401
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Role of Pfmdr1 in in vitro Plasmodium falciparum susceptibility to chloroquine, quinine, monodesethylamodiaquine, mefloquine, lumefantrine, and dihydroartemisinin. Antimicrob Agents Chemother 2014; 58:7032-40. [PMID: 25199781 DOI: 10.1128/aac.03494-14] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The involvement of Pfmdr1 (Plasmodium falciparum multidrug resistance 1) polymorphisms in antimalarial drug resistance is still debated. Here, we evaluate the association between polymorphisms in Pfmdr1 (N86Y, Y184F, S1034C, N1042D, and D1246Y) and Pfcrt (K76T) and in vitro responses to chloroquine (CQ), mefloquine (MQ), lumefantrine (LMF), quinine (QN), monodesethylamodiaquine (MDAQ), and dihydroartemisinin (DHA) in 174 Plasmodium falciparum isolates from Dakar, Senegal. The Pfmdr1 86Y mutation was identified in 14.9% of the samples, and the 184F mutation was identified in 71.8% of the isolates. No 1034C, 1042N, or 1246Y mutations were detected. The Pfmdr1 86Y mutation was significantly associated with increased susceptibility to MDAQ (P = 0.0023), LMF (P = 0.0001), DHA (P = 0.0387), and MQ (P = 0.00002). The N86Y mutation was not associated with CQ (P = 0.214) or QN (P = 0.287) responses. The Pfmdr1 184F mutation was not associated with various susceptibility responses to the 6 antimalarial drugs (P = 0.168 for CQ, 0.778 for MDAQ, 0.324 for LMF, 0.961 for DHA, 0.084 for QN, and 0.298 for MQ). The Pfmdr1 86Y-Y184 haplotype was significantly associated with increased susceptibility to MDAQ (P = 0.0136), LMF (P = 0.0019), and MQ (P = 0.0001). The additional Pfmdr1 86Y mutation increased significantly the in vitro susceptibility to MDAQ (P < 0.0001), LMF (P < 0.0001), MQ (P < 0.0001), and QN (P = 0.0026) in wild-type Pfcrt K76 parasites. The additional Pfmdr1 86Y mutation significantly increased the in vitro susceptibility to CQ (P = 0.0179) in Pfcrt 76T CQ-resistant parasites.
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402
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Hopkins Sibley C. Artemisinin resistance: the more we know, the more complicated it appears. J Infect Dis 2014; 211:667-9. [PMID: 25180242 DOI: 10.1093/infdis/jiu469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Carol Hopkins Sibley
- WorldWide Antimalarial Resistance Network (WWARN), Department of Genome Sciences, University of Washington, Seattle
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403
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Abdul-Ghani R, Al-Maktari MT, Al-Shibani LA, Allam AF. A better resolution for integrating methods for monitoring Plasmodium falciparum resistance to antimalarial drugs. Acta Trop 2014; 137:44-57. [PMID: 24801884 DOI: 10.1016/j.actatropica.2014.04.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/25/2014] [Accepted: 04/27/2014] [Indexed: 12/16/2022]
Abstract
Effective chemotherapy is the mainstay of malaria control. However, resistance of falciparum malaria to antimalarial drugs compromised the efforts to eliminate the disease and led to the resurgence of malaria epidemics. Three main approaches are used to monitor antimalarial drug efficacy and drug resistance; namely, in vivo trials, in vitro/ex vivo assays and molecular markers of drug resistance. Each approach has its implications of use as well as its advantages and drawbacks. Therefore, there is a need to use an integrated approach that would give the utmost effect to detect resistance as early as its emergence and to track it once spread. Such integration becomes increasingly needed in the era of artemisinin-based combination therapy as a forward action to deter resistance. The existence of regional and global networks for the standardization of methodology, provision of high quality reagents for the assessment of antimalarial drug resistance and dissemination of open-access data would help in approaching an integrated resistance surveillance system on a global scale.
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404
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Musset L, Pelleau S, Girod R, Ardillon V, Carvalho L, Dusfour I, Gomes MSM, Djossou F, Legrand E. Malaria on the Guiana Shield: a review of the situation in French Guiana. Mem Inst Oswaldo Cruz 2014; 109:525-33. [PMID: 25184998 PMCID: PMC4156445 DOI: 10.1590/0074-0276140031] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 06/09/2014] [Indexed: 01/02/2023] Open
Abstract
In a climate of growing concern that Plasmodium falciparum may be developing a drug resistance to artemisinin derivatives in the Guiana Shield, this review details our current knowledge of malaria and control strategy in one part of the Shield, French Guiana. Local epidemiology, test-treat-track strategy, the state of parasite drug resistance and vector control measures are summarised. Current issues in terms of mobile populations and legislative limitations are also discussed.
