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Ansah F, Nyame K, Laryea R, Owusu R, Amon D, Boyetey MJB, Ayeke D, Razak N, Kornu VE, Ashitei S, Owusu-Appiah C, Chirawurah JD, Abugri J, Aniweh Y, Opoku N, Sutherland CJ, Binka FN, Kweku M, Awandare GA, Dinko B. The temporal dynamics of Plasmodium species infection after artemisinin-based combination therapy (ACT) among asymptomatic children in the Hohoe municipality, Ghana. Malar J 2023; 22:271. [PMID: 37710288 PMCID: PMC10500816 DOI: 10.1186/s12936-023-04712-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 09/11/2023] [Indexed: 09/16/2023] Open
Abstract
BACKGROUND The routine surveillance of asymptomatic malaria using nucleic acid-based amplification tests is essential in obtaining reliable data that would inform malaria policy formulation and the implementation of appropriate control measures. METHODS In this study, the prevalence rate and the dynamics of Plasmodium species among asymptomatic children (n = 1697) under 5 years from 30 communities within the Hohoe municipality in Ghana were determined. RESULTS AND DISCUSSION The observed prevalence of Plasmodium parasite infection by polymerase chain reaction (PCR) was 33.6% (571/1697), which was significantly higher compared to that obtained by microscopy [26.6% (451/1697)] (P < 0.0001). Based on species-specific analysis by nested PCR, Plasmodium falciparum infection [33.6% (570/1697)] was dominant, with Plasmodium malariae, Plasmodium ovale and Plasmodium vivax infections accounting for 0.1% (1/1697), 0.0% (0/1697), and 0.0% (0/1697), respectively. The prevalence of P. falciparum infection among the 30 communities ranged from 0.0 to 82.5%. Following artesunate-amodiaquine (AS + AQ, 25 mg/kg) treatment of a sub-population of the participants (n = 184), there was a substantial reduction in Plasmodium parasite prevalence by 100% and 79.2% on day 7 based on microscopy and nested PCR analysis, respectively. However, there was an increase in parasite prevalence from day 14 to day 42, with a subsequent decline on day 70 by both microscopy and nested PCR. For parasite clearance rate analysis, we found a significant proportion of the participants harbouring residual Plasmodium parasites or parasite genomic DNA on day 1 [65.0% (13/20)], day 2 [65.0% (13/20)] and day 3 [60.0% (12/20)] after initiating treatment. Of note, gametocyte carriage among participants was low before and after treatment. CONCLUSION Taken together, the results indicate that a significant number of individuals could harbour residual Plasmodium parasites or parasite genomic DNA after treatment. The study demonstrates the importance of routine surveillance of asymptomatic malaria using sensitive nucleic acid-based amplification techniques.
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Affiliation(s)
- Felix Ansah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Kwamina Nyame
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Rukaya Laryea
- Department of Epidemiology and Biostatistics, Fred Newton Binka School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | - Richard Owusu
- Department of Epidemiology and Biostatistics, Fred Newton Binka School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | - Denick Amon
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Mark-Jefferson Buer Boyetey
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Dzidzor Ayeke
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Nasibatu Razak
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Victor E Kornu
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Sarah Ashitei
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Caleb Owusu-Appiah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Jersley D Chirawurah
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - James Abugri
- Department of Biochemistry and Forensic Sciences, School of Chemical and Biochemical Sciences, C. K. Tedam University of Technology and Applied Sciences, Navrongo, Ghana
| | - Yaw Aniweh
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Nicholas Opoku
- Department of Epidemiology and Biostatistics, Fred Newton Binka School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | - Colin J Sutherland
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Fred N Binka
- Department of Epidemiology and Biostatistics, Fred Newton Binka School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | - Margaret Kweku
- Department of Epidemiology and Biostatistics, Fred Newton Binka School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | - Gordon A Awandare
- West African Centre for Cell Biology of Infectious Pathogens (WACCBIP), College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Legon, Accra, Ghana
| | - Bismarck Dinko
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.
- Department of Biomedical Sciences, School of Basic and Biomedical Sciences, University of Health and Allied Sciences, Ho, Ghana.
- Department of Clinical Microbiology, School of Medicine and Dentistry College of Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ashanti Region, Ghana.
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Yin X, Li Y, Bagchus W, Yalkinoglu Ö, Bezuidenhout D, Tappert A, McCarthy J, Marquart L, Oeuvray C. Evaluation of a multiphasic parasite clearance profile after treatment of experimental human infection with the investigational anti-malarial M5717 using segmented mixed effect models. Malar J 2023; 22:199. [PMID: 37381013 DOI: 10.1186/s12936-023-04627-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 06/16/2023] [Indexed: 06/30/2023] Open
Abstract
BACKGROUND Evaluation of parasite clearance patterns in experimental human infection trials helps increase understanding of drug action. In a previously reported phase Ib trial of a new investigational anti-malarial drug M5717, parasite clearance showed a biphasic linear pattern: slow removal phase with a near flat clearance rate followed by a fast clearance phase with a steep slope. In this study three statistical approaches were implemented and compared to estimate the parasite clearance rate for each phase and the time point corresponding to the change of clearance rates (changepoint between the two phases). METHODS Data using three M5717 doses 150 mg (n = 6), 400 mg (n = 8), 800 mg (n = 8) were used to estimate biphasic clearance rates. Three models were investigated: firstly, segmented mixed models with estimated changepoint-models with/without random effects in various parameters were compared. Secondly, a segmented mixed model using grid search-this method is similar to the first except that changepoints were not estimated, instead they were selected based on model fit from given candidate values. Thirdly, a two-stage approach whereby a segmented regression model fit to each participant followed by a meta-analysis method. Hourly rate of parasite clearance (HRPC) interpreted as the percentage of parasites removed each hour was calculated. RESULTS The three models generated similar results. Using segmented mixed models, the estimated changepoints after treatment in hours (95% CI) were: 150 mg: 33.9 (28.7, 39.1); 400 mg: 57.4 (52.5, 62.4); and 800 mg: 52.8 (47.4, 58.1). For all three treatment groups, there was nearly no clearance before the changepoints, but rapid clearance in the second phase (HRPC [95% CI]): 150 mg: 16.8% (14.3, 19.1%); 400 mg: 18.6% (16.0, 21.1%); and 800 mg: 11.7% (9.3, 14.1%). CONCLUSIONS All three statistical approaches are effective tools to characterize the bi-phasic clearance of M5717 in the phase 1b experimental Plasmodium falciparum malaria human infection study. The statistical approaches produced similar results to estimate the two-phase clearance rates and the changepoint for each treatment dose of M5717. However, the segmented mixed model with random changepoints has several advantages: it is computationally efficient, provides precision for changepoint estimates and is robust concerning outlying datapoints or individuals.
