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Omedo I, Bartilol B, Kimani D, Gonçalves S, Drury E, Rono MK, Abdi AI, Almagro-Garcia J, Amato R, Pearson RD, Ochola-Oyier LI, Kwiatkowski D, Bejon P. Spatio-temporal distribution of antimalarial drug resistant gene mutations in a Plasmodium falciparum parasite population from Kilifi, Kenya: A 25-year retrospective study. Wellcome Open Res 2022. [DOI: 10.12688/wellcomeopenres.17656.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Background: Antimalarial drug resistance is a major obstacle to sustainable malaria control. Here we use amplicon sequencing to describe molecular markers of drug resistance in Plasmodium falciparum parasites from Kilifi county in the coastal region of Kenya over a 25-year period. Methods: We performed P. falciparum amplicon sequencing on 1162 malaria-infected blood samples collected between 1994 and 2018 to identify markers of antimalarial drug resistance in the Pfcrt, Pfdhfr, Pfdhps, Pfmdr1, Pfexo, Pfkelch13, plasmepsin 2/3, Pfarps10, Pffd, and Pfmdr2 genes. We further interrogated parasite population structure using a genetic barcode of 101 drug resistance-unrelated single nucleotide polymorphisms (SNPs) distributed across the genomes of 1245 P. falciparum parasites. Results: Two major changes occurred in the parasite population over the 25 years studied. In 1994, approximately 75% of parasites carried the marker of chloroquine resistance, CVIET. This increased to 100% in 1999 and then declined steadily, reaching 6.7% in 2018. Conversely, the quintuple mutation form of sulfadoxine-pyrimethamine resistance increased from 16.7% in 1994 to 83.6% in 2018. Several non-synonymous mutations were identified in the Kelch13 gene, although none of them are currently associated with artemisinin resistance. We observed a temporal increase in the Pfmdr1 NFD haplotype associated with lumefantrine resistance, but observed no evidence of piperaquine resistance. SNPs in other parts of the genome showed no significant temporal changes despite the marked changes in drug resistance loci over this period. Conclusions: We identified substantial changes in molecular markers of P. falciparum drug resistance over 25 years in coastal Kenya, but no associated changes in the parasite population structure.
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Ruwanpura V, Neukom J, Grietens KP, Price RN, Thriemer K, Lynch CA. Opening the policy blackbox: unravelling the process for changing national diagnostic and treatment guidelines for vivax malaria in seven countries. Malar J 2021; 20:428. [PMID: 34717642 PMCID: PMC8556862 DOI: 10.1186/s12936-021-03959-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 10/18/2021] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND The changing global health landscape has highlighted the need for more proactive, efficient and transparent health policy-making. After more than 60 years of limited development, novel tools for vivax malaria are finally available, but need to be integrated into national policies. This paper maps the malaria policy-making processes in seven endemic countries, to identify areas where it can be improved to align with best practices and optimal efficiency. METHODS Data were collected during a workshop, convened by the Asia Pacific Malaria Elimination Network's Vivax Working Group in 2019, and subsequent interviews with key stakeholders from Cambodia, Ethiopia, Indonesia, Pakistan, Papua New Guinea (PNG), Sri Lanka and Vietnam. Documentation of policy processes provided by respondents was reviewed. Data analysis was guided by an analytic framework focused on three a priori defined domains: "context," "actors" and "processes". RESULTS The context of policy-making varied with available funding for malaria, population size, socio-economic status, and governance systems. There was limited documentation of the process itself or terms of reference for involved actors. In all countries, the NMP plays a critical role in initiating and informing policy change, but the involvement of other actors varied considerably. Available evidence was described as a key influencer of policy change; however, the importance of local evidence and the World Health Organization's endorsement of new treatments and diagnostics varied. The policy process itself and its complexity varied but was mostly semi-siloed from other disease specific policy processes in the wider Ministry of Health. Time taken to change and introduce a new policy guideline previously varied from 3 months to 3 years. CONCLUSIONS In the medium to long term, a better alignment of anti-malarial policy-making processes with the overall health policy-making would strengthen health governance. In the immediate term, shortening the timelines for policy change will be pivotal to meet proposed malaria elimination milestones.
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Affiliation(s)
- Varunika Ruwanpura
- Global Health Division, Menzies School of Health Research and Charles Darwin University, PO Box 41096, Casuarina, Darwin, NT, 0811, Australia
| | | | - Koen Peeters Grietens
- Institute of Tropical Medicine, Antwerp, Belgium
- School of Tropical Medicine and Global Health, Nagasaki University, Nagasaki, Japan
| | - Ric N Price
- Global Health Division, Menzies School of Health Research and Charles Darwin University, PO Box 41096, Casuarina, Darwin, NT, 0811, Australia
- Mahidol-Oxford Tropical Medicine Research Unit (MORU), Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | - Kamala Thriemer
- Global Health Division, Menzies School of Health Research and Charles Darwin University, PO Box 41096, Casuarina, Darwin, NT, 0811, Australia.
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Roux AT, Maharaj L, Oyegoke O, Akoniyon OP, Adeleke MA, Maharaj R, Okpeku M. Chloroquine and Sulfadoxine-Pyrimethamine Resistance in Sub-Saharan Africa-A Review. Front Genet 2021; 12:668574. [PMID: 34249090 PMCID: PMC8267899 DOI: 10.3389/fgene.2021.668574] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/20/2021] [Indexed: 12/20/2022] Open
Abstract
Malaria is a great concern for global health and accounts for a large amount of morbidity and mortality, particularly in Africa, with sub-Saharan Africa carrying the greatest burden of the disease. Malaria control tools such as insecticide-treated bed nets, indoor residual spraying, and antimalarial drugs have been relatively successful in reducing the burden of malaria; however, sub-Saharan African countries encounter great challenges, the greatest being antimalarial drug resistance. Chloroquine (CQ) was the first-line drug in the 20th century until it was replaced by sulfadoxine–pyrimethamine (SP) as a consequence of resistance. The extensive use of these antimalarials intensified the spread of resistance throughout sub-Saharan Africa, thus resulting in a loss of efficacy for the treatment of malaria. SP was replaced by artemisinin-based combination therapy (ACT) after the emergence of resistance toward SP; however, the use of ACTs is now threatened by the emergence of resistant parasites. The decreased selective pressure on CQ and SP allowed for the reintroduction of sensitivity toward those antimalarials in regions of sub-Saharan Africa where they were not the primary drug for treatment. Therefore, the emergence and spread of antimalarial drug resistance should be tracked to prevent further spread of the resistant parasites, and the re-emergence of sensitivity should be monitored to detect the possible reappearance of sensitivity in sub-Saharan Africa.
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Affiliation(s)
- Alexandra T Roux
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Westville, South Africa
| | - Leah Maharaj
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Westville, South Africa
| | - Olukunle Oyegoke
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Westville, South Africa
| | - Oluwasegun P Akoniyon
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Westville, South Africa
| | - Matthew Adekunle Adeleke
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Westville, South Africa
| | - Rajendra Maharaj
- Office of Malaria Research, South African Medical Research Council, Cape Town, South Africa
| | - Moses Okpeku
- Discipline of Genetics, School of Life Sciences, University of KwaZulu-Natal, Westville, South Africa
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Ruwanpura VSH, Nowak S, Gerth‐Guyette E, Theodora M, Dysoley L, Haile M, Peeters Grietens K, Price RN, Lynch CA, Thriemer K. Further evidence needed to change policy for the safe and effective radical cure of vivax malaria: Insights from the 2019 annual APMEN Vivax Working Group meeting. ASIA & THE PACIFIC POLICY STUDIES 2021; 8:208-242. [PMID: 34820128 PMCID: PMC8596681 DOI: 10.1002/app5.314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 06/19/2020] [Accepted: 06/30/2020] [Indexed: 06/01/2023]
Abstract
New diagnostics and treatment options for the radical cure of Plasmodium vivax malaria are now available. At the 2019 annual meeting of the Vivax Working Group of the Asia Pacific Malaria Elimination Network, participants took part in a roundtable discussion to identify further evidence required to introduce these new tools into policy and practice. Key gaps identified were accuracy and reliability of glucose-6-phosphate-dehydrogenase deficiency tests, health system capacity, and feasibility and cost effectiveness of novel treatment strategies in routine clinical practice. As expected, there were differences in the priorities between country partners and researcher partners. To achieve the 2030 target for the regional elimination of malaria, evidence to address these issues should be generated as a matter of priority. Review of global guidelines alongside locally generated data will help to ensure the timely revision and optimisation of national treatment guidelines that will be vital to meet regional elimination goals.
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Affiliation(s)
| | | | | | | | - Lek Dysoley
- National Centre for Parasitology, Entomology and Malaria ControlCambodia
- School of Public HealthNational Institute of Public HealthCambodia
| | - Mebratom Haile
- National Malaria Control and Elimination Program, Disease Prevention and Control DirectorateFederal Ministry of HealthEthiopia
| | - Koen Peeters Grietens
- Institute of Tropical MedicineAntwerpBelgium
- School of Tropical Medicine and Global HealthNagasaki UniversityNagasakiJapan
| | - Ric Norman Price
- Global and Tropical Health DivisionMenzies School of Health Research and Charles Darwin UniversityDarwinAustralia
- Mahidol‐Oxford Tropical Medicine Research Unit, Faculty of Tropical MedicineMahidol UniversityBangkokThailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical MedicineUniversity of OxfordOxfordUK
| | - Caroline Anita Lynch
- Medicines for Malaria VentureGenevaSwitzerland
- Faculty of Epidemiology and Population HealthLondon School of Tropical Medicine and HygieneLondonUK
| | - Kamala Thriemer
- Global and Tropical Health DivisionMenzies School of Health Research and Charles Darwin UniversityDarwinAustralia
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Macharia PM, Joseph NK, Sartorius B, Snow RW, Okiro EA. Subnational estimates of factors associated with under-five mortality in Kenya: a spatio-temporal analysis, 1993-2014. BMJ Glob Health 2021; 6:e004544. [PMID: 33858833 PMCID: PMC8054106 DOI: 10.1136/bmjgh-2020-004544] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 03/26/2021] [Accepted: 03/27/2021] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND To improve child survival, it is necessary to describe and understand the spatial and temporal variation of factors associated with child survival beyond national aggregates, anchored at decentralised health planning units. Therefore, we aimed to provide subnational estimates of factors associated with child survival while elucidating areas of progress, stagnation and decline in Kenya. METHODS Twenty household surveys and three population censuses conducted since 1989 were assembled and spatially aligned to 47 subnational Kenyan county boundaries. Bayesian spatio-temporal Gaussian process regression models accounting for inadequate sample size and spatio-temporal relatedness were fitted for 43 factors at county level between 1993 and 2014. RESULTS Nationally, the coverage and prevalence were highly variable with 38 factors recording an improvement. The absolute percentage change (1993-2014) was heterogeneous ranging between 1% and 898%. At the county level, the estimates varied across space and over time with a majority showing improvements after 2008 which was preceded by a period of deterioration (late-1990 to early-2000). Counties in Northern Kenya were consistently observed to have lower coverage of interventions and remained disadvantaged in 2014 while areas around Central Kenya had and historically have had higher coverage across all intervention domains. Most factors in Western and South-East Kenya recorded moderate intervention coverage although having a high infection prevalence of both HIV and malaria. CONCLUSION The heterogeneous estimates necessitates prioritisation of the marginalised counties to achieve health equity and improve child survival uniformly across the country. Efforts are required to narrow the gap between counties across all the drivers of child survival. The generated estimates will facilitate improved benchmarking and establish a baseline for monitoring child development goals at subnational level.