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Affiliation(s)
- Lise Musset
- Laboratoire de Parasitologie, Centre National de Référence du Paludisme - Région Antilles-Guyane, WHO Collaborating Center for Surveillance of Antimalarial Drug Resistance, Cayenne, French Guiana
| | - Stéphane Pelleau
- Laboratoire de Parasitologie, Centre National de Référence du Paludisme - Région Antilles-Guyane, WHO Collaborating Center for Surveillance of Antimalarial Drug Resistance, Cayenne, French Guiana
| | - Romain Girod
- Unité d?Entomologie Médicale, Institut Pasteur de la Guyane, Cayenne, French Guiana
| | - Vanessa Ardillon
- Cellule de l?Institut de Veille Sanitaire en Région Antilles-Guyane, Cayenne, French Guiana
| | - Luisiane Carvalho
- Cellule de l?Institut de Veille Sanitaire en Région Antilles-Guyane, Cayenne, French Guiana
| | - Isabelle Dusfour
- Unité d?Entomologie Médicale, Institut Pasteur de la Guyane, Cayenne, French Guiana
| | | | - Félix Djossou
- Unité des Maladies Infectieuses et Tropicales, Centre Hospitalier Andrée Rosemon, Cayenne, French Guiana
| | - Eric Legrand
- Laboratoire de Parasitologie, Centre National de Référence du Paludisme - Région Antilles-Guyane, WHO Collaborating Center for Surveillance of Antimalarial Drug Resistance, Cayenne, French Guiana
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405
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Khim N, Witkowski B, Duru V, Ariey F, Mercereau-Puijalon O, Ménard D. La résistance de P. falciparumà l’artémisinine. Med Sci (Paris) 2014; 30:727-9. [DOI: 10.1051/medsci/20143008004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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406
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Ashley EA, Dhorda M, Fairhurst RM, Amaratunga C, Lim P, Suon S, Sreng S, Anderson JM, Mao S, Sam B, Sopha C, Chuor CM, Nguon C, Sovannaroth S, Pukrittayakamee S, Jittamala P, Chotivanich K, Chutasmit K, Suchatsoonthorn C, Runcharoen R, Hien TT, Thuy-Nhien NT, Thanh NV, Phu NH, Htut Y, Han KT, Aye KH, Mokuolu OA, Olaosebikan RR, Folaranmi OO, Mayxay M, Khanthavong M, Hongvanthong B, Newton PN, Onyamboko MA, Fanello CI, Tshefu AK, Mishra N, Valecha N, Phyo AP, Nosten F, Yi P, Tripura R, Borrmann S, Bashraheil M, Peshu J, Faiz MA, Ghose A, Hossain MA, Samad R, Rahman MR, Hasan MM, Islam A, Miotto O, Amato R, MacInnis B, Stalker J, Kwiatkowski DP, Bozdech Z, Jeeyapant A, Cheah PY, Sakulthaew T, Chalk J, Intharabut B, Silamut K, Lee SJ, Vihokhern B, Kunasol C, Imwong M, Tarning J, Taylor WJ, Yeung S, Woodrow CJ, Flegg JA, Das D, Smith J, Venkatesan M, Plowe CV, Stepniewska K, Guerin PJ, Dondorp AM, Day NP, White NJ. Spread of artemisinin resistance in Plasmodium falciparum malaria. N Engl J Med 2014; 371:411-23. [PMID: 25075834 PMCID: PMC4143591 DOI: 10.1056/nejmoa1314981] [Citation(s) in RCA: 1519] [Impact Index Per Article: 151.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Artemisinin resistance in Plasmodium falciparum has emerged in Southeast Asia and now poses a threat to the control and elimination of malaria. Mapping the geographic extent of resistance is essential for planning containment and elimination strategies. METHODS Between May 2011 and April 2013, we enrolled 1241 adults and children with acute, uncomplicated falciparum malaria in an open-label trial at 15 sites in 10 countries (7 in Asia and 3 in Africa). Patients received artesunate, administered orally at a daily dose of either 2 mg per kilogram of body weight per day or 4 mg per kilogram, for 3 days, followed by a standard 3-day course of artemisinin-based combination therapy. Parasite counts in peripheral-blood samples were measured every 6 hours, and the parasite clearance half-lives were determined. RESULTS The median parasite clearance half-lives ranged from 1.9 hours in the Democratic Republic of Congo to 7.0 hours at the Thailand-Cambodia border. Slowly clearing infections (parasite clearance half-life >5 hours), strongly associated with single point mutations in the "propeller" region of the P. falciparum kelch protein gene on chromosome 13 (kelch13), were detected throughout mainland Southeast Asia from southern Vietnam to central Myanmar. The incidence of pretreatment and post-treatment gametocytemia was higher among patients with slow parasite clearance, suggesting greater potential for transmission. In western Cambodia, where artemisinin-based combination therapies are failing, the 6-day course of antimalarial therapy was associated with a cure rate of 97.7% (95% confidence interval, 90.9 to 99.4) at 42 days. CONCLUSIONS Artemisinin resistance to P. falciparum, which is now prevalent across mainland Southeast Asia, is associated with mutations in kelch13. Prolonged courses of artemisinin-based combination therapies are currently efficacious in areas where standard 3-day treatments are failing. (Funded by the U.K. Department of International Development and others; ClinicalTrials.gov number, NCT01350856.).
