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Chaumeau V, Wasisakun P, Watson JA, Oo T, Aryalamloed S, Sue MP, Htoo GN, Tha NM, Archusuksan L, Sawasdichai S, Gornsawun G, Mehra S, White NJ, Nosten FH. Transmission-blocking activities of artesunate, chloroquine, and methylene blue on Plasmodium vivax gametocytes. Antimicrob Agents Chemother 2024:e0085324. [PMID: 39058023 DOI: 10.1128/aac.00853-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Accepted: 06/30/2024] [Indexed: 07/28/2024] Open
Abstract
Plasmodium vivax is now the main cause of malaria outside Africa. The gametocytocidal effects of antimalarial drugs are important to reduce malaria transmissibility, particularly in low-transmission settings, but they are not well characterized for P. vivax. The transmission-blocking effects of chloroquine, artesunate, and methylene blue on P. vivax gametocytes were assessed. Blood specimens were collected from patients presenting with vivax malaria, incubated with or without the tested drugs, and then fed to mosquitos from a laboratory-adapted colony of Anopheles dirus (a major malaria vector in Southeast Asia). The effects on oocyst and sporozoite development were analyzed under a multi-level Bayesian model accounting for assay variability and the heterogeneity of mosquito Plasmodium infection. Artesunate and methylene blue, but not chloroquine, exhibited potent transmission-blocking effects. Gametocyte exposures to artesunate and methylene blue reduced the mean oocyst count 469-fold (95% CI: 345 to 650) and 1,438-fold (95% CI: 970 to 2,064), respectively. The corresponding estimates for the sporozoite stage were a 148-fold reduction (95% CI: 61 to 470) and a 536-fold reduction (95% CI: 246 to 1,311) in the mean counts, respectively. In contrast, high chloroquine exposures reduced the mean oocyst count only 1.40-fold (95% CI: 1.20 to 1.64) and the mean sporozoite count 1.34-fold (95% CI: 1.12 to 1.66). This suggests that patients with vivax malaria often remain infectious to anopheline mosquitos after treatment with chloroquine. Use of artemisinin combination therapies or immediate initiation of primaquine radical cure should reduce the transmissibility of P. vivax infections.
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Affiliation(s)
- Victor Chaumeau
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, England, United Kingdom
| | - Praphan Wasisakun
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - James A Watson
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, England, United Kingdom
- Oxford University Clinical Research Unit, Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Thidar Oo
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - Sarang Aryalamloed
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - Mu Phang Sue
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - Gay Nay Htoo
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - Naw Moo Tha
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - Laypaw Archusuksan
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - Sunisa Sawasdichai
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - Gornpan Gornsawun
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
| | - Somya Mehra
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nicholas J White
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, England, United Kingdom
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - François H Nosten
- Shoklo Malaria Research Unit, Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Ramat, Tak, Thailand
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, England, United Kingdom
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2
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Ogutu B, Yeka A, Kusemererwa S, Thompson R, Tinto H, Toure AO, Uthaisin C, Verma A, Kibuuka A, Lingani M, Lourenço C, Mombo-Ngoma G, Nduba V, N'Guessan TL, Nassa GJW, Nyantaro M, Tina LO, Singh PK, El Gaaloul M, Marrast AC, Chikoto H, Csermak K, Demin I, Mehta D, Pathan R, Risterucci C, Su G, Winnips C, Kaguthi G, Fofana B, Grobusch MP. Ganaplacide (KAF156) plus lumefantrine solid dispersion formulation combination for uncomplicated Plasmodium falciparum malaria: an open-label, multicentre, parallel-group, randomised, controlled, phase 2 trial. THE LANCET. INFECTIOUS DISEASES 2023; 23:1051-1061. [PMID: 37327809 DOI: 10.1016/s1473-3099(23)00209-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/01/2023] [Accepted: 03/16/2023] [Indexed: 06/18/2023]
Abstract
BACKGROUND Emergence of drug resistance demands novel antimalarial drugs with new mechanisms of action. We aimed to identify effective and well tolerated doses of ganaplacide plus lumefantrine solid dispersion formulation (SDF) in patients with uncomplicated Plasmodium falciparum malaria. METHODS This open-label, multicentre, parallel-group, randomised, controlled, phase 2 trial was conducted at 13 research clinics and general hospitals in ten African and Asian countries. Patients had microscopically-confirmed uncomplicated P falciparum malaria (>1000 and <150 000 parasites per μL). Part A identified the optimal dose regimens in adults and adolescents (aged ≥12 years) and in part B, the selected doses were assessed in children (≥2 years and <12 years). In part A, patients were randomly assigned to one of seven groups (once a day ganaplacide 400 mg plus lumefantrine-SDF 960 mg for 1, 2, or 3 days; ganaplacide 800 mg plus lumefantrine-SDF 960 mg as a single dose; once a day ganaplacide 200 mg plus lumefantrine-SDF 480 mg for 3 days; once a day ganaplacide 400 mg plus lumefantrine-SDF 480 mg for 3 days; or twice a day artemether plus lumefantrine for 3 days [control]), with stratification by country (2:2:2:2:2:2:1) using randomisation blocks of 13. In part B, patients were randomly assigned to one of four groups (once a day ganaplacide 400 mg plus lumefantrine-SDF 960 mg for 1, 2, or 3 days, or twice a day artemether plus lumefantrine for 3 days) with stratification by country and age (2 to <6 years and 6 to <12 years; 2:2:2:1) using randomisation blocks of seven. The primary efficacy endpoint was PCR-corrected adequate clinical and parasitological response at day 29, analysed in the per protocol set. The null hypothesis was that the response was 80% or lower, rejected when the lower limit of two-sided 95% CI was higher than 80%. This study is registered with EudraCT (2020-003284-25) and ClinicalTrials.gov (NCT03167242). FINDINGS Between Aug 2, 2017, and May 17, 2021, 1220 patients were screened and of those, 12 were included in the run-in cohort, 337 in part A, and 175 in part B. In part A, 337 adult or adolescent patients were randomly assigned, 326 completed the study, and 305 were included in the per protocol set. The lower limit of the 95% CI for PCR-corrected adequate clinical and parasitological response on day 29 was more than 80% for all treatment regimens in part A (46 of 50 patients [92%, 95% CI 81-98] with 1 day, 47 of 48 [98%, 89-100] with 2 days, and 42 of 43 [98%, 88-100] with 3 days of ganaplacide 400 mg plus lumefantrine-SDF 960 mg; 45 of 48 [94%, 83-99] with ganaplacide 800 mg plus lumefantrine-SDF 960 mg for 1 day; 47 of 47 [100%, 93-100] with ganaplacide 200 mg plus lumefantrine-SDF 480 mg for 3 days; 44 of 44 [100%, 92-100] with ganaplacide 400 mg plus lumefantrine-SDF 480 mg for 3 days; and 25 of 25 [100%, 86-100] with artemether plus lumefantrine). In part B, 351 children were screened, 175 randomly assigned (ganaplacide 400 mg plus lumefantrine-SDF 960 mg once a day for 1, 2, or 3 days), and 171 completed the study. Only the 3-day regimen met the prespecified primary endpoint in paediatric patients (38 of 40 patients [95%, 95% CI 83-99] vs 21 of 22 [96%, 77-100] with artemether plus lumefantrine). The most common adverse events were headache (in seven [14%] of 51 to 15 [28%] of 54 in the ganaplacide plus lumefantrine-SDF groups and five [19%] of 27 in the artemether plus lumefantrine group) in part A, and malaria (in 12 [27%] of 45 to 23 [44%] of 52 in the ganaplacide plus lumefantrine-SDF groups and 12 [50%] of 24 in the artemether plus lumefantrine group) in part B. No patients died during the study. INTERPRETATION Ganaplacide plus lumefantrine-SDF was effective and well tolerated in patients, especially adults and adolescents, with uncomplicated P falciparum malaria. Ganaplacide 400 mg plus lumefantrine-SDF 960 mg once daily for 3 days was identified as the optimal treatment regimen for adults, adolescents, and children. This combination is being evaluated further in a phase 2 trial (NCT04546633). FUNDING Novartis and Medicines for Malaria Venture.
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Affiliation(s)
- Bernhards Ogutu
- Centre for Clinical Research, Kenya Medical Research Institute, Kisumu, Kenya
| | - Adoke Yeka
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Sylvia Kusemererwa
- Medical Research Council, Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Ricardo Thompson
- Chókwè Health Research and Training Center, Centro de Investigação e Treino em Saúde de Chókwè, National Institute of Health, Chókwè, Mozambique
| | - Halidou Tinto
- Institut de Recherche en Science de la Santé, Unité de Recherche Clinique de Nanoro, Nanoro, Burkina Faso
| | - Andre Offianan Toure
- Department of Parasitology and Mycology, Institut Pasteur de Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | | | - Amar Verma
- Department of Paediatrics, Rajendra Institute of Medical Sciences, Jharkhand, India
| | - Afizi Kibuuka
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Moussa Lingani
- Institut de Recherche en Science de la Santé, Unité de Recherche Clinique de Nanoro, Nanoro, Burkina Faso
| | - Carlos Lourenço
- Chókwè Health Research and Training Center, Centro de Investigação e Treino em Saúde de Chókwè, National Institute of Health, Chókwè, Mozambique
| | - Ghyslain Mombo-Ngoma
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Department of Implementation Research, Bernhard Nocht Institute for Tropical Medicine, Hamburg, Germany; Department of Medicine, University Medical Centre Hamburg-Eppendorf, Hamburg, Germany
| | - Videlis Nduba
- Kenya Medical Research Institute, Centre for Respiratory Diseases Research, Nairobi, Kenya
| | - Tiacoh Landry N'Guessan
- Department of Parasitology and Mycology, Institut Pasteur de Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | | | - Mary Nyantaro
- Medical Research Council, Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine Uganda Research Unit, Entebbe, Uganda
| | - Lucas Otieno Tina
- Centre for Clinical Research, Kenya Medical Research Institute, US Army Medical Research Directorate, Kisumu, Kenya
| | | | | | | | | | | | | | | | | | | | - Guoqin Su
- Novartis Pharmaceuticals, East Hanover, NJ, USA
| | | | - Grace Kaguthi
- Kenya Medical Research Institute, Centre for Respiratory Diseases Research, Nairobi, Kenya
| | | | - Martin Peter Grobusch
- Centre de Recherches Médicales de Lambaréné, Lambaréné, Gabon; Department of Infectious Diseases, Center of Tropical Medicine and Travel Medicine, Amsterdam University Medical Centers, Location AMC, University of Amsterdam, Amsterdam, Netherlands; Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany.
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3
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White NJ. The assessment of antimalarial drug efficacy in vivo. Trends Parasitol 2022; 38:660-672. [PMID: 35680541 PMCID: PMC7613059 DOI: 10.1016/j.pt.2022.05.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Revised: 05/13/2022] [Accepted: 05/16/2022] [Indexed: 11/19/2022]
Abstract
Currently recommended methods of assessing uncomplicated falciparum malaria treatment work less well in high transmission than in low transmission settings. There is also uncertainty how to assess intermittent preventive therapies and seasonal malaria chemoprevention, and P. vivax radical cure. A “pharmacometric antimalarial resistance monitoring (PARM)” approach is proposed for slowly eliminated antimalarial drugs in areas of high transmission. In PARM antimalarial drug concentrations at recurrent parasitaemia are measured to identify outliers (i.e. recurrent parasitaemias in the presence of normally suppressive drug concentrations), and to characterise changes over time. PARM requires characterization of pharmacometric profiles but should be simpler and more sensitive than current methodologies. PARM does not require parasite genotyping, and can be applied to the assessment of both prevention and treatment.
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Affiliation(s)
- Nicholas J White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand; Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford University, Oxford, UK.
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4
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Stone W, Mahamar A, Smit MJ, Sanogo K, Sinaba Y, Niambele SM, Sacko A, Keita S, Dicko OM, Diallo M, Maguiraga SO, Samake S, Attaher O, Lanke K, Ter Heine R, Bradley J, McCall MBB, Issiaka D, Traore SF, Bousema T, Drakeley C, Dicko A. Single low-dose tafenoquine combined with dihydroartemisinin-piperaquine to reduce Plasmodium falciparum transmission in Ouelessebougou, Mali: a phase 2, single-blind, randomised clinical trial. THE LANCET. MICROBE 2022; 3:e336-e347. [PMID: 35544095 PMCID: PMC9042793 DOI: 10.1016/s2666-5247(21)00356-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 12/07/2021] [Accepted: 12/15/2021] [Indexed: 11/20/2022]
Abstract
BACKGROUND Tafenoquine was recently approved as a prophylaxis and radical cure for Plasmodium vivax infection, but its Plasmodium falciparum transmission-blocking efficacy is unclear. We aimed to establish the efficacy and safety of three single low doses of tafenoquine in combination with dihydroartemisinin-piperaquine for reducing gametocyte density and transmission to mosquitoes. METHODS In this four-arm, single-blind, phase 2, randomised controlled trial, participants were recruited at the Clinical Research Unit of the Malaria Research and Training Centre of the University of Bamako in Mali. Eligible participants were aged 12-50 years, with asymptomatic P falciparum microscopy-detected gametocyte carriage, had a bodyweight of 80 kg or less, and had no clinical signs of malaria defined by fever. Participants were randomly assigned (1:1:1:1) to standard treatment with dihydroartemisinin-piperaquine, or dihydroartemisinin-piperaquine plus a single dose of tafenoquine (in solution) at a final dosage of 0·42 mg/kg, 0·83 mg/kg, or 1·66 mg/kg. Randomisation was done with a computer-generated randomisation list and concealed with sealed, opaque envelopes. Dihydroartemisinin-piperaquine was administered as oral tablets over 3 days (day 0, 1, and 2), as per manufacturer instructions. A single dose of tafenoquine was administered as oral solution on day 0 in parallel with the first dose of dihydroartemisinin-piperaquine. Tafenoquine dosing was based on bodyweight to standardise efficacy and risk variance. The primary endpoint, assessed in the per-protocol population, was median percentage change in mosquito infection rate 7 days after treatment compared with baseline. Safety endpoints included frequency and incidence of adverse events. The final follow-up visit was on Dec 23, 2021; the trial is registered with ClinicalTrials.gov, NCT04609098. FINDINGS From Oct 29 to Nov 25, 2020, 1091 individuals were screened for eligibility, 80 of whom were enrolled and randomly assigned (20 per treatment group). Before treatment, 53 (66%) individuals were infectious to mosquitoes, infecting median 12·50% of mosquitoes (IQR 3·64-35·00). Within-group reduction in mosquito infection rate on day 7 was 79·95% (IQR 57·15-100; p=0·0005 for difference from baseline) following dihydroartemisinin-piperaquine only, 100% (98·36-100; p=0·0005) following dihydroartemisinin-piperaquine plus tafenoquine 0·42 mg/kg, 100% (100-100; p=0·0001) following dihydroartemisinin-piperaquine plus tafenoquine 0·83 mg/kg, and 100% (100-100; p=0·0001) following dihydroartemisinin-piperaquine plus tafenoquine 1·66 mg/kg. 55 (69%) of 80 participants had a total of 94 adverse events over the course of the trial; 86 (92%) adverse events were categorised as mild, seven (7%) as moderate, and one (1%) as severe. The most common treatment-related adverse event was mild or moderate headache, which occurred in 15 (19%) participants (dihydroartemisinin-piperaquine n=2; dihydroartemisinin-piperaquine plus tafenoquine 0·42 mg/kg n=6; dihydroartemisinin-piperaquine plus tafenoquine 0·83 mg/kg n=3; and dihydroartemisinin-piperaquine plus tafenoquine 1·66 mg/kg n=4). No serious adverse events occurred. No significant differences in the incidence of all adverse events (p=0·73) or treatment-related adverse events (p=0·62) were observed between treatment groups. INTERPRETATION Tafenoquine was well tolerated at all doses and accelerated P falciparum gametocyte clearance. All tafenoquine doses showed improved transmission reduction at day 7 compared with dihydroartemisinin-piperaquine alone. These data support the case for further research on tafenoquine as a transmission-blocking supplement to standard antimalarials. FUNDING Bill & Melinda Gates Foundation. TRANSLATIONS For the French, Portuguese, Spanish and Swahili translations of the abstract see Supplementary Materials section.