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Affiliation(s)
- Xiaoyan Yin
- EMD Serono Research & Development Institute, Inc. (an Affiliate of Merck KGaA), 45 Middlesex Turnpike, Billerica, MA, 01821, USA.
| | - Ying Li
- EMD Serono Research & Development Institute, Inc. (an Affiliate of Merck KGaA), 45 Middlesex Turnpike, Billerica, MA, 01821, USA
| | - Wilhelmina Bagchus
- WMB: Merck Serono S.A (an Affiliate of Merck KGaA), Lausanne, Switzerland
| | | | - Deon Bezuidenhout
- WMB: Merck Serono S.A (an Affiliate of Merck KGaA), Lausanne, Switzerland
| | | | - James McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
- The Peter Doherty Institute for Infection and Immunity, The University of Melbourne and the Royal Melbourne Hospital, Melbourne, VIC, Australia
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
- School of Public Health, University of Queensland, Brisbane, Australia
| | - Claude Oeuvray
- The Global Health Institute of Merck (an Affiliate of Merck KGaA), Eysins, Switzerland
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Paris L, Tackie RG, Beshir KB, Tampuori J, Awandare GA, Binka FN, Urban BC, Dinko B, Sutherland CJ. Parasite clearance dynamics in children hospitalised with severe malaria in the Ho Teaching Hospital, Volta Region, Ghana. Parasite Epidemiol Control 2022; 19:e00276. [PMID: 36263093 PMCID: PMC9574762 DOI: 10.1016/j.parepi.2022.e00276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 08/07/2022] [Accepted: 09/30/2022] [Indexed: 11/21/2022] Open
Abstract
Background Over 90% of severe malaria (SM) cases occur in African children. Parenteral artesunate is currently the recommended treatment for SM. Studies of parasite clearance in paediatric SM cases are needed for assessment of therapeutic outcomes but are lacking in Africa. Methods Severe malaria patients were recruited in the children's emergency ward at Ho Teaching Hospital, Ghana, in 2018. Blood samples were taken upon admission, every 24 h for 3 days and 1 week after treatment, and DNA extracted. Parasitaemia and parasite densities were performed by microscopy at enrolment and the follow-up days wherever possible. Relative parasite density was measured at each timepoint by duplex qPCR and parameters of parasite clearance estimated. Results Of 25 evaluable SM patients, clearance of qPCR-detectable parasites occurred within 48 h for 17 patients, but three out of the remaining eight were still qPCR-positive on day 3. Increased time to parasite clearance was seen in children ≥5 years old, those with lower haemoglobin levels and those with a high number of previous malaria diagnoses, but these associations were not statistically significant. Conclusion We examined parasite clearance dynamics among paediatric cases of SM. Our observations suggest that daily sampling for qPCR estimation of P. falciparum peripheral density is a useful method for assessing treatment response in hospitalised SM cases. The study demonstrated varied parasite clearance response, thus illuminating the complex nature of the mechanism in this important patient group, and further investigations utilizing larger sample sizes are needed to confirm our findings.
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Affiliation(s)
- Laura Paris
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - Richmond G. Tackie
- Department of Biomedical Sciences, School of Basic and Biomedical Sciences, University of Health and Allied Sciences, Ho, Ghana
| | - Khalid B. Beshir
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - John Tampuori
- Department of Urology, Ho Teaching Hospital, Ho, Ghana
| | - Gordon A. Awandare
- West African Centre for Cell Biology of Infectious Pathogens, Department of Biochemistry, Cell and Molecular Biology, University of Ghana, Legon, Accra, Ghana
| | - Fred N. Binka
- Department of Epidemiology and Biostatistics, School of Public Health, University of Health and Allied Sciences, Ho, Ghana
| | - Britta C. Urban
- Department of Tropical Disease Biology, Faculty of Biological Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Bismarck Dinko
- Department of Biomedical Sciences, School of Basic and Biomedical Sciences, University of Health and Allied Sciences, Ho, Ghana
| | - Colin J. Sutherland
- Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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SheelaNair A, Romanczuk AS, Aogo RA, Haldar RN, Lansink LIM, Cromer D, Salinas YG, Guy RK, McCarthy JS, Davenport MP, Haque A, Khoury DS. Similarly efficacious anti-malarial drugs SJ733 and pyronaridine differ in their ability to remove circulating parasites in mice. Malar J 2022; 21:49. [PMID: 35172826 PMCID: PMC8848794 DOI: 10.1186/s12936-022-04075-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 02/06/2022] [Indexed: 11/13/2022] Open
Abstract
Background Artemisinin-based combination therapy (ACT) has been a mainstay for malaria prevention and treatment. However, emergence of drug resistance has incentivised development of new drugs. Defining the kinetics with which circulating parasitized red blood cells (pRBC) are lost after drug treatment, referred to as the “parasite clearance curve”, has been critical for assessing drug efficacy; yet underlying mechanisms remain partly unresolved. The clearance curve may be shaped both by the rate at which drugs kill parasites, and the rate at which drug-affected parasites are removed from circulation. Methods In this context, two anti-malarials, SJ733, and an ACT partner drug, pyronaridine were compared against sodium artesunate in mice infected with Plasmodium berghei (strain ANKA). To measure each compound’s capacity for pRBC removal in vivo, flow cytometric monitoring of a single cohort of fluorescently-labelled pRBC was employed, and combined with ex vivo parasite culture to assess parasite maturation and replication. Results These three compounds were found to be similarly efficacious in controlling established infection by reducing overall parasitaemia. While sodium artesunate acted relatively consistently across the life-stages, single-dose SJ733 elicited a biphasic effect, triggering rapid, partly phagocyte-dependent removal of trophozoites and schizonts, followed by arrest of residual ring-stages. In contrast, pyronaridine abrogated maturation of younger parasites, with less pronounced effects on mature parasites, while modestly increasing pRBC removal. Conclusions Anti-malarials SJ733 and pyronaridine, though similarly efficacious in reducing overall parasitaemia in mice, differed markedly in their capacity to arrest replication and remove pRBC from circulation. Thus, similar parasite clearance curves can result for anti-malarials with distinct capacities to inhibit, kill and clear parasites.
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Affiliation(s)
- Arya SheelaNair
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia
| | - Aleksandra S Romanczuk
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia
| | - Rosemary A Aogo
- Infection Analytics Program, Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, 2052, Australia
| | - Rohit Nemai Haldar
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia
| | - Lianne I M Lansink
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia.,Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Parkville, VIC, 3000, Australia
| | - Deborah Cromer
- Infection Analytics Program, Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, 2052, Australia
| | | | - R Kiplin Guy
- College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia.,Department of Infectious Diseases, Peter Doherty Institute for Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Parkville, VIC, 3000, Australia.,Victorian Infectious Diseases Service, Royal Melbourne Hospital, Parkville, VIC, 3000, Australia
| | - Miles P Davenport
- Infection Analytics Program, Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, 2052, Australia
| | - Ashraful Haque
- QIMR Berghofer Medical Research Institute, 300 Herston Road, Herston, Brisbane, QLD, 4006, Australia. .,Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, University of Melbourne, 792 Elizabeth Street, Parkville, VIC, 3000, Australia.
| | - David S Khoury
- Infection Analytics Program, Kirby Institute for Infection and Immunity, UNSW Sydney, Sydney, 2052, Australia.