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407
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Ex vivo activity of endoperoxide antimalarials, including artemisone and arterolane, against multidrug-resistant Plasmodium falciparum isolates from Cambodia. Antimicrob Agents Chemother 2014; 58:5831-40. [PMID: 25049252 DOI: 10.1128/aac.02462-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Novel synthetic endoperoxides are being evaluated as new components of artemisinin combination therapies (ACTs) to treat artemisinin-resistant Plasmodium falciparum malaria. We conducted blinded ex vivo activity testing of fully synthetic (OZ78 and OZ277) and semisynthetic (artemisone, artemiside, artesunate, and dihydroartemisinin) endoperoxides in the histidine-rich protein 2 enzyme-linked immunosorbent assay against 200 P. falciparum isolates from areas of artemisinin-resistant malaria in western and northern Cambodia in 2009 and 2010. The order of potency and geometric mean (GM) 50% inhibitory concentrations (IC50s) were as follows: artemisone (2.40 nM) > artesunate (8.49 nM) > dihydroartemisinin (11.26 nM) > artemiside (15.28 nM) > OZ277 (31.25 nM) > OZ78 (755.27 nM). Ex vivo activities of test endoperoxides positively correlated with dihydroartemisinin and artesunate. The isolates were over 2-fold less susceptible to dihydroartemisinin than the artemisinin-sensitive P. falciparum W2 clone and showed sensitivity comparable to those with test endoperoxides and artesunate, with isolate/W2 IC50 susceptibility ratios of <2.0. All isolates had P. falciparum chloroquine resistance transporter mutations, with negative correlations in sensitivity to endoperoxides and chloroquine. The activities of endoperoxides (artesunate, dihydroartemisinin, OZ277, and artemisone) significantly correlated with that of the ACT partner drug, mefloquine. Isolates had mutations associated with clinical resistance to mefloquine, with 35% prevalence of P. falciparum multidrug resistance gene 1 (pfmdr1) amplification and 84.5% occurrence of the pfmdr1 Y184F mutation. GM IC50s for mefloquine, lumefantrine, and endoperoxides (artesunate, dihydroartemisinin, OZ277, OZ78, and artemisone) correlated with pfmdr1 copy number. Given that current ACTs are failing potentially from reduced sensitivity to artemisinins and partner drugs, newly identified mutations associated with artemisinin resistance reported in the literature and pfmdr1 mutations should be examined for their combined contributions to emerging ACT resistance.
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408
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Lun ZR, Ferreira PE, Fu LC. Artemisinin resistance in Plasmodium falciparum. THE LANCET. INFECTIOUS DISEASES 2014; 14:450-1. [PMID: 24849723 DOI: 10.1016/s1473-3099(14)70706-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhao-Rong Lun
- Key Laboratory of Gene Engineering of Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Key Laboratory of Tropical Disease Control, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou 510275, China.
| | - Pedro E Ferreira
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Lin-Chun Fu
- Tropical Medicine Institute, Guangzhou University of Chinese Medicine, Guangzhou, China
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409
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Amaratunga C, Witkowski B, Khim N, Menard D, Fairhurst RM. Artemisinin resistance in Plasmodium falciparum. THE LANCET. INFECTIOUS DISEASES 2014; 14:449-50. [PMID: 24849722 DOI: 10.1016/s1473-3099(14)70777-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Chanaki Amaratunga
- Laboratory of Malaria and Vector Research, NIAID/National Institutes of Health, Rockville, MD 20852, USA
| | - Benoit Witkowski
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Nimol Khim
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Didier Menard
- Malaria Molecular Epidemiology Unit, Institut Pasteur du Cambodge, Phnom Penh, Cambodia
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, NIAID/National Institutes of Health, Rockville, MD 20852, USA.