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Affiliation(s)
- Will Stone
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK.
| | - Almahamoudou Mahamar
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Merel J Smit
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, University of Nijmegen, Nijmegen, Netherlands
| | - Koualy Sanogo
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Youssouf Sinaba
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Sidi M Niambele
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Adama Sacko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekouba Keita
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Oumar M Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Makonon Diallo
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Seydina O Maguiraga
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Siaka Samake
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Oumar Attaher
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Kjerstin Lanke
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, University of Nijmegen, Nijmegen, Netherlands
| | - Rob Ter Heine
- Department of Pharmacy and Radboud Center for Infectious Diseases, Radboud University Medical Center, University of Nijmegen, Nijmegen, Netherlands
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene & Tropical Medicine, London, UK
| | - Matthew B B McCall
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, University of Nijmegen, Nijmegen, Netherlands
| | - Djibrilla Issiaka
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekou F Traore
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Teun Bousema
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, University of Nijmegen, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
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5
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Mwaiswelo RO, Ngasala B, Msolo D, Kweka E, Mmbando BP, Mårtensson A. A single low dose of primaquine is safe and sufficient to reduce transmission of Plasmodium falciparum gametocytes regardless of cytochrome P450 2D6 enzyme activity in Bagamoyo district, Tanzania. Malar J 2022; 21:84. [PMID: 35279143 PMCID: PMC8917764 DOI: 10.1186/s12936-022-04100-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 02/23/2022] [Indexed: 11/10/2022] Open
Abstract
Background Primaquine is a pro-drug and its active metabolite is potent against mature Plasmodium falciparum gametocytes. Primaquine is metabolized by a highly polymorphic cytochrome P450 2D6 (CYP2D6) enzyme. Mutations in the gene encoding this enzyme may lead to impaired primaquine activity. This study assessed if 0.25 mg/kg single-dose primaquine is safe and sufficient to reduce transmission of gametocytes in individuals with no, reduced, or increased CYP2D6 enzyme activity. Methods Between June 2019 and January 2020 children aged 1–10 years, attending at Yombo dispensary, Bagamoyo district, with confirmed microcopy-determined uncomplicated P. falciparum malaria were enrolled in the study. The enrolled patients were treated with a standard artemether-lumefantrine regimen plus 0.25 mg/kg single-dose primaquine and followed up for 28 days for clinical and laboratory assessment. Primaquine was administered with the first dose of artemether-lumefantrine. Safety assessment involved direct questioning and recording of the nature and incidence of clinical signs and symptoms, and measurement of haemoglobin (Hb) concentration. Blood samples collected from 100 patients were used for assessment of post-treatment infectiousness on day 7 using mosquito membrane feeding assays. Molecular methods were used to determine CYP2D6 and glucose-6-phosphate dehydrogenase (G6PD) status. The primary outcome was the safety of 0.25 mg/kg single-dose primaquine based on CYP2D6 status. Results In total, 157 children [median age 6.4 (Interquartile range 4.0–8.2) years] were recruited, of whom 21.0% (33/157) and 12.7% (20/157) had reduced CYP2D6 and deficient G6PD activity, respectively. Day 3 mean absolute Hb concentration reduction was 1.50 g/dL [95% confidence interval (CI) 1.10–1.90] and 1.51 g/dL (95% CI 1.31–1.71) in reduced and normal CYP2D6 patients, respectively (t = 0.012, p = 0.990). The day 3 mean absolute Hb concentration reduction in G6PD deficient, G6PD normal and heterozygous female was 1.82 g/dL (95% CI 1.32–2.32), 1.48 g/dL (95% CI 1.30–1.67) and 1.47 g/dL (95% CI 0.76–2.18), respectively (F = 0.838, p = 0.435). Sixteen percent (16/98) of the patients each infected at least one mosquito on day 7, and of these, 10.0% (2/20) and 17.9% (14/78) had reduced and normal CYP2D6 enzyme activity, respectively (x2 = 0.736, p = 0.513). Conclusion Single-dose 0.25 mg/kg primaquine was safe and sufficient for reducing transmission of P. falciparum gametocytes regardless of CYP2D6 or G6PD status. Trial registration Study registration number: NCT03352843. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04100-1.
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Assessment
in vitro
of the antimalarial and transmission blocking activities of Cipargamin and Ganaplacide in artemisinin resistant
Plasmodium falciparum. Antimicrob Agents Chemother 2022; 66:e0148121. [DOI: 10.1128/aac.01481-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Artemisinin resistance in
Plasmodium falciparum
has emerged and spread widely in the Greater Mekong Subregion threatening current first line artemisinin combination treatments. New antimalarial drugs are needed urgently. Cipargamin (KAE609) and ganaplacide (KAF156) are promising novel antimalarial compounds in advanced stages of development. Both compounds have potent asexual blood stage activities, inhibit
P. falciparum
gametocytogenesis and reduce oocyst development in anopheline mosquitoes. In this study, we compared the asexual and sexual stage activities of cipargamin, ganaplacide and artesunate in artemisinin resistant
P. falciparum
isolates (N=7, K13 mutation; C580Y, G449A and R539T) from Thailand and Cambodia. Asexual blood stage antimalarial activity was evaluated in a SYBR-green I based 72h
in vitro
assay, and the effects on male and female mature stage V gametocytes were assessed in the
P. falciparum
dual gamete formation assay. Ganaplacide had higher activities when compared to cipargamin and artesunate, with a mean (SD) IC50 against asexual stages of 5.5 (1.1) nM, 7.8 (3.9) nM for male gametocytes and 57.9 (59.6) nM for female gametocytes. Cipargamin had a similar potency against male and female gametocytes, with a mean (SD) IC50 of 123.1 (80.2) nM for male gametocytes, 88.5 (52.7) nM for female gametocytes and 2.4 (0.6) nM for asexual stages. Both cipargamin and ganaplacide showed significant transmission-blocking activities against artemisinin resistant
P. falciparum
in vitro
.
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Stone W, Mahamar A, Sanogo K, Sinaba Y, Niambele SM, Sacko A, Keita S, Youssouf A, Diallo M, Soumare HM, Kaur H, Lanke K, ter Heine R, Bradley J, Issiaka D, Diawara H, Traore SF, Bousema T, Drakeley C, Dicko A. Pyronaridine–artesunate or dihydroartemisinin–piperaquine combined with single low-dose primaquine to prevent Plasmodium falciparum malaria transmission in Ouélessébougou, Mali: a four-arm, single-blind, phase 2/3, randomised trial. THE LANCET MICROBE 2022; 3:e41-e51. [PMID: 35028628 PMCID: PMC8721154 DOI: 10.1016/s2666-5247(21)00192-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- William Stone
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
- Correspondence to: Dr William Stone, Department of Infection Biology, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | - Almahamoudou Mahamar
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Koualy Sanogo
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Youssouf Sinaba
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Sidi M Niambele
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Adama Sacko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekouba Keita
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Ahamadou Youssouf
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Makonon Diallo
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Harouna M Soumare
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Harparkash Kaur
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Kjerstin Lanke
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, University of Nijmegen, Nijmegen, Netherlands
| | - Rob ter Heine
- Department of Pharmacy and Radboud Center for Infectious Diseases, Radboud University Medical Center, University of Nijmegen, Nijmegen, Netherlands
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene & Tropical Medicine, London, UK
| | - Djibrilla Issiaka
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Halimatou Diawara
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekou F Traore
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Teun Bousema
- Department of Medical Microbiology and Radboud Center for Infectious Diseases, Radboud University Medical Center, University of Nijmegen, Nijmegen, Netherlands
| | - Chris Drakeley
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
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8
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Abstract
Cindy S Chu and co-authors review options for diagnosis, safe and radical cure, and relapse prevention of Plasmodium Vivax.
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Affiliation(s)
- Cindy S. Chu
- 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, Headington, Oxford, United Kingdom
- * E-mail:
| | - Nicholas J. White
- Shoklo Malaria Research Unit-Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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9
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Moyo P, Mugumbate G, Eloff JN, Louw AI, Maharaj VJ, Birkholtz LM. Natural Products: A Potential Source of Malaria Transmission Blocking Drugs? Pharmaceuticals (Basel) 2020; 13:E251. [PMID: 32957668 PMCID: PMC7558993 DOI: 10.3390/ph13090251] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 12/17/2022] Open
Abstract
The ability to block human-to-mosquito and mosquito-to-human transmission of Plasmodium parasites is fundamental to accomplish the ambitious goal of malaria elimination. The WHO currently recommends only primaquine as a transmission-blocking drug but its use is severely restricted by toxicity in some populations. New, safe and clinically effective transmission-blocking drugs therefore need to be discovered. While natural products have been extensively investigated for the development of chemotherapeutic antimalarial agents, their potential use as transmission-blocking drugs is comparatively poorly explored. Here, we provide a comprehensive summary of the activities of natural products (and their derivatives) of plant and microbial origins against sexual stages of Plasmodium parasites and the Anopheles mosquito vector. We identify the prevailing challenges and opportunities and suggest how these can be mitigated and/or exploited in an endeavor to expedite transmission-blocking drug discovery efforts from natural products.
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Affiliation(s)
- Phanankosi Moyo
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Grace Mugumbate
- Department of Chemistry, School of Natural Sciences and Mathematics, Chinhoyi University of Technology, Private Bag, 7724 Chinhoyi, Zimbabwe;
| | - Jacobus N. Eloff
- Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag x04, Onderstepoort 0110 Pretoria, South Africa;
| | - Abraham I. Louw
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Vinesh J. Maharaj
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
| | - Lyn-Marié Birkholtz
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Private Bag x20, Hatfield, 0028 Pretoria, South Africa;
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10
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Bradley J, Soumaré HM, Mahamar A, Diawara H, Roh M, Delves M, Drakeley C, Churcher TS, Dicko A, Gosling R, Bousema T. Transmission-blocking Effects of Primaquine and Methylene Blue Suggest Plasmodium falciparum Gametocyte Sterilization Rather Than Effects on Sex Ratio. Clin Infect Dis 2020; 69:1436-1439. [PMID: 30753355 PMCID: PMC6763632 DOI: 10.1093/cid/ciz134] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 02/07/2019] [Indexed: 11/16/2022] Open
Abstract
Gametocyte density and sex ratio can predict the proportion of mosquitoes that will become infected after feeding on blood of patients receiving nongametocytocidal drugs. Because primaquine and methylene blue sterilize gametocytes before affecting their density and sex ratio, mosquito feeding experiments are required to demonstrate their early transmission-blocking effects.
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Affiliation(s)
- John Bradley
- Medical Research Council (MRC) Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Harouna M Soumaré
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Mali
| | - Almahamoudou Mahamar
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Mali
| | - Halimatou Diawara
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Mali
| | - Michelle Roh
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco
| | - Michael Delves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, United Kingdom
| | - Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Mali
| | - Roly Gosling
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco
| | - Teun Bousema
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
- Correspondence: T. Bousema, Radboud University Medical Center Nijmegen, Department of Medical Microbiology 268, 6525 GA Nijmegen, The Netherlands ()
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11
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Stepniewska K, Humphreys GS, Gonçalves BP, Craig E, Gosling R, Guerin PJ, Price RN, Barnes KI, Raman J, Smit MR, D’Alessandro U, Stone WJR, Bjorkman A, Samuels AM, Arroyo-Arroyo MI, Bastiaens GJH, Brown JM, Dicko A, El-Sayed BB, Elzaki SEG, Eziefula AC, Kariuki S, Kwambai TK, Maestre AE, Martensson A, Mosha D, Mwaiswelo RO, Ngasala BE, Okebe J, Roh ME, Sawa P, Tiono AB, Chen I, Drakeley CJ, Bousema T. Efficacy of Single-Dose Primaquine With Artemisinin Combination Therapy on Plasmodium falciparum Gametocytes and Transmission: An Individual Patient Meta-Analysis. J Infect Dis 2020; 225:1215-1226. [PMID: 32778875 PMCID: PMC8974839 DOI: 10.1093/infdis/jiaa498] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 08/06/2020] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Since the World Health Organization recommended single low-dose (0.25 mg/kg) primaquine (PQ) in combination with artemisinin-based combination therapies (ACTs) in areas of low transmission or artemisinin-resistant Plasmodium falciparum, several single-site studies have been conducted to assess efficacy. METHODS An individual patient meta-analysis to assess gametocytocidal and transmission-blocking efficacy of PQ in combination with different ACTs was conducted. Random effects logistic regression was used to quantify PQ effect on (1) gametocyte carriage in the first 2 weeks post treatment; and (2) the probability of infecting at least 1 mosquito or of a mosquito becoming infected. RESULTS In 2574 participants from 14 studies, PQ reduced PCR-determined gametocyte carriage on days 7 and 14, most apparently in patients presenting with gametocytemia on day 0 (odds ratio [OR], 0.22; 95% confidence interval [CI], .17-.28 and OR, 0.12; 95% CI, .08-.16, respectively). Rate of decline in gametocyte carriage was faster when PQ was combined with artemether-lumefantrine (AL) compared to dihydroartemisinin-piperaquine (DP) (P = .010 for day 7). Addition of 0.25 mg/kg PQ was associated with near complete prevention of transmission to mosquitoes. CONCLUSIONS Transmission blocking is achieved with 0.25 mg/kg PQ. Gametocyte persistence and infectivity are lower when PQ is combined with AL compared to DP.
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Affiliation(s)
- Kasia Stepniewska
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom,Infectious Diseases Data Observatory, Oxford, United Kingdom,Kasia Stepniewska, PhD, WorldWide Antimalarial Resistance Network (WWARN), Centre for Tropical Medicine and Global Health, Churchill Hospital, CCVTM, University of Oxford, Old Road, Oxford OX3 7LE, UK
| | - Georgina S Humphreys
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom,Infectious Diseases Data Observatory, Oxford, United Kingdom,Green Templeton College, University of Oxford, Oxford, United Kingdom
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Elaine Craig
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom,Infectious Diseases Data Observatory, Oxford, United Kingdom
| | - Roly Gosling
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA,Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, California, USA
| | - Philippe J Guerin
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom,Infectious Diseases Data Observatory, Oxford, United Kingdom
| | - Ric N Price
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom,Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom,Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Norther Territory, Australia,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Karen I Barnes
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom,University of Cape Town/Medical Research Council Collaborating Centre for Optimising Antimalarial Therapy, University of Cape Town, Cape Town, South Africa,Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Jaishree Raman
- University of Cape Town/Medical Research Council Collaborating Centre for Optimising Antimalarial Therapy, University of Cape Town, Cape Town, South Africa,Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Services, Johannesburg, South Africa,Wits Research Institute for Malaria, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Menno R Smit
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Umberto D’Alessandro
- Medical Research Council Unit The Gambia, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Will J R Stone
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom,Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Anders Bjorkman
- Department of Microbiology Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden
| | - Aaron M Samuels
- Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA,Centers for Disease Control and Prevention, Kisumu, Kenya
| | - Maria I Arroyo-Arroyo
- Grupo Salud y Comunidad, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia
| | - Guido J H Bastiaens
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands,Department of Microbiology and Immunology, Rijnstate Hospital, Arnhem, the Netherlands
| | - Joelle M Brown
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA
| | - Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Badria B El-Sayed
- Tropical Medicine Research Institute, National Centre for Research, Khartoum, Sudan
| | - Salah-Eldin G Elzaki
- Tropical Medicine Research Institute, National Centre for Research, Khartoum, Sudan
| | - Alice C Eziefula
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom,Department of Global Health and Infection, Brighton and Sussex Medical School, Brighton, United Kingdom
| | | | - Titus K Kwambai
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, United Kingdom,Kenya Medical Research Institute, Kisian, Kenya
| | - Amanda E Maestre
- Grupo Salud y Comunidad, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia
| | - Andreas Martensson
- Department of Women’s and Children’s Health, International Maternal and Child Health, Uppsala University, Uppsala, Sweden
| | - Dominic Mosha
- Bagamoyo Research and Training Centre, Ifakara Health Institute, Bagamoyo, Tanzania,Africa Academy for Public Health, Dar es Salaam, Tanzania
| | - Richard O Mwaiswelo
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Billy E Ngasala
- Department of Parasitology and Medical Entomology, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania
| | - Joseph Okebe
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Michelle E Roh
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, California, USA,Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, California, USA
| | - Patrick Sawa
- Human Health Division, International Centre for Insect Physiology and Ecology, Mbita Point, Kenya
| | - Alfred B Tiono
- Department of Biomedical Sciences, Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Ingrid Chen
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, California, USA
| | - Chris J Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom,Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, the Netherlands,Correspondence: Teun Bousema, PhD, Department of Medical Microbiology, Radboud Institute for Health Science, Radboudumc, PO Box 9101, 6500 HB Nijmegen, The Netherlands ()
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12
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Wang CYT, Ballard E, Llewellyn S, Marquart L, Bousema T, McCarthy JS, Collins KA. Assays for quantification of male and female gametocytes in human blood by qRT-PCR in the absence of pure sex-specific gametocyte standards. Malar J 2020; 19:218. [PMID: 32576184 PMCID: PMC7310411 DOI: 10.1186/s12936-020-03291-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 06/17/2020] [Indexed: 12/25/2022] Open
Abstract
Background Malaria transmission from humans to Anopheles mosquitoes requires the presence of gametocytes in human peripheral circulation, and the dynamics of transmission are determined largely by the density and sex ratio of the gametocytes. Molecular methods are thus employed to measure gametocyte densities, particularly when assessing transmission epidemiology and the efficacy of transmission-blocking interventions. However, accurate quantification of male and female gametocytes with molecular methods requires pure male and female gametocytes as reference standards, which are not widely available. Methods qRT-PCR assays were used to quantify levels of sex-specific mRNA transcripts in Plasmodium falciparum female and male gametocytes (pfs25 and pfMGET, respectively) using synthetic complimentary RNA standards and in vitro cultured gametocytes. Assays were validated and assay performance was investigated in blood samples of clinical trial participants using these standards and compared to absolute quantification by droplet digital PCR (ddPCR). Results The number of transcript copies per gametocyte were determined to be 279.3 (95% CI 253.5–307.6) for the female-specific transcript pfs25, and 12.5 (95% CI 10.6–14.9) for the male-specific transcript pfMGET. These numbers can be used to convert from transcript copies/mL to gametocyte/mL. The reportable range was determined to be 5.71 × 106 to 5.71 female gametocytes/mL for pfs25, and 1.73 × 107 to 1.73 × 101 male gametocytes/mL for pfMGET. The limit of detection was 3.9 (95% CI 2.5–8.2) female gametocytes/mL for pfs25, and 26.9 (95% CI 19.3–51.7) male gametocytes/mL for PfMGET. Both assays showed minimal intra-assay and inter-assay variability with coefficient of variation < 3%. No cross-reactivity was observed in both assays in uninfected human blood samples. Comparison of results from ddPCR to qRT-PCR assays on clinical blood samples indicated a high-level agreement (ICC = 0.998 for pfs25 and 0.995 for pfMGET). Conclusions This study reports the validation of qRT-PCR assays that are able to accurately quantify female and male P. falciparum gametocytes at sub-microscopic densities. The assays showed excellent reproducibility, sensitivity, precision, specificity, and accuracy. The methodology will enable the estimation of gametocyte density in the absence of pure female and male gametocyte standards, and will facilitate clinical trials and epidemiological studies.