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Dick JK, Hart GT. Natural Killer Cell Antibody-Dependent Cellular Cytotoxicity (ADCC) Activity Against Plasmodium falciparum-Infected Red Blood Cells. Methods Mol Biol 2022; 2470:641-657. [PMID: 35881380 DOI: 10.1007/978-1-0716-2189-9_48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Antibody-dependent cellular cytotoxicity (ADCC) is a mechanism of cell defense that bridges the innate and adaptive immune systems. ADCC has been found to be a major route of immune protection against both viral infections and cancer. Recently, natural killer (NK) cell-mediated ADCC has been shown as a mechanism of parasite clearance and protection against malaria (Hart et al. J Exp Med 216(6):1280-1290, 2019). NK cells bind to antibodies on the surface of Plasmodium falciparum infected red blood cells (iRBCs) via their Fc receptor, FcγRIIIa (CD16). This interaction induces the release of lytic granules (degranulation) by NK cells, which contain perforin, granzyme B, and granulysin, as well as the secretion of IFNγ. ADCC subsequently limits the growth of Plasmodium falciparum in vitro (Arora et al. Elife:7, e36806, 2018). Because NK cell-mediated ADCC has been shown to be important in malaria parasite clearance and protection, further studies understanding ADCC in malaria are warranted (Hart et al. J Exp Med 216(6):1280-1290, 2019). Therefore, this protocol describes methods to perform an in vitro ADCC functional assay with iRBCs. Specifically, it includes protocols on how to grow and culture iRBCs, how to culture peripheral blood mononuclear cells (PMBCs), and how to do in vitro PBMC assays to measure NK degranulation and IFNγ production as measures of NK ADCC function.
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Affiliation(s)
- Jenna Kelly Dick
- Center for Immunology, University of Minnesota, Minneapolis, MN, USA
- Department of Medicine, Division of Infectious Disease and International Medicine, University of Minnesota, Microbiology Research Facility, Minneapolis, MN, USA
- Medical Scientist Training Program, University of Minnesota, Minneapolis, MN, USA
| | - Geoffrey Thomas Hart
- Center for Immunology, University of Minnesota, Minneapolis, MN, USA.
- Department of Medicine, Division of Infectious Disease and International Medicine, University of Minnesota, Microbiology Research Facility, Minneapolis, MN, USA.
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Adoke Y, Zoleko-Manego R, Ouoba S, Tiono AB, Kaguthi G, Bonzela JE, Duong TT, Nahum A, Bouyou-Akotet M, Ogutu B, Ouedraogo A, Macintyre F, Jessel A, Laurijssens B, Cherkaoui-Rbati MH, Cantalloube C, Marrast AC, Bejuit R, White D, Wells TNC, Wartha F, Leroy D, Kibuuka A, Mombo-Ngoma G, Ouattara D, Mugenya I, Phuc BQ, Bohissou F, Mawili-Mboumba DP, Olewe F, Soulama I, Tinto H; FALCI Study Group. A randomized, double-blind, phase 2b study to investigate the efficacy, safety, tolerability and pharmacokinetics of a single-dose regimen of ferroquine with artefenomel in adults and children with uncomplicated Plasmodium falciparum malaria. Malar J 2021; 20:222. [PMID: 34011358 DOI: 10.1186/s12936-021-03749-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/28/2021] [Indexed: 12/17/2022] Open
Abstract
Background For uncomplicated Plasmodium falciparum malaria, highly efficacious single-dose treatments are expected to increase compliance and improve treatment outcomes, and thereby may slow the development of resistance. The efficacy and safety of a single-dose combination of artefenomel (800 mg) plus ferroquine (400/600/900/1200 mg doses) for the treatment of uncomplicated P. falciparum malaria were evaluated in Africa (focusing on children ≤ 5 years) and Asia. Methods The study was a randomized, double-blind, single-dose, multi-arm clinical trial in patients aged > 6 months to < 70 years, from six African countries and Vietnam. Patients were followed up for 63 days to assess treatment efficacy, safety and pharmacokinetics. The primary efficacy endpoint was the polymerase chain reaction (PCR)-adjusted adequate clinical and parasitological response (ACPR) at Day 28 in the Per-Protocol [PP] Set comprising only African patients ≤ 5 years. The exposure–response relationship for PCR-adjusted ACPR at Day 28 and prevalence of kelch-13 mutations were explored. Results A total of 373 patients were treated: 289 African patients ≤ 5 years (77.5%), 64 African patients > 5 years and 20 Asian patients. None of the treatment arms met the target efficacy criterion for PCR-adjusted ACPR at Day 28 (lower limit of 95% confidence interval [CI] > 90%). PCR-adjusted ACPR at Day 28 [95% CI] in the PP Set ranged from 78.4% [64.7; 88.7%] to 91.7% [81.6; 97.2%] for the 400 mg to 1200 mg ferroquine dose. Efficacy rates were low in Vietnamese patients, ranging from 20 to 40%. A clear relationship was found between drug exposure (artefenomel and ferroquine concentrations at Day 7) and efficacy (primary endpoint), with higher concentrations of both drugs resulting in higher efficacy. Six distinct kelch-13 mutations were detected in parasite isolates from 10/272 African patients (with 2 mutations known to be associated with artemisinin resistance) and 18/20 Asian patients (all C580Y mutation). Vomiting within 6 h of initial artefenomel administration was common (24.6%) and associated with lower drug exposures. Conclusion The efficacy of artefenomel/ferroquine combination was suboptimal in African children aged ≤ 5 years, the population of interest, and vomiting most likely had a negative impact on efficacy. Trial registration ClinicalTrials.gov, NCT02497612. Registered 14 Jul 2015, https://clinicaltrials.gov/ct2/show/NCT02497612?term=NCT02497612&draw=2&rank=1 Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03749-4.
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Kone A, Sissoko S, Fofana B, Sangare CO, Dembele D, Haidara AS, Diallo N, Coulibaly A, Traore A, Toure S, Haidara K, Sanogo K, Sagara I, Beshir KB, Gil JP, Doumbo OK, Djimde AA. Different Plasmodium falciparum clearance times in two Malian villages following artesunate monotherapy. Int J Infect Dis 2020; 95:399-405. [PMID: 32320811 DOI: 10.1016/j.ijid.2020.03.082] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 03/28/2020] [Accepted: 03/30/2020] [Indexed: 11/23/2022] Open
Abstract
High prevalence of residual parasitemia at day 3 post-artesunate monotherapy treatment using qPCR while no parasites were detected by microscopy at the same timepoint. A longer parasite clearance time observed in a Malian village. Artesunate treatment is still efficacious on Plasmodium falciparum in Mali.
Background Artemisinin resistance described as increased parasite clearance time (PCT) is rare in Africa. More sensitive methods such as qPCR might better characterize the clearance phenotype in sub-Saharan Africa. Methods PCT is explored in Mali using light microscopy and qPCR after artesunate for uncomplicated malaria. In two villages, patients were followed for 28 days. Blood smears and spots were collected respectively for microscopy and qPCR. Parasitemia slope half-life was calculated after microscopy. Patient residual parasitemia were measured by qPCR. Results Uncorrected adequate clinical and parasitological responses (ACPR) observed in Faladje and Bougoula-Hameau were 78% and 92%, respectively (p = 0.01). This reached 100% for both after molecular correction. Proportions of 24H microscopy positive patients in Faladje and Bougoula-Hameau were 97.2% and 72%, respectively (p < 0.0001). Slope half-life was 2.8 h in Faladje vs 2H in Bougoula-Hameau (p < 0.001) and Proportions of 72H patients with residual parasitemia were 68.5% and 40% in Faladje and Bougoula-Hameau, respectively (p = 0.003). The mean residual parasitemia was 2.9 in Faladje vs. 0.008 in Bougoula-Hameau (p = 0.002). Although artesunate is efficacious in Mali, the longer parasite clearance time with submicroscopic parasitemia observed may represent early signs of developing P. falciparum resistance to artemisinins.