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Affiliation(s)
- Peter M Macharia
- Population Health Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Noel K Joseph
- Population Health Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Benn Sartorius
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Department of Health Metrics Sciences, School of Medicine, University of Washington, Seattle, WA, USA
| | - Robert W Snow
- Population Health Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Emelda A Okiro
- Population Health Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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Pacheco MA, Schneider KA, Cheng Q, Munde EO, Ndege C, Onyango C, Raballah E, Anyona SB, Ouma C, Perkins DJ, Escalante AA. Changes in the frequencies of Plasmodium falciparum dhps and dhfr drug-resistant mutations in children from Western Kenya from 2005 to 2018: the rise of Pfdhps S436H. Malar J 2020; 19:378. [PMID: 33092587 PMCID: PMC7583259 DOI: 10.1186/s12936-020-03454-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/18/2020] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Sulfadoxine-pyrimethamine (SP) is the only anti-malarial drug formulation approved for intermittent preventive treatment in pregnancy (IPTp). However, mutations in the Plasmodium falciparum dhfr (Pfdhfr) and dhps (Pfdhps) genes confer resistance to pyrimethamine and sulfadoxine, respectively. Here, the frequencies of SP resistance-associated mutations from 2005 to 2018 were compared in samples from Kenyan children with malaria residing in a holoendemic transmission region. METHODS Partial sequences of the Pfdhfr and Pfdhps genes were amplified and sequenced from samples collected in 2005 (n = 81), 2010 (n = 95), 2017 (n = 43), and 2018 (n = 55). The frequency of known mutations conferring resistance to pyrimethamine and sulfadoxine were estimated and compared. Since artemisinin-based combination therapy (ACT) is the current first-line treatment for malaria, the presence of mutations in the propeller domain of P. falciparum kelch13 gene (Pfk13) linked to ACT-delayed parasite clearance was studied in the 2017/18 samples. RESULTS Among other changes, the point mutation of Pfdhps S436H increased in frequency from undetectable in 2005 to 28% in 2017/18. Triple Pfdhfr mutant allele (CIRNI) increased in frequency from 84% in 2005 to 95% in 2017/18, while the frequency of Pfdhfr double mutant alleles declined (allele CICNI from 29% in 2005 to 6% in 2017/18, and CNRNI from 9% in 2005 to undetectable in 2010 and 2017/18). Thus, a multilocus Pfdhfr/Pfdhps genotype with six mutations (HGEAA/CIRNI), including Pfdhps S436H, increased in frequency from 2010 to 2017/18. Although none of the mutations associated with ACT-delayed parasite clearance was observed, the Pfk13 mutation A578S, the most widespread Pfk13 SNP found in Africa, was detected in low frequency (2.04%). CONCLUSIONS There were changes in SP resistance mutant allele frequencies, including an increase in the Pfdhps S436H. Although these patterns seem consistent with directional selection due to drug pressure, there is a lack of information to determine the actual cause of such changes. These results suggest incorporating molecular surveillance of Pfdhfr/Pfdhps mutations in the context of SP efficacy studies for intermittent preventive treatment in pregnancy (IPTp).
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Affiliation(s)
- M Andreína Pacheco
- Biology Department/Institute of Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, PA, USA
| | - Kristan A Schneider
- Department of Applied Computer and Biosciences, University of Applied Sciences Mittweida, Technikumplatz, Mittweida, Germany
| | - Qiuying Cheng
- Center for Global Health, University of New Mexico Health Sciences Center, Albuquerque, NM, USA
| | - Elly O Munde
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Clinical Medicine, School of Health Sciences, Kirinyaga University, Kerugoya, Kenya
| | - Caroline Ndege
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Biomedical Sciences and Technology, Maseno University, Maseno, Kenya
| | - Clinton Onyango
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Biomedical Sciences and Technology, Maseno University, Maseno, Kenya
| | - Evans Raballah
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Medical Laboratory Sciences, School of Public Health, Biomedical Sciences and Technology, Masinde Muliro University of Science and Technology, Kakamega, Kenya
| | - Samuel B Anyona
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Medical Biochemistry, School of Medicine, Maseno University, Maseno, Kenya
| | - Collins Ouma
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya
- Department of Biomedical Sciences and Technology, Maseno University, Maseno, Kenya
| | - Douglas J Perkins
- Center for Global Health, University of New Mexico Health Sciences Center, Albuquerque, NM, USA.
- University of New Mexico-Kenya Global Health Programs, Kisumu, Siaya, Kenya.
| | - Ananias A Escalante
- Biology Department/Institute of Genomics and Evolutionary Medicine (iGEM), Temple University, Philadelphia, PA, USA.
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Lingani M, Bonkian LN, Yerbanga I, Kazienga A, Valéa I, Sorgho H, Ouédraogo JB, Mens PF, Schallig HDFH, Ravinetto R, d'Alessandro U, Tinto H. In vivo/ex vivo efficacy of artemether-lumefantrine and artesunate-amodiaquine as first-line treatment for uncomplicated falciparum malaria in children: an open label randomized controlled trial in Burkina Faso. Malar J 2020; 19:8. [PMID: 31906948 PMCID: PMC6945612 DOI: 10.1186/s12936-019-3089-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 12/25/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Artemisinin-based combination therapy (ACT) is recommended to improve malaria treatment efficacy and limit drug-resistant parasites selection in malaria endemic areas. 5 years after they were adopted, the efficacy and safety of artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ), the first-line treatments for uncomplicated malaria were assessed in Burkina Faso. METHODS In total, 440 children with uncomplicated Plasmodium falciparum malaria were randomized to receive either AL or ASAQ for 3 days and were followed up weekly for 42 days. Blood samples were collected to investigate the ex vivo susceptibility of P. falciparum isolates to lumefantrine, dihydroartemisinin (the active metabolite of artemisinin derivatives) and monodesethylamodiaquine (the active metabolite of amodiaquine). The modified isotopic micro test technique was used to determine the 50% inhibitory concentration (IC50) values. Primary endpoints were the risks of treatment failure at days 42. RESULTS Out of the 440 patients enrolled, 420 (95.5%) completed the 42 days follow up. The results showed a significantly higher PCR unadjusted cure rate in ASAQ arm (71.0%) than that in the AL arm (49.8%) on day 42, and this trend was similar after correction by PCR, with ASAQ performing better (98.1%) than AL (91.1%). Overall adverse events incidence was low and not significantly different between the two treatment arms. Ex vivo results showed that 6.4% P. falciparum isolates were resistant to monodesthylamodiaquine. The coupled in vivo/ex vivo analysis showed increased IC50 values for lumefantrine and monodesethylamodiaquine at day of recurrent parasitaemia compared to baseline values while for artesunate, IC50 values remained stable at baseline and after treatment failure (p > 0.05). CONCLUSION These findings provide substantial evidence that AL and ASAQ are highly efficacious for the treatment of uncomplicated malaria in children in Burkina Faso. However, the result of P. falciparum susceptibility to the partner drugs advocates the need to regularly replicate such surveillance studies. This would be particularly indicated when amodiaquine is associated in seasonal malaria chemoprophylaxis (SMC) mass drug administration in children under 5 years in Burkina Faso. Trial registration clinicaltrials, NCT00808951. Registered 05 December 2008,https://clinicaltrials.gov/ct2/show/NCT00808951?cond=NCT00808951&rank=1.
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Affiliation(s)
- Moussa Lingani
- Institut de Recherche en Sciences de la Santé/Direction Régionale du Centre Ouest (IRSS/DRCO), Nanoro, Burkina Faso. .,Unité de Recherche Clinique de Nanoro (URCN), Nanoro, Burkina Faso. .,École de Santé Publique, Université Libre de Bruxelles, CP594, Route de Lennik 808, 1070, Bruxelles, Belgique.
