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Pembet Singana B, Casimiro PN, Matondo Diassivi B, Kobawila SC, Youndouka JM, Basco LK, Ringwald P, Briolant S, Ndounga M. Prevalence of malaria among febrile patients and assessment of efficacy of artemether-lumefantrine and artesunate-amodiaquine for uncomplicated malaria in Dolisie, Republic of the Congo. Malar J 2022; 21:137. [PMID: 35501861 PMCID: PMC9063077 DOI: 10.1186/s12936-022-04143-4] [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: 10/21/2021] [Accepted: 03/28/2022] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND In the Republic of the Congo, malaria represents a major public health problem affecting all age groups. A regular surveillance of the current efficacy of first-line anti-malarial drugs is required in the face of possible emergence and spread of artemisinin-resistant Plasmodium falciparum strains in Africa. The purpose of this study was to determine the prevalence of malaria among febrile patients of all ages and assess the efficacy of artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ) in Congolese children. METHODS Febrile patients of all ages were initially screened for malaria by both rapid diagnostic test (RDT) and microscopy. Patients less than 12 years of age, with parasitaemia ≥ 1000 asexual parasites of P. falciparum/µL of blood, without any signs of severity, were enrolled in a therapeutic efficacy study and treated after obtaining their parents' (or legal guardian's) informed consent in two health centres in Dolisie. The patients were followed for 28 days in accordance with the 2009 World Health Organization standard protocol. If parasitaemia reappeared on or after day 7, the genetic profiles (genes expressing merozoite surface protein-1 [msp1], merozoite surface protein-2 [msp2], and glutamine-rich protein [glurp]) of pre-treatment and post-treatment isolates were compared by nested polymerase chain reaction (PCR) followed by capillary electrophoresis to make a distinction between recrudescence and re-infection. The clinical and parasitological outcome was analysed by the per-protocol method and Kaplan-Meier survival curves. RESULTS A total of 994 febrile patients of all ages were screened by RDT and microscopy. Of 994 patients, 323 (32.5%) presented a positive RDT, and 266 (26.8%) were microscopy-positive. Based on microscopy as the reference diagnostic method, the sensitivity and the specificity of the RDT were 98.9 and 91.8%, respectively. The Cohen's kappa coefficient was 0.86. A total of 121 children aged less than 12 years (61 in AL treatment group and 60 in ASAQ treatment group) were included in therapeutic efficacy study. Before PCR correction, the proportions of adequate clinical and parasitological response were 96.6% for AL and 86.0% for ASAQ in the per-protocol population (P < 0.05). The PCR-corrected efficacy rates were 98.2% and 94.2% for AL and ASAQ, respectively (P > 0.05). Both treatments were well tolerated. CONCLUSIONS AL and ASAQ remain highly effective for the first-line treatment of uncomplicated P. falciparum malaria in Dolisie. Despite high efficacy of first- and second-line treatment, there is a continuing need to scale up effective malaria preventive interventions and vector control strategies in the country. TRIAL REGISTRATION NUMBER ACTRN12616001422415.
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Affiliation(s)
- Brice Pembet Singana
- grid.442828.00000 0001 0943 7362Faculté des Sciences et Techniques, Université Marien Ngouabi, BP 69 Brazzaville, Republic of the Congo
| | - Prisca Nadine Casimiro
- Institut National de Recherche en Sciences de la Santé, Brazzaville, Republic of the Congo
| | | | - Simon Charles Kobawila
- grid.442828.00000 0001 0943 7362Faculté des Sciences et Techniques, Université Marien Ngouabi, BP 69 Brazzaville, Republic of the Congo
| | - Jean-Mermoz Youndouka
- Programme National de Lutte Contre le Paludisme, Direction Générale de l’Epidémiologie de la Maladie, Ministère de la Santé et de la Population, Brazzaville, Republic of the Congo
| | - Leonardo K. Basco
- Aix Marseille Univ., IRD, AP-HM, SSA, VITROME, Marseille, France ,grid.483853.10000 0004 0519 5986IHU-Méditerranée Infection, Marseille, France
| | - Pascal Ringwald
- grid.3575.40000000121633745Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Sébastien Briolant
- Aix Marseille Univ., IRD, AP-HM, SSA, VITROME, Marseille, France ,grid.483853.10000 0004 0519 5986IHU-Méditerranée Infection, Marseille, France ,grid.418221.cUnité de Parasitologie Entomologie, Département de Microbiologie et Maladies Infectieuses, Institut de Recherche Biomédicale des Armées, Marseille, France
| | - Mathieu Ndounga
- Programme National de Lutte Contre le Paludisme, Direction Générale de l’Epidémiologie de la Maladie, Ministère de la Santé et de la Population, Brazzaville, Republic of the Congo
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Windle ST, Lane KD, Gadalla NB, Liu A, Mu J, Caleon RL, Rahman RS, Sá JM, Wellems TE. Evidence for linkage of pfmdr1, pfcrt, and pfk13 polymorphisms to lumefantrine and mefloquine susceptibilities in a Plasmodium falciparum cross. Int J Parasitol Drugs Drug Resist 2020; 14:208-217. [PMID: 33197753 PMCID: PMC7677662 DOI: 10.1016/j.ijpddr.2020.10.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 10/21/2020] [Accepted: 10/23/2020] [Indexed: 11/13/2022]
Abstract
BACKGROUND Lumefantrine and mefloquine are used worldwide in artemisinin-based combination therapy (ACT) of malaria. Better understanding of drug susceptibility and resistance is needed and can be obtained from studies of genetic crosses. METHODS Drug response phenotypes of a cross between Plasmodium falciparum lines 803 (Cambodia) and GB4 (Ghana) were obtained as half-maximal effective concentrations (EC50s) and days to recovery (DTR) after 24 h exposure to 500 nM lumefantrine. EC50s of mefloquine, halofantrine, chloroquine, and dihydroartemisinin were also determined. Quantitative trait loci (QTL) analysis and statistical tests with candidate genes were used to identify polymorphisms associated with response phenotypes. RESULTS Lumefantrine EC50s averaged 5.8-fold higher for the 803 than GB4 parent, and DTR results were 3-5 and 16-18 days, respectively. In 803 × GB4 progeny, outcomes of these two lumefantrine assays showed strong inverse correlation; these phenotypes also correlated strongly with mefloquine and halofantrine EC50s. By QTL analysis, lumefantrine and mefloquine phenotypes mapped to a chromosome 5 region containing codon polymorphisms N86Y and Y184F in the P. falciparum multidrug resistance 1 protein (PfMDR1). Statistical tests of candidate genes identified correlations between inheritance of PfK13 Kelch protein polymorphism C580Y (and possibly K189T) and lumefantrine and mefloquine susceptibilities. Correlations were detected between lumefantrine and chloroquine EC50s and polymorphisms N326S and I356T in the CVIET-type P. falciparum chloroquine resistance transporter (PfCRT) common to 803 and GB4. CONCLUSIONS Correlations in this study suggest common mechanisms of action in lumefantrine, mefloquine, and halofantrine responses. PfK13 as well as PfMDR1 and PfCRT polymorphisms may affect access and/or action of these arylaminoalcohol drugs at locations of hemoglobin digestion and heme metabolism. In endemic regions, pressure from use of lumefantrine or mefloquine in ACTs may drive selection of PfK13 polymorphisms along with versions of PfMDR1 and PfCRT associated with lower susceptibility to these drugs.
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Affiliation(s)
- Sean T Windle
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Kristin D Lane
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Nahla B Gadalla
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Anna Liu
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Jianbing Mu
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Ramoncito L Caleon
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Rifat S Rahman
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Juliana M Sá
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA
| | - Thomas E Wellems
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20892, USA.
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Massamba L, Madamet M, Benoit N, Chevalier A, Fonta I, Mondain V, Jeandel PY, Amalvict R, Delaunay P, Mosnier J, Marty P, Pomares C, Pradines B. Late clinical failure associated with cytochrome b codon 268 mutation during treatment of falciparum malaria with atovaquone-proguanil in traveller returning from Congo. Malar J 2020; 19:37. [PMID: 31964401 PMCID: PMC6975030 DOI: 10.1186/s12936-020-3126-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2019] [Accepted: 01/16/2020] [Indexed: 12/17/2022] Open
Abstract
Background The drug combination atovaquone–proguanil, is recommended for treatment of uncomplicated falciparum malaria in France. Despite high efficacy, atovaquone–proguanil treatment failures have been reported. Resistance to cycloguanil, the active metabolite of proguanil, is conferred by multiple mutations in the Plasmodium falciparum dihydrofolate reductase (pfdhfr) and resistance to atovaquone by single mutation on codon 268 of the cytochrome b gene (pfcytb). Case presentation A 47-year-old female, native from Congo and resident in France, was admitted in hospital for uncomplicated falciparum malaria with parasitaemia of 0.5%, after travelling in Congo (Brazzaville and Pointe Noire). She was treated with atovaquone–proguanil (250 mg/100 mg) 4 tablets daily for 3 consecutive days. On day 5 after admission she was released home. However, many weeks after this episode, without having left France, she again experienced fever and intense weakness. On day 39 after the beginning of treatment, she consulted for fever, arthralgia, myalgia, photophobia, and blurred vision. She was hospitalized for uncomplicated falciparum malaria with a parasitaemia of 0.375% and treated effectively by piperaquine–artenimol (320 mg/40 mg) 3 tablets daily for 3 consecutive days. Resistance to atovaquone–proguanil was suspected. The Y268C mutation was detected in all of the isolates tested (D39, D42, D47). The genotyping of the pfdhfr gene showed a triple mutation (N51I, C59R, S108N) involved in cycloguanil resistance. Conclusion This is the first observation of a late clinical failure of atovaquone–proguanil treatment of P. falciparum uncomplicated malaria associated with pfcytb 268 mutation in a traveller returning from Congo. These data confirm that the Y268C mutation is associated with delayed recrudescence 4 weeks or more after initial treatment. Although atovaquone–proguanil treatment failures remain rare, an increased surveillance is required. It is essential to declare and publish all well-documented cases of treatment failures because it is the only way to evaluate the level of resistance to atovaquone.