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410
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Sibley CH. Understanding drug resistance in malaria parasites: basic science for public health. Mol Biochem Parasitol 2014; 195:107-14. [PMID: 24927641 DOI: 10.1016/j.molbiopara.2014.06.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/25/2014] [Accepted: 06/03/2014] [Indexed: 01/09/2023]
Abstract
The worlds of basic scientists and those involved in treating patients and making public health decisions do not always intersect. Yet, assuring that when patients are treated, they are efficiently and completely cured, and that public health decisions are based on solid evidence requires a broad foundation of up to date basic research. Research on the malaria parasite, Plasmodium falciparum provides a useful illustration of the role that basic scientific studies have played in the very long relationship between humans and this deadly parasite. Drugs have always been a principal tool in malaria treatment. The ongoing struggle between evolution of resistance to antimalarials by the parasite and public health responses is used here as an illustration of the key contributions of basic scientists to this long history.
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Affiliation(s)
- Carol Hopkins Sibley
- World Wide Antimalarial Resistance Network, Department of Genome Sciences, University of Washington, Seattle, WA 98195-5065, USA.
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411
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Genome editing in the human malaria parasite Plasmodium falciparum using the CRISPR-Cas9 system. Nat Biotechnol 2014; 32:819-21. [DOI: 10.1038/nbt.2925] [Citation(s) in RCA: 474] [Impact Index Per Article: 47.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/08/2014] [Indexed: 02/06/2023]
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412
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Tinto H, Bonkian LN, Nana LA, Yerbanga I, Lingani M, Kazienga A, Valéa I, Sorgho H, Kpoda H, Guiguemdé TR, Ouédraogo JB, Mens PF, Schallig H, D’Alessandro U. Ex vivo anti-malarial drugs sensitivity profile of Plasmodium falciparum field isolates from Burkina Faso five years after the national policy change. Malar J 2014; 13:207. [PMID: 24885950 PMCID: PMC4049403 DOI: 10.1186/1475-2875-13-207] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 05/21/2014] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND The recent reports on the decreasing susceptibility of Plasmodium falciparum to artemisinin derivatives along the Thailand and Myanmar border are worrying. Indeed it may spread to India and then Africa, repeating the same pattern observed for chloroquine resistance. Therefore, it is essential to start monitoring P. falciparum sensitivity to artemisinin derivatives and its partner drugs in Africa. Efficacy of AL and ASAQ were tested by carrying out an in vivo drug efficacy test, with an ex vivo study against six anti-malarial drugs nested into it. Results of the latter are reported here. METHODS Plasmodium falciparum ex-vivo susceptibility to chloroquine (CQ), quinine (Q), lumefantrine (Lum), monodesethylamodiaquine (MDA), piperaquine (PPQ) and dihydroartemisinin (DHA) was investigated in children (6 months - 15 years) with a parasitaemia of at least ≥4,000/μl. The modified isotopic microtest technique was used. The results of cellular proliferation were analysed using ICEstimator software to determine the 50% inhibitory concentration (IC50) values. RESULTS DHA was the most potent among the 6 drugs tested, with IC50 values ranging from 0.8 nM to 0.9 nM (Geometric mean IC50 = 0.8 nM; 95% CI [0.8 - 0.9]). High IC50 values ranged between 0.8 nM to 166.1 nM were reported for lumefantrine (Geometric mean IC50 = 25.1 nM; 95% CI [22.4 - 28.2]). MDA and Q IC50s were significantly higher in CQ-resistant than in CQ-sensitive isolates (P = 0.0001). However, the opposite occurred for Lum and DHA (P < 0.001). No difference was observed for PPQ. CONCLUSION Artemisinin derivatives are still very efficacious in Burkina Faso and DHA-PPQ seems a valuable alternative ACT. The high lumefantrine IC50 found in this study is worrying as it may indicate a decreasing efficacy of one of the first-line treatments. This should be further investigated and monitored over time with large in vivo and ex vivo studies that will include also plasma drug measurements.