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Affiliation(s)
- Claire Y T Wang
- QPID Laboratory, Centre for Children's Health Research, Brisbane, QLD, Australia
| | - Emma Ballard
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Stacey Llewellyn
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Louise Marquart
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Teun Bousema
- Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, The Netherlands
| | - James S McCarthy
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
| | - Katharine A Collins
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia. .,Radboud Institute for Health Science, Radboud University Medical Center, Nijmegen, The Netherlands.
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13
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Plasmodium vivax in the Era of the Shrinking P. falciparum Map. Trends Parasitol 2020; 36:560-570. [PMID: 32407682 PMCID: PMC7297627 DOI: 10.1016/j.pt.2020.03.009] [Citation(s) in RCA: 117] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 03/25/2020] [Accepted: 03/26/2020] [Indexed: 01/13/2023]
Abstract
Plasmodium vivax is an important cause of malaria, associated with a significant public health burden. Whilst enhanced malaria-control activities have successfully reduced the incidence of Plasmodium falciparum malaria in many areas, there has been a consistent increase in the proportion of malaria due to P. vivax in regions where both parasites coexist. This article reviews the epidemiology and biology of P. vivax, how the parasite differs from P. falciparum, and the key features that render it more difficult to control and eliminate. Since transmission of the parasite is driven largely by relapses from dormant liver stages, its timely elimination will require widespread access to safe and effective radical cure.
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14
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Significant Efficacy of a Single Low Dose of Primaquine Compared to Stand-Alone Artemisinin Combination Therapy in Reducing Gametocyte Carriage in Cambodian Patients with Uncomplicated Multidrug-Resistant Plasmodium falciparum Malaria. Antimicrob Agents Chemother 2020; 64:AAC.02108-19. [PMID: 32179526 PMCID: PMC7269483 DOI: 10.1128/aac.02108-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 03/06/2020] [Indexed: 11/22/2022] Open
Abstract
Since 2012, a single low dose of primaquine (SLDPQ; 0.25 mg/kg of body weight) with artemisinin-based combination therapies has been recommended as the first-line treatment of acute uncomplicated Plasmodium falciparum malaria to interrupt its transmission, especially in low-transmission settings of multidrug resistance, including artemisinin resistance. Policy makers in Cambodia have been reluctant to implement this recommendation due to primaquine safety concerns and a lack of data on its efficacy. Since 2012, a single low dose of primaquine (SLDPQ; 0.25 mg/kg of body weight) with artemisinin-based combination therapies has been recommended as the first-line treatment of acute uncomplicated Plasmodium falciparum malaria to interrupt its transmission, especially in low-transmission settings of multidrug resistance, including artemisinin resistance. Policy makers in Cambodia have been reluctant to implement this recommendation due to primaquine safety concerns and a lack of data on its efficacy. In this randomized controlled trial, 109 Cambodians with acute uncomplicated P. falciparum malaria received dihydroartemisinin-piperaquine (DP) alone or combined with SLDPQ on the first treatment day. The transmission-blocking efficacy of SLDPQ was evaluated on days 0, 1, 2, 3, 7, 14, 21, and 28, and recrudescence by reverse transcriptase PCR (RT-PCR) (gametocyte prevalence) and membrane feeding assays with Anopheles minimus mosquitoes (gametocyte infectivity). Without the influence of recrudescent infections, DP-SLDPQ reduced gametocyte carriage 3-fold compared to that achieved with DP. Of 48 patients tested on day 0, only 3 patients were infectious to mosquitoes (∼6%). Posttreatment, three patients were infectious on day 14 (3.5%, 1/29) and on the 1st and 7th days of recrudescence (8.3%, 1/12 for each); this overall low infectivity precluded our ability to assess its transmission-blocking efficacy. Our study confirms the effective gametocyte clearance of SLDPQ when combined with DP in multidrug-resistant P. falciparum infections and the negative impact of recrudescent infections due to poor DP efficacy. Artesunate-mefloquine (ASMQ) has replaced DP, and ASMQ-SLDPQ has been deployed to treat all patients with symptomatic P. falciparum infections to further support the elimination of multidrug-resistant P. falciparum in Cambodia. (This study has been registered at ClinicalTrials.gov under identifier NCT02434952.)
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15
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Perumal S, Lee W, Mahmud R, Ismail S, Basir R. In vivo antimalarial potential of tinospora crispa miers in mice and identification of the bioactive compound. Pharmacogn Mag 2020. [DOI: 10.4103/pm.pm_10_19] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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16
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Challenger JD, Gonçalves BP, Bradley J, Bruxvoort K, Tiono AB, Drakeley C, Bousema T, Ghani AC, Okell LC. How delayed and non-adherent treatment contribute to onward transmission of malaria: a modelling study. BMJ Glob Health 2019; 4:e001856. [PMID: 31908862 PMCID: PMC6936434 DOI: 10.1136/bmjgh-2019-001856] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 11/08/2019] [Accepted: 11/10/2019] [Indexed: 12/31/2022] Open
Abstract
Introduction Artemether-lumefantrine (AL) is the most widely-recommended treatment for uncomplicated Plasmodium falciparum malaria. Its efficacy has been extensively assessed in clinical trials. In routine healthcare settings, however, its effectiveness can be diminished by delayed access to treatment and poor adherence. As well as affecting clinical outcomes, these factors can lead to increased transmission, which is the focus of this study. Methods We extend a within-host model of P. falciparum to include gametocytes, the parasite forms responsible for onward transmission. The model includes a pharmacokinetic–pharmacodynamic model of AL, calibrated against both immature and mature gametocytes using individual-level patient data, to estimate the impact that delayed access and imperfect adherence to treatment can have on onward transmission of the parasite to mosquitoes. Results Using survey data from seven African countries to determine the time taken to acquire antimalarials following fever increased our estimates of mean total infectivity of a malaria episode by up to 1.5-fold, compared with patients treated after 24 hours. Realistic adherence behaviour, based on data from a monitored cohort in Tanzania, increased the contribution to transmission by 2.2 to 2.4-fold, compared with a perfectly-adherent cohort. This was driven largely by increased rates of treatment failure leading to chronic infection, rather than prolonged gametocytaemia in patients who have slower, but still successful, clearance of parasites after imperfect adherence to treatment. Our model estimated that the mean infectivity of untreated infections was 29–51 times higher than that of treated infections (assuming perfect drug adherence), underlining the importance of improving treatment coverage. Conclusion Using mathematical modelling, we quantify how delayed treatment and non-adherent treatment can increase transmission compared with prompt effective treatment. We also highlight that transmission from the large proportion of infections which never receive treatment is substantially higher than those treated.
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Affiliation(s)
- Joseph D Challenger
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Katia Bruxvoort
- Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, California, USA.,Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Alfred B Tiono
- Public Health Department, Centre National de Recherche et de Formation sur le Paludisme (CNRFP), Ouagadougou, Burkina Faso
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, United Kingdom.,Radboud Institute of Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Azra C Ghani
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
| | - Lucy C Okell
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom
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17
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Abstract
The scientific community worldwide has realized that malaria elimination will not be possible without development of safe and effective transmission-blocking interventions. Primaquine, the only WHO recommended transmission-blocking drug, is not extensively utilized because of the toxicity issues in G6PD deficient individuals. Therefore, there is an urgent need to develop novel therapeutic interventions that can target malaria parasites and effectively block transmission. But at first, it is imperative to unravel the existing portfolio of transmission-blocking drugs. This review highlights transmission-blocking potential of current antimalarial drugs and drugs that are in various stages of clinical development. The collective analysis of the relationships between the structure and the activity of transmission-blocking drugs is expected to help in the design of new transmission-blocking antimalarials.
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18
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Raman J, Allen E, Workman L, Mabuza A, Swanepoel H, Malatje G, Frean J, Wiesner L, Barnes KI. Safety and tolerability of single low-dose primaquine in a low-intensity transmission area in South Africa: an open-label, randomized controlled trial. Malar J 2019; 18:209. [PMID: 31234865 PMCID: PMC6592007 DOI: 10.1186/s12936-019-2841-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 06/17/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND To reduce onward falciparum malaria transmission, the World Health Organization recommends adding single low-dose (SLD) primaquine to artemisinin-based combination treatment in low transmission areas. However, uptake of this recommendation has been relatively slow given concerns about whether individual risks justify potential community benefit. This study was undertaken to generate comprehensive local data on the risk-benefit profile of SLD primaquine deployment in a pre-elimination area in South Africa. METHODS This randomized, controlled open-label trial investigated adding a single low primaquine dose on day 3 to standard artemether-lumefantrine treatment for uncomplicated falciparum malaria. Efficacy, safety and tolerability of artemether-lumefantrine and primaquine treatment were assessed on days 3, 7, 14, 28 and 42. Lumefantrine concentrations were assayed from dried blood spot samples collected on day 7. RESULTS Of 217 patients screened, 166 were enrolled with 140 randomized on day 3, 70 to each study arm (primaquine and no primaquine). No gametocytes were detected by either microscopy or PCR in any of the follow-up samples collected after randomization on day 3, precluding assessment of primaquine efficacy. Prevalence of the CYP2D6*4, CYP2D6*10 and CYP2D6*17 mutant alleles was low with allelic frequencies of 0.02, 0.11 and 0.16, respectively; none had the CYP2D6*4/*4 variant associated with null activity. Among 172 RDT-positive patients G6PD-genotyped, 24 (14%) carried the G6PD deficient (A-) variant. Median haemoglobin concentrations were similar between treatment arms throughout follow-up. A third of participants had a haemoglobin drop > 2 g/dL; this was not associated with primaquine treatment but may be associated with G6PD genotype [52.9% (9/17) with A- genotype vs. 31% (36/116) with other genotypes (p = 0.075)]. Day 7 lumefantrine concentrations and the number and nature of adverse events were similar between study arms; only one serious adverse event occurred (renal impairment in the no primaquine arm). The artemether-lumefantrine PCR-corrected adequate clinical and parasitological response rate was 100%, with only one re-infection found among the 128 patients who completed 42-day follow-up. CONCLUSIONS Safety, tolerability, CYP2D6 and G6PD variant data from this study support the deployment of the WHO-recommended SLD primaquine without G6PD testing to advance malaria elimination in South African districts with low-intensity residual transmission. Trial registration Pan African Clinical Trial Registry, PACTR201611001859416. Registered 11 November 2016, https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=1859.
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Affiliation(s)
- Jaishree Raman
- Parasitology Reference Laboratory, National Institute for Communicable Diseases, A Division of the National Health Laboratory Services, Johannesburg, South Africa
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
- UCT/MRC Collaborating Centre for Optimising Antimalarial Therapy, University of Cape Town, Cape Town, South Africa
| | - Elizabeth Allen
- UCT/MRC Collaborating Centre for Optimising Antimalarial Therapy, University of Cape Town, Cape Town, South Africa
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Lesley Workman
- UCT/MRC Collaborating Centre for Optimising Antimalarial Therapy, University of Cape Town, Cape Town, South Africa
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Aaron Mabuza
- UCT/MRC Collaborating Centre for Optimising Antimalarial Therapy, University of Cape Town, Cape Town, South Africa
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
- Mpumalanga Provincial Malaria Elimination Programme, Mpumalanga, South Africa
| | - Hendrik Swanepoel
- UP Institute for Sustainable Malaria Control and MRC Collaborating Centre for Malaria Research, University of Pretoria, Pretoria, South Africa
| | - Gillian Malatje
- Mpumalanga Provincial Malaria Elimination Programme, Mpumalanga, South Africa
| | - John Frean
- Parasitology Reference Laboratory, National Institute for Communicable Diseases, A Division of the National Health Laboratory Services, Johannesburg, South Africa
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Lubbe Wiesner
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Karen I Barnes
- UCT/MRC Collaborating Centre for Optimising Antimalarial Therapy, University of Cape Town, Cape Town, South Africa.
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa.
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19
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Henry NB, Sermé SS, Siciliano G, Sombié S, Diarra A, Sagnon N, Traoré AS, Sirima SB, Soulama I, Alano P. Biology of Plasmodium falciparum gametocyte sex ratio and implications in malaria parasite transmission. Malar J 2019; 18:70. [PMID: 30866941 PMCID: PMC6417185 DOI: 10.1186/s12936-019-2707-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/05/2019] [Indexed: 11/10/2022] Open
Abstract
While significant advances have been made in understanding Plasmodium falciparum gametocyte biology and its relationship with malaria parasite transmission, the gametocyte sex ratio contribution to this process still remains a relevant research question. The present review discusses the biology of sex determination in P. falciparum, the underlying host and parasite factors, the sex specific susceptibility to drugs, the effect of sex ratio dynamics on malaria parasite transmission and the development of gametocyte sex specific diagnosis tools. Despite the inherent differences across several studies and approaches, the emerging picture highlights a potentially relevant contribution of the P. falciparum gametocyte sex ratio in the modulation of malaria parasite transmission. The increasing availability of molecular methods to measure gametocyte sex ratio will enable evaluation of important parameters, such as the impact of drug treatment on gametocyte sex ratio in vitro and in vivo as well as the changes of gametocyte sex ratios in natural infections, key steps towards elucidating how these parameters affect parasite infectiousness to the mosquito vectors.
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Affiliation(s)
- Noëlie Béré Henry
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Samuel Sindié Sermé
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Giulia Siciliano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Salif Sombié
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Amidou Diarra
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - N'fale Sagnon
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | | | - Sodiomon Bienvenu Sirima
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.,Groupe de Recherche Action Santé, Ouagadougou, Burkina Faso
| | - Issiaka Soulama
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso.
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy.