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Affiliation(s)
- Laurencie Massamba
- Parasitologie Mycologie, Centre Hospitalo-Universitaire de Nice, Université de la Côte d'Azur, Nice, France
| | - Marylin Madamet
- Unité Parasitologie et entomologie, Département de Microbiologie et de maladies infectieuses, Institut de recherche biomédicale des armées, Marseille, France.,Aix Marseille Université, IRD, SSA, AP-HM, VITROME, Marseille, France.,IHU Méditerranée Infection, Marseille, France.,Centre national de référence du Paludisme, Marseille, France
| | - Nicolas Benoit
- Unité Parasitologie et entomologie, Département de Microbiologie et de maladies infectieuses, Institut de recherche biomédicale des armées, Marseille, France.,Aix Marseille Université, IRD, SSA, AP-HM, VITROME, Marseille, France.,IHU Méditerranée Infection, Marseille, France.,Centre national de référence du Paludisme, Marseille, France
| | - Alicia Chevalier
- Parasitologie Mycologie, Centre Hospitalo-Universitaire de Nice, Université de la Côte d'Azur, Nice, France
| | - Isabelle Fonta
- Unité Parasitologie et entomologie, Département de Microbiologie et de maladies infectieuses, Institut de recherche biomédicale des armées, Marseille, France.,Aix Marseille Université, IRD, SSA, AP-HM, VITROME, Marseille, France.,IHU Méditerranée Infection, Marseille, France.,Centre national de référence du Paludisme, Marseille, France
| | - Véronique Mondain
- Infectiologie, Centre Hospitalo-Universitaire de Nice, Université de la Côte d'Azur, Nice, France
| | - Pierre-Yves Jeandel
- Service de Médecine Interne, Centre Hospitalier Universitaire de Nice, Nice, France
| | - Rémy Amalvict
- Unité Parasitologie et entomologie, Département de Microbiologie et de maladies infectieuses, Institut de recherche biomédicale des armées, Marseille, France.,Aix Marseille Université, IRD, SSA, AP-HM, VITROME, Marseille, France.,IHU Méditerranée Infection, Marseille, France.,Centre national de référence du Paludisme, Marseille, France
| | - Pascal Delaunay
- Parasitologie Mycologie, Centre Hospitalo-Universitaire de Nice, Université de la Côte d'Azur, Nice, France.,MIVEGEC, UMR IRD 224-CNRS 5290-Université de Montpellier, Montpellier, France
| | - Joel Mosnier
- Unité Parasitologie et entomologie, Département de Microbiologie et de maladies infectieuses, Institut de recherche biomédicale des armées, Marseille, France.,Aix Marseille Université, IRD, SSA, AP-HM, VITROME, Marseille, France.,IHU Méditerranée Infection, Marseille, France.,Centre national de référence du Paludisme, Marseille, France
| | - Pierre Marty
- Parasitologie Mycologie, Centre Hospitalo-Universitaire de Nice, Université de la Côte d'Azur, Nice, France.,INSERM, U1065, Centre Méditerranéen de Médecine Moléculaire, Faculté de Médecine, Virulence microbienne et signalisation inflammatoire, Nice, France
| | - Christelle Pomares
- Parasitologie Mycologie, Centre Hospitalo-Universitaire de Nice, Université de la Côte d'Azur, Nice, France.,INSERM, U1065, Centre Méditerranéen de Médecine Moléculaire, Faculté de Médecine, Virulence microbienne et signalisation inflammatoire, Nice, France
| | - Bruno Pradines
- Unité Parasitologie et entomologie, Département de Microbiologie et de maladies infectieuses, Institut de recherche biomédicale des armées, Marseille, France. .,Aix Marseille Université, IRD, SSA, AP-HM, VITROME, Marseille, France. .,IHU Méditerranée Infection, Marseille, France. .,Centre national de référence du Paludisme, Marseille, France.
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Koukouikila-Koussounda F, Ntoumi F. Malaria epidemiological research in the Republic of Congo. Malar J 2016; 15:598. [PMID: 28010728 PMCID: PMC5180396 DOI: 10.1186/s12936-016-1617-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Accepted: 11/15/2016] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Reliable and comprehensive information on the burden of malaria is critical for guiding national and international efforts in malaria control. The purpose of this review is to provide an overview of published data and available information on malaria resulting from field studies/investigations conducted in the Republic of Congo (RoC) from 1992 to 2015, as baseline for assisting public health authorities and researchers to define future research priorities as well as interventions. METHODS This review considers data from peer-reviewed articles and information from the National Malaria Control Programme reports, based on field investigations or samples collected from 1992 to 2015. Peer-reviewed papers were searched throughout online bibliographic databases PubMed, HINARI and Google Scholar using the following terms: "malaria", "Congo", "Brazzaville", "prevalence", "antimalarial", "efficacy", "falciparum", "genetic", "diversity". Original articles and reviews were included and selection of relevant papers was made. RESULTS Twenty-eight published articles were included in this review and two additional records from the National Malaria Control Programme were also considered. The majority of studies were conducted in Brazzaville and Pointe-Noire. CONCLUSION The present systematic review reveals that number of studies have been conducted in the RoC with regard to malaria. However, their results cannot formally be generalized at the country level. This suggests a need for implementing regular multisite investigations and surveys that may be representative of the country, calling for the support and lead of the Ministry of Health.
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Affiliation(s)
| | - Francine Ntoumi
- Fondation Congolaise Pour la Recherche Médicale, Villa D6, WHO AFRO Campus, Brazzaville, Republic of Congo. .,Faculty of Sciences and Techniques, University Marien Ngouabi, Brazzaville, Republic of Congo. .,Institute for Tropical Medicine, University of Tübingen, Tübingen, Germany.
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Determinants of Adherence with Malaria Chemoprophylactic Drugs Used in a Traveler's Health Clinic. J Trop Med 2015; 2015:163716. [PMID: 26379712 PMCID: PMC4561335 DOI: 10.1155/2015/163716] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Revised: 05/20/2015] [Accepted: 05/26/2015] [Indexed: 11/17/2022] Open
Abstract
Background. The WHO recommends mefloquine, atovaquone/proguanil, and doxycycline for malaria chemoprophylaxis. Adherence to a drug is determined by many factors. Objective. To detect the determinants of travelers' adherence to malaria chemoprophylaxis. Methods. A prospective comparative study was conducted from January 2012 to July 2013 that included travelers (928 travelers) to malaria endemic countries who visited the THC. They were classified into 3 groups: the 1st is the mefloquine group (396 travelers), the 2nd is the doxycycline group (370 travelers), and finally those who did not receive any drugs (162 travelers). The participants from the 1st and 2nd groups enrolled in the study. Results. Univariate and multivariate analyses were performed. The predictors for adherence in the mefloquine group were travel to an African destination [OR = 51 (6.8–2385)], higher than a secondary school education [OR = 21 (4.1–144.2)], organized travel [OR = 4 (2.1–6.5)], traveling for leisure [OR = 2.1 (1.1–0.4)], and nationality [OR = 2 (1.11–4.00)]. In the doxycycline group, the predictors included higher than a secondary education [OR = 20.1 (4.5–125.1)], organized travel [OR = 11.4 (5.5–20.9)], travel for leisure [OR = 7 (2.3–22.9)], travel to an African destination [OR = 6.1 (0.41–417)], and nationality [OR = 4.5 (2.3–9.5)]. Conclusion. Adherence with malaria chemoprophylaxis could be affected by many factors such as nationality, education, and organized travel.
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Potent Ex Vivo Activity of Naphthoquine and Methylene Blue against Drug-Resistant Clinical Isolates of Plasmodium falciparum and Plasmodium vivax. Antimicrob Agents Chemother 2015. [PMID: 26195523 DOI: 10.1128/aac.00874-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 4-aminoquinoline naphthoquine (NQ) and the thiazine dye methylene blue (MB) have potent in vitro efficacies against Plasmodium falciparum, but susceptibility data for P. vivax are limited. The species- and stage-specific ex vivo activities of NQ and MB were assessed using a modified schizont maturation assay on clinical field isolates from Papua, Indonesia, where multidrug-resistant P. falciparum and P. vivax are prevalent. Both compounds were highly active against P. falciparum (median [range] 50% inhibitory concentration [IC50]: NQ, 8.0 nM [2.6 to 71.8 nM]; and MB, 1.6 nM [0.2 to 7.0 nM]) and P. vivax (NQ, 7.8 nM [1.5 to 34.2 nM]; and MB, 1.2 nM [0.4 to 4.3 nM]). Stage-specific drug susceptibility assays revealed significantly greater IC50s in parasites exposed at the trophozoite stage than at the ring stage for NQ in P. falciparum (26.5 versus 5.1 nM, P = 0.021) and P. vivax (341.6 versus 6.5 nM, P = 0.021) and for MB in P. vivax (10.1 versus 1.6 nM, P = 0.010). The excellent ex vivo activities of NQ and MB against both P. falciparum and P. vivax highlight their potential utility for the treatment of multidrug-resistant malaria in areas where both species are endemic.
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Low Prevalence of Pfcrt Resistance Alleles among Patients with Uncomplicated Falciparum Malaria in Niger Six Years after Chloroquine Withdrawal. Malar Res Treat 2014; 2014:614190. [PMID: 25506465 PMCID: PMC4259070 DOI: 10.1155/2014/614190] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 11/04/2014] [Indexed: 01/06/2023] Open
Abstract
Chloroquine (CQ) resistance is widespread in Africa, but few data are available for Niger. Pfcrt haplotypes (aa 56–118) and ex vivo responses to CQ and amodiaquine were characterized for 26 isolates collected in South Niger from children under 15 years of age suffering from uncomplicated falciparum malaria, six years after the introduction of artemisinin-based combinations and the withdrawal of CQ. The wild-type Pfcrt haplotype CVMNK was found in 22 of the 26 isolates, with CVIET sequences observed in only three of the samples. We also describe for the first time a new CVINT haplotype. The ex vivo responses were better for CVMNK than for CVIET parasites. Pfcrt sequence data were compared with those obtained for 26 additional parasitized blood samples collected in Gabon, from an area of CQ resistance used as a control. Our findings suggest that there has been a significant decline in CQ-resistant genotypes since the previous estimates for Niger were obtained. No such decline in molecular resistance to CQ was observed in the subset of samples collected in similar conditions from Gabon. These results have important implications for public health and support the policy implemented in Niger since 2005, which aims to increase the efficacy and availability of antimalarial drugs whilst controlling the spread of resistance.
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Migliani R, Pradines B, Michel R, Aoun O, Dia A, Deparis X, Rapp C. Malaria control strategies in French armed forces. Travel Med Infect Dis 2014; 12:307-17. [PMID: 25069406 DOI: 10.1016/j.tmaid.2014.05.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 05/11/2014] [Accepted: 05/13/2014] [Indexed: 10/25/2022]
Abstract
Each year, 40,000 French soldiers deploy or travel through malaria-endemic areas. Despite the effective control measures that were successively implemented, malaria remains a public health concern in French armed forces with several important outbreaks and one lethal case every two years. This article describes the malaria control strategy in French armed forces which is based on three combined strategies: i) Anopheles vector control to prevent infection with the implementation of personal protection against vectors (PPAV) adapted to the field living conditions of the troops. ii) Chemoprophylaxis (CP) to prevent the disease based on prescription of effective and well tolerated doxycycline. iii) Management of cases through early diagnosis and appropriate treatment to prevent death. In isolated conditions in endemic areas, rapid diagnosis tests (RDT) are used as first-line tests by military doctors. Treatment of uncomplicated Plasmodium falciparum (P. falciparum) malaria is based either on the piperaquine tetraphosphate-dihydroartemisinin association since 2013, or on the atovaquone-proguanil association. First-line treatment of severe P. falciparum malaria is based on IV artesunate. These measures are associated with constant education of the military, epidemiological surveillance of malaria cases and monitoring of parasite chemosensitivity.