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Affiliation(s)
- Halidou Tinto
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Institut de Recherche en Sciences de la Santé/Direction Régionale de l’Ouest (IRSS/DRO), Bobo-Dioulasso, Burkina Faso
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Léa N Bonkian
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Louis A Nana
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Isidore Yerbanga
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Moussa Lingani
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Adama Kazienga
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Innocent Valéa
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Hermann Sorgho
- Institut de Recherche en Sciences de la Santé/Direction Régionale de l’Ouest (IRSS/DRO), Bobo-Dioulasso, Burkina Faso
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Hervé Kpoda
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Tinga Robert Guiguemdé
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
- Institut Supérieur des Sciences de la Santé (INSSA), Bobo Dioulasso, Burkina Faso
| | - Jean Bosco Ouédraogo
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Institut de Recherche en Sciences de la Santé/Direction Régionale de l’Ouest (IRSS/DRO), Bobo-Dioulasso, Burkina Faso
| | - Petronella F Mens
- Royal Tropical Institute/Koninklijk Instituut voor de Tropen (KIT), Amsterdam, The Netherlands
| | - Henk Schallig
- Royal Tropical Institute/Koninklijk Instituut voor de Tropen (KIT), Amsterdam, The Netherlands
| | - Umberto D’Alessandro
- Medical Research Council Unit, The Gambia, Disease Control & Elimination Theme, Fajara, The Gambia
- Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium
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413
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Flow cytometry-based analysis of artemisinin-resistant Plasmodium falciparum in the ring-stage survival assay. Antimicrob Agents Chemother 2014; 58:4938-40. [PMID: 24867976 DOI: 10.1128/aac.02902-14] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The ring-stage survival assay (RSA) is a powerful tool for phenotyping artemisinin-resistant Plasmodium falciparum but requires experienced microscopists to count viable parasites among 10,000 erythrocytes in Giemsa-stained thin blood smears. Here we describe a rapid flow cytometric assay that accurately counts viable parasites among 250,000 erythrocytes in suspension. This method performs as well as light microscopy and can be used to standardize the collection of RSA data between research groups in laboratory and field settings.
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414
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Plasmodium falciparum founder populations in western Cambodia have reduced artemisinin sensitivity in vitro. Antimicrob Agents Chemother 2014; 58:4935-7. [PMID: 24867977 DOI: 10.1128/aac.03055-14] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Reduced Plasmodium falciparum sensitivity to short-course artemisinin (ART) monotherapy manifests as a long parasite clearance half-life. We recently defined three parasite founder populations with long half-lives in Pursat, western Cambodia, where reduced ART sensitivity is prevalent. Using the ring-stage survival assay, we show that these founder populations have reduced ART sensitivity in vitro at the early ring stage of parasite development and that a genetically admixed population contains subsets of parasites with normal or reduced ART sensitivity.
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415
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Affiliation(s)
- Nicholas J White
- Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand.
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416
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In the Literature. Clin Infect Dis 2014. [DOI: 10.1093/cid/ciu050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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417
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Zwang J, Dorsey G, Mårtensson A, d'Alessandro U, Ndiaye JL, Karema C, Djimde A, Brasseur P, Sirima SB, Olliaro P. Plasmodium falciparum clearance in clinical studies of artesunate-amodiaquine and comparator treatments in sub-Saharan Africa, 1999-2009. Malar J 2014; 13:114. [PMID: 24666562 PMCID: PMC3987158 DOI: 10.1186/1475-2875-13-114] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Accepted: 03/11/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Artemisinin-based combination therapy (ACT) is the recommended first-line therapy for uncomplicated Plasmodium falciparum malaria worldwide but decreased artemisinin susceptibility, phenotypically characterized as slow parasite clearance time (PCT), has now been reported in Southeast Asia. This makes it all too important to measure the dynamics of parasite clearance in African patients treated with ACT over time, to understand trends and detect changes early enough to intervene METHODS Individual patient data from 27 clinical trials of artesunate-amodiaquine (ASAQ) vs comparators conducted between 1999 and 2009 were analysed for parasite clearance on modified intent-to-treat (ITT) basis. RESULTS Overall 15,017 patients treated for uncomplicated P. falciparum malaria at 44 sites in 20 sub-Saharan African countries were included in the analysis; 51% (n=7,660) vs 49% (n=7,357) were treated with ASAQ and comparator treatments, respectively. Seventy-seven per cent (77%) were children under six years of age. The proportion of the patients treated with ASAQ with persistent parasitaemia on Day 2 was 8.6%, and 1.5% on Day 3. Risk factor for not clearing parasites on Day 2 and Day 3 calculated by multivariate logistic regression with random effect on site and controlling for treatment were: high parasitaemia before treatment was (adjusted risk ratios (AOR) 2.12, 95% CI 1.91-2.35, AOR 2.43, 95% CI 1.98-3.00, respectively); non-ACT treatment (p=0.001, for all comparisons). Anaemia (p=0.001) was an additional factor for Day 2 and young age (p=0.005) for Day 3.In patients treated with ASAQ in studies who had complete parasitaemia data every 24 hours up to Day 3 and additionally Day 7, the parasite reduction ratio was 93.9% by Day 1 and 99.9% by Day 2. Using the median parasitaemia before treatment (p0=27,125 μL) and a fitted model, the predicted PCT (pPCT = 3.614*ln (p0) - 6.135, r(2) = 0.94) in ASAQ recipients was 31 hours. CONCLUSION Within the period covered by these studies, rapid Plasmodium falciparum clearance continues to be achieved in Sub-Saharan African patients treated with ACT, and in particular with ASAQ. The prediction formula for parasite clearance time could be a pragmatic tool for studies with binary outcomes and once-daily sampling, both for research and monitoring purposes.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Piero Olliaro
- UNICEF/UNDP/WB/WHO Special Programme for Research & Training in Tropical Diseases (TDR), Geneva, Switzerland.