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20
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Moyo P, Kunyane P, Selepe MA, Eloff JN, Niemand J, Louw AI, Maharaj VJ, Birkholtz LM. Bioassay-guided isolation and identification of gametocytocidal compounds from Artemisia afra (Asteraceae). Malar J 2019; 18:65. [PMID: 30849984 PMCID: PMC6408838 DOI: 10.1186/s12936-019-2694-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 03/01/2019] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Optimal adoption of the malaria transmission-blocking strategy is currently limited by lack of safe and efficacious drugs. This has sparked the exploration of different sources of drugs in search of transmission-blocking agents. While plant species have been extensively investigated in search of malaria chemotherapeutic agents, comparatively less effort has been channelled towards exploring them in search of transmission-blocking drugs. Artemisia afra (Asteraceae), a prominent feature of South African folk medicine, is used for the treatment of a number of diseases, including malaria. In search of transmission-blocking compounds aimed against Plasmodium parasites, the current study endeavoured to isolate and identify gametocytocidal compounds from A. afra. METHODS A bioassay-guided isolation approach was adopted wherein a combination of solvent-solvent partitioning and gravity column chromatography was used. Collected fractions were continuously screened in vitro for their ability to inhibit the viability of primarily late-stage gametocytes of Plasmodium falciparum (NF54 strain), using a parasite lactate dehydrogenase assay. Chemical structures of isolated compounds were elucidated using UPLC-MS/MS and NMR data analysis. RESULTS Two guaianolide sesquiterpene lactones, 1α,4α-dihydroxybishopsolicepolide and yomogiartemin, were isolated and shown to be active (IC50 < 10 μg/ml; ~ 10 μM) against both gametocytes and intra-erythrocytic asexual P. falciparum parasites. Interestingly, 1α,4α-dihydroxybishopsolicepolide was significantly more potent against late-stage gametocytes than to early-stage gametocytes and intra-erythrocytic asexual P. falciparum parasites. Additionally, both isolated compounds were not overly cytotoxic against HepG2 cells in vitro. CONCLUSION This study provides the first instance of isolated compounds from A. afra against P. falciparum gametocytes as a starting point for further investigations on more plant species in search of transmission-blocking compounds.
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Affiliation(s)
- Phanankosi Moyo
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Phaladi Kunyane
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Mamoalosi A Selepe
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Jacobus N Eloff
- Phytomedicine Programme, Department of Paraclinical Sciences, Faculty of Veterinary Science, University of Pretoria, Private Bag x04, Onderstepoort, Pretoria, 0110, South Africa
| | - Jandeli Niemand
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Abraham I Louw
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Vinesh J Maharaj
- Department of Chemistry, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa
| | - Lyn-Marie Birkholtz
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Faculty of Natural and Agricultural Sciences, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag x20, Hatfield, 0028, South Africa.
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21
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Tadesse FG, Meerstein-Kessel L, Gonçalves BP, Drakeley C, Ranford-Cartwright L, Bousema T. Gametocyte Sex Ratio: The Key to Understanding Plasmodium falciparum Transmission? Trends Parasitol 2018; 35:226-238. [PMID: 30594415 PMCID: PMC6396025 DOI: 10.1016/j.pt.2018.12.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2018] [Revised: 11/30/2018] [Accepted: 12/03/2018] [Indexed: 11/25/2022]
Abstract
A mosquito needs to ingest at least one male and one female gametocyte to become infected with malaria. The sex of Plasmodium falciparum gametocytes can be determined microscopically but recent transcriptomics studies paved the way for the development of molecular methods that allow sex-ratio assessments at much lower gametocyte densities. These sex-specific gametocyte diagnostics were recently used to examine gametocyte dynamics in controlled and natural infections as well as the impact of different antimalarial drugs. It is currently unclear to what extent sex-specific gametocyte diagnostics obviate the need for mosquito feeding assays to formally assess transmission potential. Here, we review recent and historic assessments of gametocyte sex ratio in relation to host and parasite characteristics, treatment, and transmission potential. Recent RNA sequencing studies have uncovered a number of P. falciparum gametocyte sex-specific targets and provided new insights in gametocyte biology. After decades when gametocyte sex-ratio research was restricted to nonhuman malarias or in vitro experiments, molecular tools for assessing gametocyte sex ratio are now increasingly available for use in natural P. falciparum infections. Evidence that gametocyte sex ratio is influenced by total gametocyte density and antimalarial treatment, and improves predictions of transmission potential, highlight the relevance of understanding the gametocyte sex ratio during natural infections. The finding that the most widely used P. falciparum gametocyte marker Pfs25 is expressed predominantly by female gametocytes and has non-negligible levels of background expression in asexual parasites necessitates a re-evaluation of existing gametocyte data.
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Affiliation(s)
- Fitsum G Tadesse
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands; Armauer Hansen Research Institute (AHRI), Addis Ababa, Ethiopia; Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia; These authors contributed equally
| | - Lisette Meerstein-Kessel
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands; These authors contributed equally
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK
| | - Lisa Ranford-Cartwright
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, UK
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Centre, Nijmegen, The Netherlands; Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, London, UK.
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22
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Mayoka G, Njoroge M, Okombo J, Gibhard L, Sanches-Vaz M, Fontinha D, Birkholtz LM, Reader J, van der Watt M, Coetzer TL, Lauterbach S, Churchyard A, Bezuidenhout B, Egan TJ, Yeates C, Wittlin S, Prudêncio M, Chibale K. Structure–Activity Relationship Studies and Plasmodium Life Cycle Profiling Identifies Pan-Active N-Aryl-3-trifluoromethyl Pyrido[1,2-a]benzimidazoles Which Are Efficacious in an in Vivo Mouse Model of Malaria. J Med Chem 2018; 62:1022-1035. [DOI: 10.1021/acs.jmedchem.8b01769] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Godfrey Mayoka
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Mathew Njoroge
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa
| | - John Okombo
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Liezl Gibhard
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa
| | - Margarida Sanches-Vaz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Diana Fontinha
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Theresa L. Coetzer
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Sonja Lauterbach
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Alisje Churchyard
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Belinda Bezuidenhout
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - Clive Yeates
- Inpharma
Consultancy, 6 Dudley Hill Close, Welwyn, Hertfordshire AL60QQ, U.K
| | - Sergio Wittlin
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Miguel Prudêncio
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- South African Medical Research Council, Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
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23
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Spicer TP, Gardiner DL, Schoenen FJ, Roy S, Griffin PR, Chase P, Scampavia L, Hodder P, Trenholme KR. Identification of Antimalarial Inhibitors Using Late-Stage Gametocytes in a Phenotypic Live/Dead Assay. SLAS DISCOVERY 2018; 24:38-46. [PMID: 30142014 DOI: 10.1177/2472555218796410] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Malaria remains a major cause of morbidity and mortality worldwide with ~3.3 billion people at risk of contracting malaria and an estimated 450,000 deaths each year. While tools to reduce the infection prevalence to low levels are currently under development, additional efforts will be required to interrupt transmission. Transmission between human host and vector by the malaria parasite involves gametogenesis in the host and uptake of gametocytes by the mosquito vector. This stage is a bottleneck for reproduction of the parasite, making it a target for small-molecule drug discovery. Targeting this stage, we used whole Plasmodium falciparum gametocytes from in vitro culture and implemented them into 1536-well plates to create a live/dead phenotypic antigametocyte assay. Using specialized equipment and upon further validation, we screened ~150,000 compounds from the NIH repository currently housed at Scripps Florida. We identified 100 primary screening hits that were tested for concentration response. Additional follow-up studies to determine specificity, potency, and increased efficacy of the antigametocyte candidate compounds resulted in a starting point for initial medicinal chemistry intervention. From this, 13 chemical analogs were subsequently tested as de novo powders, which confirmed original activity from the initial analysis and now provide a point of future engagement.
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Affiliation(s)
- Timothy P Spicer
- 1 Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL, USA.,2 School of Medicine, University of Queensland, Herston, Queensland, Australia
| | - Donald L Gardiner
- 2 School of Medicine, University of Queensland, Herston, Queensland, Australia
| | - Frank J Schoenen
- 3 The University of Kansas Specialized Chemistry Center, Lawrence, KS,USA
| | - Sudeshna Roy
- 3 The University of Kansas Specialized Chemistry Center, Lawrence, KS,USA.,4 The University of Mississippi, Oxford, MS
| | - Patrick R Griffin
- 1 Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL, USA
| | - Peter Chase
- 1 Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL, USA.,5 BMS, Hopewell, NJ
| | - Louis Scampavia
- 1 Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL, USA
| | - Peter Hodder
- 1 Department of Molecular Medicine, The Scripps Research Institute, Scripps Florida, Jupiter, FL, USA.,6 Amgen, Inc., Thousand Oaks, CA, USA
| | - Katharine R Trenholme
- 2 School of Medicine, University of Queensland, Herston, Queensland, Australia.,7 Department of Cell and Molecular Biology, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia
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24
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Roth JM, Sawa P, Omweri G, Osoti V, Makio N, Bradley J, Bousema T, Schallig HDFH, Mens PF. Plasmodium falciparum gametocyte dynamics after pyronaridine-artesunate or artemether-lumefantrine treatment. Malar J 2018; 17:223. [PMID: 29866116 PMCID: PMC5987563 DOI: 10.1186/s12936-018-2373-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/29/2018] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Artemisinin-based combinations differ in their impact on gametocyte prevalence and density. This study assessed female and male gametocyte dynamics after treating children with uncomplicated Plasmodium falciparum malaria with either pyronaridine-artesunate (PA) or artemether-lumefantrine (AL). METHODS Kenyan children with uncomplicated Plasmodium falciparum malaria were included and randomly assigned to PA or AL treatment. Filter paper blood samples were collected as a source of RNA for quantitative reverse-transcription PCR (qRT-PCR) and nucleic acid sequence based amplification (QT-NASBA) to detect female gametocytes (targeting Pfs25 mRNA). Male gametocytes were detected by qRT-PCR (targeting PfMGET mRNA). Duration of gametocyte carriage, the female and male gametocyte response and the agreement between qRT-PCR and QT-NASBA were determined. RESULTS The mean duration of female gametocyte carriage was significantly longer for PA (4.9 days) than for AL (3.8 days) as estimated by QT-NASBA (P = 0.036), but this difference was less clear when determined by Pfs25 qRT-PCR (4.5 days for PA and 3.7 for AL, P = 0.166). qRT-PCR based female gametocyte prevalence decreased from 100% (75/75) at baseline to 6.06% (4/66) at day 14 in the AL group and from 97.7% (83/85) to 13.9% (11/79) in the PA group. Male gametocyte prevalence decreased from 41.3% (31/75) at baseline to 19.7% (13/66) at day 14 in the AL group and from 35.3% (30/85) to 22.8% (18/79) in the PA group. There was good agreement between Pfs25 qRT-PCR and QT-NASBA female gametocyte prevalence (0.85, 95% CI 0.82-0.87). CONCLUSIONS This study indicates that female gametocyte clearance may be slightly faster after AL compared to PA. Male gametocytes showed similar post-treatment clearance between study arms. Future studies should further address potential differences between the post-treatment transmission potential after PA compared to AL. Trial registration This study is registered at clinicaltrials.gov under NCT02411994. Registration date: 8 April 2015. https://clinicaltrials.gov/ct2/show/NCT02411994?term=pyronaridine-artesunate&cond=Malaria&cntry=KE&rank=1.
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Affiliation(s)
- Johanna M Roth
- Department of Medical Microbiology, Laboratory for Clinical Parasitology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands.
| | - Patrick Sawa
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita Point, Kenya
| | - George Omweri
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita Point, Kenya
| | - Victor Osoti
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita Point, Kenya
| | - Nicodemus Makio
- Human Health Division, International Centre of Insect Physiology and Ecology, Mbita Point, Kenya
| | - John Bradley
- Medical Research Council Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Henk D F H Schallig
- Department of Medical Microbiology, Laboratory for Clinical Parasitology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
| | - Pètra F Mens
- Department of Medical Microbiology, Laboratory for Clinical Parasitology, Academic Medical Center, Meibergdreef 9, 1105 AZ, Amsterdam, The Netherlands
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25
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Price RN, White NJ. Drugs that reduce transmission of falciparum malaria. THE LANCET. INFECTIOUS DISEASES 2018; 18:585-586. [PMID: 29422385 PMCID: PMC5985155 DOI: 10.1016/s1473-3099(18)30070-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 12/15/2017] [Indexed: 01/12/2023]
Affiliation(s)
| | - Nicholas J White
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford OX3 7FZ, UK; Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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26
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Dicko A, Roh ME, Diawara H, Mahamar A, Soumare HM, Lanke K, Bradley J, Sanogo K, Kone DT, Diarra K, Keita S, Issiaka D, Traore SF, McCulloch C, Stone WJR, Hwang J, Müller O, Brown JM, Srinivasan V, Drakeley C, Gosling R, Chen I, Bousema T. Efficacy and safety of primaquine and methylene blue for prevention of Plasmodium falciparum transmission in Mali: a phase 2, single-blind, randomised controlled trial. THE LANCET. INFECTIOUS DISEASES 2018; 18:627-639. [PMID: 29422384 PMCID: PMC5968371 DOI: 10.1016/s1473-3099(18)30044-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/10/2017] [Accepted: 12/01/2017] [Indexed: 01/01/2023]
Abstract
BACKGROUND Primaquine and methylene blue are gametocytocidal compounds that could prevent Plasmodium falciparum transmission to mosquitoes. We aimed to assess the efficacy and safety of primaquine and methylene blue in preventing human to mosquito transmission of P falciparum among glucose-6-phosphate dehydrogenase (G6PD)-normal, gametocytaemic male participants. METHODS This was a phase 2, single-blind, randomised controlled trial done at the Clinical Research Centre of the Malaria Research and Training Centre (MRTC) of the University of Bamako (Bamako, Mali). We enrolled male participants aged 5-50 years with asymptomatic P falciparum malaria. G6PD-normal participants with gametocytes detected by blood smear were randomised 1:1:1:1 in block sizes of eight, using a sealed-envelope design, to receive either sulfadoxine-pyrimethamine and amodiaquine, sulfadoxine-pyrimethamine and amodiaquine plus a single dose of 0·25 mg/kg primaquine, dihydroartemisinin-piperaquine, or dihydroartemisinin-piperaquine plus 15 mg/kg per day methylene blue for 3 days. Laboratory staff, investigators, and insectary technicians were masked to the treatment group and gametocyte density of study participants. The study pharmacist and treating physician were not masked. Participants could request unmasking. The primary efficacy endpoint, analysed in all infected patients with at least one infectivity measure before and after treatment, was median within-person percentage change in mosquito infectivity 2 and 7 days after treatment, assessed by membrane feeding. This study is registered with ClinicalTrials.gov, number NCT02831023. FINDINGS Between June 27, 2016, and Nov 1, 2016, 80 participants were enrolled and assigned to the sulfadoxine-pyrimethamine and amodiaquine (n=20), sulfadoxine-pyrimethamine and amodiaquine plus primaquine (n=20), dihydroartemisinin-piperaquine (n=20), or dihydroartemisinin-piperaquine plus methylene blue (n=20) groups. Among participants infectious at baseline (54 [68%] of 80), those in the sulfadoxine-pyrimethamine and amodiaquine plus primaquine group (n=19) had a median 100% (IQR 100 to 100) within-person reduction in mosquito infectivity on day 2, a larger reduction than was noted with sulfadoxine-pyrimethamine and amodiaquine alone (n=12; -10·2%, IQR -143·9 to 56·6; p<0·0001). The dihydroartemisinin-piperaquine plus methylene blue (n=11) group had a median 100% (IQR 100 to 100) within-person reduction in mosquito infectivity on day 2, a larger reduction than was noted with dihydroartemisinin-piperaquine alone (n=12; -6·0%, IQR -126·1 to 86·9; p<0·0001). Haemoglobin changes were similar between gametocytocidal arms and their respective controls. After exclusion of blue urine, adverse events were similar across all groups (59 [74%] of 80 participants had 162 adverse events overall, 145 [90%] of which were mild). INTERPRETATION Adding a single dose of 0·25 mg/kg primaquine to sulfadoxine-pyrimethamine and amodiaquine or 3 days of 15 mg/kg per day methylene blue to dihydroartemisinin-piperaquine was highly efficacious for preventing P falciparum transmission. Both primaquine and methylene blue were well tolerated. FUNDING Bill & Melinda Gates Foundation, European Research Council.