| | - Léa Nadège Bonkian
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Isidore Yerbanga
- Unité de Recherche Clinique de Nanoro (URCN), Nanoro, Burkina Faso
| | - Adama Kazienga
- Unité de Recherche Clinique de Nanoro (URCN), Nanoro, Burkina Faso
| | - Innocent Valéa
- Institut de Recherche en Sciences de la Santé/Direction Régionale du Centre Ouest (IRSS/DRCO), Nanoro, Burkina Faso.,Unité de Recherche Clinique de Nanoro (URCN), Nanoro, Burkina Faso
| | - Hermann Sorgho
- Institut de Recherche en Sciences de la Santé/Direction Régionale du Centre Ouest (IRSS/DRCO), Nanoro, Burkina Faso.,Unité de Recherche Clinique de Nanoro (URCN), Nanoro, Burkina Faso
| | - Jean Bosco Ouédraogo
- Institut de Recherche en Sciences de la Santé/Direction Régionale du Centre Ouest (IRSS/DRCO), Nanoro, Burkina Faso
| | - Petronella Francisca Mens
- Department of Medical Microbiology, Experimental Parasitology Unit, Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam, Amsterdam, The Netherlands
| | - Henk D F H Schallig
- Department of Medical Microbiology, Experimental Parasitology Unit, Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam, Amsterdam, The Netherlands
| | | | - Umberto d'Alessandro
- Medical Research Council Unit, The Gambia, Disease Control & Elimination Theme, Fajara, The Gambia
| | - Halidou Tinto
- Institut de Recherche en Sciences de la Santé/Direction Régionale du Centre Ouest (IRSS/DRCO), Nanoro, Burkina Faso.,Unité de Recherche Clinique de Nanoro (URCN), Nanoro, Burkina Faso
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No evidence of P. falciparum K13 artemisinin conferring mutations over a 24-year analysis in Coastal Kenya, but a near complete reversion to chloroquine wild type parasites. Antimicrob Agents Chemother 2019:AAC.01067-19. [PMID: 31591113 PMCID: PMC6879256 DOI: 10.1128/aac.01067-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Antimalarial drug resistance is a substantial impediment to malaria control. The spread of resistance has been described using genetic markers, which are important epidemiological tools. We carried out a temporal analysis of changes in allele frequencies of 12 drug resistance markers over 2 decades of changing antimalarial drug policy in Kenya. Antimalarial drug resistance is a substantial impediment to malaria control. The spread of resistance has been described using genetic markers, which are important epidemiological tools. We carried out a temporal analysis of changes in allele frequencies of 12 drug resistance markers over 2 decades of changing antimalarial drug policy in Kenya. We did not detect any of the validated kelch 13 (k13) artemisinin resistance markers; nonetheless, a single k13 allele, K189T, was maintained at a stable high frequency (>10%) over time. There was a distinct shift from chloroquine-resistant transporter (crt)-76, multidrug-resistant gene 1 (mdr1)-86 and mdr1-1246 chloroquine (CQ) resistance alleles to a 99% prevalence of CQ-sensitive alleles in the population, following the withdrawal of CQ from routine use. In contrast, the dihydropteroate synthetase (dhps) double mutant (437G and 540E) associated with sulfadoxine-pyrimethamine (SP) resistance was maintained at a high frequency (>75%), after a change from SP to artemisinin combination therapies (ACTs). The novel cysteine desulfurase (nfs) K65 allele, implicated in resistance to lumefantrine in a West African study, showed a gradual significant decline in allele frequency pre- and post-ACT introduction (from 38% to 20%), suggesting evidence of directional selection in Kenya, potentially not due to lumefantrine. The high frequency of CQ-sensitive parasites circulating in the population suggests that the reintroduction of CQ in combination therapy for the treatment of malaria can be considered in the future. However, the risk of a reemergence of CQ-resistant parasites circulating below detectable levels or being reintroduced from other regions remains.
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Muiruri P, Juma DW, Ingasia LA, Chebon LJ, Opot B, Ngalah BS, Cheruiyot J, Andagalu B, Akala HM, Nyambati VCS, Ng'ang'a JK, Kamau E. Selective sweeps and genetic lineages of Plasmodium falciparum multi-drug resistance (pfmdr1) gene in Kenya. Malar J 2018; 17:398. [PMID: 30376843 PMCID: PMC6208105 DOI: 10.1186/s12936-018-2534-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 10/20/2018] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND There are concerns that resistance to artemisinin-based combination therapy might emerge in Kenya and sub-Saharan Africa (SSA) in the same pattern as was with chloroquine and sulfadoxine-pyrimethamine. Single nucleotide polymorphisms (SNPs) in critical alleles of pfmdr1 gene have been associated with resistance to artemisinin and its partner drugs. Microsatellite analysis of loci flanking genes associated with anti-malarial drug resistance has been used in defining the geographic origins, dissemination of resistant parasites and identifying regions in the genome that have been under selection. METHODS This study set out to investigate evidence of selective sweep and genetic lineages in pfmdr1 genotypes associated with the use of artemether-lumefantrine (AL), as the first-line treatment in Kenya. Parasites (n = 252) from different regions in Kenya were assayed for SNPs at codons 86, 184 and 1246 and typed for 7 neutral microsatellites and 13 microsatellites loci flanking (± 99 kb) pfmdr1 in Plasmodium falciparum infections. RESULTS The data showed differential site and region specific prevalence of SNPs associated with drug resistance in the pfmdr1 gene. The prevalence of pfmdr1 N86, 184F, and D1246 in western Kenya (Kisumu, Kericho and Kisii) compared to the coast of Kenya (Malindi) was 92.9% vs. 66.7%, 53.5% vs. to 24.2% and 96% vs. to 87.9%, respectively. The NFD haplotype which is consistent with AL selection was at 51% in western Kenya compared to 25% in coastal Kenya. CONCLUSION Selection pressures were observed to be different in different regions of Kenya, especially the western region compared to the coastal region. The data showed independent genetic lineages for all the pfmdr1 alleles. The evidence of soft sweeps in pfmdr1 observed varied in direction from one region to another. This is challenging for malaria control programs in SSA which clearly indicate effective malaria control policies should be based on the region and not at a country wide level.
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Affiliation(s)
- Peninah Muiruri
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
- Department of Biochemistry, School of Biomedical Sciences, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000, 00200, Nairobi, Kenya
| | - Denis W Juma
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
| | - Luicer A Ingasia
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
| | - Lorna J Chebon
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
| | - Benjamin Opot
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
| | - Bidii S Ngalah
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
| | - Jelagat Cheruiyot
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
| | - Ben Andagalu
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
| | - Hoseah M Akala
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya
| | - Venny C S Nyambati
- Department of Biochemistry, School of Biomedical Sciences, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000, 00200, Nairobi, Kenya
| | - Joseph K Ng'ang'a
- Department of Biochemistry, School of Biomedical Sciences, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000, 00200, Nairobi, Kenya
| | - Edwin Kamau
- Global Emerging Infections Surveillance Program, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute, P.O. Box 54, 40100, Kisumu, Kenya.
- Walter Reed National Military Medical Center, Bethesda, Maryland, USA.
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10
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Macharia PM, Giorgi E, Noor AM, Waqo E, Kiptui R, Okiro EA, Snow RW. Spatio-temporal analysis of Plasmodium falciparum prevalence to understand the past and chart the future of malaria control in Kenya. Malar J 2018; 17:340. [PMID: 30257697 PMCID: PMC6158896 DOI: 10.1186/s12936-018-2489-9] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2018] [Accepted: 09/21/2018] [Indexed: 09/29/2023] Open
Abstract
BACKGROUND Spatial and temporal malaria risk maps are essential tools to monitor the impact of control, evaluate priority areas to reorient intervention approaches and investments in malaria endemic countries. Here, the analysis of 36 years data on Plasmodium falciparum prevalence is used to understand the past and chart a future for malaria control in Kenya by confidently highlighting areas within important policy relevant thresholds to allow either the revision of malaria strategies to those that support pre-elimination or those that require additional control efforts. METHODS Plasmodium falciparum parasite prevalence (PfPR) surveys undertaken in Kenya between 1980 and 2015 were assembled. A spatio-temporal geostatistical model was fitted to predict annual malaria risk for children aged 2-10 years (PfPR2-10) at 1 × 1 km spatial resolution from 1990 to 2015. Changing PfPR2-10 was compared against plausible explanatory variables. The fitted model was used to categorize areas with varying degrees of prediction probability for two important policy thresholds PfPR2-10 < 1% (non-exceedance probability) or ≥ 30% (exceedance probability). RESULTS 5020 surveys at 3701 communities were assembled. Nationally, there was an 88% reduction in the mean modelled PfPR2-10 from 21.2% (ICR: 13.8-32.1%) in 1990 to 2.6% (ICR: 1.8-3.9%) in 2015. The most significant decline began in 2003. Declining prevalence was not equal across the country and did not directly coincide with scaled vector control coverage or changing therapeutics. Over the period 2013-2015, of Kenya's 47 counties, 23 had an average PfPR2-10 of < 1%; four counties remained ≥ 30%. Using a metric of 80% probability, 8.5% of Kenya's 2015 population live in areas with PfPR2-10 ≥ 30%; while 61% live in areas where PfPR2-10 is < 1%. CONCLUSIONS Kenya has made substantial progress in reducing the prevalence of malaria over the last 26 years. Areas today confidently and consistently with < 1% prevalence require a revised approach to control and a possible consideration of strategies that support pre-elimination. Conversely, there remains several intractable areas where current levels and approaches to control might be inadequate. The modelling approaches presented here allow the Ministry of Health opportunities to consider data-driven model certainty in defining their future spatial targeting of resources.
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Affiliation(s)
- Peter M Macharia
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya.
| | - Emanuele Giorgi
- Lancaster Medical School, Lancaster University, Lancaster, UK
| | - Abdisalan M Noor
- Global Malaria Programme, World Health Organization, Geneva, Switzerland
| | - Ejersa Waqo
- National Malaria Control Programme, Ministry of Health, Nairobi, Kenya
| | - Rebecca Kiptui
- National Malaria Control Programme, Ministry of Health, Nairobi, Kenya
| | - Emelda A Okiro
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Robert W Snow
- Population Health Unit, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
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Genetically Determined Response to Artemisinin Treatment in Western Kenyan Plasmodium falciparum Parasites. PLoS One 2016; 11:e0162524. [PMID: 27611315 PMCID: PMC5017781 DOI: 10.1371/journal.pone.0162524] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/24/2016] [Indexed: 12/16/2022] Open
Abstract
Genetically determined artemisinin resistance in Plasmodium falciparum has been described in Southeast Asia. The relevance of recently described Kelch 13-propeller mutations for artemisinin resistance in Sub-Saharan Africa parasites is still unknown. Southeast Asia parasites have low genetic diversity compared to Sub-Saharan Africa, where parasites are highly genetically diverse. This study attempted to elucidate whether genetics provides a basis for discovering molecular markers in response to artemisinin drug treatment in P. falciparum in Kenya. The genetic diversity of parasites collected pre- and post- introduction of artemisinin combination therapy (ACT) in western Kenya was determined. A panel of 12 microsatellites and 91 single nucleotide polymorphisms (SNPs) distributed across the P. falciparum genome were genotyped. Parasite clearance rates were obtained for the post-ACT parasites. The 12 microsatellites were highly polymorphic with post-ACT parasites being significantly more diverse compared to pre-ACT (p < 0.0001). The median clearance half-life was 2.55 hours for the post-ACT parasites. Based on SNP analysis, 15 of 90 post-ACT parasites were single-clone infections. Analysis revealed 3 SNPs that might have some causal association with parasite clearance rates. Further, genetic analysis using Bayesian tree revealed parasites with similar clearance phenotypes were more closely genetically related. With further studies, SNPs described here and genetically determined response to artemisinin treatment might be useful in tracking artemisinin resistance in Kenya.