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Akano K, Ntadom G, Agomo C, Happi CT, Folarin OA, Gbotosho GO, Mokuolu O, Finomo F, Ebenebe JC, Jiya N, Ambe J, Wammanda R, Emechebe G, Basorun OK, Wewe OA, Amoo S, Ezeigwe N, Oguche S, Fatunmbi B, Sowunmi A. Parasite reduction ratio one day after initiation of artemisinin-based combination therapies and its relationship with parasite clearance time in acutely malarious children. Infect Dis Poverty 2018; 7:122. [PMID: 30522524 PMCID: PMC6284283 DOI: 10.1186/s40249-018-0503-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 11/13/2018] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND In acute falciparum malaria, asexual parasite reduction ratio two days post-treatment initiation (PRRD2) ≥ 10 000 per cycle has been used as a measure of the rapid clearance of parasitaemia and efficacy of artemisinin derivatives. However, there is little evaluation of alternative measures; for example, parasite reduction ratio one day after treatment initiation (PRRD1) and its relationship with parasite clearance time (PCT) or PRRD2. This study evaluated the use of PRRD1 as a measure of responsiveness to antimalarial drugs. METHODS In acutely malarious children treated with artesunate-amodiaquine (AA), artemether-lumefantrine (AL) or dihydroartemisinin-piperaquine (DHP), the relationships between PRRD1 or PRRD2 and PCT, and between PRRD1 and PRRD2 were evaluated using linear regression. Agreement between estimates of PCT using PRRD1 and PRRD2 linear regression equations was evaluated using the Bland-Altman analysis. Predictors of PRRD1 > 5000 per half cycle and PRRD2 ≥ 10 000 per cycle were evaluated using stepwise multiple logistic regression models. Using the linear regression equation of the relationship between PRRD1 and PCT previously generated in half of the DHP-treated children during the early study phase, PCT estimates were compared in a prospective blinded manner with PCTs determined by microscopy during the later study phase in the remaining half. RESULTS In 919 malarious children, PRRD1 was significantly higher in DHP- and AA-treated compared with AL-treated children (P < 0.0001). PRRD1 or PRRD2 values correlated significantly negatively with PCT values (P < 0.0001 for each) and significantly positively with each other (P < 0.0001). PCT estimates from linear regression equations for PRRD1 and PRRD2 showed insignificant bias on the Bland-Altman plot (P = 0.7) indicating the estimates can be used interchangeably. At presentation, age > 15 months, parasitaemia > 10 000/μl and DHP treatment independently predicted PRRD1 > 5000 per half cycle, while age > 30 months, haematocrit ≥31%, body temperature > 37.4 °C, parasitaemia > 100 000/μl, PRRD1 value > 1000 and no gametocytaemia independently predicted PRRD2 ≥ 10 000 per cycle. Using the linear regression equation generated during the early phase in 166 DHP-treated children, PCT estimates and PCTs determined by microscopy in the 155 children in the later phase were similar in the same patients. CONCLUSIONS PRRD1 and estimates of PCT using PRRD1 linear regression equation of PRRD1 and PCT can be used in therapeutic efficacy studies. TRIAL REGISTRATION Pan African Clinical Trial Registration PACTR201709002064150, 1 March 2017, http://www.pactr.org.
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Affiliation(s)
- Kazeem Akano
- Department of Pharmacology and Therapeutics, University of Ibadan, Ibadan, Nigeria
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
| | - Godwin Ntadom
- Department of Pharmacology and Therapeutics, University of Ibadan, Ibadan, Nigeria
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
| | - Chimere Agomo
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Medical Laboratory Science, University of Lagos, Lagos, Nigeria
| | - Christian T. Happi
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Biological Sciences and African Centre of Excellence for Genomics of Infectious Diseases (ACEGID), Redeemer University, Ede, Nigeria
| | - Onikepe A. Folarin
- Department of Biological Sciences and African Centre of Excellence for Genomics of Infectious Diseases (ACEGID), Redeemer University, Ede, Nigeria
| | - Grace O. Gbotosho
- Department of Pharmacology and Therapeutics, University of Ibadan, Ibadan, Nigeria
- Institute for Medical Research and Training, University of Ibadan, Ibadan, Nigeria
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Ibadan, Ibadan, Nigeria
| | - Olugbenga Mokuolu
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Paediatrics, University of Ilorin, Ilorin, Nigeria
| | - Finomo Finomo
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Paediatrics, Federal Medical Centre, Yenagoa, Nigeria
| | - Joy C. Ebenebe
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Paediatrics, Nnamdi Azikiwe University, Awka, Nigeria
| | - Nma Jiya
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Paediatrics, Uthman Dan Fodio University, Sokoto, Nigeria
| | - Jose Ambe
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Paediatrics, University of Maiduguri, Maiduguri, Nigeria
| | - Robinson Wammanda
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Paediatrics, Ahmadu Bello University, Zaria, Nigeria
| | - George Emechebe
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Paediatrics, Imo State University Teaching Hospital, Orlu, Nigeria
| | | | - Olubunmi A. Wewe
- Department of Pharmacology and Therapeutics, University of Ibadan, Ibadan, Nigeria
| | - Sikiru Amoo
- Department of Pharmacology and Therapeutics, University of Ibadan, Ibadan, Nigeria
| | - Nnenna Ezeigwe
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
| | - Stephen Oguche
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Department of Paediatrics, University of Jos, Jos, Nigeria
| | - Bayo Fatunmbi
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- World Health Organization, Country Office, Kampala, Uganda
| | - Akintunde Sowunmi
- Department of Pharmacology and Therapeutics, University of Ibadan, Ibadan, Nigeria
- Antimalarial Therapeutic Efficacy Monitoring Group, National Malaria Elimination Programme, The Federal Ministry of Health, Abuja, Nigeria
- Institute for Medical Research and Training, University of Ibadan, Ibadan, Nigeria
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9
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Byakika-Kibwika P, Nyakato P, Lamorde M, Kiragga AN. Assessment of parasite clearance following treatment of severe malaria with intravenous artesunate in Ugandan children enrolled in a randomized controlled clinical trial. Malar J 2018; 17:400. [PMID: 30376860 PMCID: PMC6208070 DOI: 10.1186/s12936-018-2552-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 10/26/2018] [Indexed: 11/12/2022] Open
Abstract
Background Malaria control largely depends on availability of highly efficacious drugs, however, over the years, has been threatened by emergence of drug resistance. It is, therefore, important to monitor the impact of recurrent anti-malarial treatment on the long-term efficacy of anti-malarial regimens, especially in sub-Saharan African countries with high malaria transmission. Evaluation of parasite clearance following treatment of severe malaria with intravenous artesunate among patients in Eastern Uganda, was performed, as a contribution to monitoring anti-malarial effectiveness. Methods Parasite clearance data obtained from a clinical trial whose objective was to evaluate the 42-day parasitological treatment outcomes and safety following treatment of severe malaria with intravenous artesunate plus artemisinin-based combination therapy among patients attending Tororo District Hospital in Eastern Uganda, were analysed. Serial blood smears were performed at 0, 1, 2, 4, 6, 8, 10, 12, 16, 20, 24 h, followed by 6-hourly blood smears post start of treatment until 6 h post the first negative blood smear when parasite clearance was achieved. Study endpoints were; parasite clearance half-life (the time required for parasitaemia to decrease by 50% based on the linear portion of the parasite clearance slope) and parasite clearance time (time required for complete clearance of initial parasitaemia). Results One hundred and fifty participants with severe malaria were enrolled. All participants were treated with intravenous artesunate. All study participants tolerated artesunate well with rapid recovery from symptoms and ability to take oral mediation within 24 h. No immediate adverse events were recorded. The median (IQR) number of days to complete parasite clearance was of 2 (1–2). The median (IQR) time to clear 50% and 99% parasites was 4.8 (3.61–7.10) and 17.55 (14.66–20.66) h, respectively. The median estimated clearance rate constant per hour was 0.32. The median (IQR) slope half-life was 2.15 (1.64, 2.61) h. Conclusion Parasite clearance following treatment with intravenous artesunate was rapid and adequate. This finding provides supportive evidence that resistance to artemisinins is unlikely to have emerged in this study area. Continuous monitoring of artemisinin effectiveness for malaria treatment should be established in high malaria transmission areas in sub-Saharan Africa where spread of resistance would be disastrous. Trial registration The study was registered with the Pan African Clinical Trial Registry (PACTR201110000321348). Registered 7th October 2011, http://www.pactr.org/) Electronic supplementary material The online version of this article (10.1186/s12936-018-2552-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Pauline Byakika-Kibwika
- Department of Medicine, College of Health Sciences, Makerere University, P. O. Box 7072, Kampala, Uganda. .,Infectious Diseases Institute, Kampala, Uganda.