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Affiliation(s)
- Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Michelle E Roh
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, CA, USA; Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA.
| | - Halimatou Diawara
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Almahamoudou Mahamar
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Harouna M Soumare
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Kjerstin Lanke
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, UK
| | - Koualy Sanogo
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Daouda T Kone
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Kalifa Diarra
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Sekouba Keita
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Djibrilla Issiaka
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Sekou F Traore
- Malaria Research and Training Centre, Faculty of Pharmacy, Medicine, and Dentistry, University of Science, Techniques, and Technologies of Bamako, Bamako, Mali
| | - Charles McCulloch
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
| | - Will J R Stone
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands; Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Jimee Hwang
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, CA, USA; President's Malaria Initiative, Malaria Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Olaf Müller
- Institute of Public Health, Ruprecht-Karls-University, Heidelberg, Germany
| | - Joelle M Brown
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
| | - Vinay Srinivasan
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USA
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Roly Gosling
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, CA, USA; Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA
| | - Ingrid Chen
- Global Health Group, Malaria Elimination Initiative, University of California, San Francisco, CA, USA
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands; Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
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27
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Tine RC, Sylla K, Faye BT, Poirot E, Fall FB, Sow D, Wang D, Ndiaye M, Ndiaye JL, Faye B, Greenwood B, Gaye O, Milligan P. Safety and Efficacy of Adding a Single Low Dose of Primaquine to the Treatment of Adult Patients With Plasmodium falciparum Malaria in Senegal, to Reduce Gametocyte Carriage: A Randomized Controlled Trial. Clin Infect Dis 2018; 65:535-543. [PMID: 28605472 PMCID: PMC5848230 DOI: 10.1093/cid/cix355] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 04/25/2017] [Indexed: 12/30/2022] Open
Abstract
Introduction More information is needed about the safety of low-dose primaquine in populations where G6PD deficiency is common. Methods Adults with Plasmodium falciparum malaria were randomized to receive 1 of 3 artemisinin combination therapies (ACTs) with or without primaquine (0.25 mg/kg). Glucose-6-phosphate dehydrogenase (G6PD) status was determined using a rapid test. Patients were followed for 28 days to record hemoglobin concentration, adverse events, and gametocyte carriage. The primary end point was the change in Hb at day 7. Results In sum, 274 patients were randomized, 139 received an ACT alone, and 135 received an ACT + primaquine. The mean reduction in Hb at day 7 was similar in each group, a difference in the ACT + PQ versus the ACT alone group of −0.04 g/dL (95% confidence interval [CI] −0.23, 0.31), but the effect of primaquine differed according to G6PD status. In G6PD-deficient patients the drop in Hb was 0.63 g/dL (95% CI 0.03, 1.24) greater in those who received primaquine than in those who received an ACT alone. In G6PD-normal patients, the reduction in Hb was 0.22 g/dL (95% CI −0.08, 0.52) less in those who received primaquine (interaction P = .01). One G6PD normal patient who received primaquine developed moderately severe anaemia (Hb < 8 g/dL). Dark urine was more frequent in patients who received primaquine. Primaquine was associated with a 73% (95% CI 24–90) reduction in gametocyte carriage (P = .013). Conclusion Primaquine substantially reduced gametocyte carriage. However, the fall in Hb concentration at day 7 was greater in G6PD-deficient patients who received primaquine than in those who did not and one patient who received primaquine developed moderately severe anemia. Clinical Trial registration PACTR201411000937373 (www.pactr.org)
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Affiliation(s)
- Roger C Tine
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Khadime Sylla
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Babacar T Faye
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Eugenie Poirot
- Malaria Elimination Initiative, Global Health Group, University of California, San Francisco
| | - Fatou B Fall
- National Malaria Control Programme, Ministère de la Santé et de l'Action sociale, Dakar, Senegal
| | - Doudou Sow
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Duolao Wang
- Liverpool School of Tropical Medicine, Liverpool, UK
| | - Magatte Ndiaye
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Jean Louis Ndiaye
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Babacar Faye
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Brian Greenwood
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Oumar Gaye
- Department of Medical Parasitology, Faculty of Medicine, University Cheikh Anta Diop, Dakar, Senegal
| | - Paul Milligan
- Faculty of Epidemiology and Public Health, London School of Hygiene and Tropical Medicine, London, United Kingdom
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28
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Ippolito MM, Johnson J, Mullin C, Mallow C, Morgan N, Wallender E, Li T, Rosenthal PJ. The Relative Effects of Artemether-lumefantrine and Non-artemisinin Antimalarials on Gametocyte Carriage and Transmission of Plasmodium falciparum: A Systematic Review and Meta-analysis. Clin Infect Dis 2018; 65:486-494. [PMID: 28402391 DOI: 10.1093/cid/cix336] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 04/07/2017] [Indexed: 11/14/2022] Open
Abstract
Background Artemisinin-based combination therapies (ACTs) have been widely adopted as first-line agents to treat uncomplicated falciparum malaria due to their activity against multidrug resistant parasites. ACTs may also disrupt transmission through a direct antigametocyte effect, but the extent of this effect is uncertain. We assessed the evidence for and estimated the effects of the most widely-deployed ACT, artemether-lumefantrine (AL), relative to non-ACTs on gametocyte clearance and transmission interruption. Methods We searched electronic databases for randomized controlled trials comparing AL to non-ACTs that reported gametocyte counts or results of mosquito-feeding assays. Two authors working independently assessed eligibility, extracted data, and evaluated the risk of bias. We conducted meta-analyses using a random-effects model. Results We identified 22 eligible trials. The pooled odds of gametocytemia at 1 week were lower in AL- compared to non-ACT-treated participants (odds ratio [OR] 0.09; 95% confidence interval [CI], 0.06-0.15; I2 = 0.60, P < .01; 15 trials). The odds of transmission to mosquitoes were also lower in AL treatment groups (OR 0.06; 95% CI, 0.00-0.47, P < .01 at 7 days post-treatment; 1 trial; OR 0.56; 95% CI, 0.36-0.88, P = .01 at 14 days post-treatment; 1 trial). Conclusion AL is superior to non-ACTs in reducing gametocytemia, and, based on limited evidence, abating transmission to mosquitoes. The transmission-limiting benefit of AL has relevance for policymakers planning optimal utilization of control strategies, including use of ACTs for malaria treatment and chemoprevention.
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Affiliation(s)
- Matthew M Ippolito
- Department of Medicine, Johns Hopkins University School of Medicine.,Graduate Training Program in Clinical Investigation, Johns Hopkins University Bloomberg School of Public Health
| | - Julia Johnson
- Graduate Training Program in Clinical Investigation, Johns Hopkins University Bloomberg School of Public Health.,Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Christopher Mullin
- Department of Medicine, Johns Hopkins University School of Medicine.,Graduate Training Program in Clinical Investigation, Johns Hopkins University Bloomberg School of Public Health
| | - Christopher Mallow
- Department of Medicine, Johns Hopkins University School of Medicine.,Graduate Training Program in Clinical Investigation, Johns Hopkins University Bloomberg School of Public Health
| | - Nadia Morgan
- Department of Medicine, Johns Hopkins University School of Medicine.,Graduate Training Program in Clinical Investigation, Johns Hopkins University Bloomberg School of Public Health
| | - Erika Wallender
- Department of Medicine, University of California San Francisco
| | - Tianjing Li
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
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29
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Birget PLG, Greischar MA, Reece SE, Mideo N. Altered life history strategies protect malaria parasites against drugs. Evol Appl 2018; 11:442-455. [PMID: 29636798 PMCID: PMC5891063 DOI: 10.1111/eva.12516] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Accepted: 06/30/2017] [Indexed: 11/26/2022] Open
Abstract
Drug resistance has been reported against all antimalarial drugs, and while parasites can evolve classical resistance mechanisms (e.g., efflux pumps), it is also possible that changes in life history traits could help parasites evade the effects of treatment. The life history of malaria parasites is governed by an intrinsic resource allocation problem: specialized stages are required for transmission, but producing these stages comes at the cost of producing fewer of the forms required for within-host survival. Drug treatment, by design, alters the probability of within-host survival, and so should alter the costs and benefits of investing in transmission. Here, we use a within-host model of malaria infection to predict optimal patterns of investment in transmission in the face of different drug treatment regimes and determine the extent to which alternative patterns of investment can buffer the fitness loss due to drugs. We show that over a range of drug doses, parasites are predicted to adopt "reproductive restraint" (investing more in asexual replication and less in transmission) to maximize fitness. By doing so, parasites recoup some of the fitness loss imposed by drugs, though as may be expected, increasing dose reduces the extent to which altered patterns of transmission investment can benefit parasites. We show that adaptation to drug-treated infections could result in more virulent infections in untreated hosts. This work emphasizes that in addition to classical resistance mechanisms, drug treatment generates selection for altered parasite life history. Understanding how any shifts in life history will alter the efficacy of drugs, as well as any limitations on such shifts, is important for evaluating and predicting the consequences of drug treatment.
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Affiliation(s)
- Philip L. G. Birget
- Institutes of Evolutionary Biology, Immunology and Infection ResearchUniversity of EdinburghEdinburghUK
| | - Megan A. Greischar
- Department of Ecology & Evolutionary BiologyUniversity of TorontoTorontoONCanada
| | - Sarah E. Reece
- Institutes of Evolutionary Biology, Immunology and Infection ResearchUniversity of EdinburghEdinburghUK
| | - Nicole Mideo
- Department of Ecology & Evolutionary BiologyUniversity of TorontoTorontoONCanada
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30
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Koepfli C, Yan G. Plasmodium Gametocytes in Field Studies: Do We Measure Commitment to Transmission or Detectability? Trends Parasitol 2018; 34:378-387. [PMID: 29544966 DOI: 10.1016/j.pt.2018.02.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/07/2018] [Accepted: 02/21/2018] [Indexed: 01/05/2023]
Abstract
The proportion of Plasmodium spp. infections carrying gametocytes, and gametocyte densities, are often reported as surrogate markers for transmission potential. It remains unclear whether parasites under natural conditions adjust commitment to transmission depending on external factors. Population-based surveys comprising mostly asymptomatic low-density infections are always impacted by the sensitivity of the assays used to diagnose infections and detect gametocytes. Asexual parasite density is an important predictor for the probability of detecting gametocytes, and in many cases it can explain patterns in gametocyte carriage without the need for an adjustment of the gametocyte conversion rate. When reporting gametocyte data, quantification of blood-stage parasitemia and its inclusion as a confounder in multivariable analyses is essential.
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Affiliation(s)
- Cristian Koepfli
- Program in Public Health, University of California, Irvine, CA, 92697, USA.
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, CA, 92697, USA
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31
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Miura K, Crompton PD. What goes around comes around: modeling malaria transmission from humans back to mosquitos. J Clin Invest 2018. [PMID: 29528336 DOI: 10.1172/jci120260] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Malaria, caused by mosquito-transmitted Plasmodium parasites, continues to take a major toll on global health. The development of drugs and vaccines that reduce malaria transmission from humans back to mosquitos could contribute to the control and eventual eradication of malaria, but research models for the early clinical evaluation of candidate interventions are lacking. In this issue of the JCI, Collins and colleagues report the successful transmission of Plasmodium falciparum parasites from humans to mosquitoes during controlled human malaria infection, thus providing a potential tool to accelerate the development of much needed transmission-blocking drugs and vaccines.
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Affiliation(s)
- Kazutoyo Miura
- Malaria Immunology Section, Laboratory of Malaria and Vector Research, and
| | - Peter D Crompton
- Malaria Infection Biology and Immunity Section, Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, NIH, Rockville, Maryland, USA
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32
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Reuling IJ, van de Schans LA, Coffeng LE, Lanke K, Meerstein-Kessel L, Graumans W, van Gemert GJ, Teelen K, Siebelink-Stoter R, van de Vegte-Bolmer M, de Mast Q, van der Ven AJ, Ivinson K, Hermsen CC, de Vlas S, Bradley J, Collins KA, Ockenhouse CF, McCarthy J, Sauerwein RW, Bousema T. A randomized feasibility trial comparing four antimalarial drug regimens to induce Plasmodium falciparum gametocytemia in the controlled human malaria infection model. eLife 2018; 7:31549. [PMID: 29482720 PMCID: PMC5828662 DOI: 10.7554/elife.31549] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Accepted: 01/14/2018] [Indexed: 12/16/2022] Open
Abstract
Background Malaria elimination strategies require a thorough understanding of parasite transmission from human to mosquito. A clinical model to induce gametocytes to understand their dynamics and evaluate transmission-blocking interventions (TBI) is currently unavailable. Here, we explore the use of the well-established Controlled Human Malaria Infection model (CHMI) to induce gametocyte carriage with different antimalarial drug regimens. Methods In a single centre, open-label randomised trial, healthy malaria-naive participants (aged 18–35 years) were infected with Plasmodium falciparum by bites of infected Anopheles mosquitoes. Participants were randomly allocated to four different treatment arms (n = 4 per arm) comprising low-dose (LD) piperaquine (PIP) or sulfadoxine-pyrimethamine (SP), followed by a curative regimen upon recrudescence. Male and female gametocyte densities were determined by molecular assays. Results Mature gametocytes were observed in all participants (16/16, 100%). Gametocytes appeared 8.5–12 days after the first detection of asexual parasites. Peak gametocyte densities and gametocyte burden was highest in the LD-PIP/SP arm, and associated with the preceding asexual parasite biomass (p=0.026). Male gametocytes had a mean estimated circulation time of 2.7 days (95% CI 1.5–3.9) compared to 5.1 days (95% CI 4.1–6.1) for female gametocytes. Exploratory mosquito feeding assays showed successful sporadic mosquito infections. There were no serious adverse events or significant differences in the occurrence and severity of adverse events between study arms (p=0.49 and p=0.28). Conclusions The early appearance of gametocytes indicates gametocyte commitment during the first wave of asexual parasites emerging from the liver. Treatment by LD-PIP followed by a curative SP regimen, results in the highest gametocyte densities and the largest number of gametocyte-positive days. This model can be used to evaluate the effect of drugs and vaccines on gametocyte dynamics, and lays the foundation for fulfilling the critical unmet need to evaluate transmission-blocking interventions against falciparum malaria for downstream selection and clinical development. Funding Funded by PATH Malaria Vaccine Initiative (MVI). Clinical trial number NCT02836002.