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12
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Mwendera C, de Jager C, Longwe H, Phiri K, Hongoro C, Mutero CM. Malaria research and its influence on anti-malarial drug policy in Malawi: a case study. Health Res Policy Syst 2016; 14:41. [PMID: 27246503 PMCID: PMC4888534 DOI: 10.1186/s12961-016-0108-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 04/28/2016] [Indexed: 11/30/2022] Open
Abstract
Background In 1993, Malawi changed its first-line anti-malarial treatment for uncomplicated malaria from chloroquine to sulfadoxine-pyrimethamine (SP), and in 2007, it changed from SP to lumefantrine-artemether. The change in 1993 raised concerns about whether it had occurred timely and whether it had potentially led to early development of Plasmodium falciparum resistance to SP. This case study examined evidence from Malawi in order to assess if the policy changes were justifiable and supported by evidence. Methods A systematic review of documents and published evidence between 1984 and 1993, when chloroquine was the first-line drug, and 1994 and 2007, when SP was the first-line drug, was conducted herein. The review was accompanied with key informant interviews. Results A total of 1287 publications related to malaria drug policy changes in sub-Saharan Africa were identified. Using the inclusion criteria, four articles from 1984 to 1993 and eight articles from 1994 to 2007 were reviewed. Between 1984 and 1993, three studies reported on chloroquine poor efficacy prompting policy change according to WHO’s recommendation. From 1994 to 2007, four studies conducted in the early years of policy change reported a high SP efficacy of above 80%, retaining it as a first-line drug. Unpublished sentinel site studies between 2005 and 2007 showed a reduced efficacy of SP, influencing policy change to lumefantrine-artemether. The views of key informants indicate that the switch from chloroquine to SP was justified based on local evidence despite unavailability of WHO’s policy recommendations, while the switch to lumefantrine-artemether was uncomplicated as the country was following the recommendations from WHO. Conclusion Ample evidence from Malawi influenced and justified the policy changes. Therefore, locally generated evidence is vital for decision making during policy change.
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Affiliation(s)
- Chikondi Mwendera
- University of Pretoria Centre for Sustainable Malaria Control (UP CSMC), School of Health Systems and Public Health (SHSPH), University of Pretoria, Private Bag X363, Pretoria, 0001, South Africa
| | - Christiaan de Jager
- University of Pretoria Centre for Sustainable Malaria Control (UP CSMC), School of Health Systems and Public Health (SHSPH), University of Pretoria, Private Bag X363, Pretoria, 0001, South Africa.
| | - Herbert Longwe
- Department of Basic Medical Sciences, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Kamija Phiri
- School of Public Health and Family Medicine, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Charles Hongoro
- University of Pretoria Centre for Sustainable Malaria Control (UP CSMC), School of Health Systems and Public Health (SHSPH), University of Pretoria, Private Bag X363, Pretoria, 0001, South Africa.,Population Health, Health Systems and Innovation, Human Sciences Research Council (HSRC), Pretoria, South Africa
| | - Clifford M Mutero
- University of Pretoria Centre for Sustainable Malaria Control (UP CSMC), School of Health Systems and Public Health (SHSPH), University of Pretoria, Private Bag X363, Pretoria, 0001, South Africa.,International Centre of Insect Physiology and Ecology, Nairobi, Kenya
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13
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Targeting vivax malaria in the Asia Pacific: The Asia Pacific Malaria Elimination Network Vivax Working Group. Malar J 2015; 14:484. [PMID: 26627892 PMCID: PMC4667409 DOI: 10.1186/s12936-015-0958-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 10/21/2015] [Indexed: 11/17/2022] Open
Abstract
The Asia Pacific Malaria Elimination Network (APMEN) is a collaboration of 18 country partners committed to eliminating malaria from within their borders. Over the past 5 years, APMEN has helped to build the knowledge, tools and in-country technical expertise required to attain this goal. At its inaugural meeting in Brisbane in 2009, Plasmodium vivax infections were identified across the region as a common threat to this ambitious programme; the APMEN Vivax Working Group was established to tackle specifically this issue. The Working Group developed a four-stage strategy to identify knowledge gaps, build regional consensus on shared priorities, generate evidence and change practice to optimize malaria elimination activities. This case study describes the issues faced and the solutions found in developing this robust strategic partnership between national programmes and research partners within the Working Group. The success of the approach adopted by the group may facilitate similar applications in other regions seeking to deploy evidence-based policy and practice.
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Affiliation(s)
- The Vivax Working Group
- The APMEN Vivax Working Group, Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, NT 0810 Australia
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14
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Kiarie WC, Wangai L, Agola E, Kimani FT, Hungu C. Chloroquine sensitivity: diminished prevalence of chloroquine-resistant gene marker pfcrt-76 13 years after cessation of chloroquine use in Msambweni, Kenya. Malar J 2015; 14:328. [PMID: 26296743 PMCID: PMC4546357 DOI: 10.1186/s12936-015-0850-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Accepted: 08/16/2015] [Indexed: 11/10/2022] Open
Abstract
Background Plasmodium falciparum resistance to chloroquine (CQ) denied healthcare providers access to a cheap and effective anti-malarial drug. Resistance has been proven to be due to point mutations on the parasite’s pfcrt gene, particularly on codon 76, resulting in an amino acid change from lysine to threonine. This study sought to determine the prevalence of the pfcrt K76T mutation 13 years after CQ cessation in Msambweni, Kenya. Methods Finger-prick whole blood was collected on 3MM Whatman® filter paper from 99 falciparum malaria patients. Parasite DNA was extracted via the Chelex method from individual blood spots and used as template in nested PCR amplification of pfcrt. Apo1 restriction enzyme was used to digest the amplified DNA to identify the samples as wild type or sensitive at codon 76. Prevalence figures of the mutant pfcrt 76T gene were calculated by dividing the number of samples bearing the mutant gene with the total number of samples multiplied by 100 %. Chi square tests were used to test the significance of the findings against previous prevalence figures. Results Out of 99 clinical samples collected in 2013, prevalence of the mutant pfcrt 76T gene stood at 41 %. Conclusion The results indicate a significant [χ2 test, P ≤ 0.05 (2006 vs 2013)] reversal to sensitivity by the P. falciparum population in the study site compared to the situation reported in 2006 at the same study site. This could primarily be driven by diminished use of CQ in the study area in line with the official policy. Studies to establish prevalence of the pfcrt 76T gene could be expanded countrywide to establish the CQ sensitivity status and predict a date when CQ may be re-introduced as part of malaria chemotherapy.
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Affiliation(s)
- William Chege Kiarie
- Institute of Tropical Medicine and Infectious Diseases (ITROMID), PO Box 54840-00200, Nairobi, Kenya. .,Kenya Medical Research Institute, Centre for Biotechnology Research and Development (KEMRI, CBRD), PO Box 54840-00200, Nairobi, Kenya.
| | - Laura Wangai
- School of Health Sciences, Kirinyaga University College (Constituent College of JKUAT), P.O. Box 143-10300, Kerugoya, Kenya.
| | - Eric Agola
- Kenya Medical Research Institute, Centre for Biotechnology Research and Development (KEMRI, CBRD), PO Box 54840-00200, Nairobi, Kenya.
| | - Francis T Kimani
- Kenya Medical Research Institute, Centre for Biotechnology Research and Development (KEMRI, CBRD), PO Box 54840-00200, Nairobi, Kenya.
| | - Charity Hungu
- Kenya Medical Research Institute, Centre for Biotechnology Research and Development (KEMRI, CBRD), PO Box 54840-00200, Nairobi, Kenya.
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15
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Achieng AO, Muiruri P, Ingasia LA, Opot BH, Juma DW, Yeda R, Ngalah BS, Ogutu BR, Andagalu B, Akala HM, Kamau E. Temporal trends in prevalence of Plasmodium falciparum molecular markers selected for by artemether-lumefantrine treatment in pre-ACT and post-ACT parasites in western Kenya. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2015; 5:92-9. [PMID: 26236581 PMCID: PMC4501530 DOI: 10.1016/j.ijpddr.2015.05.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 05/27/2015] [Accepted: 05/28/2015] [Indexed: 01/17/2023]
Abstract
Artemether–lumefantrine (AL) became the first-line treatment for uncomplicated malaria in Kenya in 2006. Studies have shown AL selects for SNPs in pfcrt and pfmdr1 genes in recurring parasites compared to the baseline infections. The genotypes associated with AL selection are K76 in pfcrt and N86, 184F and D1246 in pfmdr1. To assess the temporal change of these genotypes in western Kenya, 47 parasite isolates collected before (pre-ACT; 1995–2003) and 745 after (post-ACT; 2008–2014) introduction of AL were analyzed. In addition, the associations of parasite haplotype against the IC50 of artemether and lumefantrine, and clearance rates were determined. Parasite genomic DNA collected between 1995 and 2014 was analyzed by sequencing or PCR-based single-base extension on Sequenom MassARRAY. IC50s were determined for a subset of the samples. One hundred eighteen samples from 2013 to 2014 were from an efficacy trial of which 68 had clearance half-lives. Data revealed there were significant differences between pre-ACT and post-ACT genotypes at the four codons (chi-square analysis; p < 0.0001). The prevalence of pfcrt K76 and N86 increased from 6.4% in 1995–1996 to 93.2% in 2014 and 0.0% in 2002–2003 to 92.4% in 2014 respectively. Analysis of parasites carrying pure alleles of K + NFD or T + YYY haplotypes revealed that 100.0% of the pre-ACT parasites carried T + YYY and 99.3% of post-ACT parasites carried K + NFD. There was significant correlation (p = 0.04) between lumefantrine IC50 and polymorphism at pfmdr1 codon 184. There was no difference in parasite clearance half-lives based on genetic haplotype profiles. This study shows there is a significant change in parasite genotype, with key molecular determinants of AL selection almost reaching saturation. The implications of these findings are not clear since AL remains highly efficacious. However, there is need to closely monitor parasite genotypic, phenotypic and clinical dynamics in response to continued use of AL in western Kenya. The prevalence of pfcrt K76 increased from 6.4% in 1995 to 93.2% in 2014 and pfmdr1 N86 from 0% in 2002 to 92.4% in 2014. 100% of pre-ACTs parasites carried T+YYY haplotype whereas 99.3% post-ACTs parasites carried K+NFD haplotype. There is resurgence of chloroquine sensitive parasite in western Kenya. AL is still highly efficacious but there are drastic genetic changes taking place in the parasite population.