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Affiliation(s)
| | - B Pradines
- Institut de recherche biomédicale des armées, Brétigny-sur-Orge, France; Aix Marseille Université, Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, UM 63, CNRS 7278, IRD 198, Inserm 1095, Marseille, France
| | - R Michel
- Centre d'épidémiologie et de santé publique des armées, Marseille, France
| | - O Aoun
- Service des maladies infectieuses et tropicales, Hôpital d'instruction des armées Bégin, Saint-Mandé, France
| | - A Dia
- Centre d'épidémiologie et de santé publique des armées, Marseille, France
| | - X Deparis
- Ecole du Val de Grâce, Paris, France; Centre d'épidémiologie et de santé publique des armées, Marseille, France
| | - C Rapp
- Ecole du Val de Grâce, Paris, France; Service des maladies infectieuses et tropicales, Hôpital d'instruction des armées Bégin, Saint-Mandé, France
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Antimalarial efficacy of hydroxyethylapoquinine (SN-119) and its derivatives. Antimicrob Agents Chemother 2013; 58:820-7. [PMID: 24247136 DOI: 10.1128/aac.01704-13] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Quinine and other cinchona-derived alkaloids, although recently supplanted by the artemisinins (ARTs), continue to be important for treatment of severe malaria. Quinine and quinidine have narrow therapeutic indices, and a safer quinine analog is desirable, particularly with the continued threat of antimalarial drug resistance. Hydroxyethylapoquinine (HEAQ), used at 8 g a day for dosing in humans in the 1930s and halving mortality from bacterial pneumonias, was shown to cure bird malaria in the 1940s and was also reported as treatment for human malaria cases. Here we describe synthesis of HEAQ and its novel stereoisomer hydroxyethylapoquinidine (HEAQD) along with two intermediates, hydroxyethylquinine (HEQ) and hydroxyethylquinidine (HEQD), and demonstrate comparable but elevated antimalarial 50% inhibitory concentrations (IC50) of 100 to 200 nM against Plasmodium falciparum quinine-sensitive strain 3D7 (IC50, 56 nM). Only HEAQD demonstrated activity against quinine-tolerant P. falciparum strains Dd2 and INDO with IC50s of 300 to 700 nM. HEQD had activity only against Dd2 with an IC50 of 313 nM. In the lethal mouse malaria model Plasmodium berghei ANKA, only HEQD had activity at 20 mg/kg of body weight comparable to that of the parent quinine or quinidine drugs measured by parasite inhibition and 30-day survival. In addition, HEQ, HEQD, and HEAQ (IC50 ≥ 90 μM) have little to no human ether-à-go-go-related gene (hERG) channel inhibition expressed in CHO cells compared to HEAQD, quinine, and quinidine (hERG IC50s of 27, 42, and 4 μM, respectively). HEQD more closely resembled quinine in vitro and in vivo for Plasmodium inhibition and demonstrated little hERG channel inhibition, suggesting that further optimization and preclinical studies are warranted for this molecule.
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Gharbi M, Flegg JA, Pradines B, Berenger A, Ndiaye M, Djimdé AA, Roper C, Hubert V, Kendjo E, Venkatesan M, Brasseur P, Gaye O, Offianan AT, Penali L, Le Bras J, Guérin PJ, Study MOTFNRCFIM. Surveillance of travellers: an additional tool for tracking antimalarial drug resistance in endemic countries. PLoS One 2013; 8:e77775. [PMID: 24204960 PMCID: PMC3813754 DOI: 10.1371/journal.pone.0077775] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 09/04/2013] [Indexed: 12/21/2022] Open
Abstract
INTRODUCTION There are growing concerns about the emergence of resistance to artemisinin-based combination therapies (ACTs). Since the widespread adoption of ACTs, there has been a decrease in the systematic surveillance of antimalarial drug resistance in many malaria-endemic countries. The aim of this work was to test whether data on travellers returning from Africa with malaria could serve as an additional surveillance system of local information sources for the emergence of drug resistance in endemic-countries. METHODOLOGY Data were collected from travellers with symptomatic Plasmodium falciparum malaria returning from Senegal (n = 1,993), Mali (n = 2,372), Cote d'Ivoire (n = 4,778) or Cameroon (n = 3,272) and recorded in the French Malaria Reference Centre during the period 1996-2011. Temporal trends of the proportion of parasite isolates that carried the mutant genotype, pfcrt 76T, a marker of resistance to chloroquine (CQ) and pfdhfr 108N, a marker of resistance to pyrimethamine, were compared for travellers and within-country surveys that were identified through a literature review in PubMed. The in vitro response to CQ was also compared between these two groups for parasites from Senegal. RESULTS The trends in the proportion of parasites that carried pfcrt 76T, and pfdhfr 108N, were compared for parasites from travellers and patients within-country using the slopes of the curves over time; no significant differences in the trends were found for any of the 4 countries. These results were supported by in vitro analysis of parasites from the field in Senegal and travellers returning to France, where the trends were also not significantly different. CONCLUSION The results have not shown different trends in resistance between parasites derived from travellers or from parasites within-country. This work highlights the value of an international database of drug responses in travellers as an additional tool to assess the emergence of drug resistance in endemic areas where information is limited.
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Affiliation(s)
- Myriam Gharbi
- Unité Mixte de Recherche 216, Institut de Recherche et de Développement, Paris, France
- PRES Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom
- Ecole des Hautes Etudes en Santé Publique, Sorbonne Paris Cité, Rennes, France
| | - Jennifer A. Flegg
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom
- Centre for Tropical Medicine & Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Bruno Pradines
- Département d’Infectiologie de Terrain, Institut de Recherche Biomédicale des Armées, Marseille, France
- Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes, Aix Marseille Université, Marseille, France
- Centre National de Référence du Paludisme, Marseille, France
| | - Ako Berenger
- Malariology Department, Institut Pasteur de Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | - Magatte Ndiaye
- Service de parasitologie, Faculté de Médecine et Pharmacie Université Cheikh Anta Diop, Dakar, Sénégal
| | - Abdoulaye A. Djimdé
- Malaria Research and Training Center & Department of Epidemiology of Parasitic Diseases, Faculty of Pharmacy University of Sciences Techniques and Technologies of Bamako, Bamako, Mali
| | - Cally Roper
- Pathogen Molecular Biology Department of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Véronique Hubert
- Centre National de Référence du Paludisme & Service de Parasitologie Mycologie, CHU Bichat-Claude Bernard APHP, Paris, France
| | - Eric Kendjo
- Centre National de Référence du Paludisme and Service de Parasitologie Mycologie, CHU Pitié-Salpétrière APHP, Paris, France
| | - Meera Venkatesan
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom
- University of Maryland School of Medicine, Baltimore, Maryland, United States of America
| | - Philippe Brasseur
- UMR 198, Institut de Recherche pour le Développement, Dakar, Sénégal
| | - Oumar Gaye
- Service de parasitologie, Faculté de Médecine et Pharmacie Université Cheikh Anta Diop, Dakar, Sénégal
| | - André T. Offianan
- Malariology Department, Institut Pasteur de Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | - Louis Penali
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom
| | - Jacques Le Bras
- Unité Mixte de Recherche 216, Institut de Recherche et de Développement, Paris, France
- PRES Sorbonne Paris Cité, Faculté de Pharmacie, Paris, France
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom
- Centre National de Référence du Paludisme & Service de Parasitologie Mycologie, CHU Bichat-Claude Bernard APHP, Paris, France
| | - Philippe J. Guérin
- WorldWide Antimalarial Resistance Network, Oxford, United Kingdom
- Ecole des Hautes Etudes en Santé Publique, Sorbonne Paris Cité, Rennes, France
- Centre for Tropical Medicine & Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
- UMR S 707: Epidemiology Information Systems Modeling, INSERM and Université Pierre et Marie-Curie-Paris6, Paris, France
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Plasmodium falciparum Polymorphisms associated with ex vivo drug susceptibility and clinical effectiveness of artemisinin-based combination therapies in Benin. Antimicrob Agents Chemother 2013; 58:1-10. [PMID: 24100489 DOI: 10.1128/aac.01790-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Artemisinin-based combination therapies (ACTs) are the main option to treat malaria, and their efficacy and susceptibility must be closely monitored to avoid resistance. We assessed the association of Plasmodium falciparum polymorphisms and ex vivo drug susceptibility with clinical effectiveness. Patients enrolled in an effectiveness trial comparing artemether-lumefantrine (n = 96), fixed-dose artesunate-amodiaquine (n = 96), and sulfadoxine-pyrimethamine (n = 48) for the treatment of uncomplicated malaria 2007 in Benin were assessed. pfcrt, pfmdr1, pfmrp1, pfdhfr, and pfdhps polymorphisms were analyzed pretreatment and in recurrent infections. Drug susceptibility was determined in fresh baseline isolates by Plasmodium lactate dehydrogenase enzyme-linked immunosorbent assay (ELISA). A majority had 50% inhibitory concentration (IC50) estimates (the concentration required for 50% growth inhibition) lower than those of the 3D7 reference clone for desethylamodiaquine, lumefantrine, mefloquine, and quinine and was considered to be susceptible, while dihydroartemisinin and pyrimethamine IC50s were higher. No association was found between susceptibility to the ACT compounds and treatment outcome. Selection was observed for the pfmdr1 N86 allele in artemether-lumefantrine recrudescences (recurring infections) (4/7 [57.1%] versus 36/195 [18.5%]), and of the opposite allele, 86Y, in artesunate-amodiaquine reinfections (new infections) (20/22 [90.9%] versus 137/195 [70.3%]) compared to baseline infections. The importance of pfmdr1 N86 in lumefantrine tolerance was emphasized by its association with elevated lumefantrine IC50s. Genetic linkage between N86 and Y184 was observed, which together with the low frequency of 1246Y may explain regional differences in selection of pfmdr1 loci. Selection of opposite alleles in artemether-lumefantrine and artesunate-amodiaquine recurrent infections supports the strategy of multiple first-line treatment. Surveillance based on clinical, ex vivo, molecular, and pharmacological data is warranted.
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12
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Ex vivo responses of Plasmodium falciparum clinical isolates to conventional and new antimalarial drugs in Niger. Antimicrob Agents Chemother 2013; 57:3415-9. [PMID: 23612203 DOI: 10.1128/aac.02383-12] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Little is known about resistance of Plasmodium falciparum to antimalarials in Sahelian countries. Here we investigated the drug susceptibilities of fresh isolates collected in Niger post-deployment of artemisinin-based combination therapies (ACTs). We found that the parasites remained highly susceptible to new (dihydroartemisinin, lumefantrine, pyronaridine, and piperaquine) and conventional (amodiaquine and chloroquine) antimalarial drugs. The introduction of ACTs in 2005 and their further deployment nationwide have therefore not resulted in a decrease in P. falciparum susceptibilities to these antimalarials.
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Texier G, Machault V, Barragti M, Boutin JP, Rogier C. Environmental determinant of malaria cases among travellers. Malar J 2013; 12:87. [PMID: 23496931 PMCID: PMC3599338 DOI: 10.1186/1475-2875-12-87] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 02/26/2013] [Indexed: 11/10/2022] Open
Abstract
Background Approximately 125 million travellers visit malaria-endemic countries annually and about 10,000 cases of malaria are reported after returning home. Due to the fact that malaria is insect vector transmitted, the environment is a key determinant of the spread of infection. Geo-climatic factors (such as temperature, moisture, water quality) determine the presence of Anopheles breeding sites, vector densities, adult mosquito survival rate, longevity and vector capacity. Several studies have shown the association between environmental factors and malaria incidence in autochthonous population. The association between the incidence of clinical malaria cases among non-immune travellers and environmental factors is yet to be evaluated. The objective of the present study was to identify, at a country scale (Ivory Coast), the environmental factors that are associated with clinical malaria among non-immune travellers, opening the way for a remote sensing-based counselling for malaria risk prevention among travellers. Methods The study sample consisted in 87 cohorts, including 4,531 French soldiers who travelled to Ivory Coast, during approximately four months, between September 2002 and December 2006. Their daily locations were recorded during the entire trip. The association between the incidence of clinical malaria and other factors (including individual, collective and environmental factors evaluated by remote sensing methods) was analysed in a random effect mixed Poisson regression model to take into account the sampling design. Results One hundred and forty clinical malaria cases were recorded during 572,363 person-days of survey, corresponding to an incidence density of 7.4 clinical malaria episodes per 1,000 person-months under survey. The risk of clinical malaria was significantly associated with the cumulative time spent in areas with NDVI > 0.35 (RR = 2,42), a mean temperature higher than 27°C (RR = 2,4), a longer period of dryness during the preceding month (RR = 0,275) and the cumulative time spent in urban areas (RR = 0,52). Conclusions The present results suggest that remotely-sensed environmental data could be used as good predictors of the risk of clinical malaria among vulnerable individuals travelling through African endemic areas.