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Affiliation(s)
- Isaie J Reuling
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Lisanne A van de Schans
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | | | - Wouter Graumans
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Geert-Jan van Gemert
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Karina Teelen
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Rianne Siebelink-Stoter
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | | | - Quirijn de Mast
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - André J van der Ven
- Department of Internal Medicine, Radboud University Medical Center, Nijmegen, Netherlands
| | - Karen Ivinson
- PATH Malaria Vaccine Initiative, Washington, United States
| | - Cornelus C Hermsen
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Sake de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - James McCarthy
- Clinical Tropical Medicine Laboratory, QIMR Berghofer, Brisbane, Australia
| | - Robert W Sauerwein
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
| | - Teun Bousema
- Department of Medical Microbiology, Radboud university medical center, Nijmegen, Netherlands
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33
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Graves PM, Choi L, Gelband H, Garner P. Primaquine or other 8-aminoquinolines for reducing Plasmodium falciparum transmission. Cochrane Database Syst Rev 2018; 2:CD008152. [PMID: 29393511 PMCID: PMC5815493 DOI: 10.1002/14651858.cd008152.pub5] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND The 8-aminoquinoline (8AQ) drugs act on Plasmodium falciparum gametocytes, which transmit malaria from infected people to mosquitoes. In 2012, the World Health Organization (WHO) recommended a single dose of 0.25 mg/kg primaquine (PQ) be added to malaria treatment schedules in low-transmission areas or those with artemisinin resistance. This replaced the previous recommendation of 0.75 mg/kg, aiming to reduce haemolysis risk in people with glucose-6-phosphate dehydrogenase deficiency, common in people living in malarious areas. Whether this approach, and at this dose, is effective in reducing transmission is not clear. OBJECTIVES To assess the effects of single dose or short-course PQ (or an alternative 8AQ) alongside treatment for people with P. falciparum malaria. SEARCH METHODS We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library; and the WHO International Clinical Trials Registry Platform (ICRTP) portal using 'malaria*', 'falciparum', 'primaquine', '8-aminoquinoline', and eight 8AQ drug names as search terms. We checked reference lists of included trials, and contacted researchers and organizations. Date of last search: 21 July 2017. SELECTION CRITERIA Randomized controlled trials (RCTs) or quasi-RCTs in children or adults, adding PQ (or alternative 8AQ) as a single dose or short course alongside treatment for P. falciparum malaria. DATA COLLECTION AND ANALYSIS Two authors screened abstracts, applied inclusion criteria, and extracted data. We sought evidence on transmission (community incidence), infectiousness (people infectious and mosquitoes infected), and potential infectiousness (gametocyte measures assessed by microscopy or polymerase chain reaction [PCR]). We grouped trials into artemisinin and non-artemisinin treatments, and stratified by PQ dose (low, 0.2 to 0.25 mg/kg; moderate, 0.4 to 0.5 mg/kg; high, 0.75 mg/kg). We used GRADE, and absolute effects of infectiousness using trial control groups. MAIN RESULTS We included 24 RCTs and one quasi-RCT, comprising 43 arms. Fourteen trials evaluated artemisinin treatments (23 arms), nine trials evaluated non-artemisinin treatments (13 arms), and two trials included both artemisinin and non-artemisinin arms (three and two arms, respectively). Two trial arms used bulaquine. Seven PQ arms used low dose (six with artemisinin), 11 arms used moderate dose (seven with artemisinin), and the remaining arms used high dose. Fifteen trials tested for G6PD status: 11 excluded participants with G6PD deficiency, one included only those with G6PD deficiency, and three included all, irrespective of status. The remaining 10 trials either did not test or did not report on testing.No cluster trials evaluating community effects on malaria transmission met the inclusion criteria.With artemisinin treatmentLow dose PQInfectiousness (participants infectious to mosquitoes) was reduced (day 3 or 4: RR 0.12, 95% CI 0.02 to 0.88, 3 trials, 105 participants; day 8: RR 0.34, 95% CI 0.07 to 1.58, 4 trials, 243 participants; low certainty evidence). This translates to a reduction in percentage of people infectious on day 3 or 4 from 14% to 2%, and, for day 8, from 4% to 1%; the waning infectiousness in the control group by day 8 making the absolute effect smaller by day 8. For gametocytes detected by PCR, there was little or no effect of PQ at day 3 or 4 (RR 1.02, 95% CI 0.87 to 1.21; 3 trials, 414 participants; moderate certainty evidence); with reduction at day 8 (RR 0.52, 95% CI 0.41 to 0.65; 4 trials, 532 participants; high certainty evidence). Severe haemolysis was infrequent, with or without PQ, in these groups with few G6PD-deficient individuals (RR 0.98, 95% CI 0.69 to 1.39; 4 trials, 752 participants, moderate certainty evidence).Moderate dose PQInfectiousness was reduced (day 3 or 4: RR 0.13, 95% CI 0.02 to 0.94; 3 trials, 109 participants; day 8 RR 0.33, 95% CI 0.07 to 1.57; 4 trials, 246 participants; low certainty evidence). Illustrative risk estimates for moderate dose were the same as low dose. The pattern and level of certainty of evidence with gametocytes detected by PCR was the same as low dose, and severe haemolysis was infrequent in both groups.High dose PQInfectiousness was reduced (day 4: RR 0.2, 95% CI 0.02 to 1.68, 1 trial, 101 participants; day 8: RR 0.18, 95% CI 0.02 to 1.41, 2 trials, 181 participants, low certainty evidence). The effects on gametocyte prevalence showed a similar pattern to moderate and low dose PQ. Trials did not systematically report evidence of haemolysis.With non-artemisinin treatmentTrials with non-artemisinin treatment have been conducted only for moderate and high dose PQ. With high dose, infectiousness appeared markedly reduced on day 5 (RR 0.09, 95% CI 0.01 to 0.62; 30 participants, very low certainty evidence), with similar reductions at day 8. For both moderate dose (two trials with 221 people) and high dose (two trials with 30 people), reduction in gametocytes (detected by microscopy) showed similar patterns as for artemisinin treatments, with little or no effect at day 4 or 5, and larger effects by day 8. No trials with non-artemisinin partner drugs systematically sought evidence of severe haemolysis.Two trials comparing bulaquine with PQ suggest bulaquine may have larger effects on gametocytes by microscopy on day 8 (RR 0.41, 95% CI 0.26 to 0.66; 2 trials, 112 participants). AUTHORS' CONCLUSIONS A single low dose of PQ (0.25 mg/kg) added to artemisinin-based combination therapy for malaria reduces infectiousness of people to mosquitoes at day 3-4 and day 8, and appears as effective as higher doses. The absolute effect is greater at day 3 or 4, and smaller at day 8, in part because of the lower infectiousness in the control group. There was no evidence of increased haemolysis at 0.25 mg/kg, but few G6PD-deficient individuals were included in the trials. The effect on infectiousness precedes the effect of PQ on gametocyte prevalence. We do not know whether single dose PQ could reduce malaria transmission at community level.
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Affiliation(s)
- Patricia M Graves
- James Cook UniversityCollege of Public Health, Medical and Veterinary SciencesPO Box 6811CairnsQueenslandAustralia4870
| | - Leslie Choi
- Liverpool School of Tropical MedicineDepartment of Clinical SciencesPembroke PlaceLiverpoolUKL3 5QA
| | | | - Paul Garner
- Liverpool School of Tropical MedicineDepartment of Clinical SciencesPembroke PlaceLiverpoolUKL3 5QA
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Taylor WR, Naw HK, Maitland K, Williams TN, Kapulu M, D'Alessandro U, Berkley JA, Bejon P, Okebe J, Achan J, Amambua AN, Affara M, Nwakanma D, van Geertruyden JP, Mavoko M, Lutumba P, Matangila J, Brasseur P, Piola P, Randremanana R, Lasry E, Fanello C, Onyamboko M, Schramm B, Yah Z, Jones J, Fairhurst RM, Diakite M, Malenga G, Molyneux M, Rwagacondo C, Obonyo C, Gadisa E, Aseffa A, Loolpapit M, Henry MC, Dorsey G, John C, Sirima SB, Barnes KI, Kremsner P, Day NP, White NJ, Mukaka M. Single low-dose primaquine for blocking transmission of Plasmodium falciparum malaria - a proposed model-derived age-based regimen for sub-Saharan Africa. BMC Med 2018; 16:11. [PMID: 29347975 PMCID: PMC5774032 DOI: 10.1186/s12916-017-0990-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Accepted: 12/12/2017] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND In 2012, the World Health Organization recommended blocking the transmission of Plasmodium falciparum with single low-dose primaquine (SLDPQ, target dose 0.25 mg base/kg body weight), without testing for glucose-6-phosphate dehydrogenase deficiency (G6PDd), when treating patients with uncomplicated falciparum malaria. We sought to develop an age-based SLDPQ regimen that would be suitable for sub-Saharan Africa. METHODS Using data on the anti-infectivity efficacy and tolerability of primaquine (PQ), the epidemiology of anaemia, and the risks of PQ-induced acute haemolytic anaemia (AHA) and clinically significant anaemia (CSA), we prospectively defined therapeutic-dose ranges of 0.15-0.4 mg PQ base/kg for children aged 1-5 years and 0.15-0.5 mg PQ base/kg for individuals aged ≥6 years (therapeutic indices 2.7 and 3.3, respectively). We chose 1.25 mg PQ base for infants aged 6-11 months because they have the highest rate of baseline anaemia and the highest risks of AHA and CSA. We modelled an anthropometric database of 661,979 African individuals aged ≥6 months (549,127 healthy individuals, 28,466 malaria patients and 84,386 individuals with other infections/illnesses) by the Box-Cox transformation power exponential and tested PQ doses of 1-15 mg base, selecting dosing groups based on calculated mg/kg PQ doses. RESULTS From the Box-Cox transformation power exponential model, five age categories were selected: (i) 6-11 months (n = 39,886, 6.03%), (ii) 1-5 years (n = 261,036, 45.46%), (iii) 6-9 years (n = 20,770, 3.14%), (iv) 10-14 years (n = 12,155, 1.84%) and (v) ≥15 years (n = 328,132, 49.57%) to receive 1.25, 2.5, 5, 7.5 and 15 mg PQ base for corresponding median (1st and 99th centiles) mg/kg PQ base of: (i) 0.16 (0.12-0.25), (ii) 0.21 (0.13-0.37), (iii) 0.25 (0.16-0.38), (iv) 0.26 (0.15-0.38) and (v) 0.27 (0.17-0.40). The proportions of individuals predicted to receive optimal therapeutic PQ doses were: 73.2 (29,180/39,886), 93.7 (244,537/261,036), 99.6 (20,690/20,770), 99.4 (12,086/12,155) and 99.8% (327,620/328,132), respectively. CONCLUSIONS We plan to test the safety of this age-based dosing regimen in a large randomised placebo-controlled trial (ISRCTN11594437) of uncomplicated falciparum malaria in G6PDd African children aged 0.5 - 11 years. If the regimen is safe and demonstrates adequate pharmacokinetics, it should be used to support malaria elimination.
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Affiliation(s)
- W Robert Taylor
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Mahidol University, 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Division of Tropical and Humanitarian Medicine, University Hospitals of Geneva, Geneva, Switzerland.
| | - Htee Khu Naw
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Mahidol University, 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
| | - Kathryn Maitland
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
- Wellcome Trust Centre for Clinical Tropical Medicine and Department of Paediatrics, Faculty of Medicine, Imperial College, London, UK
| | - Thomas N Williams
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
- Wellcome Trust Centre for Clinical Tropical Medicine and Department of Paediatrics, Faculty of Medicine, Imperial College, London, UK
| | - Melissa Kapulu
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Umberto D'Alessandro
- MRC Unit, Fajara, Banjul, The Gambia
- Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
| | - James A Berkley
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | - Philip Bejon
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- KEMRI-Wellcome Trust Research Programme, Centre for Geographic Medicine Research-Coast, Kilifi, Kenya
| | | | | | | | | | | | | | - Muhindo Mavoko
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Pascal Lutumba
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Junior Matangila
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | | | - Patrice Piola
- Institut Pasteur de Madagascar, BP 1274, Antananarivo, Madagascar
| | | | - Estrella Lasry
- Kinshasa Mahidol Oxford Research Unit, Kinshasa, Democratic Republic of Congo
| | - Caterina Fanello
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Kinshasa School of Public Health, Kinshasa, Democratic Republic of Congo
| | - Marie Onyamboko
- Kinshasa Mahidol Oxford Research Unit, Kinshasa, Democratic Republic of Congo
- Kinshasa School of Public Health, Kinshasa, Democratic Republic of Congo
| | | | - Zolia Yah
- National Malaria Control Programme, Monrovia, Sierra Leone
| | - Joel Jones
- National Malaria Control Programme, Monrovia, Sierra Leone
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | | | | | - Malcolm Molyneux
- Malawi-Liverpool-Wellcome Trust Clinical Research Programme, Blantyre, Malawi
| | | | | | | | - Abraham Aseffa
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | | | | | - Grant Dorsey
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
| | - Chandy John
- Department of Pediatrics, Indiana University, Indianapolis, IN, USA
| | - Sodiomon B Sirima
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
- Groupe de Recherche Action en Santé (GRAS), Ouagadougou, Burkina Faso
| | - Karen I Barnes
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Peter Kremsner
- Institute of Tropical Medicine, University of Tubingen, Tubingen, Germany
| | - Nicholas P Day
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Mahidol University, 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Mahidol University, 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Mavuto Mukaka
- Mahidol Oxford Tropical Medicine Research Unit (MORU), Mahidol University, 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Essuman E, Grabias B, Verma N, Chorazeczewski JK, Tripathi AK, Mlambo G, Addison EA, Amoah AGB, Quakyi I, Oakley MS, Kumar S. A Novel Gametocyte Biomarker for Superior Molecular Detection of the Plasmodium falciparum Infectious Reservoirs. J Infect Dis 2017; 216:1264-1272. [PMID: 28968664 DOI: 10.1093/infdis/jix442] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Accepted: 08/22/2017] [Indexed: 01/15/2023] Open
Abstract
Background Complete malaria eradication and optimal use of transmission-reducing interventions require knowledge of submicroscopic infectious reservoirs among asymptomatic individuals. Even submicroscopic levels of Plasmodium falciparum gametocytes can infect mosquitoes and promote onward transmission. Most efforts to identify gametocyte carriers use polymerase chain reaction amplification of the gametocyte-specific transcript Pfs25. Methods To expand the repertoire of biomarkers available for superior gametocyte detection, we compared the gene expression profiles of gametocytes and asynchronous blood-stage P. falciparum parasites by microarray technology. This allowed the identification of 56 molecules abundantly expressed in the gametocyte stage of the parasite. The analytical sensitivity for gametocyte detection was evaluated for 25 genes with the highest expression levels. Results One candidate, Pfg17, exhibited superior analytical sensitivity against a panel of gametocyte-spiked whole blood, detecting 10 gametocytes/mL; in comparison, Pfs25 detected only 25.3 gametocytes/mL. Pfg17 also exhibited superior clinical sensitivity, identifying 19.1% more samples from blood-film microscopy-negative Ghanaian children and 40% more samples from asymptomatic adults as gametocyte positive. Conclusions Cumulatively, our results suggest Pfg17 is an excellent biomarker for detecting asymptomatic infectious reservoirs otherwise missed by the most sensitive molecular method available. Our study has also improved the repertoire of transmission-stage antigens available for evaluation as candidate vaccines.
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Affiliation(s)
- Edward Essuman
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases
| | - Bryan Grabias
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases
| | - Nitin Verma
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases
| | - Joanna K Chorazeczewski
- Laboratory of Mucosal Pathogens and Cellular Immunology, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring
| | - Abhai K Tripathi
- Johns Hopkins Malaria Research Institute.,Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland
| | - Godfree Mlambo
- Johns Hopkins Malaria Research Institute.,Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland
| | - Ebenezer A Addison
- School of Public Health, College of Health Sciences, University of Ghana, Legon
| | - Albert G B Amoah
- School of Public Health, College of Health Sciences, University of Ghana, Legon
| | - Isabella Quakyi
- School of Public Health, College of Health Sciences, University of Ghana, Legon
| | - Miranda S Oakley
- Laboratory of Mucosal Pathogens and Cellular Immunology, Division of Bacterial, Parasitic, and Allergenic Products, Center for Biologics Evaluation and Research, Food and Drug Administration, Silver Spring
| | - Sanjai Kumar
- Laboratory of Emerging Pathogens, Division of Emerging and Transfusion Transmitted Diseases
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Stone W, Sawa P, Lanke K, Rijpma S, Oriango R, Nyaurah M, Osodo P, Osoti V, Mahamar A, Diawara H, Woestenenk R, Graumans W, van de Vegte-Bolmer M, Bradley J, Chen I, Brown J, Siciliano G, Alano P, Gosling R, Dicko A, Drakeley C, Bousema T. A Molecular Assay to Quantify Male and Female Plasmodium falciparum Gametocytes: Results From 2 Randomized Controlled Trials Using Primaquine for Gametocyte Clearance. J Infect Dis 2017; 216:457-467. [PMID: 28931236 PMCID: PMC5853855 DOI: 10.1093/infdis/jix237] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Background Single low-dose primaquine (PQ) reduces Plasmodium falciparum infectivity before it impacts gametocyte density. Here, we examined the effect of PQ on gametocyte sex ratio as a possible explanation for this early sterilizing effect. Methods Quantitative reverse-transcription polymerase chain reaction assays were developed to quantify female gametocytes (targeting Pfs25 messenger RNA [mRNA]) and male gametocytes (targeting Pf3D7_1469900 mRNA) in 2 randomized trials in Kenya and Mali, comparing dihydroartemisinin-piperaquine (DP) alone to DP with PQ. Gametocyte sex ratio was examined in relation to time since treatment and infectivity to mosquitoes. Results In Kenya, the median proportion of male gametocytes was 0.33 at baseline. Seven days after treatment, gametocyte density was significantly reduced in the DP-PQ arm relative to the DP arm (females: 0.05% [interquartile range {IQR}, 0.0–0.7%] of baseline; males: 3.4% [IQR, 0.4%–32.9%] of baseline; P < .001). Twenty-four hours after treatment, gametocyte sex ratio became male-biased and was not significantly different between the DP and DP-PQ groups. In Mali, there was no significant difference in sex ratio between the DP and DP-PQ groups (>0.125 mg/kg) 48 hours after treatment, and gametocyte sex ratio was not associated with mosquito infection rates. Conclusions The early sterilizing effects of PQ may not be explained by the preferential clearance of male gametocytes and may be due to an effect on gametocyte fitness.