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Affiliation(s)
- Angela O Achieng
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
| | - Peninah Muiruri
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya ; Department of Biochemistry, College of Health Sciences, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Luicer A Ingasia
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
| | - Benjamin H Opot
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
| | - Dennis W Juma
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
| | - Redemptah Yeda
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
| | - Bidii S Ngalah
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya ; Institute of Tropical Medicine and Infectious Diseases, College of Health Sciences, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
| | - Bernhards R Ogutu
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
| | - Ben Andagalu
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
| | - Hoseah M Akala
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
| | - Edwin Kamau
- Department of Emerging Infectious Diseases, United States Army Medical Research Unit-Kenya/Kenya Medical Research Institute, Kisumu, Kenya
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16
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Snow RW, Kibuchi E, Karuri SW, Sang G, Gitonga CW, Mwandawiro C, Bejon P, Noor AM. Changing Malaria Prevalence on the Kenyan Coast since 1974: Climate, Drugs and Vector Control. PLoS One 2015; 10:e0128792. [PMID: 26107772 PMCID: PMC4479373 DOI: 10.1371/journal.pone.0128792] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/30/2015] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Progress toward reducing the malaria burden in Africa has been measured, or modeled, using datasets with relatively short time-windows. These restricted temporal analyses may miss the wider context of longer-term cycles of malaria risk and hence may lead to incorrect inferences regarding the impact of intervention. METHODS 1147 age-corrected Plasmodium falciparum parasite prevalence (PfPR2-10) surveys among rural communities along the Kenyan coast were assembled from 1974 to 2014. A Bayesian conditional autoregressive generalized linear mixed model was used to interpolate to 279 small areas for each of the 41 years since 1974. Best-fit polynomial splined curves of changing PfPR2-10 were compared to a sequence of plausible explanatory variables related to rainfall, drug resistance and insecticide-treated bed net (ITN) use. RESULTS P. falciparum parasite prevalence initially rose from 1974 to 1987, dipped in 1991-92 but remained high until 1998. From 1998 onwards prevalence began to decline until 2011, then began to rise through to 2014. This major decline occurred before ITNs were widely distributed and variation in rainfall coincided with some, but not all, short-term transmission cycles. Emerging resistance to chloroquine and introduction of sulfadoxine/pyrimethamine provided plausible explanations for the rise and fall of malaria transmission along the Kenyan coast. CONCLUSIONS Progress towards elimination might not be as predictable as we would like, where natural and extrinsic cycles of transmission confound evaluations of the effect of interventions. Deciding where a country lies on an elimination pathway requires careful empiric observation of the long-term epidemiology of malaria transmission.
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Affiliation(s)
- Robert W. Snow
- Spatial Health Metrics Group, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine & Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Eliud Kibuchi
- Spatial Health Metrics Group, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Stella W. Karuri
- Spatial Health Metrics Group, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Gilbert Sang
- Spatial Health Metrics Group, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Caroline W. Gitonga
- Spatial Health Metrics Group, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
| | - Charles Mwandawiro
- Eastern and Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya
| | - Philip Bejon
- Centre for Tropical Medicine & Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
- Centre for Geographic Medicine-Coast, KEMRI-Wellcome Trust programme, Kilifi, Kenya
| | - Abdisalan M. Noor
- Spatial Health Metrics Group, Kenya Medical Research Institute-Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine & Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
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Okombo J, Kamau AW, Marsh K, Sutherland CJ, Ochola-Oyier LI. Temporal trends in prevalence of Plasmodium falciparum drug resistance alleles over two decades of changing antimalarial policy in coastal Kenya. Int J Parasitol Drugs Drug Resist 2014; 4:152-63. [PMID: 25516825 PMCID: PMC4266795 DOI: 10.1016/j.ijpddr.2014.07.003] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 07/16/2014] [Accepted: 07/17/2014] [Indexed: 12/17/2022]
Abstract
Molecular surveillance of drug resistance markers through time provides crucial information on genomic adaptations, especially in parasite populations exposed to changing drug pressures. To assess temporal trends of established genotypes associated with tolerance to clinically important antimalarials used in Kenya over the last two decades, we sequenced a region of the pfcrt locus encompassing codons 72-76 of the Plasmodium falciparum chloroquine resistance transporter, full-length pfmdr1 - encoding multi-drug resistance protein, P-glycoprotein homolog (Pgh1) and pfdhfr encoding dihydrofolate reductase, in 485 archived Plasmodium falciparum positive blood samples collected in coastal Kenya at four different time points between 1995 and 2013. Microsatellite loci were also analyzed to compare the genetic backgrounds of parasite populations circulating before and after the withdrawal of chloroquine and sulfadoxine/pyrimethamine. Our results reveal a significant increase in the prevalence of the pfcrt K76 wild-type allele between 1995 and 2013 from 38% to 81.7% (p < 0.0001). In contrast, we noted a significant decline in wild-type pfdhfr S108 allele (p < 0.0001) culminating in complete absence of this allele in 2013. We also observed a significant increase in the prevalence of the wild-type pfmdr1 N86/Y184/D1246 haplotype from 14.6% in 1995 to 66.0% in 2013 (p < 0.0001) and a corresponding decline of the mutant pfmdr1 86Y/184Y/1246Y allele from 36.4% to 0% in 19 years (p < 0.0001). We also show extensive genetic heterogeneity among the chloroquine-sensitive parasites before and after the withdrawal of the drug in contrast to a selective sweep around the triple mutant pfdhfr allele, leading to a mono-allelic population at this locus. These findings highlight the importance of continual surveillance and characterization of parasite genotypes as indicators of the therapeutic efficacy of antimalarials, particularly in the context of changes in malaria treatment policy.
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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
| | - Alice W. Kamau
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230-80108, Kilifi, Kenya
| | - Kevin Marsh
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230-80108, Kilifi, Kenya
| | - Colin J. Sutherland
- Department of Immunology & Infection, Faculty of Infectious & Tropical Diseases, London School of Hygiene & Tropical Medicine, Keppel St, London WC1E 7HT, UK
| | - Lynette Isabella Ochola-Oyier
- Kenya Medical Research Institute (KEMRI)/Wellcome Trust Collaborative Research Program, P.O. Box 230-80108, Kilifi, Kenya
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Teboh-Ewungkem MI, Mohammed-Awel J, Baliraine FN, Duke-Sylvester SM. The effect of intermittent preventive treatment on anti-malarial drug resistance spread in areas with population movement. Malar J 2014; 13:428. [PMID: 25398463 PMCID: PMC4289180 DOI: 10.1186/1475-2875-13-428] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Accepted: 10/25/2014] [Indexed: 11/30/2022] Open
Abstract
Background The use of intermittent preventive treatment in pregnant women (IPTp), children (IPTc) and infant (IPTi) is an increasingly popular preventive strategy aimed at reducing malaria risk in these vulnerable groups. Studies to understand how this preventive intervention can affect the spread of anti-malarial drug resistance are important especially when there is human movement between neighbouring low and high transmission areas. Because the same drug is sometimes utilized for IPTi and for symptomatic malaria treatment, distinguishing their individual roles on accelerating the spread of drug resistant malaria, with or without human movement, may be difficult to isolate experimentally or by analysing data. A theoretical framework, as presented here, is thus relevant as the role of IPTi on accelerating the spread of drug resistance can be isolated in individual populations and when the populations are interconnected and interact. Methods A previously published model is expanded to include human movement between neighbouring high and low transmission areas, with focus placed on the malaria parasites. Parasite fitness functions, determined by how many humans the parasites can infect, are used to investigate how fast resistance can spread within the neighbouring communities linked by movement, when the populations are at endemic equilibrium. Results Model simulations indicate that population movement results in resistance spreading fastest in high transmission areas, and the more complete the anti-malarial resistance the faster the resistant parasite will tend to spread through a population. Moreover, the demography of infection in low transmission areas tends to change to reflect the demography of high transmission areas. Additionally, when regions are strongly connected the rate of spread of partially resistant parasites (R1) relative to drug sensitive parasites (RS), and fully resistant parasites (R2) relative to partially resistant parasites (R1) tend to behave the same in both populations, as should be expected. Conclusions In fighting anti-malarial drug resistance, different drug resistance monitoring and management policies are needed when the area in question is an isolated high or low transmission area, or when it is close and interacting with a neighbouring high or low transmission area, with human movement between them. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-428) contains supplementary material, which is available to authorized users.
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Nabyonga-Orem J, Ssengooba F, Macq J, Criel B. Malaria treatment policy change in Uganda: what role did evidence play? Malar J 2014; 13:345. [PMID: 25179532 PMCID: PMC4164770 DOI: 10.1186/1475-2875-13-345] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 08/26/2014] [Indexed: 01/22/2023] Open
Abstract
Background Although increasing attention is being paid to knowledge translation (KT), research findings are not being utilized to the desired extent. The present study explores the role of evidence, barriers, and factors facilitating the uptake of evidence in the change in malaria treatment policy in Uganda, building on previous work in Uganda that led to the development of a middle range theory (MRT) outlining the main facilitatory factors for KT. Application of the MRT to a health policy case will contribute to refining it. Methods Using a case study approach and mixed methods, perceptions of respondents on whether evidence was available, had been considered and barriers and facilitatory factors to the uptake of evidence were explored. In addition, the respondents’ rating of the degree of consistency between the policy decision and available evidence was assessed. Data collection methods included key informant interviews and document review. Qualitative data were analysed using content thematic analysis, whereas quantitative data were analysed using Excel spreadsheets. The two data sets were eventually triangulated. Results Evidence was used to change the malaria treatment policy, though the consistency between evidence and policy decisions varied along the policy development cycle. The availability of high-quality and contextualized evidence, including effective dissemination, Ministry of Health institutional capacity to lead the KT process, intervention of the WHO and a regional professional network, the existence of partnerships for KT with mutual trust and availability of funding, tools, and inputs to implement evidence, were the most important facilitatory factors that enhanced the uptake of evidence. Among the barriers that had to be overcome were resistance from implementers, the health system capacity to implement evidence, and financial sustainability. Conclusion The results agree with facilitatory factors identified in the earlier developed MRT, though additional factors emerged. These results refine the earlier MRT stating that high-quality and contextualized evidence will be taken up in policies, leading to evidence-informed policies when the MoH leads the KT process, partnerships are in place for KT, the WHO and regional professional bodies play a role, and funding, tools, and required inputs for implementing evidence are available. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-345) contains supplementary material, which is available to authorized users.