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Affiliation(s)
- Gaëtan Texier
- Public Health and Epidemiology Centre of the French Army (CESPA) &SESSTIM UMR912, Allée du Médecin Colonel Jamot, Parc du Pharo, BP60109,13262 Marseille cedex 07, France
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Gharbi M, Flegg JA, Hubert V, Kendjo E, Metcalf JE, Bertaux L, Guérin PJ, Le Bras J, Aboubaca A, Agnamey P, Angoulvant A, Barbut P, Basset D, Belkadi G, Bellanger AP, Bemba D, Benoit-Vica F, Berry A, Bigel ML, Bonhomme J, Botterel F, Bouchaud O, Bougnoux ME, Bourée P, Bourgeois N, Branger C, Bret L, Buret B, Casalino E, Chevrier S, Conquere de Monbrison F, Cuisenier B, Danis M, Darde ML, De Gentile L, Delarbre JM, Delaunay P, Delaval A, Desoubeaux G, Develoux M, Dunand J, Durand R, Eloy O, Fauchet N, Faugere B, Faye A, Fenneteau O, Flori P, Fontrouge M, Garabedian C, Gayandrieu F, Godineau N, Houzé P, Houzé S, Hurst JP, Ichou H, Lachaud L, Lebuisson A, Lefevre M, LeGuern AS, Le Moal G, Lusina D, Machouart MC, Malvy D, Matheron S, Maubon D, Mechali D, Megarbane B, Menard G, Millon L, Aiach MM, Minodier P, Morelle C, Nevez G, Parola P, Parzy D, Patey O, Patoz P, Penn P, Perignon A, Picot S, Pilo JE, Poilane I, Pons D, Poupart M, Pradines B, Raffenot D, Rapp C, Receveur MC, Sarfati C, Senghor Y, Simon F, Siriez JY, Taudon N, Thellier M, Thouvenin M, Toubas D. Longitudinal study assessing the return of chloroquine susceptibility of Plasmodium falciparum in isolates from travellers returning from West and Central Africa, 2000-2011. Malar J 2013; 12:35. [PMID: 23351608 PMCID: PMC3583707 DOI: 10.1186/1475-2875-12-35] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Accepted: 01/19/2013] [Indexed: 11/10/2022] Open
Abstract
Background Chloroquine (CQ) was the main malaria therapy worldwide from the 1940s until the 1990s. Following the emergence of CQ-resistant Plasmodium falciparum, most African countries discontinued the use of CQ, and now promote artemisinin-based combination therapy as the first-line treatment. This change was generally initiated during the last decade in West and Central Africa. The aim of this study is to describe the changes in CQ susceptibility in this African region, using travellers returning from this region as a sentinel system. Methods The study was conducted by the Malaria National Reference Centre, France. The database collated the pfcrtK76T molecular marker for CQ susceptibility and the in vitro response to CQ of parasites from travellers’ isolates returning from Senegal, Mali, Ivory Coast or Cameroon. As a proxy of drug pressure, data regarding CQ intake in febrile children were collated for the study period. Logistic regression models were used to detect trends in the proportions of CQ resistant isolates. Results A total of 2874 parasite isolates were genotyped between 2000–2011. The prevalence of the pfcrt76T mutant genotype significantly decreased for Senegal (from 78% to 47%), Ivory Coast (from 63% to 37%), Cameroon (from 90% to 59%) and remained stable for Mali. The geometric mean of the 50% inhibitory concentration (IC50) of CQ in vitro susceptibility and the proportion of resistant isolates (defining resistance as an IC50 value > 100 nM) significantly decreased for Senegal (from 86 nM (59%) to 39 nM (25%)), Mali (from 84 nM (50%) to 51 nM (31%)), Ivory Coast (from 75 nM (59%) to 29 nM (16%)) and Cameroon (from 181 nM (75%) to 51 nM (37%)). Both analyses (molecular and in vitro susceptibility) were performed for the 2004–2011 period, after the four countries had officially discontinued CQ and showed an accelerated decline of the resistant isolates for the four countries. Meanwhile, CQ use among children significantly deceased in this region (fixed effects slope = −0.3, p < 10-3). Conclusions An increase in CQ susceptibility following official withdrawal of the drug was observed in travellers returning from West and Central African countries. The same trends were observed for molecular and in vitro analysis between 2004-2011and they correlated to the decrease of the drug pressure.
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Affiliation(s)
- Myriam Gharbi
- Mère et enfant face aux infections tropicales, IRD unité mixte de recherche 216, Université Paris Descartes-Paris V, 4 avenue de l'Observatoire, Paris Cedex 06 75270, France.
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Abstract
Malaria chemotherapy is under constant threat from the emergence and spread of multidrug resistance of Plasmodium falciparum. Resistance has been observed to almost all currently used antimalarials. Some drugs are also limited by toxicity. A fundamental component of the strategy for malaria chemotherapy is based on prompt, effective and safe antimalarial drugs. To counter the threat of resistance of P. falciparum to existing monotherapeutic regimens, current malaria treatment is based principally on the artemisinin group of compounds, either as monotherapy or artemisinin-based combination therapies for treatment of both uncomplicated and severe falciparum malaria. Key advantages of artemisinins over the conventional antimalarials include their rapid and potent action, with good tolerability profiles. Their action also covers transmissible gametocytes, resulting in decreased disease transmission. Up to now there has been no prominent report of drug resistance to this group of compounds. Treatment of malaria in pregnant women requires special attention in light of limited treatment options caused by potential teratogenicity coupled with a paucity of safety data for the mother and fetus. Treatment of other malaria species is less problematic and chloroquine is still the drug of choice, although resistance of P. vivax to chloroquine has been reported. Multiple approaches to the identification of new antimalarial targets and promising antimalarial drugs are being pursued in order to cope with drug resistance.
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Affiliation(s)
- Kesara Na-Bangchang
- Faculty of Allied Health Sciences, Thammasat University (Rangsit Campus), Paholyothin Road, Klong Luang District, Pathumtanee 12121, Thailand.
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Anvikar AR, Sharma B, Sharma S, Ghosh S, Bhatt R, Kumar A, Mohanty S, Pillai C, Dash A, Valecha N. In vitro assessment of drug resistance in Plasmodium falciparum in five States of India. Indian J Med Res 2012; 135:494-9. [PMID: 22664496 PMCID: PMC3385232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/13/2010] [Indexed: 11/21/2022] Open
Abstract
BACKGROUND & OBJECTIVES In vitro assays are an important tool to assess baseline sensitivity and monitor the drug response of Plasmodium falciparum over time and place and, therefore, can provide background information for the development and evaluation of drug policies. This study was aimed at determining the in vitro sensitivity of P. falciparum isolates to antimalarials. METHODS The in vitro activity of 108 P. falciparum isolates obtained from five States of India was evaluated using WHO microtest (Mark III) to chloroquine, monodesethylamodiaquine, dihydroartesunate and mefloquine. Samples were collected from the States of Orissa, Jharkhand, Karnataka, Goa and Chhattisgarh from September 2007 to August 2009. In addition, representative samples from different States of India cryopreserved and culture adapted in the Malaria Parasite Bank of National Institute of Malaria Research, New Delhi, were also evaluated. RESULTS The proportion of isolates resistant to chloroquine and monodesethylamodiaquine was 44.4 and 25 per cent, respectively. Of the 27 isolates resistant to monodesethylamodiaquine, 16 (59.3%) were cross-resistant to chloroquine. No isolate showed resistance to dihydroartesunate and mefloquine. Isolates from Orissa showed the highest degree of resistance to chloroquine and amodiaquine followed by Jharkhand. Forty two isolates were genotyped for pfcrt T76K chloroquine resistant mutation; mutations were seen in 38 (90.47%) isolates. INTERPRETATION & CONCLUSIONS The Indian P. falciparum isolates showed a high degree of resistance to chloroquine followed by monodesethylamodiaquine. No resistance was recorded to mefloquine and dihydroartesunate.
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Affiliation(s)
| | - Bhawna Sharma
- Drugs for Neglected Diseases initiative, New Delhi, India
| | | | | | | | | | - S.S. Mohanty
- Desert Medicine Research Centre (ICMR), Jodhpur, India
| | - C.R. Pillai
- National Institute of Malaria Research (NIMR, ICMR), New Delhi, India
| | - A.P. Dash
- National Institute of Malaria Research (NIMR, ICMR), New Delhi, India
| | - Neena Valecha
- National Institute of Malaria Research (NIMR, ICMR), New Delhi, India
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Fall B, Diawara S, Sow K, Baret E, Diatta B, Fall KB, Mbaye PS, Fall F, Diémé Y, Rogier C, Wade B, Bercion R, Pradines B. Ex vivo susceptibility of Plasmodium falciparum isolates from Dakar, Senegal, to seven standard anti-malarial drugs. Malar J 2011; 10:310. [PMID: 22014157 PMCID: PMC3210113 DOI: 10.1186/1475-2875-10-310] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 10/20/2011] [Indexed: 11/15/2022] Open
Abstract
Background As a result of widespread chloroquine and sulphadoxine-pyrimethamine resistance, artemisinin-based combination therapy (ACT) (which includes artemether-lumefantrine and artesunate-amodiaquine) has been recommended as a first-line anti-malarial regimen in Senegal since 2006. Since then, there have been very few reports on the ex vivo susceptibility of Plasmodium falciparum to anti-malarial drugs. To examine whether parasite susceptibility has been affected by the widespread use of ACT, the ex vivo susceptibility of local isolates was assessed at the military hospital of Dakar. Methods The ex vivo susceptibility of 93 P. falciparum isolates from Dakar was successfully determined using the Plasmodium lactate dehydrogenase (pLDH) ELISA for the following drugs: chloroquine (CQ), quinine (QN), mefloquine (MQ), monodesethylamodiaquine (MDAQ), lumefantrine (LMF), dihydroartemisinin (DHA) and doxycycline (DOX). Results After transformation of the isolate IC50 in ratio of IC50 according to the susceptibility of the 3D7 reference strain (isolate IC50/3D7 IC50), the prevalence of the in vitro resistant isolates with reduced susceptibility was 50% for MQ, 22% for CQ, 12% for DOX, 6% for both QN and MDAQ and 1% for the drugs LMF and DHA. The highest significant positive correlations were shown between responses to CQ and MDAQ (r = 0.569; P < 0.0001), LMF and QN (r = 0.511; P < 0.0001), LMF and DHA (r = 0.428; P = 0.0001), LMF and MQ (r = 0.413; P = 0.0002), QN and DHA (r = 0.402; P = 0.0003) and QN and MQ (r = 0.421; P = 0.0001). Conclusions The introduction of ACT in 2002 has not induced a decrease in P. falciparum susceptibility to the drugs DHA, MDAQ and LMF, which are common ACT components. However, the prevalence of P. falciparum isolates with reduced susceptibility has increased for both MQ and DOX. Taken together, these data suggest that intensive surveillance of the P. falciparum in vitro susceptibility to anti-malarial drugs in Senegal is required.
