCID: PMC3999151 DOI: 10.1371/journal.ppat.1004019] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 02/06/2014] [Indexed: 11/19/2022] Open
Abstract
The evolution of drug resistance, a key challenge for our ability to treat and control infections, depends on two processes: de-novo resistance mutations, and the selection for and spread of resistant mutants within a population. Understanding the factors influencing the rates of these two processes is essential for maximizing the useful lifespan of drugs and, therefore, effective disease control. For malaria parasites, artemisinin-based drugs are the frontline weapons in the fight against disease, but reports from the field of slower parasite clearance rates during drug treatment are generating concern that the useful lifespan of these drugs may be limited. Whether slower clearance rates represent true resistance, and how this provides a selective advantage for parasites is uncertain. Here, we show that Plasmodium chabaudi malaria parasites selected for resistance to artesunate (an artemisinin derivative) through a step-wise increase in drug dose evolved slower clearance rates extremely rapidly. In single infections, these slower clearance rates, similar to those seen in the field, provided fitness advantages to the parasite through increased overall density, recrudescence after treatment and increased transmission potential. In mixed infections, removal of susceptible parasites by drug treatment led to substantial increases in the densities and transmission potential of resistant parasites (competitive release). Our results demonstrate the double-edged sword for resistance management: in our initial selection experiments, no parasites survived aggressive chemotherapy, but after selection, the fitness advantage for resistant parasites was greatest at high drug doses. Aggressive treatment of mixed infections resulted in resistant parasites dominating the pool of gametocytes, without providing additional health benefits to hosts. Slower clearance rates can evolve rapidly and can provide a strong fitness advantage during drug treatment in both single and mixed strain infections.
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Affiliation(s)
- Laura C. Pollitt
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Centre for Immunology, Infection and Evolution, The University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
| | - Silvie Huijben
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Derek G. Sim
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Rahel M. Salathé
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Matthew J. Jones
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Andrew F. Read
- Center for Infectious Disease Dynamics, Department of Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America
- Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, United States of America
- Fogarty International Center, National Institutes of Health, Bethesda, Maryland, United States of America
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153
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Taylor AR, Flegg JA, Nsobya SL, Yeka A, Kamya MR, Rosenthal PJ, Dorsey G, Sibley CH, Guerin PJ, Holmes CC. Estimation of malaria haplotype and genotype frequencies: a statistical approach to overcome the challenge associated with multiclonal infections. Malar J 2014; 13:102. [PMID: 24636676 PMCID: PMC4004158 DOI: 10.1186/1475-2875-13-102] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 02/26/2014] [Indexed: 11/16/2022] Open
Abstract
Background Reliable measures of anti-malarial resistance are crucial for malaria control. Resistance is typically a complex trait: multiple mutations in a single parasite (a haplotype or genotype) are necessary for elaboration of the resistant phenotype. The frequency of a genetic motif (proportion of parasite clones in the parasite population that carry a given allele, haplotype or genotype) is a useful measure of resistance. In areas of high endemicity, malaria patients generally harbour multiple parasite clones; they have multiplicities of infection (MOIs) greater than one. However, most standard experimental procedures only allow measurement of marker prevalence (proportion of patient blood samples that test positive for a given mutation or combination of mutations), not frequency. It is misleading to compare marker prevalence between sites that have different mean MOIs; frequencies are required instead. Methods A Bayesian statistical model was developed to estimate Plasmodium falciparum genetic motif frequencies from prevalence data collected in the field. To assess model performance and computational speed, a detailed simulation study was implemented. Application of the model was tested using datasets from five sites in Uganda. The datasets included prevalence data on markers of resistance to sulphadoxine-pyrimethamine and an average MOI estimate for each study site. Results The simulation study revealed that the genetic motif frequencies that were estimated using the model were more accurate and precise than conventional estimates based on direct counting. Importantly, the model did not require measurements of the MOI in each patient; it used the average MOI in the patient population. Furthermore, if a dataset included partially genotyped patient blood samples, the model imputed the data that were missing. Using the model and the Ugandan data, genotype frequencies were estimated and four biologically relevant genotypes were identified. Conclusions The model allows fast, accurate, reliable estimation of the frequency of genetic motifs associated with resistance to anti-malarials using prevalence data collected from malaria patients. The model does not require per-patient MOI measurements and can easily analyse data from five markers. The model will be a valuable tool for monitoring markers of anti-malarial drug resistance, including markers of resistance to artemisinin derivatives and partner drugs.