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Mutero CM, Kramer RA, Paul C, Lesser A, Miranda ML, Mboera LEG, Kiptui R, Kabatereine N, Ameneshewa B. Factors influencing malaria control policy-making in Kenya, Uganda and Tanzania. Malar J 2014; 13:305. [PMID: 25107509 PMCID: PMC4249611 DOI: 10.1186/1475-2875-13-305] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 08/04/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Policy decisions for malaria control are often difficult to make as decision-makers have to carefully consider an array of options and respond to the needs of a large number of stakeholders. This study assessed the factors and specific objectives that influence malaria control policy decisions, as a crucial first step towards developing an inclusive malaria decision analysis support tool (MDAST). METHODS Country-specific stakeholder engagement activities using structured questionnaires were carried out in Kenya, Uganda and Tanzania. The survey respondents were drawn from a non-random purposeful sample of stakeholders, targeting individuals in ministries and non-governmental organizations whose policy decisions and actions are likely to have an impact on the status of malaria. Summary statistics across the three countries are presented in aggregate. RESULTS Important findings aggregated across countries included a belief that donor preferences and agendas were exerting too much influence on malaria policies in the countries. Respondents on average also thought that some relevant objectives such as engaging members of parliament by the agency responsible for malaria control in a particular country were not being given enough consideration in malaria decision-making. Factors found to influence decisions regarding specific malaria control strategies included donor agendas, costs, effectiveness of interventions, health and environmental impacts, compliance and/acceptance, financial sustainability, and vector resistance to insecticides. CONCLUSION Malaria control decision-makers in Kenya, Uganda and Tanzania take into account health and environmental impacts as well as cost implications of different intervention strategies. Further engagement of government legislators and other policy makers is needed in order to increase funding from domestic sources, reduce donor dependence, sustain interventions and consolidate current gains in malaria.
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Affiliation(s)
- Clifford M Mutero
- Centre for Sustainable Malaria Control and School of Health Systems and Public Health, University of Pretoria, Private Bag 323, Pretoria, 0001, South Africa.
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Sibley CH. Understanding drug resistance in malaria parasites: basic science for public health. Mol Biochem Parasitol 2014; 195:107-14. [PMID: 24927641 DOI: 10.1016/j.molbiopara.2014.06.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/25/2014] [Accepted: 06/03/2014] [Indexed: 01/09/2023]
Abstract
The worlds of basic scientists and those involved in treating patients and making public health decisions do not always intersect. Yet, assuring that when patients are treated, they are efficiently and completely cured, and that public health decisions are based on solid evidence requires a broad foundation of up to date basic research. Research on the malaria parasite, Plasmodium falciparum provides a useful illustration of the role that basic scientific studies have played in the very long relationship between humans and this deadly parasite. Drugs have always been a principal tool in malaria treatment. The ongoing struggle between evolution of resistance to antimalarials by the parasite and public health responses is used here as an illustration of the key contributions of basic scientists to this long history.
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Affiliation(s)
- Carol Hopkins Sibley
- World Wide Antimalarial Resistance Network, Department of Genome Sciences, University of Washington, Seattle, WA 98195-5065, USA.
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Tinto H, Bonkian LN, Nana LA, Yerbanga I, Lingani M, Kazienga A, Valéa I, Sorgho H, Kpoda H, Guiguemdé TR, Ouédraogo JB, Mens PF, Schallig H, D’Alessandro U. Ex vivo anti-malarial drugs sensitivity profile of Plasmodium falciparum field isolates from Burkina Faso five years after the national policy change. Malar J 2014; 13:207. [PMID: 24885950 PMCID: PMC4049403 DOI: 10.1186/1475-2875-13-207] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2014] [Accepted: 05/21/2014] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND The recent reports on the decreasing susceptibility of Plasmodium falciparum to artemisinin derivatives along the Thailand and Myanmar border are worrying. Indeed it may spread to India and then Africa, repeating the same pattern observed for chloroquine resistance. Therefore, it is essential to start monitoring P. falciparum sensitivity to artemisinin derivatives and its partner drugs in Africa. Efficacy of AL and ASAQ were tested by carrying out an in vivo drug efficacy test, with an ex vivo study against six anti-malarial drugs nested into it. Results of the latter are reported here. METHODS Plasmodium falciparum ex-vivo susceptibility to chloroquine (CQ), quinine (Q), lumefantrine (Lum), monodesethylamodiaquine (MDA), piperaquine (PPQ) and dihydroartemisinin (DHA) was investigated in children (6 months - 15 years) with a parasitaemia of at least ≥4,000/μl. The modified isotopic microtest technique was used. The results of cellular proliferation were analysed using ICEstimator software to determine the 50% inhibitory concentration (IC50) values. RESULTS DHA was the most potent among the 6 drugs tested, with IC50 values ranging from 0.8 nM to 0.9 nM (Geometric mean IC50 = 0.8 nM; 95% CI [0.8 - 0.9]). High IC50 values ranged between 0.8 nM to 166.1 nM were reported for lumefantrine (Geometric mean IC50 = 25.1 nM; 95% CI [22.4 - 28.2]). MDA and Q IC50s were significantly higher in CQ-resistant than in CQ-sensitive isolates (P = 0.0001). However, the opposite occurred for Lum and DHA (P < 0.001). No difference was observed for PPQ. CONCLUSION Artemisinin derivatives are still very efficacious in Burkina Faso and DHA-PPQ seems a valuable alternative ACT. The high lumefantrine IC50 found in this study is worrying as it may indicate a decreasing efficacy of one of the first-line treatments. This should be further investigated and monitored over time with large in vivo and ex vivo studies that will include also plasma drug measurements.
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Affiliation(s)
- Halidou Tinto
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Institut de Recherche en Sciences de la Santé/Direction Régionale de l’Ouest (IRSS/DRO), Bobo-Dioulasso, Burkina Faso
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Léa N Bonkian
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Louis A Nana
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Isidore Yerbanga
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Moussa Lingani
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Adama Kazienga
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Innocent Valéa
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Hermann Sorgho
- Institut de Recherche en Sciences de la Santé/Direction Régionale de l’Ouest (IRSS/DRO), Bobo-Dioulasso, Burkina Faso
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
| | - Hervé Kpoda
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Tinga Robert Guiguemdé
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Clinical Research Unit of Nanoro (IRSS-CRUN), Nanoro, Burkina Faso
- Institut Supérieur des Sciences de la Santé (INSSA), Bobo Dioulasso, Burkina Faso
| | - Jean Bosco Ouédraogo
- Unité de Recherche sur le Paludisme et Maladies Tropicales Négligées, Centre Muraz, Bobo-Dioulasso, Burkina Faso
- Institut de Recherche en Sciences de la Santé/Direction Régionale de l’Ouest (IRSS/DRO), Bobo-Dioulasso, Burkina Faso
| | - Petronella F Mens
- Royal Tropical Institute/Koninklijk Instituut voor de Tropen (KIT), Amsterdam, The Netherlands
| | - Henk Schallig
- Royal Tropical Institute/Koninklijk Instituut voor de Tropen (KIT), Amsterdam, The Netherlands
| | - Umberto D’Alessandro
- Medical Research Council Unit, The Gambia, Disease Control & Elimination Theme, Fajara, The Gambia
- Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium
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A genome wide association study of Plasmodium falciparum susceptibility to 22 antimalarial drugs in Kenya. PLoS One 2014; 9:e96486. [PMID: 24809681 PMCID: PMC4014544 DOI: 10.1371/journal.pone.0096486] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Accepted: 04/08/2014] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Drug resistance remains a chief concern for malaria control. In order to determine the genetic markers of drug resistant parasites, we tested the genome-wide associations (GWA) of sequence-based genotypes from 35 Kenyan P. falciparum parasites with the activities of 22 antimalarial drugs. METHODS AND PRINCIPAL FINDINGS Parasites isolated from children with acute febrile malaria were adapted to culture, and sensitivity was determined by in vitro growth in the presence of anti-malarial drugs. Parasites were genotyped using whole genome sequencing techniques. Associations between 6250 single nucleotide polymorphisms (SNPs) and resistance to individual anti-malarial agents were determined, with false discovery rate adjustment for multiple hypothesis testing. We identified expected associations in the pfcrt region with chloroquine (CQ) activity, and other novel loci associated with amodiaquine, quinazoline, and quinine activities. Signals for CQ and primaquine (PQ) overlap in and around pfcrt, and interestingly the phenotypes are inversely related for these two drugs. We catalog the variation in dhfr, dhps, mdr1, nhe, and crt, including novel SNPs, and confirm the presence of a dhfr-164L quadruple mutant in coastal Kenya. Mutations implicated in sulfadoxine-pyrimethamine resistance are at or near fixation in this sample set. CONCLUSIONS/SIGNIFICANCE Sequence-based GWA studies are powerful tools for phenotypic association tests. Using this approach on falciparum parasites from coastal Kenya we identified known and previously unreported genes associated with phenotypic resistance to anti-malarial drugs, and observe in high-resolution haplotype visualizations a possible signature of an inverse selective relationship between CQ and PQ.
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Kalayjian BC, Malhotra I, Mungai P, Holding P, King CL. Marked decline in malaria prevalence among pregnant women and their offspring from 1996 to 2010 on the south Kenyan Coast. Am J Trop Med Hyg 2013; 89:1129-34. [PMID: 24080635 DOI: 10.4269/ajtmh.13-0250] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Expanded malaria control in Kenya since the early 2000s has resulted in marked reduction in hospital admissions for malaria; however, no studies have reported changes in malaria infection rates in the same population over this period. Randomly selected archived blood samples from four cohorts of pregnant women and their children from 1996 to 2010 in Kwale District, Coast Province, Kenya, were examined for Plasmodium falciparum (Pf), P. malariae, P. ovale, and Plasmodium vivax by quantitative polymerase chain reaction (PCR) and microscopy. Maternal delivery Pf prevalence by PCR declined from 40% in 2000-2005 to 1% in 2009-2010, concordant with increased bed net and malaria chemoprophylaxis use. Individual risk of Pf infection in children from birth to 3 years in serial longitudinal cohort studies declined from almost 100% in 1996-1999 to 15% in 2006-2010. Declines in P. malariae and P. ovale infections rates were also observed. These results show a profound reduction in malaria transmission in coastal Kenya.
