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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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Dormoi J, Briolant S, Desgrouas C, Pradines B. Impact of methylene blue and atorvastatin combination therapy on the apparition of cerebral malaria in a murine model. Malar J 2013; 12:127. [PMID: 23587099 PMCID: PMC3637457 DOI: 10.1186/1475-2875-12-127] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 04/10/2013] [Indexed: 11/30/2022] Open
Abstract
Background Proveblue®, a methylene blue dye that complies with European Pharmacopoeia and contains limited organic impurities and heavy metals of recognized toxicity, showed in vitro synergy against Plasmodium falciparum when combined with atorvastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-Coenzyme A reductase. The objective of this study was to evaluate the in vivo efficacy of Proveblue® when combined with atorvastatin in a murine model of experimental cerebral malaria. Methods Forty female C57Bl6/N mice were divided into four groups (control, atorvastatin 40 mg/kg for seven days, Proveblue® 10 mg/kg for five days and atorvastatin combined with Proveblue®), infected with Plasmodium berghei ANKA parasites by intraperitoneal inoculation and observed for 45 days. Results Treatment with atorvastatin alone did not demonstrate an effect significantly different from no treatment (p = 0.0573). All the mice treated by atorvastatin alone died. Treatment with Proveblue® or a combination of Proveblue® and atorvastatin was significantly increased survival of cerebral malaria (p = 0.0011 and 0.0002, respectively). Although there was only one death in the atorvastatin and Proveblue® combination treatment group (10%) versus two deaths (22%) with Proveblue® treatment, the effect on cerebral malaria was not significant (p = 0.283). Conclusions The present work demonstrated, for the first time, the high efficacy of Proveblue® in preventing cerebral malaria. Atorvastatin alone or in combination appears to possess limited use for preventing cerebral malaria. Combination of atorvastatin with lower doses of Proveblue® (<10 mg/kg/day) should be evaluated to show potential synergistic effects in cerebral malaria prevention.
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Amaratunga C, Mao S, Sreng S, Suon S, Fairhurst RM. Slow parasite clearance rates in response to artemether in patients with severe malaria. THE LANCET. INFECTIOUS DISEASES 2013; 13:113-4. [PMID: 23347631 DOI: 10.1016/s1473-3099(12)70347-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Saunders D, Duplessis C, Lescano A, Andagalu B, Thomas A, Fukuda M, Cummings J. US Department of Defense contributions to malaria surveillance. THE LANCET. INFECTIOUS DISEASES 2013; 13:293-4. [PMID: 23538221 DOI: 10.1016/s1473-3099(13)70065-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Eziefula AC, Staedke SG, Yeung S, Webb E, Kamya M, White NJ, Bousema T, Drakeley C. Study protocol for a randomised controlled double-blinded trial of the dose-dependent efficacy and safety of primaquine for clearance of gametocytes in children with uncomplicated falciparum malaria in Uganda. BMJ Open 2013; 3:bmjopen-2013-002759. [PMID: 23535703 PMCID: PMC3612795 DOI: 10.1136/bmjopen-2013-002759] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
OBJECTIVES For the purpose of blocking transmission of Plasmodium falciparum malaria from humans to mosquitoes, a single dose of primaquine is recommended by the WHO as an addition to artemisinin combination therapy. Primaquine clears gametocytes but causes dose-dependent haemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Evidence is needed to inform the optimal dosing of primaquine for malaria elimination programmes and for the purpose of interrupting the spread of artemisinin-resistant malaria. This study investigates the efficacy and safety of reducing doses of primaquine for clearance of gametocytes in participants with normal G6PD status. METHODS AND ANALYSIS In this prospective, four-armed randomised placebo-controlled double-blinded trial, children aged 1-10 years, weighing over 10 kg, with haemoglobin ≥8 g/dl and uncomplicated P falciparum malaria are treated with artemether lumefantrine and randomised to receive a dose of primaquine (0.1, 0.4 or 0.75 mg base/kg) or placebo on the third day of treatment. Participants are followed up for 28 days. Gametocytaemia is measured by quantitative nucleic acid sequence-based analysis on days 0, 2, 3, 7, 10 and 14 with a primary endpoint of the number of days to gametocyte clearance in each treatment arm and secondarily the area under the curve of gametocyte density over time. Analysis is for non-inferiority of efficacy compared to the reference dose, 0.75 mg base/kg. Safety is assessed by pair-wise comparisons of the arithmetic mean (±SD) change in haemoglobin concentration per treatment arm and analysed for superiority to placebo and incidence of adverse events. Ethics and dissemination Approval was obtained from the ethical committees of Makerere University School of Medicine, the Ugandan National Council of Science and Technology and the London School of Hygiene and Tropical Medicine. RESULTS These will be disseminated to inform malaria elimination policy, through peer-reviewed publication and academic presentations.