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Affiliation(s)
- Aimee R Taylor
- WorldWide Antimalarial Resistance Network (WWARN), Oxford, UK.
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154
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Showler AJ, Wilson ME, Kain KC, Boggild AK. Parasitic diseases in travelers: a focus on therapy. Expert Rev Anti Infect Ther 2014; 12:497-521. [DOI: 10.1586/14787210.2014.892827] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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155
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Kayentao K, Guirou EA, Doumbo OK, Venkatesan M, Plowe CV, Parsons TL, Hendrix CW, Nyunt MM. Preliminary study of quinine pharmacokinetics in pregnant women with malaria-HIV co-infection. Am J Trop Med Hyg 2014; 90:530-534. [PMID: 24420779 PMCID: PMC3945700 DOI: 10.4269/ajtmh.13-0655] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Pregnant women bear the greatest burden of malaria–human immunodeficiency virus co-infection. Previous studies suggest that interaction with antiretroviral drugs may compromise antimalarial pharmacokinetics and treatment outcomes. We conducted a preliminary clinical study to assess quinine pharmacokinetics in Malian pregnant women with acute malaria who reported taking nevirapine-based antiretroviral therapy. Of seven women, six had stable concentrations of nevirapine in the plasma and one had none. Quinine concentrations were lower, and its metabolite 3-hydroxyquinine higher, in the six women with nevirapine than in the one without, and quinine concentrations were below the recommended therapeutic range in 50% of the women. This preliminary observation warrants further research to understand the impact of long-term antiretroviral therapy on the treatment of acute malaria.
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Affiliation(s)
| | | | | | | | | | | | | | - Myaing M. Nyunt
- *Address correspondence to Myaing M. Nyunt, 615 North Wolfe Street, E5541, Baltimore, MD 21205. E-mail:
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156
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Ariey F, Witkowski B, Amaratunga C, Beghain J, Langlois AC, Khim N, Kim S, Duru V, Bouchier C, Ma L, Lim P, Leang R, Duong S, Sreng S, Suon S, Chuor CM, Bout DM, Ménard S, Rogers WO, Genton B, Fandeur T, Miotto O, Ringwald P, Le Bras J, Berry A, Barale JC, Fairhurst RM, Benoit-Vical F, Mercereau-Puijalon O, Ménard D. A molecular marker of artemisinin-resistant Plasmodium falciparum malaria. Nature 2014; 505:50-5. [PMID: 24352242 PMCID: PMC5007947 DOI: 10.1038/nature12876] [Citation(s) in RCA: 1406] [Impact Index Per Article: 140.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 11/12/2013] [Indexed: 12/24/2022]
Abstract
Plasmodium falciparum resistance to artemisinin derivatives in southeast Asia threatens malaria control and elimination activities worldwide. To monitor the spread of artemisinin resistance, a molecular marker is urgently needed. Here, using whole-genome sequencing of an artemisinin-resistant parasite line from Africa and clinical parasite isolates from Cambodia, we associate mutations in the PF3D7_1343700 kelch propeller domain ('K13-propeller') with artemisinin resistance in vitro and in vivo. Mutant K13-propeller alleles cluster in Cambodian provinces where resistance is prevalent, and the increasing frequency of a dominant mutant K13-propeller allele correlates with the recent spread of resistance in western Cambodia. Strong correlations between the presence of a mutant allele, in vitro parasite survival rates and in vivo parasite clearance rates indicate that K13-propeller mutations are important determinants of artemisinin resistance. K13-propeller polymorphism constitutes a useful molecular marker for large-scale surveillance efforts to contain artemisinin resistance in the Greater Mekong Subregion and prevent its global spread.