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Affiliation(s)
- Benjamin C Kalayjian
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, Ohio; Veterans Affairs Medical Center, Cleveland, Ohio; Division of Vector Borne Diseases, Nairobi, Kenya
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Zakai HA, Khan W, Asma U. Prevalence of mutation and phenotypic expression associated with sulfadoxine-pyrimethamine resistance in Plasmodium falciparum and Plasmodium vivax. Folia Parasitol (Praha) 2013; 60:372-6. [DOI: 10.14411/fp.2013.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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A randomized trial of artemether-lumefantrine and dihydroartemisinin-piperaquine in the treatment of uncomplicated malaria among children in western Kenya. Malar J 2013; 12:254. [PMID: 23870627 PMCID: PMC3722085 DOI: 10.1186/1475-2875-12-254] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 07/09/2013] [Indexed: 12/03/2022] Open
Abstract
Background Artemether-lumefantrine (AL) was adopted as first-line treatment for uncomplicated malaria in Kenya in 2006. Monitoring drug efficacy at regular intervals is essential to prevent unnecessary morbidity and mortality. The efficacy of AL and dihydroartemisinin-piperaquine (DP) were evaluated for the treatment of uncomplicated malaria in children aged six to 59 months in western Kenya. Methods From October 2010 to August 2011, children with fever or history of fever with uncomplicated Plasmodium falciparum mono-infection were enrolled in an in vivo efficacy trial in accordance with World Health Organization (WHO) guidelines. The children were randomized to treatment with a three-day course of AL or DP and efficacy outcomes were measured at 28 and 42 days after treatment initiation. Results A total of 137 children were enrolled in each treatment arm. There were no early treatment failures and all children except one had cleared parasites by day 3. Polymerase chain reaction (PCR)-uncorrected adequate clinical and parasitological response rate (ACPR) was 61% in the AL arm and 83% in the DP arm at day 28 (p = 0.001). PCR-corrected ACPR at day 28 was 97% in the AL group and 99% in the DP group, and it was 96% in both arms at day 42. Conclusions AL and DP remain efficacious for the treatment of uncomplicated malaria among children in western Kenya. The longer half-life of piperaquine relative to lumefantrine may provide a prophylactic effect, accounting for the lower rate of re-infection in the first 28 days after treatment in the DP arm.
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Cruz VO, Walt G. Brokering the boundary between science and advocacy: the case of intermittent preventive treatment among infants. Health Policy Plan 2012; 28:616-25. [PMID: 23161588 PMCID: PMC3753881 DOI: 10.1093/heapol/czs101] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The process of translating research into policy has gained considerable attention in recent years and a number of studies have investigated the nexus between the two ‘worlds’ of research and policy. One issue that has been little addressed is about the boundaries between research and advocacy: how far scientists do, or should, promote particular findings to policy makers and others. This article analyses a particular intervention in malaria control and the Consortium set up to accelerate its potential implementation. Using a framework that emphasizes the interplay of interests, institutions and ideas, it provides an example of how a network of committed researchers and funders attempted to follow a rational policy process, but faced conflicts and fundamental questions about their roles in generating scientific evidence and influencing global health policy. In an era of ever more and larger researcher groups and consortia, the findings offer insights and lessons to those engaged in the process of knowledge translation.
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Affiliation(s)
- Valeria Oliveira Cruz
- Department of Global Health and Development, Faculty of Public Health and Policy, London School of Hygiene & Tropical Medicine, Keppel Street, London WC1E 7HT, UK.
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Mang’era CM, Mbai FN, Omedo IA, Mireji PO, Omar SA. Changes in genotypes of Plasmodium falciparum human malaria parasite following withdrawal of chloroquine in Tiwi, Kenya. Acta Trop 2012; 123:202-7. [PMID: 22641431 DOI: 10.1016/j.actatropica.2012.05.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2011] [Revised: 05/14/2012] [Accepted: 05/16/2012] [Indexed: 10/28/2022]
Abstract
Chloroquine (CQ) drug was withdrawn in 1998 as a first-line treatment of uncomplicated malaria in Kenya. This was in response to resistance to the drug in Plasmodium falciparum malaria parasite. Investigations were conducted to determine prevalence of CQ resistance genotypes in the parasites in Tiwi, a malaria endemic town in Kenya, before and about a decade after the withdrawal of the drug. Blood samples were collected and spotted on filter papers in 1999 and 2008 from 75 and 77 out-patients respectively with uncomplicated malaria. The sampling was conducted using finger pricking technique. DNA was extracted from individual spots in the papers and screened for the presence of P. falciparum chloroquine resistance transporter (Pfcrt) and multi drug resistance (Pfmdr-1) markers using nested PCR. Nature of mutations (haplotypes) in the Pfcrt and Pfmdr-1 markers in the samples were confirmed using dot blot hybridization technique. Changes in pattern of CQ resistance in the parasite samples in 1999 and 2008 were assessed by Chi Square test. There was a significant (P<0.05) reduction in CQ resistant genotypes of the parasite between 1999 and 2008. Pfmdr and Pfcrt CQ resistant genotypes in 2008 reduced to 54.10 and 63.64% respectively, from 75.39 and 88.0% respectively in 1999. This reduction was accompanied by emergence of Pfcrt specific CQ sensitive (IEK) and intermediate/partially CQ resistant (MET) haplotypes. Results suggest significant reversal of the phenotype of the parasite from chloroquine resistant to wild/sensitive type. The novel haplotypes indicates transitional phase of the parasite to the wild type. Current prevalence of chloroquine resistant genotype is definitely above the threshold for efficacious re-introduction of chloroquine for treatment of malaria in Tiwi.
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Brooks A, Ba-Nguz A. Country planning for health interventions under development: lessons from the malaria vaccine decision-making framework and implications for other new interventions. Health Policy Plan 2012; 27 Suppl 2:ii50-61. [PMID: 22513733 PMCID: PMC3328760 DOI: 10.1093/heapol/czs039] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Traditionally it has taken years or decades for new public health interventions targeting diseases found in developing countries to be accessible to those most in need. One reason for the delay has been insufficient anticipation of the eventual processes and evidence required for decision making by countries. This paper describes research into the anticipated processes and data needed to inform decision making on malaria vaccines, the most advanced of which is still in phase 3 trials. From 2006 to 2008, a series of country consultations in Africa led to the development of a guide to assist countries in preparing their malaria vaccine decision-making frameworks. The guide builds upon the World Health Organization's Vaccine Introduction Guidelines. It identifies the processes and data for decisions, when they would be needed relative to the development timelines of the intervention, and where they will come from. Policy development will be supported by data (e.g. malaria disease burden; roles of other malaria interventions; malaria vaccine impact; economic and financial issues; malaria vaccine efficacy, quality and safety) as will implementation decisions (e.g. programmatic issues and socio-cultural environment). This generic guide can now be applied to any future malaria vaccine. The paper discusses the opportunities and challenges to early planning for country decision-making-from the potential for timely, evidence-informed decisions to the risks of over-promising around an intervention still under development. Careful and well-structured planning by countries is an important way to ensure that new interventions do not remain unused for years or decades after they become available.
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Affiliation(s)
- Alan Brooks
- PATH Malaria Vaccine Initiative, Ferney-Voltaire, France
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Nanyunja M, Nabyonga Orem J, Kato F, Kaggwa M, Katureebe C, Saweka J. Malaria treatment policy change and implementation: the case of Uganda. Malar Res Treat 2011; 2011:683167. [PMID: 22312571 PMCID: PMC3265287 DOI: 10.4061/2011/683167] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 07/07/2011] [Indexed: 11/20/2022] Open
Abstract
Malaria due to P. falciparum is the number one cause of morbidity and mortality in Uganda where it is highly endemic in 95% of the country. The use of efficacious and effective antimalarial medicines is one of the key strategies for malaria control. Until 2000, Chloroquine (CQ) was the first-line drug for treatment of uncomplicated malaria in Uganda. Due to progressive resistance to CQ and to a combination of CQ with Sulfadoxine-Pyrimethamine, Uganda in 2004 adopted the use of ACTs as first-line drug for treating uncomplicated malaria. A review of the drug policy change process and postimplementation reports highlight the importance of managing the policy change process, generating evidence for policy decisions and availability of adequate and predictable funding for effective policy roll-out. These and other lessons learnt can be used to guide countries that are considering anti-malarial drug change in future.
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Affiliation(s)
- Miriam Nanyunja
- Disease Prevention and Control Cluster: World Health Organization, Uganda Country Office, P.O. Box 24578, Kampala, Uganda
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Akala HM, Eyase FL, Cheruiyot AC, Omondi AA, Ogutu BR, Waters NC, Johnson JD, Polhemus ME, Schnabel DC, Walsh DS. Antimalarial drug sensitivity profile of western Kenya Plasmodium falciparum field isolates determined by a SYBR Green I in vitro assay and molecular analysis. Am J Trop Med Hyg 2011; 85:34-41. [PMID: 21734121 DOI: 10.4269/ajtmh.2011.10-0674] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
In vitro drug sensitivity and molecular analyses of Plasmodium falciparum track drug resistance. DNA-binding fluorescent dyes like SYBR Green I may allow field laboratories, proximal to P. falciparum collection sites, to conduct drug assays. In 2007-2008, we assayed 121 P. falciparum field isolates from western Kenya for 50% inhibitory concentrations (IC(50)) against 6 antimalarial drugs using a SYBR Green I in vitro assay: 91 immediate ex vivo (IEV) and 30 culture-adapted, along with P. falciparum reference clones D6 (chloroquine [CQ] sensitive) and W2 (CQ resistant). We also assessed P. falciparum mdr1 (Pfmdr1) copy number and single nucleotide polymorphisms (SNPs) at four codons. The IC(50)s for IEV and culture-adapted P. falciparum isolates were similar, and approximated historical IC(50)s. For Pfmdr1, mean copy number was 1, with SNPs common at codons 86 and 184. The SYBR Green I assay adapted well to our field-based laboratory, for both IEV and culture-adapted P. falciparum, warranting continued use.
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Affiliation(s)
- Hoseah M Akala
- Global Emerging Infections Surveillance (GEIS) Program, United States Army Medical Research Unit-Kenya (USAMRU-K), Kenya Medical Research Institute (KEMRI)-Walter Reed Project, Kisumu and Nairobi, Kenya.