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Affiliation(s)
- Alice Chijioke Eziefula
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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Malmberg M, Ngasala B, Ferreira PE, Larsson E, Jovel I, Hjalmarsson A, Petzold M, Premji Z, Gil JP, Björkman A, Mårtensson A. Temporal trends of molecular markers associated with artemether-lumefantrine tolerance/resistance in Bagamoyo district, Tanzania. Malar J 2013; 12:103. [PMID: 23506218 PMCID: PMC3732084 DOI: 10.1186/1475-2875-12-103] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2012] [Accepted: 03/09/2013] [Indexed: 12/19/2022] Open
Abstract
Background Development and spread of Plasmodium falciparum resistance to artemisinin-based combination therapy (ACT) constitutes a major threat to recent global malaria control achievements. Surveillance of molecular markers could act as an early warning system of ACT-resistance before clinical treatment failures are apparent. The aim of this study was to analyse temporal trends of established genotypes associated with artemether-lumefantrine tolerance/resistance before and after its deployment as first-line treatment for uncomplicated malaria in Tanzania 2006. Methods Single nucleotide polymorphisms in the P. falciparum multidrug resistance gene 1 (pfmdr1) N86Y, Y184F, D1246Y and P. falciparum chloroquine transporter gene (pfcrt) K76T were analysed from dried blood spots collected during six consecutive studies from children with uncomplicated P. falciparum malaria in Fukayosi village, Bagamoyo District, Tanzania, between 2004–2011. Results There was a statistically significant yearly increase of pfmdr1 N86, 184F, D1246 and pfcrt K76 between 2006–2011 from 14% to 61% (yearly OR = 1.38 [95% CI 1.25-1.52] p < 0.0001), 14% to 35% (OR = 1.17 [95% CI 1.07-1.30] p = 0.001), 54% to 85% (OR = 1.21 [95% CI 1.03-1.42] p = 0.016) and 49% to 85% (OR = 1.33 [95% CI 1.17-1.51] p < 0.0001), respectively. Unlike for the pfmdr1 SNP, a significant increase of pfcrt K76 was observed already between 2004–2006, from 26% to 49% (OR = 1.68 [95% CI 1.17-2.40] p = 0.005). From 2006 to 2011 the pfmdr1 NFD haplotype increased from 10% to 37% (OR = 1.25 [95% CI 1.12-1.39] p < 0.0001), whereas the YYY haplotype decreased from 31% to 6% (OR = 0.73 [95% CI 0.56-0.98] p = 0.018). All 390 successfully analysed samples had one copy of the pfmdr1 gene. Conclusion The temporal selection of molecular markers associated with artemether-lumefantrine tolerance/resistance may represent an early warning sign of impaired future drug efficacy. This calls for stringent surveillance of artemether-lumefantrine efficacy in Tanzania and emphasizes the importance of molecular surveillance as a complement to standard in vivo trials.
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Affiliation(s)
- Maja Malmberg
- Malaria Research, Department of Medicine Solna, Karolinska Institutet, Stockholm, Sweden.