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Affiliation(s)
- Frédéric Ariey
- 1] Institut Pasteur, Parasite Molecular Immunology Unit, 75724 Paris Cedex 15, France [2] Centre National de la Recherche Scientifique, Unité de Recherche Associée 2581, 75724 Paris Cedex 15, France [3] Institut Pasteur, Genetics and Genomics of Insect Vectors Unit, 75724 Paris Cedex 15, France (F.A.); Institut Pasteur, Functional Genetics of Infectious Diseases Unit, 75724 Paris Cedex 15, France (J.B.); Centre de Physiopathologie de Toulouse-Purpan, Institut National de la Santé et de la Recherche Médicale UMR1043, Centre National de la Recherche Scientifique UMR5282, Université Toulouse III, 31024 Toulouse Cedex 3, France Institut Pasteur, Unité de Biologie et Génétique du Paludisme, Team Malaria Targets and Drug Development, 75724 Paris Cedex 15, France (J.-C.B.)
| | - Benoit Witkowski
- Institut Pasteur du Cambodge, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Chanaki Amaratunga
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Johann Beghain
- 1] Institut Pasteur, Parasite Molecular Immunology Unit, 75724 Paris Cedex 15, France [2] Centre National de la Recherche Scientifique, Unité de Recherche Associée 2581, 75724 Paris Cedex 15, France [3] Institut Pasteur, Genetics and Genomics of Insect Vectors Unit, 75724 Paris Cedex 15, France (F.A.); Institut Pasteur, Functional Genetics of Infectious Diseases Unit, 75724 Paris Cedex 15, France (J.B.); Centre de Physiopathologie de Toulouse-Purpan, Institut National de la Santé et de la Recherche Médicale UMR1043, Centre National de la Recherche Scientifique UMR5282, Université Toulouse III, 31024 Toulouse Cedex 3, France Institut Pasteur, Unité de Biologie et Génétique du Paludisme, Team Malaria Targets and Drug Development, 75724 Paris Cedex 15, France (J.-C.B.)
| | - Anne-Claire Langlois
- 1] Institut Pasteur, Parasite Molecular Immunology Unit, 75724 Paris Cedex 15, France [2] Centre National de la Recherche Scientifique, Unité de Recherche Associée 2581, 75724 Paris Cedex 15, France
| | - Nimol Khim
- Institut Pasteur du Cambodge, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Saorin Kim
- Institut Pasteur du Cambodge, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Valentine Duru
- Institut Pasteur du Cambodge, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Christiane Bouchier
- Institut Pasteur, Plate-forme Génomique, Département Génomes et Génétique, 75724 Paris Cedex 15, France
| | - Laurence Ma
- Institut Pasteur, Plate-forme Génomique, Département Génomes et Génétique, 75724 Paris Cedex 15, France
| | - Pharath Lim
- 1] Institut Pasteur du Cambodge, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia [2] Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA [3] National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Rithea Leang
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Socheat Duong
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Sokunthea Sreng
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Seila Suon
- 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
| | - Denis Mey Bout
- SSA WHO, Drug Monitoring in Cambodia, National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Sandie Ménard
- 1] Service de Parasitologie et Mycologie, Centre Hospitalier Universitaire de Toulouse, 31059 Toulouse Cedex 9, France [2] Institut Pasteur, Genetics and Genomics of Insect Vectors Unit, 75724 Paris Cedex 15, France (F.A.); Institut Pasteur, Functional Genetics of Infectious Diseases Unit, 75724 Paris Cedex 15, France (J.B.); Centre de Physiopathologie de Toulouse-Purpan, Institut National de la Santé et de la Recherche Médicale UMR1043, Centre National de la Recherche Scientifique UMR5282, Université Toulouse III, 31024 Toulouse Cedex 3, France Institut Pasteur, Unité de Biologie et Génétique du Paludisme, Team Malaria Targets and Drug Development, 75724 Paris Cedex 15, France (J.-C.B.)