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418
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Salcedo-Sora JE, Caamano-Gutierrez E, Ward SA, Biagini GA. The proliferating cell hypothesis: a metabolic framework for Plasmodium growth and development. Trends Parasitol 2014; 30:170-5. [PMID: 24636355 PMCID: PMC3989997 DOI: 10.1016/j.pt.2014.02.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 02/02/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
Abstract
The hypothesis offers a framework to explain the atypical features of parasite metabolism. Aerobic glycolysis is hypothesised to meet the biosynthetic demands of rapid proliferation. Differentiation may be epigenetically regulated in response to nutrient-linked metabolism.
We hypothesise that intraerythrocytic malaria parasite metabolism is not merely fulfilling the need for ATP generation, but is evolved to support rapid proliferation, similar to that seen in other rapidly proliferating cells such as cancer cells. Deregulated glycolytic activity coupled with impaired mitochondrial metabolism is a metabolic strategy to generate glycolytic intermediates essential for rapid biomass generation for schizogony. Further, we discuss the possibility that Plasmodium metabolism is not only a functional consequence of the ‘hard-wired’ genome and argue that metabolism may also have a causal role in triggering the cascade of events that leads to developmental stage transitions. This hypothesis offers a framework to rationalise the observations of aerobic glycolysis, atypical mitochondrial metabolism, and metabolic switching in nonproliferating stages.
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Affiliation(s)
| | - Eva Caamano-Gutierrez
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK; Warwick Systems Biology Centre, Senate House, University of Warwick, Coventry, CV4 7AL, UK
| | - Stephen A Ward
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Giancarlo A Biagini
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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419
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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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420
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Krishna S, Pulcini S, Moore CM, Teo BHY, Staines HM. Pumped up: reflections on PfATP6 as the target for artemisinins. Trends Pharmacol Sci 2014; 35:4-11. [DOI: 10.1016/j.tips.2013.10.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 10/11/2013] [Accepted: 10/21/2013] [Indexed: 12/01/2022]
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421
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Affiliation(s)
- Christopher V Plowe
- Howard Hughes Medical Institute and the Center for Vaccine Development, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA
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422
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Quashie NB, Duah NO, Abuaku B, Quaye L, Ayanful-Torgby R, Akwoviah GA, Kweku M, Johnson JD, Lucchi NW, Udhayakumar V, Duplessis C, Kronmann KC, Koram KA. A SYBR Green 1-based in vitro test of susceptibility of Ghanaian Plasmodium falciparum clinical isolates to a panel of anti-malarial drugs. Malar J 2013; 12:450. [PMID: 24341604 PMCID: PMC3878558 DOI: 10.1186/1475-2875-12-450] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/10/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Based on report of declining efficacy of chloroquine, Ghana shifted to the use of artemisinin-based combination therapy (ACT) in 2005 as the first-line anti-malarial drug. Since then, there has not been any major evaluation of the efficacy of anti-malarial drugs in Ghana in vitro. The sensitivity of Ghanaian Plasmodium falciparum isolates to anti-malarial drugs was, therefore, assessed and the data compared with that obtained prior to the change in the malaria treatment policy. METHODS A SYBR Green 1 fluorescent-based in vitro drug sensitivity assay was used to assess the susceptibility of clinical isolates of P. falciparum to a panel of 12 anti-malarial drugs in three distinct eco-epidemiological zones in Ghana. The isolates were obtained from children visiting health facilities in sentinel sites located in Hohoe, Navrongo and Cape Coast municipalities. The concentration of anti-malarial drug inhibiting parasite growth by 50% (IC50) for each drug was estimated using the online program, ICEstimator. RESULTS Pooled results from all the sentinel sites indicated geometric mean IC50 values of 1.60, 3.80, 4.00, 4.56, 5.20, 6.11, 10.12, 28.32, 31.56, 93.60, 107.20, and 8952.50 nM for atovaquone, artesunate, dihydroartemisin, artemether, lumefantrine, amodiaquine, mefloquine, piperaquine, chloroquine, tafenoquine, quinine, and doxycycline, respectively. With reference to the literature threshold value indicative of resistance, the parasites showed resistance to all the test drugs except the artemisinin derivatives, atovaquone and to a lesser extent, lumefantrine. There was nearly a two-fold decrease in the IC50 value determined for chloroquine in this study compared to that determined in 2004 (57.56 nM). This observation is important, since it suggests a significant improvement in the efficacy of chloroquine, probably as a direct consequence of reduced drug pressure after cessation of its use. Compared to that measured prior to the change in treatment policy, significant elevation of artesunate IC50 value was observed. The results also suggest the existence of possible cross-resistance among some of the test drugs. CONCLUSION Ghanaian P. falciparum isolates, to some extent, have become susceptible to chloroquine in vitro, however the increasing trend in artesunate IC50 value observed should be of concern. Continuous monitoring of ACT in Ghana is recommended.