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10
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Oyebola KM, Aina OO, Idowu ET, Olukosi YA, Ajibaye OS, Otubanjo OA, Awolola TS, Awandare GA, Amambua-Ngwa A. A barcode of multilocus nuclear DNA identifies genetic relatedness in pre- and post-Artemether/Lumefantrine treated Plasmodium falciparum in Nigeria. BMC Infect Dis 2018; 18:392. [PMID: 30103683 PMCID: PMC6205152 DOI: 10.1186/s12879-018-3314-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 08/06/2018] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The decline in the efficacy of artemisinin-based combination treatment (ACT) in some endemic regions threatens the progress towards global elimination of malaria. Molecular surveillance of drug resistance in malaria-endemic regions is vital to detect the emergence and spread of mutant strains. METHODS We observed 89 malaria patients for the efficacy of artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum infections in Lagos, Nigeria and determined the prevalence of drug resistant strains in the population. Parasite clearance rates were determined by microscopy and the highly sensitive var gene acidic terminal sequence (varATS) polymerase chain reaction for 65 patients with samples on days 0, 1, 3, 7, 14, 21 and 28 after commencement of treatment. The genomic finger print of parasite DNA from pre- and post-treatment samples were determined using 24 nuclear single nucleotide polymorphisms (SNP) barcode for P. falciparum. Drug resistance associated alleles in chloroquine resistance transporter gene (crt-76), multidrug resistance genes (mdr1-86 and mdr1-184), dihydropteroate synthase (dhps-540), dihydrofolate reductase (dhfr-108) and kelch domain (K-13580) were genotyped by high resolution melt analysis of polymerase chain reaction (PCR) fragments. RESULTS By varATS qPCR, 12 (18.5%) of the participants had detectable parasite DNA in their blood three days after treatment, while eight (12.3%) individuals presented with genotypable day 28 parasitaemia. Complexity of infection (CoI) was 1.30 on day 0 and 1.34 on day 28, the mean expected heterozygosity (HE) values across all barcodes were 0.50 ± 0.05 and 0.56 ± 0.05 on days 0 and 28 respectively. Barcode (π) pairwise comparisons showed high genetic relatedness of day 0 and day 28 parasite isolates in three (37.5%) of the eight individuals who presented with re-appearing infections. Crt-76 mutant allele was present in 38 (58.5%) isolates. The mdr1-86 mutant allele was found in 56 (86.2%) isolates. No mutation in the K-13580 was observed. CONCLUSIONS Persistence of DNA-detectable parasitaemia in more than 18% of cases after treatment and indications of genetic relatedness between pre- and post-treatment infections warrants further investigation of a larger population for signs of reduced ACT efficacy in Nigeria.
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Affiliation(s)
- Kolapo Muyiwa Oyebola
- Medical Research Council Unit of The London School of Hygiene and Tropical Medicine, Bakau, The Gambia
- Parasitology and Bioinformatics, Department of Zoology, Faculty of Science, University of Lagos, Lagos, Nigeria
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Accra Ghana
| | | | - Emmanuel Taiwo Idowu
- Parasitology and Bioinformatics, Department of Zoology, Faculty of Science, University of Lagos, Lagos, Nigeria
| | - Yetunde Adeola Olukosi
- Parasitology and Bioinformatics, Department of Zoology, Faculty of Science, University of Lagos, Lagos, Nigeria
- Malaria Research Group, Nigerian Institute of Medical Research, Lagos, Nigeria
| | | | - Olubunmi Adetoro Otubanjo
- Parasitology and Bioinformatics, Department of Zoology, Faculty of Science, University of Lagos, Lagos, Nigeria
| | | | - Gordon Akanzuwine Awandare
- West African Centre for Cell Biology of Infectious Pathogens, College of Basic and Applied Sciences, University of Ghana, Legon, Accra Ghana
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit of The London School of Hygiene and Tropical Medicine, Bakau, The Gambia
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Mandara CI, Kavishe RA, Gesase S, Mghamba J, Ngadaya E, Mmbuji P, Mkude S, Mandike R, Njau R, Mohamed A, Lemnge MM, Warsame M, Ishengoma DS. High efficacy of artemether-lumefantrine and dihydroartemisinin-piperaquine for the treatment of uncomplicated falciparum malaria in Muheza and Kigoma Districts, Tanzania. Malar J 2018; 17:261. [PMID: 29996849 PMCID: PMC6042436 DOI: 10.1186/s12936-018-2409-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 07/03/2018] [Indexed: 12/05/2022] Open
Abstract
BACKGROUND Artemether-lumefantrine (AL) is the recommended first-line artemisinin-based combination therapy (ACT) for the treatment of uncomplicated falciparum malaria in most of the malaria-endemic countries, including Tanzania. Recently, dihydroartemisinin-piperaquine (DP) has been recommended as the alternative anti-malarial to ensure effective case management in Tanzania. This study assessed the parasite clearance rate and efficacy of AL and DP among patients aged 6 months to 10 years with uncomplicated falciparum malaria in two sites with different malaria transmission intensity. METHODS This was an open-label, randomized trial that was conducted at two sites of Muheza Designated District Hospital and Ujiji Health Centre in Tanga and Kigoma regions, respectively. Patients meeting inclusion criteria were enrolled, treated with either AL or DP and followed up for 28 (extended to 42) and 42 (63) days for AL and DP, respectively. Parasite clearance time was monitored in the first 72 h post treatment and the clearance rate constant and half-life were calculated using an established parasite clearance estimator. The primary outcome was parasitological cure on days 28 and 42 for AL and DP, respectively, while secondary outcome was extended parasitological cure on days 42 and 63 for AL and DP, respectively. RESULTS Of the 509 children enrolled (192 at Muheza and 317 at Ujiji), there was no early treatment failure and PCR uncorrected cure rates on day 28 in the AL group were 77.2 and 71.2% at Muheza and Ujiji, respectively. In the DP arm, the PCR uncorrected cure rate on day 42 was 73.6% at Muheza and 72.5% at Ujiji. With extended follow-up (to day 42 for AL and 63 for DP) cure rates were lower at Ujiji compared to Muheza (AL: 60.2 and 46.1%, p = 0.063; DP: 57.6 and 40.3% in Muheza and Ujiji, respectively, p = 0.021). The PCR corrected cure rate ranged from 94.6 to 100% for all the treatment groups at both sites. Parasite clearance rate constant was similar in the two groups and at both sites (< 0.28/h); the slope half-life was < 3.0 h and all but only one patient cleared parasites by 72 h. CONCLUSION These findings confirm high efficacy of the first- and the newly recommended alternative ACT for treatments for uncomplicated falciparum malaria in Tanzania. The high parasite clearance rate suggests absence of suspected artemisinin resistance, defined as delayed parasite clearance. Trial registration This trial is registered at ClinicalTrials.gov under registration number NCT02590627.