| | | | - Blaise Genton
- Swiss Tropical and Public Health Institute, 4051 Basel, Switzerland
| | - Thierry Fandeur
- 1] Institut Pasteur, Parasite Molecular Immunology Unit, 75724 Paris Cedex 15, France [2] Institut Pasteur du Cambodge, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia
| | - Olivo Miotto
- 1] MRC Centre for Genomics and Global Health, University of Oxford, Oxford OX3 7BN, UK [2] Mahidol-Oxford Tropical Medicine Research Unit, Mahidol University, Bangkok 10400, Thailand [3] Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, UK
| | - Pascal Ringwald
- Global Malaria Program, World Health Organization, 1211 Geneva, Switzerland
| | - Jacques Le Bras
- Centre National de Référence du Paludisme, CHU Bichat-Claude Bernard, APHP, PRES Sorbonne Paris Cité, 75018 Paris, France
| | - Antoine Berry
- 1] Service de Parasitologie et Mycologie, Centre Hospitalier Universitaire de Toulouse, 31059 Toulouse Cedex 9, France [2] Institut Pasteur, Genetics and Genomics of Insect Vectors Unit, 75724 Paris Cedex 15, France (F.A.); Institut Pasteur, Functional Genetics of Infectious Diseases Unit, 75724 Paris Cedex 15, France (J.B.); Centre de Physiopathologie de Toulouse-Purpan, Institut National de la Santé et de la Recherche Médicale UMR1043, Centre National de la Recherche Scientifique UMR5282, Université Toulouse III, 31024 Toulouse Cedex 3, France Institut Pasteur, Unité de Biologie et Génétique du Paludisme, Team Malaria Targets and Drug Development, 75724 Paris Cedex 15, France (J.-C.B.)
| | - Jean-Christophe Barale
- 1] Institut Pasteur, Parasite Molecular Immunology Unit, 75724 Paris Cedex 15, France [2] Centre National de la Recherche Scientifique, Unité de Recherche Associée 2581, 75724 Paris Cedex 15, France [3] Institut Pasteur, Genetics and Genomics of Insect Vectors Unit, 75724 Paris Cedex 15, France (F.A.); Institut Pasteur, Functional Genetics of Infectious Diseases Unit, 75724 Paris Cedex 15, France (J.B.); Centre de Physiopathologie de Toulouse-Purpan, Institut National de la Santé et de la Recherche Médicale UMR1043, Centre National de la Recherche Scientifique UMR5282, Université Toulouse III, 31024 Toulouse Cedex 3, France Institut Pasteur, Unité de Biologie et Génétique du Paludisme, Team Malaria Targets and Drug Development, 75724 Paris Cedex 15, France (J.-C.B.)