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Affiliation(s)
- Neils B Quashie
- Centre for Tropical Clinical Pharmacology and Therapeutics, University of Ghana Medical School, Accra, Ghana.
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423
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Sibley CH. Tracking artemisinin resistance in Plasmodium falciparum. THE LANCET. INFECTIOUS DISEASES 2013; 13:999-1000. [DOI: 10.1016/s1473-3099(13)70260-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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424
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Genome-wide screen identifies new candidate genes associated with artemisinin susceptibility in Plasmodium falciparum in Kenya. Sci Rep 2013; 3:3318. [PMID: 24270944 PMCID: PMC3839035 DOI: 10.1038/srep03318] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 10/21/2013] [Indexed: 11/12/2022] Open
Abstract
Early identification of causal genetic variants underlying antimalarial drug resistance could provide robust epidemiological tools for timely public health interventions. Using a novel natural genetics strategy for mapping novel candidate genes we analyzed >75,000 high quality single nucleotide polymorphisms selected from high-resolution whole-genome sequencing data in 27 isolates of Plasmodium falciparum. We identified genetic variants associated with susceptibility to dihydroartemisinin that implicate one region on chromosome 13, a candidate gene on chromosome 1 (PFA0220w, a UBP1 ortholog) and others (PFB0560w, PFB0630c, PFF0445w) with putative roles in protein homeostasis and stress response. There was a strong signal for positive selection on PFA0220w, but not the other candidate loci. Our results demonstrate the power of full-genome sequencing-based association studies for uncovering candidate genes that determine parasite sensitivity to artemisinins. Our study provides a unique reference for the interpretation of results from resistant infections.
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425
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Flegg JA, Guérin PJ, Nosten F, Ashley EA, Phyo AP, Dondorp AM, Fairhurst RM, Socheat D, Borrmann S, Björkman A, Mårtensson A, Mayxay M, Newton PN, Bethell D, Se Y, Noedl H, Diakite M, Djimde AA, Hien TT, White NJ, Stepniewska K. Optimal sampling designs for estimation of Plasmodium falciparum clearance rates in patients treated with artemisinin derivatives. Malar J 2013; 12:411. [PMID: 24225303 PMCID: PMC3842737 DOI: 10.1186/1475-2875-12-411] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 10/28/2013] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The emergence of Plasmodium falciparum resistance to artemisinins in Southeast Asia threatens the control of malaria worldwide. The pharmacodynamic hallmark of artemisinin derivatives is rapid parasite clearance (a short parasite half-life), therefore, the in vivo phenotype of slow clearance defines the reduced susceptibility to the drug. Measurement of parasite counts every six hours during the first three days after treatment have been recommended to measure the parasite clearance half-life, but it remains unclear whether simpler sampling intervals and frequencies might also be sufficient to reliably estimate this parameter. METHODS A total of 2,746 parasite density-time profiles were selected from 13 clinical trials in Thailand, Cambodia, Mali, Vietnam, and Kenya. In these studies, parasite densities were measured every six hours until negative after treatment with an artemisinin derivative (alone or in combination with a partner drug). The WWARN Parasite Clearance Estimator (PCE) tool was used to estimate "reference" half-lives from these six-hourly measurements. The effect of four alternative sampling schedules on half-life estimation was investigated, and compared to the reference half-life (time zero, 6, 12, 24 (A1); zero, 6, 18, 24 (A2); zero, 12, 18, 24 (A3) or zero, 12, 24 (A4) hours and then every 12 hours). Statistical bootstrap methods were used to estimate the sampling distribution of half-lives for parasite populations with different geometric mean half-lives. A simulation study was performed to investigate a suite of 16 potential alternative schedules and half-life estimates generated by each of the schedules were compared to the "true" half-life. The candidate schedules in the simulation study included (among others) six-hourly sampling, schedule A1, schedule A4, and a convenience sampling schedule at six, seven, 24, 25, 48 and 49 hours. RESULTS The median (range) parasite half-life for all clinical studies combined was 3.1 (0.7-12.9) hours. Schedule A1 consistently performed the best, and schedule A4 the worst, both for the