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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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Folate metabolism in human malaria parasites—75 years on. Mol Biochem Parasitol 2013; 188:63-77. [DOI: 10.1016/j.molbiopara.2013.02.008] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 02/15/2013] [Accepted: 02/19/2013] [Indexed: 12/21/2022]
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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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Wongsrichanalai C. Artemisinin resistance or artemisinin-based combination therapy resistance? THE LANCET. INFECTIOUS DISEASES 2013; 13:114-5. [DOI: 10.1016/s1473-3099(12)70349-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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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: 198] [Impact Index Per Article: 16.5] [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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Hien TT, Thuy-Nhien NT, Phu NH, Boni MF, Thanh NV, Nha-Ca NT, Thai LH, Thai CQ, Toi PV, Thuan PD, Long LT, Dong LT, Merson L, Dolecek C, Stepniewska K, Ringwald P, White NJ, Farrar J, Wolbers M. In vivo susceptibility of Plasmodium falciparum to artesunate in Binh Phuoc Province, Vietnam. Malar J 2012; 11:355. [PMID: 23101492 PMCID: PMC3504531 DOI: 10.1186/1475-2875-11-355] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 10/20/2012] [Indexed: 11/25/2022] Open
Abstract
Background By 2009, there were worrying signs from western Cambodia that parasitological responses to artesunate-containing treatment regimens for uncomplicated Plasmodium falciparum malaria were slower than elsewhere which suggested the emergence of artemisinin resistance. Vietnam shares a long land border with Cambodia with a large number of migrants crossing it on a daily basis. Therefore, there is an urgent need to investigate whether there is any evidence of a change in the parasitological response to the artemisinin derivatives in Vietnam. Methods From August 2010 to May 2011, a randomized controlled clinical trial in uncomplicated falciparum malaria was conducted to compare two doses of artesunate (AS) (2mg/kg/day versus 4 mg/kg/day for three days) followed by dihydroartemisinin-piperaquine (DHA-PPQ) and a control arm of DHA-PPQ. The goal was characterization of the current efficacy of artesunate in southern Vietnam. The primary endpoint of this study was the parasite clearance half-life; secondary endpoints included the parasite reduction ratios at 24 and 48 hours and the parasite clearance time. Results 166 patients were recruited into the study. The median parasite clearance half-lives were 3.54 (AS 2mg/kg), 2.72 (AS 4mg/kg), and 2.98 hours (DHA-PPQ) (p=0.19). The median parasite-reduction ratio at 24 hours was 48 in the AS 2mg/kg group compared with 212 and 113 in the other two groups, respectively (p=0.02). The proportions of patients with a parasite clearance time of >72 hours for AS 2mg/kg, AS 4mg/kg and DHA-PPQ were 27%, 27%, and 22%, respectively. Early treatment failure occurred in two (4%) and late clinical failure occurred in one (2%) of the 55 patients in the AS 2mg/kg group, as compared with none in the other two study arms. The PCR-corrected adequate clinical and parasitological response (APCR) rates in the three groups were 94%, 100%, and 100% (p=0.04). Conclusions This study demonstrated faster P. falciparum parasite clearance in southern Vietnam than in western Cambodia but slower clearance in comparison with historical data from Vietnam. Further studies to determine whether this represents the emergence of artemisinin resistance in this area are needed. Currently, the therapeutic response to DHA-PPQ remains satisfactory in southern Vietnam. Trial registration NTC01165372
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Affiliation(s)
- Tran Tinh Hien
- Wellcome Trust Major Overseas Programme (MOP), Oxford University Clinical Research Unit (OUCRU), Ho Chi Minh City, Vietnam.
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Breman JG. Resistance to artemisinin-based combination therapy. THE LANCET. INFECTIOUS DISEASES 2012; 12:820-2. [PMID: 22940026 DOI: 10.1016/s1473-3099(12)70226-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- Joel G Breman
- Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA.
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