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Affiliation(s)
- Bécaye Fall
- 1Laboratoire d’étude de la chimiosensibilité du paludisme, Fédération deslaboratoires, Hôpital Principal de Dakar, Dakar, Sénégal
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Identification and functional validation of the novel antimalarial resistance locus PF10_0355 in Plasmodium falciparum. PLoS Genet 2011; 7:e1001383. [PMID: 21533027 PMCID: PMC3080868 DOI: 10.1371/journal.pgen.1001383] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Accepted: 03/25/2011] [Indexed: 11/25/2022] Open
Abstract
The Plasmodium falciparum parasite's ability to adapt to
environmental pressures, such as the human immune system and antimalarial drugs,
makes malaria an enduring burden to public health. Understanding the genetic
basis of these adaptations is critical to intervening successfully against
malaria. To that end, we created a high-density genotyping array that assays
over 17,000 single nucleotide polymorphisms (∼1 SNP/kb), and applied it to
57 culture-adapted parasites from three continents. We characterized genome-wide
genetic diversity within and between populations and identified numerous loci
with signals of natural selection, suggesting their role in recent adaptation.
In addition, we performed a genome-wide association study (GWAS), searching for
loci correlated with resistance to thirteen antimalarials; we detected both
known and novel resistance loci, including a new halofantrine resistance locus,
PF10_0355. Through functional testing we demonstrated that
PF10_0355 overexpression decreases sensitivity to
halofantrine, mefloquine, and lumefantrine, but not to structurally unrelated
antimalarials, and that increased gene copy number mediates resistance. Our GWAS
and follow-on functional validation demonstrate the potential of genome-wide
studies to elucidate functionally important loci in the malaria parasite
genome. Malaria infection with the human pathogen Plasmodium falciparum
results in almost a million deaths each year, mostly in African children.
Efforts to eliminate malaria are underway, but the parasite is adept at eluding
both the human immune response and antimalarial treatments. Thus, it is
important to understand how the parasite becomes resistant to drugs and to
develop strategies to overcome resistance mechanisms. Toward this end, we used
population genetic strategies to identify genetic loci that contribute to
parasite adaptation and to identify candidate genes involved in drug resistance.
We examined over 17,000 genetic variants across the parasite genome in over 50
strains in which we also measured responses to many known antimalarial
compounds. We found a number of genetic loci showing signs of recent natural
selection and a number of loci potentially involved in modulating the
parasite's response to drugs. We further demonstrated that one of the novel
candidate genes (PF10_0355) modulates resistance to the
antimalarial compounds halofantrine, mefloquine, and lumefantrine. Overall, this
study confirms that we can use genome-wide approaches to identify clinically
relevant genes and demonstrates through functional testing that at least one of
these candidate genes is indeed involved in antimalarial drug resistance.
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Briolant S, Pelleau S, Bogreau H, Hovette P, Zettor A, Castello J, Baret E, Amalvict R, Rogier C, Pradines B. In vitro susceptibility to quinine and microsatellite variations of the Plasmodium falciparum Na+/H+ exchanger (Pfnhe-1) gene: the absence of association in clinical isolates from the Republic of Congo. Malar J 2011; 10:37. [PMID: 21314947 PMCID: PMC3055222 DOI: 10.1186/1475-2875-10-37] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Accepted: 02/11/2011] [Indexed: 11/24/2022] Open
Abstract
Background Quinine is still recommended as an effective therapy for severe cases of Plasmodium falciparum malaria, but the parasite has developed resistance to the drug in some cases. Investigations into the genetic basis for quinine resistance (QNR) suggest that QNR is complex and involves several genes, with either an additive or a pairwise effect. The results obtained when assessing one of these genes, the plasmodial Na+/H+ exchanger, Pfnhe-1, were found to depend upon the geographic origin of the parasite strain. Most of the associations identified have been made in Asian strains; in contrast, in African strains, the influence of Pfnhe on QNR is not apparent. However, a recent study carried out in Kenya did show a significant association between a Pfnhe polymorphism and QNR. As genetic differences may exist across the African continent, more field data are needed to determine if this association exists in other African regions. In the present study, association between Pfnhe and QNR is investigated in a series of isolates from central Africa. Methods The sequence analysis of the polymorphisms at the Pfnhe-1 ms4760 microsatellite and the evaluation of in vitro quinine susceptibility (by isotopic assay) were conducted in 74 P. falciparum isolates from the Republic of Congo. Results Polymorphisms in the number of DNNND or NHNDNHNNDDD repeats in the Pfnhe-1 ms4760 microsatellite were not associated with quinine susceptibility. Conclusions The polymorphism in the microsatellite ms4760 in Pfnhe-1 that cannot be used to monitor quinine response in the regions of the Republic of Congo, where the isolates came from. This finding suggests that there exists a genetic background associated with geographic area for the association that will prevent the use of Pfnhe as a molecular marker for QNR. The contribution of Pfnhe to the in vitro response to quinine remains to be assessed in other regions, including in countries with different levels of drug pressure.
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Affiliation(s)
- Sébastien Briolant
- Unité de Parasitologie, Unité Mixte de Recherche 6236, Institut de Recherche Biomédicale des Armées-Antenne de Marseille, Marseille, France
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Pascual A, Basco LK, Baret E, Amalvict R, Travers D, Rogier C, Pradines B. Use of the atmospheric generators for capnophilic bacteria Genbag-CO2 for the evaluation of in vitro Plasmodium falciparum susceptibility to standard anti-malarial drugs. Malar J 2011; 10:8. [PMID: 21235757 PMCID: PMC3031278 DOI: 10.1186/1475-2875-10-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2010] [Accepted: 01/14/2011] [Indexed: 01/08/2023] Open
Abstract
Background The aim of this study was to evaluate the cultivation system in which the proper atmospheric conditions for growing Plasmodium falciparum parasites were maintained in a sealed bag. The Genbag® system associated with the atmospheric generators for capnophilic bacteria Genbag CO2® was used for in vitro susceptibility test of nine standard anti-malarial drugs and compared to standard incubator conditions. Methods The susceptibility of 36 pre-identified parasite strains from a wide panel of countries was assessed for nine standard anti-malarial drugs (chloroquine, quinine, mefloquine, monodesethylamodiaquine, lumefantrine, dihydroartemisinin, atovaquone and pyrimethamine) by the standard 42-hour 3H-hypoxanthine uptake inhibition method using the Genbag CO2® system and compared to controlled incubator conditions (5% CO2 and 10% O2). Results The counts per minute values in the control wells in incubator atmospheric conditions (5% CO2 and 10% O2) were significantly higher than those of Genbag® conditions (2738 cpm vs 2282 cpm, p < 0.0001). The geometric mean IC50 estimated under the incubator atmospheric conditions was significantly lower for atovaquone (1.2 vs 2.1 nM, p = 0.0011) and higher for the quinolines: chloroquine (127 vs 94 nM, p < 0.0001), quinine (580 vs 439 nM, p < 0.0001), monodesethylamodiaquine (41.4 vs 31.8 nM, p < 0.0001), mefloquine (57.5 vs 49.7 nM, p = 0.0011) and lumefantrine (23.8 vs 21.2 nM, p = 0.0044). There was no significant difference of IC50 between the 2 conditions for dihydroartemisinin, doxycycline and pyrimethamine. To reduce this difference in term of anti-malarial susceptibility, a specific cut-off was estimated for each drug under Genbag® conditions by regression. The cut-off was estimated at 77 nM for chloroquine (vs 100 nM in 10% O2), 611 nM for quinine (vs 800 nM), 30 nM for mefloquine (vs 30 nM), 61 nM for monodesethylamodiaquine (vs 80 nM) and 1729 nM for pyrimethamine (vs 2000 nM). Conclusions The atmospheric generators for capnophilic bacteria Genbag CO2® is an appropriate technology that can be transferred to the field for epidemiological surveys of drug-resistant malaria. The present data suggest the importance of the gas mixture on in vitro microtest results for anti-malarial drugs and the importance of determining the microtest conditions before comparing and analysing the data from different laboratories and concluding on malaria resistance.
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Affiliation(s)
- Aurélie Pascual
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Institut de Recherche Biomédicale des Armées--antenne de Marseille, Marseille, France
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Limited ability of Plasmodium falciparum pfcrt, pfmdr1, and pfnhe1 polymorphisms to predict quinine in vitro sensitivity or clinical effectiveness in Uganda. Antimicrob Agents Chemother 2010; 55:615-22. [PMID: 21078941 DOI: 10.1128/aac.00954-10] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Quinine is a standard drug for treating severe malaria in Africa, and it is also increasingly used to treat uncomplicated disease. However, failures of quinine therapy are common, and it is unknown if failures in Africa are due to drug resistance. Recent studies have identified associations between in vitro quinine sensitivity and polymorphisms in genes encoding putative transporters, including well-described polymorphisms in pfcrt and pfmdr1 and varied numbers of DNNND or DDNHNDNHNND repeats in microsatellite 4760 (ms4760) of the predicted sodium-hydrogen exchanger, pfnhe1. To better characterize mediators of quinine response, we assessed associations between genetic polymorphisms, in vitro quinine sensitivity, and quinine treatment responses in Kampala, Uganda. Among 172 fresh clinical isolates tested in vitro, decreasing sensitivity to quinine was associated with accumulation of pfmdr1 mutations at codons 86, 184, and 1246. Nearly all parasites had pfcrt 76T, preventing analysis of associations with this mutation. pfnhe1 ms4760 was highly polymorphic. Parasites with 2 copies of either ms4760 repeat showed modest decreases in quinine sensitivity compared to those with 1 or ≥3 repeats, but the differences were not statistically significant. None of the above polymorphisms predicted treatment failure among 66 subjects treated with quinine for uncomplicated malaria. Our data suggest that quinine sensitivity is a complex trait and that known polymorphisms in pfcrt, pfmdr1, and pfnhe1, while associated with quinine sensitivity, are not robust markers for quinine resistance.
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Okombo J, Kiara SM, Rono J, Mwai L, Pole L, Ohuma E, Borrmann S, Ochola LI, Nzila A. In vitro activities of quinine and other antimalarials and pfnhe polymorphisms in Plasmodium isolates from Kenya. Antimicrob Agents Chemother 2010; 54:3302-7. [PMID: 20516285 PMCID: PMC2916339 DOI: 10.1128/aac.00325-10] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 04/25/2010] [Accepted: 05/23/2010] [Indexed: 01/24/2023] Open
Abstract
Resistance to the amino alcohol quinine has been associated with polymorphisms in pfnhe, a sodium hydrogen exchanger. We investigated the role of this gene in quinine resistance in vitro in isolates from Kenya. We analyzed pfnhe whole-gene polymorphisms, using capillary sequencing, and pfcrt at codon 76 (pfcrt-76) and pfmdr1 at codon 86 (pfmdr1-86), using PCR-enzyme restriction methodology, in 29 isolates from Kilifi, Kenya, for association with the in vitro activities of quinine and 2 amino alcohols, mefloquine and halofantrine. In vitro activity was assessed as the drug concentration that inhibits 50% of parasite growth (IC50). The median IC50s of quinine, halofantrine, and mefloquine were 92, 22, and 18 nM, respectively. The presence of 2 DNNND repeats in microsatellite ms4760 of pfnhe was associated with reduced susceptibility to quinine (60 versus 227 nM for 1 and 2 repeats, respectively; P<0.05), while 3 repeats were associated with restoration of susceptibility. The decrease in susceptibility conferred by the 2 DNNND repeats was more pronounced in parasites harboring the pfmdr1-86 mutation. No association was found between susceptibility to quinine and the pfcrt-76 mutation or between susceptibility to mefloquine or halofantrine and the pfnhe gene and the pfcrt-76 and pfmdr1-86 mutations. Using previously published data on the in vitro activities of chloroquine, lumefantrine, piperaquine, and dihydroartemisinin, we investigated the association of their activities with pfnhe polymorphism. With the exception of a modulation of the activity of lumefantrine by a mutation at position 1437, pfnhe did not modulate their activities. Two DNNND repeats combined with the pfmdr1-86 mutation could be used as an indicator of reduced susceptibility to quinine.