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Affiliation(s)
- Will Stone
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Patrick Sawa
- Human Health Division, International Centre for Insect Physiology and Ecology, Mbita Point, Kenya
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Sanna Rijpma
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Robin Oriango
- Human Health Division, International Centre for Insect Physiology and Ecology, Mbita Point, Kenya
| | - Maureen Nyaurah
- Human Health Division, International Centre for Insect Physiology and Ecology, Mbita Point, Kenya
| | - Paul Osodo
- Human Health Division, International Centre for Insect Physiology and Ecology, Mbita Point, Kenya
| | - Victor Osoti
- Human Health Division, International Centre for Insect Physiology and Ecology, Mbita Point, Kenya
| | - Almahamoudou Mahamar
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Mali
| | - Halimatou Diawara
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Mali
| | - Rob Woestenenk
- Department of Laboratory Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Wouter Graumans
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands
| | | | - John Bradley
- Medical Research Council Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Ingrid Chen
- Global Health Group, Malaria Elimination Initiative
| | - Joelle Brown
- Department of Epidemiology and Biostatistics, University of California, San Francisco
| | - Giulia Siciliano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Istituto Superiore di Sanità, Rome, Italy
| | - Roly Gosling
- Global Health Group, Malaria Elimination Initiative.,Department of Epidemiology and Biostatistics, University of California, San Francisco
| | - Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Mali
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.,Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
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Bretscher MT, Griffin JT, Ghani AC, Okell LC. Modelling the benefits of long-acting or transmission-blocking drugs for reducing Plasmodium falciparum transmission by case management or by mass treatment. Malar J 2017; 16:341. [PMID: 28814310 PMCID: PMC5559805 DOI: 10.1186/s12936-017-1988-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Accepted: 08/09/2017] [Indexed: 11/16/2022] Open
Abstract
Background Anti-malarial drugs are an important tool for malaria control and elimination. Alongside their direct benefit in the treatment of disease, drug use has a community-level effect, clearing the reservoir of infection and reducing onward transmission of the parasite. Different compounds potentially have different impacts on transmission—with some providing periods of prolonged chemoprophylaxis whilst others have greater transmission-blocking potential. The aim was to quantify the relative benefit of such properties for transmission reduction to inform target product profiles in the drug development process and choice of first-line anti-malarial treatment in different endemic settings. Methods A mathematical model of Plasmodium falciparum epidemiology was used to estimate the transmission reduction that can be achieved by using drugs of varying chemoprophylactic (protection for 3, 30 or 60 days) or transmission-blocking activity (blocking 79, 92 or 100% of total onward transmission). Simulations were conducted at low, medium or high transmission intensity (slide-prevalence in 2–10 year olds being 1, 10 or 40%, respectively), with drugs administered either via case management or mass drug administration (MDA). Results Transmission reductions depend strongly on deployment strategy, treatment coverage and endemicity level. Transmission-blocking was most effective at low endemicity, whereas chemoprophylaxis was most useful at high endemicity levels. Increasing the duration of protection as much as possible was beneficial. Increasing transmission-blocking activity from the level of ACT to a 100% transmission-blocking drug (close to the effect estimated for ACT combined with primaquine) produced moderate impact but was not as effective as increasing the duration of protection in medium-to-high transmission settings (slide prevalence 10–40%). Combining both good transmission-blocking activity (e.g. as achieved by ACT or ACT + primaquine) and a long duration of protection (30 days or more, such as provided by piperaquine or mefloquine) within a drug regimen can substantially increase impact compared with drug regimens with only one of these properties in medium to high transmission areas (slide-prevalence in 2–10 year olds ~10 to 40%). These results applied whether the anti-malarials were used for case management or for MDA. Discussion These results emphasise the importance of increasing access to treatment for routine case management, and the potential value of choosing first-line anti-malarial treatment policies according to local malaria epidemiology to maximise impact on transmission. There is no indication that the optimal drug choice should differ between delivery via case management or MDA. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1988-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Michael T Bretscher
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis & Modelling, Imperial College, London, UK.,F. Hoffmann-La Roche Ltd, Basel, Switzerland
| | - Jamie T Griffin
- School of Mathematical Sciences, Queen Mary University of London, London, UK
| | - Azra C Ghani
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis & Modelling, Imperial College, London, UK
| | - Lucy C Okell
- Department of Infectious Disease Epidemiology, MRC Centre for Outbreak Analysis & Modelling, Imperial College, London, UK.
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Concentration of Plasmodium falciparum gametocytes in whole blood samples by magnetic cell sorting enhances parasite infection rates in mosquito feeding assays. Malar J 2017; 16:315. [PMID: 28779750 PMCID: PMC5545093 DOI: 10.1186/s12936-017-1959-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 07/28/2017] [Indexed: 01/07/2023] Open
Abstract
Background Mosquito-feeding assays are important tools to guide the development and support the evaluation of transmission-blocking interventions. These functional bioassays measure the sporogonic development of gametocytes in blood-fed mosquitoes. Measuring the infectivity of low gametocyte densities has become increasingly important in malaria elimination scenarios. This will pose challenges to the sensitivity and throughput of existing mosquito-feeding assay protocols. Here, different gametocyte concentration methods of blood samples were explored to optimize conditions for detection of positive mosquito infections. Methods Mature gametocytes of Plasmodium falciparum were diluted into whole blood samples of malaria-naïve volunteers. Standard centrifugation, Percoll gradient, magnetic cell sorting (MACS) enrichment were compared using starting blood volumes larger than the control (direct) feed. Results MACS gametocyte enrichment resulted in the highest infection intensity with statistically significant increases in mean oocyst density in 2 of 3 experiments (p = 0.0003; p ≤ 0.0001; p = 0.2348). The Percoll gradient and standard centrifugation procedures resulted in variable infectivity. A significant increase in the proportion of infected mosquitoes and oocyst density was found when larger volumes of gametocyte-infected blood were used with the MACS procedure. Conclusions The current study demonstrates that concentration methods of P. falciparum gametocyte-infected whole blood samples can enhance transmission in mosquito-feeding assays. Gametocyte purification by MACS was the most efficient method, allowing the assessment of gametocyte infectivity in low-density gametocyte infections, as can be expected in natural or experimental conditions. Electronic supplementary material The online version of this article (doi:10.1186/s12936-017-1959-9) contains supplementary material, which is available to authorized users.
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Arroyo-Arroyo M, Arango E, Carmona-Fonseca J, Aristizabal B, Yanow S, Maestre A. Efficacy of Different Primaquine Regimens to Control Plasmodium falciparum Gametocytemia in Colombia. Am J Trop Med Hyg 2017; 97:712-718. [PMID: 28749756 DOI: 10.4269/ajtmh.16-0974] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Treatment against Plasmodium falciparum malaria includes blood schizonticides to clear asexual parasites responsible for disease. The addition of gametocytocidal drugs can eliminate infectious sexual stages with potential for transmission and the World Health Organization recommends a single dose (SD) of primaquine (PQ) to this end. The efficacy of PQ at 0.75 mg/kg to suppress gametocytemia when administered in single or fractionated doses was evaluated. A clinical controlled study with an open-label design was executed; three groups of 20 subjects were studied sequentially. All subjects were treated with the standard dose of artemether-lumefantrine plus the total dose of 0.75 mg/kg of PQ administered (without previous G6PD testing) in three different ways: Group "0.75d-3" received 0.75 mg/kg on day 3; Group "0.50d-1 + 0.25d-3" received 0.50 mg/kg on day 1 and 0.25 mg/kg on day 3; Group "0.25d-1,2,3" received 0.25 mg/kg on days 1, 2, and 3. Subjects were evaluated on days 1, 4, and 7 by thick smear microscopy and quantitative polymerase chain reaction to determine the carriage of immature and mature gametocytes. There were no adverse events. The three schemes caused a marked reduction (75-85%) in prevalence of gametocytes on day 4 compared with day 1, but only the group that received 0.75 mg/kg on day 3 maintained the reduced gametocyte burden until day 7. None of the three treatments were able to clear gametocyte carriage on days 4 or 7, but the group that received the SD had the lowest prevalence of gametocytes (15%). Further studies are needed to establish a PQ regimen with complete efficacy against gametocytes.
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Affiliation(s)
- Maria Arroyo-Arroyo
- Grupo Salud y Comunidad, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia
| | - Eliana Arango
- Grupo Salud y Comunidad, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia
| | - Jaime Carmona-Fonseca
- Grupo Salud y Comunidad, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia
| | - Beatriz Aristizabal
- Laboratorio de Biología Molecular, Hospital Pablo Tobon Uribe, Medellin, Colombia
| | - Stephanie Yanow
- School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | - Amanda Maestre
- Grupo Salud y Comunidad, Facultad de Medicina, Universidad de Antioquia, Medellin, Colombia
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Affiliation(s)
- Robert E. Sinden
- Department of Life Sciences, Imperial College London, London, United Kingdom
- * E-mail:
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Single dose primaquine to reduce gametocyte carriage and Plasmodium falciparum transmission in Cambodia: An open-label randomized trial. PLoS One 2017; 12:e0168702. [PMID: 28591198 PMCID: PMC5462369 DOI: 10.1371/journal.pone.0168702] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Accepted: 11/26/2016] [Indexed: 12/19/2022] Open
Abstract
Background Single low dose primaquine (SLD PQ, 0.25mg/kg) is recommended in combination with artemisinin-based combination therapy (ACT) as a gametocytocide to prevent Plasmodium falciparum transmission in areas threatened by artemisinin resistance. To date, no randomized controlled trials have measured primaquine’s effect on infectiousness to Anopheline mosquitoes in Southeast Asia. Methods Cambodian adults with uncomplicated falciparum malaria were randomized to receive a single 45mg dose of primaquine (equivalent to three SLD PQ) or no primaquine after the third dose of dihydroartemisin-piperaquine (DHP) therapy. A membrane-feeding assay measured infectiousness to Anopheles dirus on days 0, 3, 7, and 14 of blood-stage therapy. Gametocytemia was evaluated by microscopy and reverse-transcriptase PCR. Results Prior to trial halt for poor DHP treatment efficacy, 101 participants were randomized and 50 received primaquine. Overall microscopic gametocyte prevalence was low (9%), but gametocytemic subjects given primaquine were gametocyte-free by day 14, and significantly less likely to harbor gametocytes by day 7 compared to those treated with DHP-alone, who remained gametocytemic for a median of two weeks. Only one infectious subject was randomized to the primaquine group, precluding assessment of transmission-blocking efficacy. However, he showed a two-fold reduction in oocyst density of infected mosquitoes less than 24 hours after primaquine dosing. In the DHP-alone group, four subjects remained infectious through day 14, infecting roughly the same number of mosquitoes pre and post-treatment. Overall, microscopic gametocytemia was an excellent predictor of infectiousness, and performed better than submicroscopic gametocytemia post-treatment, with none of 474 mosquitoes infected post-treatment arising from submicroscopic gametocytes. Conclusions In a setting of established ACT resistance, a single dose of 45mg primaquine added to DHP rapidly and significantly reduced gametocytemia, while DHP-alone failed to reduce gametocytemia and prevent malaria transmission to mosquitoes. Continued efforts to make single dose primaquine widely available are needed to help achieve malaria elimination.
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Hundreds of dual-stage antimalarial molecules discovered by a functional gametocyte screen. Nat Commun 2017; 8:15160. [PMID: 28513586 PMCID: PMC5442318 DOI: 10.1038/ncomms15160] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 03/03/2017] [Indexed: 02/07/2023] Open
Abstract
Plasmodium falciparum stage V gametocytes are responsible for parasite transmission, and drugs targeting this stage are needed to support malaria elimination. We here screen the Tres Cantos Antimalarial Set (TCAMS) using the previously developed P. falciparum female gametocyte activation assay (Pf FGAA), which assesses stage V female gametocyte viability and functionality using Pfs25 expression. We identify over 400 compounds with activities <2 μM, chemically classified into 57 clusters and 33 singletons. Up to 68% of the hits are chemotypes described for the first time as late-stage gametocyte-targeting molecules. In addition, the biological profile of 90 compounds representing the chemical diversity is assessed. We confirm in vitro transmission-blocking activity of four of the six selected molecules belonging to three distinct scaffold clusters. Overall, this TCAMS gametocyte screen provides 276 promising antimalarial molecules with dual asexual/sexual activity, representing starting points for target identification and candidate selection. There is a need for Plasmodium transmission blocking drugs for malaria elimination. Here, Miguel-Blanco et al. screen >10,000 compounds against stage V female gametocytes, identify active compounds belonging to 57 chemotypes and confirm transmission blocking activity of four selected compounds in vitro.
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[Role of primaquine in malaria control and elimination in French-speaking Africa]. BULLETIN DE LA SOCIETE DE PATHOLOGIE EXOTIQUE (1990) 2017; 110:198-206. [PMID: 28417346 DOI: 10.1007/s13149-017-0556-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 12/05/2016] [Indexed: 12/20/2022]
Abstract
Primaquine, an 8-aminoquinoline, is a relatively unknown and underutilized drug in French-speaking African countries. It acts against the liver stage parasites of all human malaria species, asexual blood stages of Plasmodium vivax and, to a lesser degree, Plasmodium falciparum; P. falciparum mature gametocytes, and P. vivax and Plasmodium ovale hypnozoites. Gastrointestinal disturbances are its most common side effects. The clinical utility of primaquine is limited due to its hematological side effects in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency and other contraindications (pregnant woman, breastfeeding woman, infants less than 6 months old). In the light of the recent recommendations of the World Health Organization (WHO), we propose to examine how primaquine can be used in French-speaking Africa to improve malaria control and move towards malaria elimination. Two indications supported by the WHO are of relevance in Africa. First, artemisinin-based combination therapies and primaquine given as a single low dose (0.25 mg base/kg) are effective to kill asexual and sexual parasites of P. falciparum, are well-tolerated, and have very little risk even in mild to moderate G6PD-deficient patients. This strategy may be helpful to contain transmission in an area in Africa where P. falciparum malaria incidence has decreased considerably. There is an ethical concern in administering primaquine as a gametocytocide as it does not confer any direct benefit to the treated patient. However, the single low-dose primaquine is most likely associated with very low risk for adverse hematological effects, and WHO recommends its use even without prior G6PD testing. In our opinion, clinical studies including G6PD test should be conducted to assess the safety of low-dose primaquine in African patients. Second, primaquine is effective and necessary for radical treatment of P. vivax and P. ovale, but the standard 14-day treatment (0.25-0.5 mg base/kg/day) is not recommended in patients with G6PD deficiency. Prior G6PD testing is required before prescribing primaquine for radical treatment. The use of primaquine for radical treatment in patients without contraindications does not raise any major ethical problem since the probability of relapse in patients who do not receive anti-hypnozoite treatment can be relatively high and each relapse can cause or aggravate anemia, especially in children. In our opinion, patients with mild or moderate G6PD deficiency should not be treated with primaquine at present. Further clinical studies are necessary to define the role of this drug for radical treatment in G6PD-deficient African patients. Without primaquine, the eventual elimination of P. vivax and P. ovale malaria appears to be very difficult. Updated epidemiological data on G6PD, Duffy antigen, and the current distribution of and burden due to P. vivax and P. ovale are required for a rational use of primaquine in the African continent. Moreover, clinical studies on primaquine are required in Africa.
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Abstract
Following anti-malarial drug treatment asexual malaria parasite killing and clearance appear to be first order processes. Damaged malaria parasites in circulating erythrocytes are removed from the circulation mainly by the spleen. Splenic clearance functions increase markedly in acute malaria. Either the entire infected erythrocytes are removed because of their reduced deformability or increased antibody binding or, for the artemisinins which act on young ring stage parasites, splenic pitting of drug-damaged parasites is an important mechanism of clearance. The once-infected erythrocytes returned to the circulation have shortened survival. This contributes to post-artesunate haemolysis that may follow recovery in non-immune hyperparasitaemic patients. As the parasites mature Plasmodium vivax-infected erythrocytes become more deformable, whereas Plasmodium falciparum-infected erythrocytes become less deformable, but they escape splenic filtration by sequestering in venules and capillaries. Sequestered parasites are killed in situ by anti-malarial drugs and then disintegrate to be cleared by phagocytic leukocytes. After treatment with artemisinin derivatives some asexual parasites become temporarily dormant within their infected erythrocytes, and these may regrow after anti-malarial drug concentrations decline. Artemisinin resistance in P. falciparum reflects reduced ring stage susceptibility and manifests as slow parasite clearance. This is best assessed from the slope of the log-linear phase of parasitaemia reduction and is commonly measured as a parasite clearance half-life. Pharmacokinetic-pharmacodynamic modelling of anti-malarial drug effects on parasite clearance has proved useful in predicting therapeutic responses and in dose-optimization.
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Affiliation(s)
- Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400, Thailand.