| | - Rick M Fairhurst
- 1] Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA [2]
| | - Françoise Benoit-Vical
- 1] Centre National de la Recherche Scientifique, Laboratoire de Chimie de Coordination UPR8241, 31077 Toulouse Cedex 4, France [2] Université de Toulouse, UPS, Institut National Polytechnique de Toulouse, 31077 Toulouse Cedex 4, France [3]
| | - Odile Mercereau-Puijalon
- 1] Institut Pasteur, Parasite Molecular Immunology Unit, 75724 Paris Cedex 15, France [2] Centre National de la Recherche Scientifique, Unité de Recherche Associée 2581, 75724 Paris Cedex 15, France [3]
| | - Didier Ménard
- 1] Institut Pasteur du Cambodge, Malaria Molecular Epidemiology Unit, Phnom Penh, Cambodia [2]
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157
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Mharakurwa S, Sialumano M, Liu K, Scott A, Thuma P. Selection for chloroquine-sensitive Plasmodium falciparum by wild Anopheles arabiensis in Southern Zambia. Malar J 2013; 12:453. [PMID: 24354640 PMCID: PMC3878239 DOI: 10.1186/1475-2875-12-453] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/17/2013] [Indexed: 11/20/2022] Open
Abstract
Background The emergence of parasite drug resistance, especially Plasmodium falciparum, persists as a major obstacle for malaria control and elimination. To develop effective public health containment strategies, a clear understanding of factors that govern the emergence and spread of resistant parasites in the field is important. The current study documents selection for chloroquine-sensitive malaria parasites by wild Anopheles arabiensis in southern Zambia. Methods In a 2,000-sq km region, mosquitoes were collected from human sleeping rooms using pyrethrum spray catches during the 2006 malaria transmission season. After morphological examination and molecular confirmation, vector mosquitoes were dissected to separate head and thorax from the abdominal section, followed by PCR screening for P. falciparum infection. Human residents of all ages were tested for P. falciparum parasitaemia by microscopy and PCR. Plasmodium falciparum infections were genotyped at the chloroquine resistance-conferring amino acid codon 76 of the PfCRT gene, using PCR and restriction enzyme digestion. Results In the human population there was nearly 90% prevalence of the chloroquine-resistant PfCRT K76T mutant, with no significant differences in polymorphism among smear-positive and smear-negative (submicroscopic) infections (p = 0.323, n = 128). However, infections in both abdominal and salivary gland phases of the An. arabiensis vector exhibited wild type K76-bearing parasites with up to 9X higher odds (OR (95% CI): 9 (3.7-20.2), p < 0.0005, n = 125), despite having been acquired from humans within a few weeks. Conclusions Anopheles arabiensis selects for wild-type K76-bearing P. falciparum during both abdominal and salivary gland phases of parasite development. The rapid vectorial selection, also recently seen with antifolate resistance, is evidence for parasite fitness cost in the mosquito, and may underpin regional heterogeneity in the emergence, spread and waning of drug resistance. Understanding the nature and direction of vector selection could be instrumental for rational curtailment of the spread of drug resistance in integrated malaria control and elimination programmes.
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158
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Canier L, Khim N, Kim S, Sluydts V, Heng S, Dourng D, Eam R, Chy S, Khean C, Loch K, Ken M, Lim H, Siv S, Tho S, Masse-Navette P, Gryseels C, Uk S, Van Roey K, Grietens KP, Sokny M, Thavrin B, Chuor CM, Deubel V, Durnez L, Coosemans M, Ménard D. An innovative tool for moving malaria PCR detection of parasite reservoir into the field. Malar J 2013; 12:405. [PMID: 24206649 PMCID: PMC3829804 DOI: 10.1186/1475-2875-12-405] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 11/05/2013] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND To achieve the goal of malaria elimination in low transmission areas such as in Cambodia, new, inexpensive, high-throughput diagnostic tools for identifying very low parasite densities in asymptomatic carriers are required. This will enable a switch from passive to active malaria case detection in the field. METHODS DNA extraction and real-time PCR assays were implemented in an "in-house" designed mobile laboratory allowing implementation of a robust, sensitive and rapid malaria diagnostic strategy in the field. This tool was employed in a survey organized in the context of the MalaResT project (NCT01663831). RESULTS The real-time PCR screening and species identification assays were performed in the mobile laboratory between October and November 2012, in Rattanakiri Province, to screen approximately 5,000 individuals in less than four weeks and treat parasite carriers within 24-48 hours after sample collection. An average of 240 clinical samples (and 40 quality control samples) was tested every day, six/seven days per week. Some 97.7% of the results were available <24 hours after the collection. A total of 4.9% were positive for malaria. Plasmodium vivax was present in 61.1% of the positive samples, Plasmodium falciparum in 45.9%, Plasmodium malariae in 7.0% and Plasmodium ovale in 2.0%. CONCLUSIONS The operational success of this diagnostic set-up proved that molecular testing and subsequent treatment is logistically achievable in field settings. This will allow the detection of clusters of asymptomatic carriers and to provide useful epidemiological information. Fast results will be of great help for staff in the field to track and treat asymptomatic parasitaemic cases. The concept of the mobile laboratory could be extended to other countries for the molecular detection of malaria or other pathogens, or to culture vivax parasites, which does not support long-time delay between sample collection and culture.