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Affiliation(s)
- John Okombo
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Steven M. Kiara
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Josea Rono
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Leah Mwai
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Lewa Pole
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Eric Ohuma
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Steffen Borrmann
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Lynette Isabella Ochola
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
| | - Alexis Nzila
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230, 80108 Kilifi, Kenya, University of Oxford, Nuffield Department of Medicine, John Radcliffe Hospital, Oxford, United Kingdom, Institute of Hygiene, University of Heidelberg School of Medicine, Heidelberg, Germany
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Yavo W, Bla KB, Djaman AJ, Assi SB, Basco LK, Mazabraud A, Koné M. In vitro susceptibility of Plasmodium falciparum to monodesethylamodiaquine, quinine, mefloquine and halofantrine in Abidjan (Côte d'Ivoire). Afr Health Sci 2010; 10:111-116. [PMID: 21326960 PMCID: PMC2956299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023] Open
Abstract
BACKGROUND Malaria is the primary cause of hospitalization in Côte d'Ivoire. Early treatment is one of the strategies to control this illness. However, the spread of resistance of Plasmodium falciparum to antimalarial drugs can seriously compromise this strategy. OBJECTIVES The aim of this study was to assess the in vitro susceptibility of P. falciparum to monodesethylamodiaquine and aminoalcohols in Abidjan (Côte d'Ivoire). METHODS We assessed the in vitro susceptibility of isolates collected from patients with uncomplicated malaria by using the WHO optical microtest technique. RESULTS The proportions of resistance to monodesethylamodiaquine, méfloquine and halofantrine were 12.5%, 15.6% and 25.9%, respectively. For quinine, none of isolates showed evidence of in vitro resistance. However, two isolates (6.1%) had IC(50) values above 300 nM. The IC(50) of each drug was positively and significantly correlated to that of the other three drugs, and the correlation was higher between halofantrine and mefloquine. CONCLUSIONS Our results showed that the in vitro chloroquine resistance reported in previous studies has been extended to other antimalarial drugs investigated in this study except for quinine. Therefore, it is necessary to implement a long-term monitoring system of antimalarial drug resistance.
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Affiliation(s)
- W Yavo
- Department of Parasitology and Mycology, Faculty of Pharmaceutical and Biological Sciences, University of Cocody-Abidjan, Côte d'Ivoire.
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Diap G, Amuasi J, Boakye I, Sevcsik AM, Pecoul B. Anti-malarial market and policy surveys in sub-Saharan Africa. Malar J 2010; 9 Suppl 1:S1. [PMID: 20423536 DOI: 10.1186/1475-2875-9-s1-s1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
At a recent meeting (Sept 18, 2009) in which reasons for the limited access to artemisinin-based combination therapy (ACT) in sub-Saharan Africa were discussed, policy and market surveys on anti-malarial drug availability and accessibility in Burundi and Sierra Leone were presented in a highly interactive brainstorming session among key stakeholders across private, public, and not-for-profit sectors. The surveys, the conduct of which directly involved the national malaria control programme managers of the two countries, provides the groundwork for evidence-based policy implementation. The results of the surveys could be extrapolated to other countries with similar socio-demographic and malaria profiles. The meeting resulted in recommendations on key actions to be taken at the global, national, and community level for better ACT accessibility. At the global level, both public and private sectors have actions to take to strengthen policies that lead to the replacement of loose blister packs with fixed-dose ACT products, develop strategies to ban inappropriate anti-malarials and regulate those bans, and facilitate technology and knowledge transfer to scale up production of fixed-dose ACT products, which should be readily available and affordable to those patients who are in the greatest need of these medicines. At the national level, policies that regulate the anti-malarial medicines market should be enacted and enforced. The public sector, including funding donors, should participate in ensuring that the private sector is engaged in the ACT implementation process. Research similar to the surveys discussed is important for other countries to develop and evaluate the right incentives at a local level. At the community level, community outreach and education about appropriate preventive and treatment measures must continue and be strengthened, with service delivery systems developed within both public and private sectors, among other measures, to decrease access to ineffective and inappropriate anti-malarial medicines. What was clear during the meeting is that continuing commitment, strengthened interaction and transparency among various stakeholders, with focus on communities, national governments, and evidence-based policy and action are the only way to sustainably address the control of malaria, a disease which continues to have a significant health and socio-economic impact worldwide, particularly in sub-Saharan Africa. Details on the methodology employed in carrying out the studies discussed at this meeting, as well as more detailed results, data analysis and discussion of the studies are soon to be published.
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Affiliation(s)
- Graciela Diap
- Drugs for Neglected Diseases initiative (DNDi), Geneva 1202, Switzerland.
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Resseguier N, Machault V, Ollivier L, Orlandi-Pradines E, Texier G, Pradines B, Gaudart J, Buguet A, Tourette-Turgis C, Rogier C. Determinants of compliance with malaria chemoprophylaxis among French soldiers during missions in inter-tropical Africa. Malar J 2010; 9:41. [PMID: 20128921 PMCID: PMC2829034 DOI: 10.1186/1475-2875-9-41] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 02/03/2010] [Indexed: 11/10/2022] Open
Abstract
Background The effectiveness of malaria chemoprophylaxis is limited by the lack of compliance whose determinants are not well known. Methods The compliance with malaria chemoprophylaxis has been estimated and analysed by validated questionnaires administered before and after the short-term missions (about four months) in five tropical African countries of 2,093 French soldiers from 19 military companies involved in a prospective cohort study. "Correct compliance" was defined as "no missed doses" of daily drug intake during the entire mission and was analysed using multiple mixed-effect logistic regression model. Results The averaged prevalence rate of correct compliance was 46.2%, ranging from 9.6%to 76.6% according to the companies. Incorrect compliance was significantly associated with eveningness (p = 0.028), a medical history of clinical malaria (p < 0.001) and a perceived mosquito attractiveness inferior or superior to the others (p < 0.007). Correct compliance was significantly associated with the systematic use of protective measures against mosquito bites (p < 0.001), the type of military operations (combat vs. training activities, p < 0.001) and other individual factors (p < 0.05). Conclusions The identification of circumstances and profiles of persons at higher risk of lack of compliance would pave the way to specifically targeted strategies aimed to improve compliance with malaria chemoprophylaxis and, therefore, its effectiveness.
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Affiliation(s)
- Noémie Resseguier
- Institute for Biomedical Research of the French Army & URMITE UMR6236, Allée du Médecin Colonel Jamot, Parc du Pharo, Marseille cedex 07, France
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Wong RPM, Lautu D, Tavul L, Hackett SL, Siba P, Karunajeewa HA, Ilett KF, Mueller I, Davis TME. In vitro sensitivity of Plasmodium falciparum to conventional and novel antimalarial drugs in Papua New Guinea. Trop Med Int Health 2010; 15:342-9. [PMID: 20070627 DOI: 10.1111/j.1365-3156.2009.02463.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Recent clinical studies have shown high rates of malaria treatment failure in endemic areas of Papua New Guinea (PNG), necessitating a change of treatment from chloroquine (CQ) or amodiaquine (AQ) plus sulphadoxine-pyrimethamine to the artemisinin combination therapy (ACT) artemether plus lumefantrine (LM). To facilitate the monitoring of antimalarial drug resistance in this setting, we assessed the in vitro sensitivity of Plasmodium falciparum isolates from Madang Province. METHODS A validated colorimetric lactate dehydrogenase assay was used to assess growth inhibition of 64 P. falciparum isolates in the presence of nine conventional or novel antimalarial drugs [CQ, AQ, monodesethyl-amodiaquine (DAQ), piperaquine (PQ), naphthoquine (NQ), mefloquine (MQ), LM, dihydroartemisinin and azithromycin (AZ)]. RESULTS The geometric mean (95% confidence interval) concentration required to inhibit parasite growth by 50% (IC(50)) was 167 (141-197) nM for CQ, and 82% of strains were resistant (threshold 100 nM), consistent with near-fixation of the CQ resistance-associated pfcrt allele in PNG. Except for AZ [8.351 (5.418-12.871) nM], the geometric mean IC(50) for the other drugs was <20 nM. There were strong associations between the IC(50)s of 4-aminoquinoline (CQ, AQ, DAQ and NQ), bisquinoline (PQ) and aryl aminoalcohol (MQ) compounds suggesting cross-resistance, but LM IC(50) only correlated with that of MQ. Conclusions Most PNG isolates are resistant to CQ in vitro but not to other ACT partner drugs. The non-isotopic semi-automated high-throughput nature of the Plasmodium lactate dehydrogenase assay facilitates the convenient serial assessment of local parasite sensitivity, so that emerging resistance can be identified with relative confidence at an early stage.
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Affiliation(s)
- Rina P M Wong
- Fremantle Unit, School of Medicine and Pharmacology, University of Western Australia, Nedlands, WA, Australia
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In vitro sensitivities of Plasmodium falciparum to different antimalarial drugs in Uganda. Antimicrob Agents Chemother 2010; 54:1200-6. [PMID: 20065051 DOI: 10.1128/aac.01412-09] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The control of malaria is challenged by resistance of Plasmodium falciparum to multiple drugs. New combination regimens are now advocated for the treatment of uncomplicated falciparum malaria, but the extent of resistance to newer agents is incompletely understood. We measured the in vitro sensitivity of P. falciparum parasites cultured from children enrolled in a drug efficacy trial in Kampala, Uganda, from 2006 to 2008. Sensitivities were measured by comparing levels of histidine-rich protein-2 in parasites incubated with different concentrations of drugs with those in untreated controls. The cultured parasites exhibited a wide range of sensitivities to chloroquine (CQ); monodesethylamodiaquine (MDAQ), the major active metabolite of amodiaquine; and quinine (QN). Mean 50% inhibitory concentration (IC(50)) results were above standard cutoffs for resistance for CQ and MDAQ. Parasites were generally sensitive to dihydroartemisinin (DHA), lumefantrine (LM), and piperaquine (PQ). For CQ, MDAQ, and QN but not the other drugs, activities against individual strains were highly correlated. We also assessed known resistance-mediating polymorphisms in two putative transporters, pfcrt and pfmdr1. When parasites that were least and most sensitive to each drug were compared, the pfmdr1 86Y mutation was significantly more common in parasites that were most resistant to CQ and MDAQ, and the pfmdr1 D1246Y mutation was significantly more common in parasites that were most resistant to MDAQ and QN. In summary, we demonstrated in parasites from Kampala a range of sensitivities to older drugs; correlation of sensitivities to CQ, MDAQ, and QN; and good activity against nearly all strains for DHA, LM, and PQ.