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Affiliation(s)
- Celine I Mandara
- National Institute for Medical Research, Tanga Centre, Tanga, Tanzania.
- Kilimanjaro Christian Medical University College, Moshi, Tanzania.
| | | | - Samuel Gesase
- National Institute for Medical Research, Tanga Centre, Tanga, Tanzania
| | - Janneth Mghamba
- Epidemiology and Disease Control Section, Ministry of Health, Community Development, Gender, Elderly and Children, Dar es Salaam, Tanzania
| | - Esther Ngadaya
- National Institute for Medical Research, Muhimbili Centre, Dar es Salaam, Tanzania
| | - Peter Mmbuji
- Epidemiology and Disease Control Section, Ministry of Health, Community Development, Gender, Elderly and Children, Dar es Salaam, Tanzania
| | - Sigsbert Mkude
- National Malaria Control Program, Dar es Salaam, Tanzania
| | - Renata Mandike
- National Malaria Control Program, Dar es Salaam, Tanzania
| | - Ritha Njau
- World Health Organization Country Office, Dar es Salaam, Tanzania
| | - Ally Mohamed
- National Malaria Control Program, Dar es Salaam, Tanzania
| | - Martha M Lemnge
- National Institute for Medical Research, Tanga Centre, Tanga, Tanzania
| | | | - Deus S Ishengoma
- National Institute for Medical Research, Tanga Centre, Tanga, Tanzania
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12
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Lohy Das JP, Kyaw MP, Nyunt MH, Chit K, Aye KH, Aye MM, Karlsson MO, Bergstrand M, Tarning J. Population pharmacokinetic and pharmacodynamic properties of artesunate in patients with artemisinin sensitive and resistant infections in Southern Myanmar. Malar J 2018; 17:126. [PMID: 29566683 PMCID: PMC5865368 DOI: 10.1186/s12936-018-2278-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 03/15/2018] [Indexed: 11/24/2022] Open
Abstract
Background Artemisinins are the most effective anti-malarial drugs for uncomplicated and severe Plasmodium falciparum malaria. However, widespread artemisinin resistance in the Greater Mekong Region of Southeast Asia is threatening the possibility to control and eliminate malaria. This work aimed to evaluate the pharmacokinetic and pharmacodynamic properties of artesunate and its active metabolite, dihydroartemisinin, in patients with sensitive and resistant falciparum infections in Southern Myanmar. In addition, a simple nomogram previously developed to identify artemisinin resistant malaria infections was evaluated. Methods Fifty-three (n = 53) patients were recruited and received daily oral artesunate monotherapy (4 mg/kg) for 7 days. Frequent artesunate and dihydroartemisinin plasma concentration measurements and parasite microscopy counts were obtained and evaluated using nonlinear mixed-effects modelling. Results The absorption of artesunate was best characterized by a transit-compartment (n = 3) model, followed by one-compartment disposition models for artesunate and dihydroartemisinin. The drug-dependent parasite killing effect of dihydroartemisinin was described using an Emax function, with a mixture model discriminating between artemisinin sensitive and resistant parasites. Overall, 56% of the studied population was predicted to have resistant malaria infections. Application of the proposed nomogram to identify artemisinin-resistant malaria infections demonstrated an overall sensitivity of 90% compared to 55% with the traditional day-3 positivity test. Conclusion The pharmacokinetic-pharmacodynamic properties of artesunate and dihydroartemisinin were well-characterized with a mixture model to differentiate between drug sensitive and resistant infections in these patients. More than half of all patients recruited in this study had artemisinin-resistant infections. The relatively high sensitivity of the proposed nomogram highlights its potential clinical usefulness.
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Affiliation(s)
| | - Myat P Kyaw
- Department of Medical Research, Yangon, Republic of the Union of Myanmar
| | - Myat H Nyunt
- Department of Medical Research, Yangon, Republic of the Union of Myanmar
| | - Khin Chit
- Department of Medical Research, Yangon, Republic of the Union of Myanmar
| | - Kyin H Aye
- Department of Medical Research, Yangon, Republic of the Union of Myanmar
| | - Moe M Aye
- Department of Medical Research, Yangon, Republic of the Union of Myanmar
| | - Mats O Karlsson
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Martin Bergstrand
- Department of Pharmaceutical Biosciences, Uppsala University, Uppsala, Sweden
| | - Joel Tarning
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
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13
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Grandesso F, Guindo O, Woi Messe L, Makarimi R, Traore A, Dama S, Laminou IM, Rigal J, de Smet M, Ouwe Missi Oukem-Boyer O, Doumbo OK, Djimdé A, Etard JF. Efficacy of artesunate-amodiaquine, dihydroartemisinin-piperaquine and artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in Maradi, Niger. Malar J 2018; 17:52. [PMID: 29370844 PMCID: PMC5785863 DOI: 10.1186/s12936-018-2200-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/20/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria endemic countries need to assess efficacy of anti-malarial treatments on a regular basis. Moreover, resistance to artemisinin that is established across mainland South-East Asia represents today a major threat to global health. Monitoring the efficacy of artemisinin-based combination therapies is of paramount importance to detect as early as possible the emergence of resistance in African countries that toll the highest burden of malaria morbidity and mortality. METHODS A WHO standard protocol was used to assess efficacy of the combinations artesunate-amodiaquine (AS-AQ Winthrop®), dihydroartemisinin-piperaquine (DHA-PPQ, Eurartesim®) and artemether-lumefantrine (AM-LM, Coartem®) taken under supervision and respecting pharmaceutical recommendations. The study enrolled for each treatment arm 212 children aged 6-59 months living in Maradi (Niger) and suffering with uncomplicated falciparum malaria. The Kaplan-Meier 42-day PCR-adjusted cure rate was the primary outcome. A standardized parasite clearance estimator was used to assess delayed parasite clearance as surrogate maker of suspected artemisinin resistance. RESULTS No early treatment failures were found in any of the study treatment arms. The day-42 PCR-adjusted cure rate estimates were 99.5, 98.4 and 99.0% in the AS-AQ, DHA-PPQ and AM-LM arms, respectively. The reinfection rate (expressed also as Kaplan-Meier estimates) was higher in the AM-LM arm (32.4%) than in the AS-AQ (13.8%) and the DHA-PPQ arm (24.9%). The parasite clearance rate constant was 0.27, 0.26 and 0.25 per hour for AS-AQ, DHA-PPQ and AM-LM, respectively. CONCLUSIONS All the three treatments evaluated largely meet WHO criteria (at least 95% efficacy). AS-AQ and AL-LM may continue to be used and DHA-PPQ may be also recommended as first-line treatment for uncomplicated falciparum malaria in Maradi. The parasite clearance rate were consistent with reference values indicating no suspected artemisinin resistance. Nevertheless, the monitoring of anti-malarial drug efficacy should continue. Trial registration details Registry number at ClinicalTrial.gov: NCT01755559.