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Affiliation(s)
- Lydie Canier
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Nimol Khim
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Saorin Kim
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | | | - Somony Heng
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
- Institute of Tropical Medicine, Antwerp, Belgium
| | - Dany Dourng
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Rotha Eam
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Sophy Chy
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Chanra Khean
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Kaknika Loch
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Malen Ken
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Hokkean Lim
- Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Sovannaroath Siv
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Sochantha Tho
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | | | | | - Sambunny Uk
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | | | | | - Mao Sokny
- National Center for Parasitology, Entomology and Malaria Control, Phnom Penh, Cambodia
| | - Boukheng Thavrin
- 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
| | | | - Lies Durnez
- Institute of Tropical Medicine, Antwerp, Belgium
| | - Marc Coosemans
- Institute of Tropical Medicine, Antwerp, Belgium
- Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
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159
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Evidence for pyronaridine as a highly effective partner drug for treatment of artemisinin-resistant malaria in a rodent model. Antimicrob Agents Chemother 2013; 58:183-95. [PMID: 24145526 DOI: 10.1128/aac.01466-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The increasing prevalence in Southeast Asia of Plasmodium falciparum infections with delayed parasite clearance rates, following treatment of malaria patients with the artemisinin derivative artesunate, highlights an urgent need to identify which of the currently available artemisinin-based combination therapies (ACTs) are most suitable to treat populations with emerging artemisinin resistance. Here, we demonstrate that the rodent Plasmodium berghei SANA strain has acquired artemisinin resistance following drug pressure, as defined by reduced parasite clearance and early recrudescence following daily exposure to high doses of artesunate or the active metabolite dihydroartemisinin. Using the SANA strain and the parental drug-sensitive N strain, we have interrogated the antimalarial activity of five ACTs, namely, artemether-lumefantrine, artesunate-amodiaquine, artesunate-mefloquine, dihydroartemisinin-piperaquine, and the newest combination artesunate-pyronaridine. By monitoring parasitemia and outcome for 30 days following initiation of treatment, we found that infections with artemisinin-resistant P. berghei SANA parasites can be successfully treated with artesunate-pyronaridine used at doses that are curative for the parental drug-sensitive N strain. No other partner drug combination was as effective in resolving SANA infections. Of the five partner drugs tested, pyronaridine was also the most effective at suppressing the recrudescence of SANA parasites. These data support the potential benefit of implementing ACTs with pyronaridine in regions affected by artemisinin-resistant malaria.