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Karl S, Wong RP, St Pierre TG, Davis TM. A comparative study of a flow-cytometry-based assessment of in vitro Plasmodium falciparum drug sensitivity. Malar J 2009; 8:294. [PMID: 20003396 PMCID: PMC2799432 DOI: 10.1186/1475-2875-8-294] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2009] [Accepted: 12/14/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Recently developed Sybr Green-based in vitro Plasmodium falciparum drug sensitivity assays provide an attractive alternative to current manual and automated methods. The present study evaluated flow cytometry measurement of DNA staining with Sybr Green in comparison with the P. falciparum lactate dehydrogenase assay, the tritiated hypoxanthine incorporation assay, a previously described Sybr Green based plate reader assay and light microscopy. METHODS All assays were set up in standardized format in 96-well plates. The 50% inhibitory concentrations (IC50) of chloroquine, mefloquine and dihydroartemisinin against the laboratory adapted P. falciparum strains 3D7, E8B, W2mef and Dd2 were determined using each method. RESULTS The resolution achieved by flow cytometry allowed quantification of the increase in individual cell DNA content after an incubation period of only 24 h. Regression, and Bland and Altman analyses showed that the IC50 values determined using the flow cytometry assay after 24 h agreed well with those obtained using the hypoxanthine incorporation assay, the P. falciparum lactate dehydrogenase assay, the Sybr Green plate reader assay and light microscopy. However the values obtained with the flow cytometry assay after 48 h of incubation differed significantly from those obtained with the hypoxanthine incorporation assay, and the P. falciparum lactate dehydrogenase assay at low IC50 values, but agreed well with the Sybr Green plate reader assay and light microscopy. CONCLUSIONS Although flow cytometric equipment is expensive, the necessary reagents are inexpensive, the procedure is simple and rapid, and the cell volume required is minimal. This should allow field studies using fingerprick sample volumes.
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Affiliation(s)
- Stephan Karl
- School of Physics, M013, The University of Western Australia, 35 Stirling Highway, Crawley WA 6009, Australia
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Nawaz F, Nsobya SL, Kiggundu M, Joloba M, Rosenthal PJ. Selection of parasites with diminished drug susceptibility by amodiaquine-containing antimalarial regimens in Uganda. J Infect Dis 2009; 200:1650-7. [PMID: 19905933 DOI: 10.1086/647988] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Amodiaquine (AQ) is paired with artesunate (AS) or sulfadoxine-pyrimethamine (SP) in recommended antimalarial regimens. It is unclear how readily AQ resistance will be selected with combination chemotherapy. METHODS We collected 61 Plasmodium falciparum samples from a cohort of Ugandan children randomized for treatment with AQ-SP, AS-AQ, or artemether-lumefantrine (AL) for uncomplicated malaria. In vitro susceptibility to monodesethylamodiaquine (MDAQ) was measured with a histidine-rich protein 2-based enzyme-linked immunosorbent assay, and potential resistance-mediating polymorphisms in pfmdr1 were evaluated. RESULTS Parasites collected from patients treated with AQ-SP or AS-AQ within the prior 12 weeks were less susceptible to MDAQ (n = 18; mean of the median inhibitory concentration [IC(50)], 62.9 nmol/L; range, 12.7-158.3 nmol/L) than were parasites from those not treated within 12 weeks (n = 43; mean IC(50), 37.5 nmol/L; range, 6.3-184.7 nmol/L; P=.009) or only from those patients in the treatment arm that did not receive AQ (n = 12; mean IC(50), 28.8 nmol/L; range, 6.3-121.8 nmol/L; P = .004). The proportion of strains with polymorphisms expected to mediate diminished response to AQ (pfmdr1 86Y and 1246Y) increased after AQ therapy, although differences were not statistically significant. CONCLUSIONS Prior therapy selected for diminished response to MDAQ, which suggests that AQ-containing regimens may rapidly lose efficacy in Africa. The mechanism of diminished MDAQ response is not fully explained by known mutations in pfmdr1.
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Affiliation(s)
- Fatima Nawaz
- Department of Medicine, University of California, San Francisco, CA, USA
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ABC - antibiotics-based combinations for the treatment of severe malaria? Trends Parasitol 2009; 25:540-4. [DOI: 10.1016/j.pt.2009.09.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2009] [Revised: 07/28/2009] [Accepted: 09/07/2009] [Indexed: 11/20/2022]
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Eastman RT, Fidock DA. Artemisinin-based combination therapies: a vital tool in efforts to eliminate malaria. Nat Rev Microbiol 2009; 7:864-74. [PMID: 19881520 DOI: 10.1038/nrmicro2239] [Citation(s) in RCA: 358] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Plasmodium falciparum resistance to chloroquine and sulphadoxine-pyrimethamine has led to the recent adoption of artemisinin-based combination therapies (ACTs) as the first line of treatment against malaria. ACTs comprise semisynthetic artemisinin derivatives paired with distinct chemical classes of longer acting drugs. These artemisinins are exceptionally potent against the pathogenic asexual blood stages of Plasmodium parasites and also act on the transmissible sexual stages. These combinations increase the rates of clinical and parasitological cures and decrease the selection pressure for the emergence of antimalarial resistance. This Review article discusses our current knowledge about the mode of action of ACTs, their pharmacological properties and the proposed mechanisms of drug resistance.
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Affiliation(s)
- Richard T Eastman
- Department of Microbiology & Immunology, Columbia University College of Physicians and Surgeons, Hammer Health Sciences Center, Room 1502, 701 West 168th Street, New York 10032, New York, USA.
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In vitro activities of piperaquine, lumefantrine, and dihydroartemisinin in Kenyan Plasmodium falciparum isolates and polymorphisms in pfcrt and pfmdr1. Antimicrob Agents Chemother 2009; 53:5069-73. [PMID: 19770282 DOI: 10.1128/aac.00638-09] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We have analyzed the in vitro chemosensitivity profiles of 115 Kenyan isolates for chloroquine (CQ), piperaquine, lumefantrine (LM), and dihydroartemisinin in association with polymorphisms in pfcrt at codon 76 and pfmdr1 at codon 86, as well as with variations of the copy number of pfmdr1. The median drug concentrations that inhibit 50% of parasite growth (IC(50)s) were 41 nM (interquartile range [IQR], 18 to 73 nM), 50 nM (IQR, 29 to 96 nM), 32 nM (IQR, 17 to 46 nM), and 2 nM (IQR, 1 to 3 nM) for CQ, LM, piperaquine, and dihydroartemisinin, respectively. The activity of CQ correlated inversely with that of LM (r(2) = -0.26; P = 0.02). Interestingly, parasites for which LM IC(50)s were higher were wild type for pfcrt-76 and pfmdr1-86. All isolates had one pfmdr1 copy. Thus, the decrease in LM activity is associated with the selection of wild-type pfcrt-76 and pfmdr1-86 parasites, a feature that accounts for the inverse relationship between CQ and LM. Therefore, the use of LM-artemether is likely to lead to the selection of more CQ-susceptible parasites.
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Pomares-Estran C, Delaunay P, Mottard A, Cua E, Roger PM, Pradines B, Parzy D, Bogreau H, Rogier C, Jeannin C, Karch S, Fontenille D, Dejour-Salamanca D, Legros F, Marty P. Atypical aetiology of a conjugal fever: autochthonous airport malaria between Paris and French Riviera: a case report. Malar J 2009; 8:202. [PMID: 19698152 PMCID: PMC2734347 DOI: 10.1186/1475-2875-8-202] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2009] [Accepted: 08/23/2009] [Indexed: 11/10/2022] Open
Abstract
Endemic malaria has been eradicated from France, but some falciparum malaria cases have been described in patients who have never travelled outside the country. Ms. V. 21 year-old and Mr. M. 23 year-old living together in Paris were on holiday in Saint Raphaël (French Riviera). They presented with fever, vertigo and nausea. A blood smear made to control thrombocytopaenia revealed intra-erythrocytic forms of Plasmodium falciparum. The parasitaemia level was 0.15% for Ms. V and 3.2% for Mr. M. This couple had no history of blood transfusion or intravenous drug use. They had never travelled outside metropolitan France, but had recently travelled around France: to Saint Mard (close to Paris Charles de Gaulle (CdG) airport), to Barneville plage (in Normandy) and finally to Saint Raphaël. The most probable hypothesis is an infection transmitted in Saint Mard by an imported anopheline mosquito at CdG airport. The DNA analysis of parasites from Ms. V.'s and Mr. M.'s blood revealed identical genotypes. Because it is unlikely that two different anopheline mosquitoes would be infected by exactly the same clones, the two infections must have been caused by the infective bites of the same infected mosquito.
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Affiliation(s)
- Christelle Pomares-Estran
- Laboratoire de Parasitologie-Mycologie, Centre Hospitalier Universitaire L'Archet, 151 route de Saint Antoine de Ginestière, BP 3079 06202 Nice Cedex 3 France.
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Achan J, Tibenderana JK, Kyabayinze D, Wabwire Mangen F, Kamya MR, Dorsey G, D'Alessandro U, Rosenthal PJ, Talisuna AO. Effectiveness of quinine versus artemether-lumefantrine for treating uncomplicated falciparum malaria in Ugandan children: randomised trial. BMJ 2009; 339:b2763. [PMID: 19622553 PMCID: PMC2714631 DOI: 10.1136/bmj.b2763] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To compare the effectiveness of oral quinine with that of artemether-lumefantrine in treating uncomplicated malaria in children. DESIGN Randomised, open label effectiveness study. SETTING Outpatient clinic of Uganda's national referral hospital in Kampala. PARTICIPANTS 175 children aged 6 to 59 months with uncomplicated malaria. INTERVENTIONS Participants were randomised to receive oral quinine or artemether-lumefantrine administered by care givers at home. MAIN OUTCOME MEASURES Primary outcomes were parasitological cure rates after 28 days of follow-up unadjusted and adjusted by genotyping to distinguish recrudescence from new infections. Secondary outcomes were adherence to study drug, presence of gametocytes, recovery of haemoglobin concentration from baseline at day 28, and safety profiles. RESULTS Using survival analysis the cure rate unadjusted by genotyping was 96% for the artemether-lumefantrine group compared with 64% for the quinine group (hazard ratio 10.7, 95% confidence interval 3.3 to 35.5, P=0.001). In the quinine group 69% (18/26) of parasitological failures were due to recrudescence compared with none in the artemether-lumefantrine group. The mean adherence to artemether-lumefantrine was 94.5% compared with 85.4% to quinine (P=0.0008). Having adherence levels of 80% or more was associated with a decreased risk of treatment failure (0.44, 0.19 to 1.02, P=0.06). Adverse events did not differ between the two groups. CONCLUSIONS The effectiveness of a seven day course of quinine for the treatment of uncomplicated malaria in Ugandan children was significantly lower than that of artemether-lumefantrine. These findings question the advisability of the recommendation for quinine therapy for uncomplicated malaria in Africa. TRIAL REGISTRATION ClinicalTrials.gov NCT00540202.
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Affiliation(s)
- Jane Achan
- Makerere University School of Health Sciences, PO Box 7475, Kampala, Uganda.