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Affiliation(s)
| | | | | | | | - Aliou Traore
- Malaria Research and Training Centre, Department of Epidemiology of Parasitic Diseases, Faculty of Pharmacy, University of Science, Techniques and Technologies of Bamako, P.O. Box: 1805 Point G, Bamako, Mali
| | - Souleymane Dama
- Malaria Research and Training Centre, Department of Epidemiology of Parasitic Diseases, Faculty of Pharmacy, University of Science, Techniques and Technologies of Bamako, P.O. Box: 1805 Point G, Bamako, Mali
| | | | - Jean Rigal
- Médecins Sans Frontières, 8 rue Saint-Sabin, 75011, Paris, France
| | - Martin de Smet
- Médecins Sans Frontières, rue de l'Arbre Bénit 46, 1050, Brussels, Belgium
| | | | - Ogobara K Doumbo
- Malaria Research and Training Centre, Department of Epidemiology of Parasitic Diseases, Faculty of Pharmacy, University of Science, Techniques and Technologies of Bamako, P.O. Box: 1805 Point G, Bamako, Mali
| | - Abdoulaye Djimdé
- Malaria Research and Training Centre, Department of Epidemiology of Parasitic Diseases, Faculty of Pharmacy, University of Science, Techniques and Technologies of Bamako, P.O. Box: 1805 Point G, Bamako, Mali
| | - Jean-François Etard
- Epicentre, 8 rue Saint-Sabin, 75011, Paris, France.,IRD UMI 233, INSERM U1175, Unité TransVIHMI, Université de Montpellier, 34000, Montpellier, France
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14
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Lin J, Huang X, Qin G, Zhang S, Sun W, Wang Y, Ren K, Xu J, Han X. Manual exchange transfusion for severe imported falciparum malaria: a retrospective study. Malar J 2018; 17:32. [PMID: 29338720 PMCID: PMC5771211 DOI: 10.1186/s12936-018-2174-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 01/08/2018] [Indexed: 12/16/2022] Open
Abstract
Background This study was designed to evaluate the efficacy of exchange transfusion in patients with severe imported falciparum malaria. Twelve patients who met the diagnostic criteria for severe malaria were treated with exchange transfusion 14 times according to a conventional anti-malarial treatment. This study evaluated the efficacy of exchange transfusion for severe imported falciparum malaria. Methods Clinical data of severe imported falciparum malaria patients admitted to the intensive care unit (ICU) of Nantong Third People’s Hospital from January 2007 to December 2016 were investigated in this retrospective study. Patients were divided into the intervention group, which received exchange transfusion, and the control group. This study assessed parasite clearance and outcomes of the two groups, and levels of erythrocytes, haemoglobin, platelets, coagulation, liver function, lactate, C-reactive protein, and procalcitonin, before and after exchange transfusion in the intervention group. Results There was no significant difference in the severity of admitted patients. Exchange transfusion was successfully applied 14 times in the intervention group. Differences in the levels of erythrocytes, haemoglobin and platelets did not reach statistical significance. Exchange transfusion improved coagulation, liver function, lactic acid, C-reactive protein, and procalcitonin. No differences were observed in parasite clearance, ICU and hospital length of stay, in-hospital mortality, and costs of hospitalization between the two groups. Conclusion Exchange transfusion as adjunctive therapy for severe malaria was observed to be safe in this setting. Exchange transfusion can improve liver function and coagulation and reduce inflammation, but it failed to improve parasite clearance and the outcomes of severe imported falciparum malaria in this case series.
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Affiliation(s)
- Jinfeng Lin
- Department of Critical Care Medicine, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China
| | - Xiaoying Huang
- Department of Critical Care Medicine, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China
| | - Gang Qin
- Center for Liver Diseases, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China
| | - Suyan Zhang
- Department of Critical Care Medicine, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China
| | - Weiwei Sun
- Department of Critical Care Medicine, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China
| | - Yadong Wang
- Department of Critical Care Medicine, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China
| | - Ke Ren
- Department of Critical Care Medicine, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China
| | - Junxian Xu
- Department of Critical Care Medicine, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China
| | - Xudong Han
- Department of Critical Care Medicine, Nantong Third People's Hospital, Nantong University, 60 Mid-Youth Road, Nantong, 226006, China.
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15
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Bonnington CA, Phyo AP, Ashley EA, Imwong M, Sriprawat K, Parker DM, Proux S, White NJ, Nosten F. Plasmodium falciparum Kelch 13 mutations and treatment response in patients in Hpa-Pun District, Northern Kayin State, Myanmar. Malar J 2017; 16:480. [PMID: 29178921 PMCID: PMC5702082 DOI: 10.1186/s12936-017-2128-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Accepted: 11/18/2017] [Indexed: 12/13/2022] Open
Abstract
Background Artemisinin resistance, linked to polymorphisms in the Kelch gene on chromosome 13 of Plasmodium falciparum (k13), has outpaced containment efforts in South East Asia. For national malaria control programmes in the region, it is important to establish a surveillance system which includes monitoring for k13 polymorphisms associated with the clinical phenotype. Methods Between February and December 2013, parasite clearance was assessed in 35 patients with uncomplicated P. falciparum treated with artesunate monotherapy followed by 3-day ACT in an isolated area on the Myanmar–Thai border with relatively low artemisinin drug pressure. Molecular testing for k13 mutations was performed on dry blood spots collected on admission. Results The proportion of k13 mutations in these patients was 41.7%, and only 5 alleles were detected: C580Y, I205T, M476I, R561H, and F446I. Of these, F446I was the most common, and was associated with a longer parasite clearance half-life (median) 4.1 (min–max 2.3–6.7) hours compared to 2.5 (min–max 1.6–8.7) in wildtype (p = 0·01). The prevalence of k13 mutant parasites was much lower than the proportion of k13 mutants detected 200 km south in a much less remote setting where the prevalence of k13 mutants was 84% with 15 distinct alleles in 2013 of which C580Y predominated. Conclusions This study provides evidence of artemisinin resistance in a remote part of eastern Myanmar. The prevalence of k13 mutations as well as allele diversity varies considerably across short distances, presumably because of historical patterns of artemisinin use and population movements. Electronic supplementary material The online version of this article (10.1186/s12936-017-2128-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Craig A Bonnington
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Aung Pyae Phyo
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand. .,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
| | - Elizabeth A Ashley
- Myanmar Oxford Clinical Research Unit, Yangon, Myanmar.,Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Mallika Imwong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Kanlaya Sriprawat
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Daniel M Parker
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Stephane Proux
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Nicholas J White
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Francois Nosten
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand.,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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16
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Adepiti AO, Iwalewa EO. Evaluation of the combination of Uvaria chamae (P. Beauv.) and amodiaquine in murine malaria. J Ethnopharmacol 2016; 193:30-35. [PMID: 27416806 DOI: 10.1016/j.jep.2016.07.035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Revised: 06/11/2016] [Accepted: 07/09/2016] [Indexed: 06/06/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE The leaf and fruit of Uvaria chamae P. Beauv (Annonaceae) are used in antimalarial ethnomedical preparations. Therefore, they were investigated for antimalarial activities as well as possible herb-drug interaction with amodiaquine (AQ). MATERIALS AND METHODS The methanol extracts of the leaf (UCL) and fruit (UCF) were administered orally at 100-800mg/kg/day in mice infected with chloroquine (CQ)-sensitive Plasmodium berghei NK65 using the four-day, curative and prophylactic antimalarial test models. The UCL was further evaluated at 100-800mg/kg as twice-daily doses and combinations of UCL+AQ using the four-day test. Mice infected with CQ-resistant P. berghei ANKA were treated with UCL at 400mg/kg and AQ at 10mg/kg - [UCL400+AQ10]mg/kg - in the four-day and curative test models. RESULT At 800mg/kg/day, UCL, UCF gave chemosuppression of 42, 28% (four-day test), parasite clearance of 36.3, 49.5% on day 5 (curative test) and 64.3, 82.6% (prophylactic test), respectively. The twice-daily dose of UCL at 800mg/kg showed activity of 51.50% while the combination of [UCL200+AQ5]mg/kg exhibited chemosuppression of 91.66%, which was not significantly different (p>0.05) from AQ at 10mg/kg (85.41%). In the CQ-resistant P. berghei experiment, the combination gave a chemosuppression of 45.80%, significantly lower (p<0.05) than AQ (78.40%) while the parasite clearance was not significantly different from AQ (curative test). CONCLUSION The leaf extract showed moderate chemosuppressive activity. The lower-dose combination of the leaf extract and amodiaquine had better antimalarial activity in CQ-sensitive murine malaria. However, the tested combination had no beneficial antimalarial effect in CQ-resistant murine malaria.