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160
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Smithuis FM, Kyaw MK, Phe UO, van der Broek I, Katterman N, Rogers C, Almeida P, Kager PA, Stepniewska K, Lubell Y, Simpson JA, White NJ. The effect of insecticide-treated bed nets on the incidence and prevalence of malaria in children in an area of unstable seasonal transmission in western Myanmar. Malar J 2013; 12:363. [PMID: 24119916 PMCID: PMC3854704 DOI: 10.1186/1475-2875-12-363] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2013] [Accepted: 09/20/2013] [Indexed: 12/02/2022] Open
Abstract
Background Insecticide-treated bed nets (ITN) reduce malaria morbidity and mortality consistently in Africa, but their benefits have been less consistent in Asia. This study’s objective was to evaluate the malaria protective efficacy of village-wide usage of ITN in Western Myanmar and estimate the cost-effectiveness of ITN compared with extending early diagnosis and treatment services. Methods A cluster-randomized controlled trial was conducted in Rakhine State to assess the efficacy of ITNs in preventing malaria and anaemia in children and their secondary effects on nutrition and development. The data were aggregated for each village to obtain cluster-level infection rates. In total 8,175 children under 10 years of age were followed up for 10 months, which included the main malaria transmission period. The incidence and prevalence of Plasmodium falciparum and Plasmodium vivax infections, and the biting behaviour of Anopheles mosquitoes in the area were studied concurrently. The trial data along with costs for current recommended treatment practices were modelled to estimate the cost-effectiveness of ITNs compared with, or in addition to extending the coverage of early diagnosis and treatment services. Results In aggregate, malaria infections, spleen rates, haemoglobin concentrations, and weight for height, did not differ significantly during the study period between villages with and without ITNs, with a weighted mean difference of −2.6 P. falciparum episodes per 1,000 weeks at risk (95% Confidence Interval −7 to 1.8). In areas with a higher incidence of malaria there was some evidence ITN protective efficacy. The economic analysis indicated that, despite the uncertainty and variability in their protective efficacy in the different study sites, ITN could still be cost-effective, but not if they displaced funding for early diagnosis and effective treatment which is substantially more cost-effective. Conclusion In Western Myanmar deployment of ITNs did not provide consistent protection against malaria in children living in malaria endemic villages. Early diagnosis and effective treatment is a more cost effective malaria control strategy than deployment of ITNs in this area where the main vector bites early in the evening, often before people are protected by an ITN.
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Affiliation(s)
- Frank M Smithuis
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Rajvithi Rd,, Ratchathewi District, Bangkok 10400, Thailand.
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van Schalkwyk DA, Burrow R, Henriques G, Gadalla NB, Beshir KB, Hasford C, Wright SG, Ding XC, Chiodini PL, Sutherland CJ. Culture-adapted Plasmodium falciparum isolates from UK travellers: in vitro drug sensitivity, clonality and drug resistance markers. Malar J 2013; 12:320. [PMID: 24028570 PMCID: PMC3847303 DOI: 10.1186/1475-2875-12-320] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 09/10/2013] [Indexed: 01/20/2023] Open
Abstract
Background The screening of lead compounds against in vitro parasite cultures is an essential step in the development of novel anti-malarial drugs, but currently relies on laboratory parasite lines established in vitro during the last century. This study sought to establish in continuous culture a series of recent Plasmodium falciparum isolates to represent the current parasite populations in Africa, all of which are now exposed to artemisinin combination therapy. Methods Pre-treatment P. falciparum isolates were obtained in EDTA, and placed into continuous culture after sampling of DNA. One post-treatment blood sample was also collected for each donor to monitor parasite clonality during clearance in vivo. IC50 estimates were obtained for 11 anti-malarial compounds for each established parasite line, clonal multiplicity measured in vivo and in vitro, and polymorphic sites implicated in parasite sensitivity to drugs were investigated at the pfmdr1, pfcrt, pfdhfr, pfdhps and pfap2mu loci before and after treatment, and in the cultured lines. Results Plasmodium falciparum isolates from seven malaria patients with recent travel to three West African and two East African countries were successfully established in long-term culture. One of these, HL1211, was from a patient with recrudescent parasitaemia 14 days after a full course of artemether-lumefantrine. All established culture lines were shown to be polyclonal, reflecting the in vivo isolates from which they were derived, and at least two lines reliably produce gametocytes in vitro. Two lines displayed high chloroquine IC50 estimates, and carried the CVIET haplotype at codons 72–76, whereas the remaining five lines carried the CVMNK haplotype and were sensitive in vitro. All were sensitive to the endoperoxides dihydroartemisinin and OZ277, but IC50 estimates for lumefantrine varied, with the least sensitive parasites carrying pfmdr1 alleles encoding Asn at codon 86. Conclusions This study describes the establishment in continuous culture, in vitro drug sensitivity testing and molecular characterization of a series of multiclonal P. falciparum isolates taken directly from UK malaria patients following recent travel to various malaria-endemic countries in Africa. These “HL” isolates are available as an open resource for studies of drug response, antigenic diversity and other aspects of parasite biology.