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Kurth F, Pongratz P, Bélard S, Mordmüller B, Kremsner PG, Ramharter M. In vitro activity of pyronaridine against Plasmodium falciparum and comparative evaluation of anti-malarial drug susceptibility assays. Malar J 2009; 8:79. [PMID: 19389221 PMCID: PMC2679051 DOI: 10.1186/1475-2875-8-79] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2008] [Accepted: 04/23/2009] [Indexed: 11/21/2022] Open
Abstract
Background Pyronaridine, a Mannich base anti-malarial with high efficacy against drug resistant Plasmodium falciparum, is currently evaluated as a fixed dose combination with artesunate for the treatment of uncomplicated malaria. In this study, the in vitro activity of pyronaridine against clinical isolates of P. falciparum from Lambaréné, Gabon, was assessed in order to obtain baseline data on its activity prior to its future use in routine therapy. Moreover, follow-up assessment on the in vitro activity of chloroquine, artesunate and quinine was performed. Methods In vitro response of field isolates of P. falciparum to pyronaridine, chloroquine, artesunate and quinine was assessed using the traditional WHO microtest. In addition, the histidine-rich protein 2 (HRP-2) assay was performed and evaluated for its future implementation for follow-up of drug susceptibility testing. Results Pyronaridine exhibited a high in vitro activity against P. falciparum, with a geometric mean cut-off concentration of 9.3 nmol/l. Fifty percent effective concentrations were 1.9 nmol/l and 2.0 nmol/l in the WHO microtest and HRP-2 assay, respectively. Results matched closely in vivo findings from a recent clinical trial on pyronaridine-artesunate treatment. One isolate showed diminished sensitivity to artesunate. For chloroquine and quinine resistance levels were comparable to prior studies from Lambaréné. Results from the novel HRP-2 assay corresponded well to those obtained by the WHO microtest. Conclusion Pyronaridine is highly active in chloroquine-resistant parasites and seems a promising partner drug for artemisinin-based combination therapy in Africa.
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Affiliation(s)
- Florian Kurth
- Medical Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon.
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Multinormal in vitro distribution model suitable for the distribution of Plasmodium falciparum chemosusceptibility to doxycycline. Antimicrob Agents Chemother 2008; 53:688-95. [PMID: 19047651 DOI: 10.1128/aac.00546-08] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The distribution and range of 50% inhibitory concentrations (IC(50)s) of doxycycline were determined for 747 isolates obtained between 1997 and 2006 from patients living in Senegal, Republic of the Congo, and Gabon and patients hospitalized in France for imported malaria. The statistical analysis was designed to answer the specific question of whether Plasmodium falciparum has different phenotypes of susceptibility to doxycycline. A triple normal distribution was fitted to the data using a Bayesian mixture modeling approach. The IC(50) geometric mean ranged from 6.2 microM to 11.1 microM according to the geographical origin, with a mean of 9.3 microM for all 747 parasites. The values for all 747 isolates were classified into three components: component A, with an IC(50) mean of 4.9 microM (+/-2.1 microM [standard deviation]); component B, with an IC(50) mean of 7.7 microM (+/-1.2 microM); and component C, with an IC(50) mean of 17.9 microM (+/-1.4 microM). According to the origin of the P. falciparum isolates, the triple normal distribution was found in each subgroup. However, the proportion of isolates predicted to belong to component B was most important in isolates from Gabon and Congo and in isolates imported from Africa (from 46 to 56%). In Senegal, 55% of the P. falciparum isolates were predicted to be classified as component C. The cutoff of reduced susceptibility to doxycycline in vitro was estimated to be 35 microM.
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Hayton K, Su XZ. Drug resistance and genetic mapping in Plasmodium falciparum. Curr Genet 2008; 54:223-39. [PMID: 18802698 DOI: 10.1007/s00294-008-0214-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Revised: 08/27/2008] [Accepted: 08/28/2008] [Indexed: 11/30/2022]
Abstract
Drug resistance in malaria parasites is a serious public health burden, and resistance to most of the antimalarial drugs currently in use has been reported. A better understanding of the molecular mechanisms of drug resistance is urgently needed to slow or circumvent the spread of resistance, to allow local treatments to be deployed more effectively to prolong the life span of the current drugs, and to develop new drugs. Although mutations in genes determining resistance to drugs such as chloroquine and the antifolates have been identified, we still do not have a full understanding of the resistance mechanisms, and genes that contribute to resistance to many other drugs remain to be discovered. Genetic mapping is a powerful tool for the identification of mutations conferring drug resistance in malaria parasites because most drug-resistant phenotypes were selected within the past 60 years. High-throughput methods for genotyping large numbers of single nucleotide polymorphisms (SNPs) and microsatellites (MSs) are now available or are being developed, and genome-wide association studies for malaria traits will soon become a reality. Here we discuss strategies and issues related to mapping genes contributing to drug resistance in the human malaria parasite Plasmodium falciparum.
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Affiliation(s)
- Karen Hayton
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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A network to monitor antimalarial drug resistance: a plan for moving forward. Trends Parasitol 2007; 24:43-8. [PMID: 18042432 DOI: 10.1016/j.pt.2007.09.008] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2007] [Revised: 09/25/2007] [Accepted: 09/25/2007] [Indexed: 01/27/2023]
Abstract
The spread of resistance to antimalarial drugs has required changes in the recommended first-line treatment for falciparum malaria in almost all regions. Most drugs recommended currently are combinations of a long-acting antimalarial and an artemisinin derivative. This article presents the rationale for establishing a web-based, open-access database of antimalarial drug resistance and efficacy: the World Antimalarial Resistance Network (WARN). The goal of this network is to assemble the tools and information that will enable the malaria community to collate, analyze and share contemporary information on antimalarial-drug efficacy in all endemic regions so that decisions on antimalarial-drug use are based on solid evidence.
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Briolant S, Parola P, Fusaï T, Madamet-Torrentino M, Baret E, Mosnier J, Delmont JP, Parzy D, Minodier P, Rogier C, Pradines B. Influence of oxygen on asexual blood cycle and susceptibility of Plasmodium falciparum to chloroquine: requirement of a standardized in vitro assay. Malar J 2007; 6:44. [PMID: 17437625 PMCID: PMC1855060 DOI: 10.1186/1475-2875-6-44] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Accepted: 04/16/2007] [Indexed: 11/18/2022] Open
Abstract
Objective The main objective of this study was to assess the influence of gas mixtures on in vitro Plasmodium falciparum growth and 50% inhibitory concentration (IC50) for chloroquine. Methods The study was performed between February 2004 and December 2005. 136 Plasmodium falciparum isolates were used to evaluate gas mixtures effect on IC50 for chloroquine by isotopic microtest. The oxygen effect on asexual blood cycle of 3D7 and W2 clones was determined by thin blood smears examination and tritiated hypoxanthine uptake. Results From 5% O2 to 21% O2 conditions, no parasiticide effect of O2 concentration was observed in vitro on the clones 3D7 and W2. A parasitostatic effect was observed during the exposure of mature trophozoïtes and schizonts at 21% O2 with an increase in the length of schizogony. The chloroquine IC50 at 10% O2 were significantly higher than those at 21% O2, means of 173.5 nM and 121.5 nM respectively (p < 0.0001). In particular of interest, among the 63 isolates that were in vitro resistant to chloroquine (IC50 > 100 nM) at 10% O2, 17 were sensitive to chloroquine (IC50 < 100 nM) at 21% O2. Conclusion Based on these results, laboratories should use the same gas mixture to realize isotopic microtest. Further studies on comparison of isotopic and non-isotopic assays are needed to establish a standardized in vitro assay protocol to survey malaria drug resistance.
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Affiliation(s)
- Sébastien Briolant
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | - Philippe Parola
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
- Service de Maladies Infectieuses et Tropicales, Hôpital Nord, Marseille, France
| | - Thierry Fusaï
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | - Marilyn Madamet-Torrentino
- Unité de Recherche en Pharmacologie et Physiopathologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | - Eric Baret
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | - Joël Mosnier
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | - Jean P Delmont
- Service de Maladies Infectieuses et Tropicales, Hôpital Nord, Marseille, France
| | - Daniel Parzy
- Unité de Recherche en Pharmacologie et Physiopathologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | | | - Christophe Rogier
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
| | - Bruno Pradines
- Unité de Recherche en Biologie et Epidémiologie Parasitaires, Institut de Médecine Tropicale du Service de Santé des Armées, Marseille, France
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Affiliation(s)
- Sandrine Cojean
- Hôpital Bichat Claude Bernard, Assistance Publique–Hôpitaux de Paris, Paris, France
- Université Paris 5, Paris, France
| | - Véronique Hubert
- Hôpital Bichat Claude Bernard, Assistance Publique–Hôpitaux de Paris, Paris, France
| | - Jacques Le Bras
- Hôpital Bichat Claude Bernard, Assistance Publique–Hôpitaux de Paris, Paris, France
- Université Paris 5, Paris, France
- Hôpital Avicenne, Bobigny, France
| | - Rémy Durand
- Hôpital Bichat Claude Bernard, Assistance Publique–Hôpitaux de Paris, Paris, France
- Hôpital Avicenne, Bobigny, France
- Université Paris 13, Bobigny, France
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Bennett TN, Patel J, Ferdig MT, Roepe PD. Plasmodium falciparum Na+/H+ exchanger activity and quinine resistance. Mol Biochem Parasitol 2007; 153:48-58. [PMID: 17353059 PMCID: PMC2747254 DOI: 10.1016/j.molbiopara.2007.01.018] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2006] [Revised: 01/29/2007] [Accepted: 01/31/2007] [Indexed: 11/19/2022]
Abstract
Mutations in the Plasmodium falciparum pfcrt gene cause resistance to the 4-amino quinoline chloroquine (CQ) and other antimalarial drugs. Mutations and/or overexpression of a P. falciparum multidrug resistance gene homologue (pfmdr1) may further modify or tailor the degree of quinoline drug resistance. Recently [Ferdig MT, Cooper RA, Mu JB, et al. Dissecting the loci of low-level quinine resistance in malaria parasites. Mol Microbiol 2004;52:985-97] QTL analysis further implicated a region of P. falciparum chromosome 13 as a partner (with pfcrt) in conferring resistance to the first quinoline-based antimalarial drug, quinine (QN). Since QN resistance (QNR) and CQR are often (but not always) observed together in parasite strains, since elevated cytosolic pH is frequently (but not always) found in CQR parasites, and since the chr 13 segment linked to QNR prominently harbors a gene encoding what appears to be a P. falciparum Na(+)/H(+) exchanger (PfNHE), we have systematically measured cytosolic pH and PfNHE activity for an extended series of parasite strains used in the QTL analysis. Altered PfNHE activity does not correlate with CQR as previously proposed, but significantly elevated PfNHE activity is found for strains with high levels of QNR, regardless their CQR status. We propose that either an elevated pH(cyt) or a higher vacuolar pH-to-cytosolic pH gradient contributes to one common route to malarial QNR that is also characterized by recently defined chr 13-chr 9 pairwise interactions. Based on sequence analysis we propose a model whereby observed polymorphisms in PfNHE may lead to altered Na(+)/H(+) set point regulation in QNR parasites.
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Affiliation(s)
- Tyler N. Bennett
- Dept. Chemistry, Dept. Biochemistry & Molecular Biology, Program in Tumor Biology, Lombardi Cancer Center, and Center for Infectious Diseases, Georgetown University, 37 and O Streets, Washington, DC 20057
| | - Jigar Patel
- Dept. Biological Sciences, University of Notre Dame, Notre Dame, IN
| | | | - Paul D. Roepe
- Dept. Chemistry, Dept. Biochemistry & Molecular Biology, Program in Tumor Biology, Lombardi Cancer Center, and Center for Infectious Diseases, Georgetown University, 37 and O Streets, Washington, DC 20057
- To whom correspondence should be addressed: tel 202 687 7300; fax 202 687 6209;
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