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Affiliation(s)
- Awodayo O Adepiti
- Department of Pharmacognosy, Obafemi Awolowo University, Ile-Ife, Nigeria.
| | - Ezekiel O Iwalewa
- Department of Pharmacology and Therapeutics, University of Ibadan, Ibadan, Nigeria
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17
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Teja-Isavadharm P, Siriyanonda D, Rasameesoraj M, Limsalakpeth A, Chanarat N, Komcharoen N, Weina PJ, Saunders DL, Gettayacamin M, Scott Miller R. Comparative pharmacokinetics and pharmacodynamics of intravenous artelinate versus artesunate in uncomplicated Plasmodium coatneyi-infected rhesus monkey model. Malar J 2016; 15:453. [PMID: 27599723 DOI: 10.1186/s12936-016-1456-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/28/2016] [Indexed: 11/25/2022] Open
Abstract
Background The US Army designed artelinate/lysine salt (AL) to overcome the instability of sodium artesunate in aqueous solution (AS). To select the most efficacious artemisinin treatment, direct comparison was performed in an uncomplicated non-human primate malaria model. Methods Splenectomized rhesus monkeys were inoculated with Plasmodium coatneyi and on day six, single equimolar loading dose of IV AL (11.8 mg kg−1) or IV AS (8 mg kg−1) were administered followed by 1/2 the first dose once daily for 2 more days. Blood smear were performed twice daily and the number of parasites were counted microscopically. Blood samples were obtained after the first dose within 6 h for pharmacokinetic (PK) and ex vivo pharmacodynamic evaluation by simultaneously measuring plasma drug concentration and anti-malarial activity against Plasmodium falciparum in vitro. Results The anti-P. coatneyi in vivo activity of both compounds were comparable, but the ex vivo anti-P. falciparum potency of the IV AS regimen as administered was sevenfold higher than that of IV AL. Comparing in vivo pharmacodynamics of AL and AS, daily assessed parasite counts showed comparable 99 % parasite clearance times (PC99: 2.03, 1.84 day), parasite clearance rates (5.34, 4.13 per min) and clearance half-life (PCt1/2: 7.79, 10.1 h). This study showed strong and significant inverse correlation between PCt1/2 and t1/2 of AS + DHA, and AUC0–∞ of DHA, and correlated with Vz of AS (r2 > 0.7, p ≤ 0.002). Lastly, following IV AL, there was a modest inverse correlation between PCt1/2 and Cmax (r2 0.6, p ≤ 0.04). Although all tested monkeys recrudesced subsequently, two died following AL regimen before parasite clearance. While the aetiology of those deaths could not be definitively determined, pathologic evidence favoured a sepsis-like syndrome and suggested that severe malaria was more likely than drug toxicity. Conclusion The model demonstrated that both AS and DHA contributed to the anti-malarial activity of IV AS, while IV AL activity was largely restricted to the parent drug. Parasite clearance was strongly and linearly dependent on drug exposure for both artemisinin regimens. However, IV AS had higher ex vivo potency against P. falciparum, leading to an IND filing for GMP manufactured AS in the United States. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1456-6) contains supplementary material, which is available to authorized users.
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18
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Lo E, Nguyen J, Oo W, Hemming-Schroeder E, Zhou G, Yang Z, Cui L, Yan G. Examining Plasmodium falciparum and P. vivax clearance subsequent to antimalarial drug treatment in the Myanmar-China border area based on quantitative real-time polymerase chain reaction. BMC Infect Dis 2016; 16:154. [PMID: 27084511 PMCID: PMC4833920 DOI: 10.1186/s12879-016-1482-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 03/25/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Recent emergence of artemisinin-resistant P. falciparum has posed a serious hindrance to the elimination of malaria in the Greater Mekong Subregion. Parasite clearance time, a measure of change in peripheral parasitaemia in a sequence of samples taken after treatment, can be used to reflect the susceptibility of parasites or the efficiency of antimalarials. The association of genetic polymorphisms and artemisinin resistance has been documented. This study aims to examine clearance time of P. falciparum and P. vivax parasitemia as well as putative gene mutations associated with residual or recurred parasitemia in Myanmar. METHODS A total of 63 P. falciparum and 130 P. vivax samples collected from two internally-displaced populations and one surrounding village were examined for parasitemia changes. At least four samples were taken from each patient, at the first day of diagnosis up to 3 months following the initial treatment. The amount of parasite gene copy number was estimated using quantitative real-time PCR based on a species-specific region of the 18S rRNA gene. For samples that showed residual or recurred parasitemia after treatment, microsatellites were used to identify the 'post-treatment' parasite genotype and compared such with the 'pre-treatment' genotype. Mutations in genes pfcrt, pfmdr1, pfatp6, pfmrp1 and pfK13 that are potentially associated with ACT resistance were examined to identify if mutation is a factor for residual or persistent parasitemia. RESULTS Over 30% of the P. falciprium infections showed delayed clearance of parasitemia after 2-3 days of treatment and 9.5% showed recurred parasitemia. Mutations in codon 876 of the pfmrp1 corroborated significance association with slow clearance time. However, no association was observed in the variation in pfmdr1 gene copy number as well as mutations of various codonsinpfatp6, pfcrt, and pfK13 with clearance time. For P. vivax, over 95% of the infections indicated cleared parasitemia at days 2-3 of treatment. Four samples were found to be re-infected with new parasite strains based on microsatellite genotypes after initial treatment. CONCLUSION The appearance of P.falciparum infected samples showing delayed clearance or recurred parasitemia after treatment raises concerns on current treatment and ACT drug resistance.
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Affiliation(s)
- Eugenia Lo
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
| | - Jennifer Nguyen
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
| | - Winny Oo
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
| | | | - Guofa Zhou
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
| | - Zhaoqing Yang
- />Department of Pathogen Biology and Immunology, Kunming Medical University, Kunming, China
| | - Liwang Cui
- />Department of Entomology, Pennsylvania State University, University Park, PA USA
| | - Guiyun Yan
- />Program in Public Health, University of California at Irvine, Irvine, CA 92697-4050 USA
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