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Affiliation(s)
- Donelly A van Schalkwyk
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
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162
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Witkowski B, Amaratunga C, Khim N, Sreng S, Chim P, Kim S, Lim P, Mao S, Sopha C, Sam B, Anderson JM, Duong S, Chuor CM, Taylor WRJ, Suon S, Mercereau-Puijalon O, Fairhurst RM, Menard D. Novel phenotypic assays for the detection of artemisinin-resistant Plasmodium falciparum malaria in Cambodia: in-vitro and ex-vivo drug-response studies. THE LANCET. INFECTIOUS DISEASES 2013; 13:1043-9. [PMID: 24035558 DOI: 10.1016/s1473-3099(13)70252-4] [Citation(s) in RCA: 426] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Artemisinin resistance in Plasmodium falciparum lengthens parasite clearance half-life during artemisinin monotherapy or artemisinin-based combination therapy. Absence of in-vitro and ex-vivo correlates of artemisinin resistance hinders study of this phenotype. We aimed to assess whether an in-vitro ring-stage survival assay (RSA) can identify culture-adapted P falciparum isolates from patients with slow-clearing or fast-clearing infections, to investigate the stage-dependent susceptibility of parasites to dihydroartemisinin in the in-vitro RSA, and to assess whether an ex-vivo RSA can identify artemisinin-resistant P falciparum infections. METHODS We culture-adapted parasites from patients with long and short parasite clearance half-lives from a study done in Pursat, Cambodia, in 2010 (registered with ClinicalTrials.gov, number NCT00341003) and used novel in-vitro survival assays to explore the stage-dependent susceptibility of slow-clearing and fast-clearing parasites to dihydroartemisinin. In 2012, we implemented the RSA in prospective parasite clearance studies in Pursat, Preah Vihear, and Ratanakiri, Cambodia (NCT01736319), to measure the ex-vivo responses of parasites from patients with malaria. Continuous variables were compared with the Mann-Whitney U test. Correlations were analysed with the Spearman correlation test. FINDINGS In-vitro survival rates of culture-adapted parasites from 13 slow-clearing and 13 fast-clearing infections differed significantly when assays were done on 0-3 h ring-stage parasites (10·88% vs 0·23%; p=0·007). Ex-vivo survival rates significantly correlated with in-vivo parasite clearance half-lives (n=30, r=0·74, 95% CI 0·50-0·87; p<0·0001). INTERPRETATION The in-vitro RSA of 0-3 h ring-stage parasites provides a platform for the molecular characterisation of artemisinin resistance. The ex-vivo RSA can be easily implemented where surveillance for artemisinin resistance is needed. FUNDING Institut Pasteur du Cambodge and the Intramural Research Program, NIAID, NIH.
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Affiliation(s)
- Benoit Witkowski
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
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Mideo N, Kennedy DA, Carlton JM, Bailey JA, Juliano JJ, Read AF. Ahead of the curve: next generation estimators of drug resistance in malaria infections. Trends Parasitol 2013; 29:321-8. [PMID: 23746748 PMCID: PMC3694767 DOI: 10.1016/j.pt.2013.05.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 05/06/2013] [Accepted: 05/07/2013] [Indexed: 12/16/2022]
Abstract
Drug resistance is a major obstacle to controlling infectious diseases. A key challenge is detecting the early signs of drug resistance when little is known about its genetic basis. Focusing on malaria parasites, we propose a way to do this. Newly developing or low level resistance at low frequency in patients can be detected through a phenotypic signature: individual parasite variants clearing more slowly following drug treatment. Harnessing the abundance and resolution of deep sequencing data, our 'selection differential' approach addresses some limitations of extant methods of resistance detection, should allow for the earliest detection of resistance in malaria or other multi-clone infections, and has the power to uncover the true scale of the drug resistance problem.
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Affiliation(s)
- Nicole Mideo
- Center for Infectious Disease Dynamics, Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA.
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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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