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Abstract
This article attempts to draw together current knowledge on the biology of Plasmodium and experience gained from past control campaigns to interpret and guide current efforts to discover and develop exciting new strategies targeting the parasite with the objective of interrupting transmission. Particular note is made of the advantages of targeting often unappreciated small, yet vital, bottleneck populations to enhance both the impact and the useful lifetime of hard-won interventions. A case is made for the standardization of methods to measure transmission blockade to permit the rational comparison of how diverse interventions (drugs, vaccines, insecticides, Genetically Modified technologies) targeting disparate aspects of parasite biology may impact upon the commonly used parameter of parasite prevalence in the human population.
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Affiliation(s)
- R E Sinden
- The Jenner Institute, Oxford, United Kingdom.
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Pett H, Gonçalves BP, Dicko A, Nébié I, Tiono AB, Lanke K, Bradley J, Chen I, Diawara H, Mahamar A, Soumare HM, Traore SF, Baber I, Sirima SB, Sauerwein R, Brown J, Gosling R, Felger I, Drakeley C, Bousema T. Comparison of molecular quantification of Plasmodium falciparum gametocytes by Pfs25 qRT-PCR and QT-NASBA in relation to mosquito infectivity. Malar J 2016; 15:539. [PMID: 27821171 PMCID: PMC5100312 DOI: 10.1186/s12936-016-1584-z] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 10/28/2016] [Indexed: 11/24/2022] Open
Abstract
Background Quantifying gametocyte densities in natural malaria infections is important to estimate malaria transmission potential. Two molecular methods (Pfs25 mRNA quantitative reverse transcriptase PCR (qRT-PCR) and Pfs25 mRNA quantitative nucleic acid sequence based amplification (QT-NASBA)) are commonly used to determine gametocyte densities in clinical and epidemiological studies and allow gametocyte detection at densities below the microscopic threshold for detection. Here, reproducibility of these measurements and the association between estimated gametocyte densities and mosquito infection rates were compared. Methods To quantify intra- and inter-assay variation of QT-NASBA and qRT-PCR, a series of experiments was performed using culture-derived mature Plasmodium falciparum gametocytes from three different parasite isolates (NF54, NF135, NF166). Pfs25 mRNA levels were also determined in samples from clinical trials in Mali and Burkina Faso using both methods. Agreement between the two methods and association with mosquito infection rates in membrane feeding assays were assessed. Results Intra- and inter-assay variability was larger in QT-NASBA compared to qRT-PCR, particularly at low gametocyte densities (< 1 gametocyte per μL). Logistic models, including log-transformed gametocytaemia estimated by QT-NASBA, explained variability in mosquito feeding experiment results as well as log-transformed gametocytaemia by qRT-PCR (marginal R2 0.28 and 0.22, respectively). Densities determined by both methods strongly correlated with mosquito infection rates [Spearman’s rank correlation coefficient, 0.59 for qRT-PCR and 0.64 for QT-NASBA (P < 0.001 for both)]. Gametocyte densities estimated by qRT-PCR were higher than levels estimated by QT-NASBA or light microscopy at high densities (>100 gametocyte per μL). Samples collected in one of the two transmission studies had extremely low gametocyte densities by both molecular methods, which is suggestive of RNA degradation due to an unknown number of freeze–thaw cycles and illustrates the reliance of molecular gametocyte diagnostics on a reliable cold-chain. Conclusions The experiments indicate that both qRT-PCR and QT-NASBA are of value for quantifying mature gametocytes in samples collected in field studies. For both assays, estimated gametocyte densities correlated well with mosquito infection rates. QT-NASBA is less reproducible than qRT-PCR, particularly for low gametocyte densities. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1584-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Helmi Pett
- Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, 6500 HB, Nijmegen, The Netherlands
| | - Bronner P Gonçalves
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Alassane Dicko
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Issa Nébié
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Kjerstin Lanke
- Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, 6500 HB, Nijmegen, The Netherlands
| | - John Bradley
- MRC Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
| | - Ingrid Chen
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA
| | - Halimatou Diawara
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Almahamoudou Mahamar
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Harouna M Soumare
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Sekou F Traore
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Ibrahima Baber
- Malaria Research and Training Centre, Faculty of Pharmacy and Faculty of Medicine and Dentistry, University of Science, Techniques and Technologies of Bamako, Bamako, Mali
| | - Sodiomon B Sirima
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Robert Sauerwein
- Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, 6500 HB, Nijmegen, The Netherlands
| | - Joelle Brown
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA
| | - Roly Gosling
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA
| | - Ingrid Felger
- Molecular Diagnostics Unit, Swiss Tropical and Public Health Institute, Basel, Switzerland
| | - Chris Drakeley
- Department of Immunology and Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Geert Grooteplein Zuid 26-28, 6500 HB, Nijmegen, The Netherlands.
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Leang R, Khu NH, Mukaka M, Debackere M, Tripura R, Kheang ST, Chy S, Kak N, Buchy P, Tarantola A, Menard D, Roca-Felterer A, Fairhurst RM, Kheng S, Muth S, Ngak S, Dondorp AM, White NJ, Taylor WRJ. An optimised age-based dosing regimen for single low-dose primaquine for blocking malaria transmission in Cambodia. BMC Med 2016; 14:171. [PMID: 27784313 PMCID: PMC5081959 DOI: 10.1186/s12916-016-0701-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Accepted: 09/20/2016] [Indexed: 01/03/2023] Open
Abstract
BACKGROUND In 2012, the World Health Organization recommended the addition of single low-dose primaquine (SLDPQ, 0.25 mg base/kg body weight) to artemisinin combination therapies to block the transmission of Plasmodium falciparum without testing for glucose-6-phosphate dehydrogenase deficiency. The targeted group was non-pregnant patients aged ≥ 1 year (later changed to ≥ 6 months) with acute uncomplicated falciparum malaria, primarily in countries with artemisinin-resistant P. falciparum (ARPf). No dosing regimen was suggested, leaving malaria control programmes and clinicians in limbo. Therefore, we designed a user-friendly, age-based SLDPQ regimen for Cambodia, the country most affected by ARPf. METHODS By reviewing primaquine's pharmacology, we defined a therapeutic dose range of 0.15-0.38 mg base/kg (9-22.5 mg in a 60-kg adult) for a therapeutic index of 2.5. Primaquine doses (1-20 mg) were tested using a modelled, anthropometric database of 28,138 Cambodian individuals (22,772 healthy, 4119 with malaria and 1247 with other infections); age distributions were: 0.5-4 years (20.0 %, n = 5640), 5-12 years (9.1 %, n = 2559), 13-17 years (9.1 %, n = 2550), and ≥ 18 years (61.8 %, n = 17,389). Optimal age-dosing groups were selected according to calculated mg base/kg doses and proportions of individuals receiving a therapeutic dose. RESULTS Four age-dosing bands were defined: (1) 0.5-4 years, (2) 5-9 years, (3) 10-14 years, and (4) ≥15 years to receive 2.5, 5, 7.5, and 15 mg of primaquine base, resulting in therapeutic doses in 97.4 % (5494/5640), 90.5 % (1511/1669), 97.7 % (1473/1508), and 95.7 % (18,489/19,321) of individuals, respectively. Corresponding median (1st-99th centiles) mg base/kg doses of primaquine were (1) 0.23 (0.15-0.38), (2) 0.29 (0.18-0.45), (3) 0.27 (0.15-0.39), and (4) 0.29 (0.20-0.42). CONCLUSIONS This age-based SLDPQ regimen could contribute substantially to malaria elimination and requires urgent evaluation in Cambodia and other countries with similar anthropometric characteristics. It guides primaquine manufacturers on suitable tablet strengths and doses for paediatric-friendly formulations. Development of similar age-based dosing recommendations for Africa is needed.
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Affiliation(s)
- Rithea Leang
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Naw Htee Khu
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
| | - Mavuto Mukaka
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Mark Debackere
- MSF Belgium Cambodia Malaria Program, #19, Street 388, Sangkat Tuol Svay Prey, Khan Chamkarmon, PO Box 1933, Phnom Penh, Cambodia
| | - Rupam Tripura
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand
| | - Soy Ty Kheang
- University Research Co., LLC, MK Building, House #10 (2nd floor), St. 214, Chey Chumneas, Daun Penh, Phnom Penh, Cambodia
| | - Say Chy
- University Research Co., LLC, MK Building, House #10 (2nd floor), St. 214, Chey Chumneas, Daun Penh, Phnom Penh, Cambodia
| | - Neeraj Kak
- University Research Co., LLC Washington DC: 7200 Wisconsin Ave, Bethesda, MD, 20814, USA
| | - Philippe Buchy
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Arnaud Tarantola
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Didier Menard
- Institut Pasteur du Cambodge, 5 Monivong Boulevard, PO Box 983, Phnom Penh, 12201, Cambodia
| | - Arantxa Roca-Felterer
- Malaria Consortium, House #91 Street 95, Boeung Trabek, Chamkar Morn, Phnom Penh, Cambodia
| | - Rick M Fairhurst
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Sim Kheng
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Sinoun Muth
- National Center for Parasitology, Entomology and Malaria Control, Corner St. 92, Trapeng Svay Village, Sangkat Phnom Penh, Thmei, Khan Sen Sok, Phnom Penh, Cambodia
| | - Song Ngak
- FHI 360 Cambodia Office, #03, Street 330 Boeung Keng Kang III Khan Chamkamon, PO Box: 2586, Phnom Penh, Cambodia
| | - Arjen M Dondorp
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand.,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK
| | - Walter Robert John Taylor
- Mahidol Oxford Tropical Medicine Research Unit (MORU), 420/6 Rajvithi Road, Rajthevee, Bangkok, 10400, Thailand. .,Oxford Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine Research Building, University of Oxford, Old Road Campus, Roosevelt Drive, Oxford, OX3 7FZ, UK. .,Centre de Médecine Humanitaire, Hôpitaux Universitaires de Genève, Genève, Switzerland.
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Okebe J, Bousema T, Affara M, Di Tanna GL, Dabira E, Gaye A, Sanya-Isijola F, Badji H, Correa S, Nwakanma D, Van Geertruyden JP, Drakeley C, D'Alessandro U. The Gametocytocidal Efficacy of Different Single Doses of Primaquine with Dihydroartemisinin-piperaquine in Asymptomatic Parasite Carriers in The Gambia: A Randomized Controlled Trial. EBioMedicine 2016; 13:348-355. [PMID: 27825738 PMCID: PMC5264436 DOI: 10.1016/j.ebiom.2016.10.032] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/14/2016] [Accepted: 10/19/2016] [Indexed: 11/23/2022] Open
Abstract
Background Asymptomatic low-density gametocyte carriers represent the majority of malaria-infected individuals. However, the impact of recommended treatment with single low dose of primaquine and an artemisinin-based combination therapy to reduce transmission in this group is unknown. Methods This was a four-arm, open label, randomized controlled trial comparing the effect of dihydroartemisinin-piperaquine (DHAP) alone or combined with single dose of primaquine (PQ) at 0.20 mg/kg, 0.40 mg/kg, or 0.75 mg/kg on Plasmodium falciparum gametocytaemia, infectiousness to mosquitoes and hemoglobin change in asymptomatic, malaria-infected, glucose-6-phosphate dehydrogenase (G6PD) normal individuals. Randomization was done using a computer-generated sequence of uneven block sizes with codes concealed in sequentially numbered opaque envelopes. The primary endpoint was the prevalence of P. falciparum gametocytemia at day 7 of follow-up determined by quantitative nucleic acid sequence based assay and analysis was by intention to treat. The trial has been concluded (registration number: NCT01838902; https://clinicaltrials.gov/ct2/show/NCT01838902). Results A total of 694 asymptomatic, malaria-infected individuals were enrolled. Gametocyte prevalence at day 7 was 37.0% (54/146; 95% CI 29.2–45.4), 19.0% (27/142; 95% CI 12.9–26.4), 17.2% (25/145; 95% CI 11.0–23.5) and 10.6% (15/141; 95% CI 6.1–16.9) in the DHAP alone, 0.20 mg/kg, 0.40 mg/kg, and 0.75 mg/kg PQ arms, respectively. The main adverse events reported include headache (130/471, 27.6%), cough (73/471, 15.5%), history of fever (61/471, 13.0%) and abdominal pain (57/471, 12.1%). There were five serious adverse events however, none was related to the interventions. Interpretation A single course of PQ significantly reduces gametocyte carriage in malaria-infected asymptomatic, G6PD-normal individuals without increasing the risk of clinical anemia. The limited number of successful mosquito infections suggests that post-treatment transmission potential in this asymptomatic population is low. Treatment with primaquine and an artemisinin-based combination therapy is part of malaria elimination strategies. Its slow uptake, despite specific recommendations highlights the need for evidence on primaquine's efficacy and safety. About 50% of asymptomatic P. falciparum-infected individuals carry gametocytes detectable by sensitive molecular methods. Primaquine reduced gametocyte prevalence at day 7 and carriage time in the study population at all doses tested.
Adding a single dose (0.75 mg/kg) of primaquine to the treatment of uncomplicated falciparum malaria was recommended in 2010 on the basis of weak evidence. Primaquine, at doses as low as 0.20 mg/kg, can reduce substantially gametocyte carriage in asymptomatic, malaria-infected individuals, representing the majority of the human reservoir of infection. Post-treatment transmission potential is low with artemisinin-based combination alone or with the 0.20 mg/kg dose but may occur despite reductions in gametocyte carriage.
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Affiliation(s)
- Joseph Okebe
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia; Epidemiology for Global Health Institute, Faculty of Medicine & Health Sciences, University of Antwerp, Antwerp, Belgium.
| | - Teun Bousema
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom; Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, The Netherlands.
| | - Muna Affara
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Gian Luca Di Tanna
- Pragmatic Clinical Trials Unit, Centre for Primary Care and Public Health, Queen Mary University of London, United Kingdom.
| | - Edgard Dabira
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Abdoulaye Gaye
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Frank Sanya-Isijola
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Henry Badji
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Simon Correa
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Davis Nwakanma
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia.
| | - Jean-Pierre Van Geertruyden
- Epidemiology for Global Health Institute, Faculty of Medicine & Health Sciences, University of Antwerp, Antwerp, Belgium.
| | - Chris Drakeley
- Department of Immunology and Infection, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom.
| | - Umberto D'Alessandro
- Disease Control & Elimination Theme, Medical Research Council Unit, Fajara, The Gambia; Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom; Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium.
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Landier J, Parker DM, Thu AM, Carrara VI, Lwin KM, Bonnington CA, Pukrittayakamee S, Delmas G, Nosten FH. The role of early detection and treatment in malaria elimination. Malar J 2016; 15:363. [PMID: 27421656 PMCID: PMC4946177 DOI: 10.1186/s12936-016-1399-y] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 06/17/2016] [Indexed: 12/30/2022] Open
Abstract
Falciparum malaria persists in hard-to-reach areas or demographic groups that are missed by conventional healthcare systems but could be reached by trained community members in a malaria post (MP). The main focus of a MP is to provide uninterrupted and rapid access to rapid diagnostic tests (RDTs) and artemisinin-based combination therapy (ACT) too all inhabitants of a village. RDTs allow trained community members to perform malaria diagnosis accurately and prescribe appropriate treatment, reducing as much as possible any delay between the onset of fever and treatment. Early treatment with ACT and with a low-dose of primaquine prevents further transmission from human to mosquito. A functioning MP represents an essential component of any malaria elimination strategy. Implementing large-scale, high-coverage, community-based early diagnosis and treatment through MPs requires few technological innovations but relies on a very well structured organization able to train, supervise and supply MPs, to monitor activity and to perform strict malaria surveillance.
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Affiliation(s)
- Jordi Landier
- 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
| | - Aung Myint Thu
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Verena I Carrara
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Khin Maung Lwin
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - Craig A Bonnington
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | | | - Gilles Delmas
- Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand
| | - François H 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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Abstract
There has been increasing interest in the role of malaria drugs in preventing malaria transmission from humans to mosquitoes, which would help augment malaria control and elimination strategies. Nevertheless, only one stage in the malaria parasite life cycle, the gametocyte, is infectious to mosquitoes. The Worldwide Antimalarial Resistance Network (WWARN) have analyzed data from 48,840 patients from 141 clinical trials in order to define the nature and determinants of gametocyte clearance following artemisinin combination treatment (ACT) for symptomatic malaria infections. However, the presence of gametocytes does not always predict their infectivity, meaning that the microscopy-based methods used by the WWARN investigators represent an imperfect surrogate marker of transmissibility. Their findings, that some ACTs clear gametocytes faster than others, should be interpreted in light of these limitations and important gaps in our understanding of the biology and epidemiology of malaria transmission.Please see related article: https://bmcmedicine.biomedcentral.com/articles/10.1186/s12916-016-0621-7.
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