individual patient estimates and for the populations generated with the bootstrapping algorithm. In both cases, the differences between the reference and alternative schedules decreased as half-life increased. In the simulation study, 24-hourly sampling performed the worst, and six-hourly sampling the best. The simulation study confirmed that more dense parasite sampling schedules are required to accurately estimate half-life for profiles with short half-life (≤ three hours) and/or low initial parasite density (≤ 10,000 per μL). Among schedules in the simulation study with six or fewer measurements in the first 48 hours, a schedule with measurements at times (time windows) of 0 (0-2), 6 (4-8), 12 (10-14), 24 (22-26), 36 (34-36) and 48 (46-50) hours, or at times 6, 7 (two samples in time window 5-8), 24, 25 (two samples during time 23-26), and 48, 49 (two samples during time 47-50) hours, until negative most accurately estimated the "true" half-life. For a given schedule, continuing sampling after two days had little effect on the estimation of half-life, provided that adequate sampling was performed in the first two days and the half-life was less than three hours. If the measured parasitaemia at two days exceeded 1,000 per μL, continued sampling for at least once a day was needed for accurate half-life estimates. CONCLUSIONS This study has revealed important insights on sampling schedules for accurate and reliable estimation of Plasmodium falciparum half-life following treatment with an artemisinin derivative (alone or in combination with a partner drug). Accurate measurement of short half-lives (rapid clearance) requires more dense sampling schedules (with more than twice daily sampling). A more intensive sampling schedule is, therefore, recommended in locations where P. falciparum susceptibility to artemisinins is not known and the necessary resources are available. Counting parasite density at six hours is important, and less frequent sampling is satisfactory for estimating long parasite half-lives in areas where artemisinin resistance is present.
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Affiliation(s)
- Jennifer A Flegg
- WorldWide Antimalarial Resistance Network (WWARN), University of Oxford, Oxford, UK.
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426
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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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427
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Leang R, Ros S, Duong S, Navaratnam V, Lim P, Ariey F, Kiechel JR, Ménard D, Taylor WRJ. Therapeutic efficacy of fixed dose artesunate-mefloquine for the treatment of acute, uncomplicated Plasmodium falciparum malaria in Kampong Speu, Cambodia. Malar J 2013; 12:343. [PMID: 24060207 PMCID: PMC3852322 DOI: 10.1186/1475-2875-12-343] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2013] [Accepted: 09/10/2013] [Indexed: 11/10/2022] Open
Abstract
Background Cambodia stopped using co-blistered, non-fixed, artesunate-mefloquine (ASMQ) in 2008 when treatment failure rates approximated 20%. Fixed dose combination (FDC) ASMQ is efficacious against acute uncomplicated, drug resistant Plasmodium falciparum malaria in Southeast Asia but has not been tested in Cambodia. Methods A 42-day WHO therapeutic efficacy study (TES) was conducted in 2010 in Oral, Kampong Speu province, south-west Cambodia, in patients with acute uncomplicated P. falciparum. Daily administered FDC ASMQ for three days was dosed by age. Genotyping of isolates at day 0 and day of recrudescence by polymerase chain reaction (PCR) classified post-treatment recurrent falciparum parasitaemia. Ex vivo drug sensitivity testing ([3H] hypoxanthine method) was performed on baseline parasites and reported as the drug concentration inhibiting 50% parasite growth vs no drug (IC50). Results Recruited patients numbered 45; five aged <15 years. On day 3, five of 45 [11.1 (3.7-24.05)] % patients were still parasite-positive; one of whom later failed treatment on day 21. There were 5/45 (11.1%) late treatment failures on day 21, 28 and 35; all were PCR diagnosed recrudescent infections. The day 0 MQ IC50s ranged from 11.5-238.9 (median 58.6) nM. Conclusions This TES demonstrated reasonable efficacy in an area of possible reduced artemisinin sensitivity and high MQ IC50s. Efficacy testing of FDC ASMQ should continue in Cambodia and be considered for reintroduction if efficacy returns.
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Affiliation(s)
- Rithea Leang
- National Centre for Parasitology, Entomology and Malaria Control, #372, Monivong Blvd, Corner St, 322, Phnom Penh, Cambodia.
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