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Frosch AEP, Venkatesan M, Laufer MK. Patterns of chloroquine use and resistance in sub-Saharan Africa: a systematic review of household survey and molecular data. Malar J 2011; 10:116. [PMID: 21554692 PMCID: PMC3112453 DOI: 10.1186/1475-2875-10-116] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 05/09/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND As a result of widespread chloroquine and sulphadoxine-pyrimethamine (SP) resistance, 90% of sub-Saharan African countries had adopted policies of artemisinin-based combination therapy (ACT) for treatment of uncomplicated malaria by 2007. In Malawi, cessation of chloroquine use was followed by the re-emergence of chloroquine-susceptible malaria. It was expected that introduction of ACT would lead to a return in chloroquine susceptibility throughout Africa, but this has not yet widely occurred. This observation suggests that there is continuing use of ineffective anti-malarials in Africa and that persistent chloroquine-resistant malaria is due to ongoing drug pressure despite national policy changes. METHODS To estimate drug use on a national level, 2006-2007 Demographic Health Survey and Multiple Indicator Cluster Survey data from 21 African countries were analysed. Resistance data were compiled by systematic review of the published literature on the prevalence of the Plasmodium falciparum chloroquine resistance transporter polymorphism at codon 76, which causes chloroquine resistance. RESULTS Chloroquine was the most common anti-malarial used according to surveys from 14 of 21 countries analysed, predominantly in West Africa. SP was most commonly reported in two of 21 countries. Among eight countries with longitudinal molecular resistance data, the four countries where the highest proportion of children treated for fever received chloroquine (Uganda, Burkina Faso, Guinea Bissau, and Mali) also showed no significant declines in the prevalence of chloroquine-resistant infections. The three countries with low or decreasing chloroquine use among children who reported fever treatment (Malawi, Kenya, and Tanzania) had statistically significant declines in the prevalence of chloroquine resistance. CONCLUSIONS This study demonstrates that in 2006-2007, chloroquine and SP continued to be used at high rates in many African countries. In countries reporting sustained chloroquine use, chloroquine-resistant malaria persists. In contrast, a low level of estimated chloroquine use is associated with a declining prevalence of chloroquine resistance.
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Affiliation(s)
- Anne E P Frosch
- Center for Vaccine Development, University of Maryland School of Medicine, 685 West Baltimore Street, Baltimore, MD, USA
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Wells WA, Brooks A. Adoption of new health products in low and middle income settings: how product development partnerships can support country decision making. Health Res Policy Syst 2011; 9:15. [PMID: 21453529 PMCID: PMC3079693 DOI: 10.1186/1478-4505-9-15] [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: 12/17/2010] [Accepted: 03/31/2011] [Indexed: 11/10/2022] Open
Abstract
When a new health product becomes available, countries have a choice to adopt the product into their national health systems or to pursue an alternate strategy to address the public health problem. Here, we describe the role for product development partnerships (PDPs) in supporting this decision-making process. PDPs are focused on developing new products to respond to health problems prevalent in low and middle income settings. The impact of these products within public sector health systems can only be realized after a country policy process. PDPs may be the organizations most familiar with the evidence which assists decision making, and this generally translates into involvement in international policy development, but PDPs have limited reach into endemic countries. In a few individual countries, there may be more extensive involvement in tracking adoption activities and generating local evidence. This local PDP involvement begins with geographical prioritization based on disease burden, relationships established during clinical trials, PDP in-country resources, and other factors. Strategies adopted by PDPs to establish a presence in endemic countries vary from the opening of country offices to engagement of part-time consultants or with long-term or ad hoc committees. Once a PDP commits to support country decision making, the approaches vary, but include country consultations, regional meetings, formation of regional, product-specific committees, support of in-country advocates, development of decision-making frameworks, provision of technical assistance to aid therapeutic or diagnostic guideline revision, and conduct of stakeholder and Phase 4 studies. To reach large numbers of countries, the formation of partnerships, particularly with WHO, are essential. At this early stage, impact data are limited. But available evidence suggests PDPs can and do play an important catalytic role in their support of country decision making in a number of target countries.
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Affiliation(s)
- William A Wells
- Global Alliance for TB Drug Development, 40 Wall St, New York NY 10005 USA.
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Meremikwu M, Udoh E, Nwagbara B, Effa E, Oringanje C, Edet B, Nwagbara E, Bello S, Eke F. Priority setting for systematic review of health care interventions in Nigeria. Health Policy 2011; 99:244-9. [PMID: 21131092 DOI: 10.1016/j.healthpol.2010.11.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 11/06/2010] [Accepted: 11/07/2010] [Indexed: 10/18/2022]
Abstract
OBJECTIVES In an era of evidence based medicine and systematic review, this study seeks to identify priority systematic review topics that address common health problems in Nigeria. METHODS Firstly, a primary list of health problems was compiled from the National Health Management Information Systems and information from key informants (health professionals, researchers and NGOs) drawn from the six geo-political zones in Nigeria. Key steps included compilation and ranking of a comprehensive list of health problems into 4 categories: adult communicable, non-communicable, maternal and child health; searching the Cochrane Library and electronic databases for systematic reviews on identified priority problems, analysis of search outputs to identify gaps; listing and ranking of new priority systematic review topics using pre-determined criteria. RESULTS Eighteen questions made the final list of priorities systematic reviews and 9 of them were related to malaria. There were 7 additional issues that the panelists identified as crucial cross-cutting issues that need to be addressed in systematic reviews. CONCLUSION Identification and prioritization of systematic reviews relevant to health care in Nigeria will improve the opportunity to deliver evidence-based and equitable health care to the people. These topics are likely to be also important for health care decision in other resource-poor settings.
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Affiliation(s)
- Martin Meremikwu
- Institute of Tropical Diseases Research and Prevention, University of Calabar Teaching Hospital, Calabar, Nigeria.
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Spalding MD, Eyase FL, Akala HM, Bedno SA, Prigge ST, Coldren RL, Moss WJ, Waters NC. Increased prevalence of the pfdhfr/phdhps quintuple mutant and rapid emergence of pfdhps resistance mutations at codons 581 and 613 in Kisumu, Kenya. Malar J 2010; 9:338. [PMID: 21106088 PMCID: PMC3001743 DOI: 10.1186/1475-2875-9-338] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2010] [Accepted: 11/24/2010] [Indexed: 12/01/2022] Open
Abstract
Background Anti-malarial drug resistance in Kenya prompted two drug policy changes within a decade: sulphadoxine-pyrimethamine (SP) replaced chloroquine (CQ) as the first-line anti-malarial in 1998 and artemether-lumefantrine (AL) replaced SP in 2004. Two cross-sectional studies were conducted to monitor changes in the prevalence of molecular markers of drug resistance over the period in which SP was used as the first-line anti-malarial. The baseline study was carried out from 1999-2000, shortly after implementation of SP, and the follow-up study occurred from 2003-2005, during the transition to AL. Materials and methods Blood was collected from malaria smear-positive, symptomatic patients presenting to outpatient centers in Kisumu, Kenya, during the baseline and follow-up studies. Isolates were genotyped at codons associated with SP and CQ resistance. In vitro IC50 values for antifolates and quinolones were determined for isolates from the follow-up study. Results The prevalence of isolates containing the pfdhfr N51I/C59R/S108N/pfdhps A437G/K540E quintuple mutant associated with SP-resistance rose from 21% in the baseline study to 53% in the follow-up study (p < 0.001). Isolates containing the pfdhfr I164L mutation were absent from both studies. The pfdhps mutations A581G and A613S/T were absent from the baseline study but were present in 85% and 61%, respectively, of isolates from the follow-up study. At follow-up, parasites with mutations at five pfdhps codons, 436, 437, 540, 581, and 613, accounted for 39% of isolates. The CQ resistance-associated mutations pfcrt K76T and pfmdr1 N86Y rose from 82% to 97% (p = 0.001) and 44% to 76% (p < 0.001), respectively, from baseline to follow-up. Conclusions During the period in which SP was the first-line anti-malarial in Kenya, highly SP-resistant parasites emerged, including isolates harboring pfdhps mutations not previously observed there. SP continues to be widely used in Kenya; however, given the highly resistant genotypes observed in this study, its use as a first-line anti-malarial should be discouraged, particularly for populations without acquired immunity to malaria. The increase in the pfcrt K76T prevalence, despite efforts to reduce CQ use, suggests that either these efforts are not adequate to alleviate CQ pressure in Kisumu, or that drug pressure is derived from another source, such as the second-line anti-malarial amodiaquine.
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Affiliation(s)
- Maroya D Spalding
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
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Okiro EA, Alegana VA, Noor AM, Snow RW. Changing malaria intervention coverage, transmission and hospitalization in Kenya. Malar J 2010; 9:285. [PMID: 20946689 PMCID: PMC2972305 DOI: 10.1186/1475-2875-9-285] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 10/15/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Reports of declining incidence of malaria disease burden across several countries in Africa suggest that the epidemiology of malaria across the continent is in transition. Whether this transition is directly related to the scaling of intervention coverage remains a moot point. METHODS Paediatric admission data from eight Kenyan hospitals and their catchments have been assembled across two three-year time periods: September 2003 to August 2006 (pre-scaled intervention) and September 2006 to August 2009 (post-scaled intervention). Interrupted time series (ITS) models were developed adjusting for variations in rainfall and hospital use by surrounding communities to show changes in malaria hospitalization over the two periods. The temporal changes in factors that might explain changes in disease incidence were examined sequentially for each hospital setting, compared between hospital settings and ranked according to plausible explanatory factors. RESULTS In six out of eight sites there was a decline in Malaria admission rates with declines between 18% and 69%. At two sites malaria admissions rates increased by 55% and 35%. Results from the ITS models indicate that before scaled intervention in September 2006, there was a significant month-to-month decline in the mean malaria admission rates at four hospitals (trend P < 0.05). At the point of scaled intervention, the estimated mean admission rates for malaria was significantly less at four sites compared to the pre-scaled period baseline. Following scaled intervention there was a significant change in the month-to-month trend in the mean malaria admission rates in some but not all of the sites. Plausibility assessment of possible drivers of change pre- versus post-scaled intervention showed inconsistent patterns however, allowing for the increase in rainfall in the second period, there is a suggestion that starting transmission intensity and the scale of change in ITN coverage might explain some but not all of the variation in effect size. At most sites where declines between observation periods were documented admission rates were changing before free mass ITN distribution and prior to the implementation of ACT across Kenya. CONCLUSION This study provides evidence of significant within and between location heterogeneity in temporal trends of malaria disease burden. Plausible drivers for changing disease incidence suggest a complex combination of mechanisms, not easily measured retrospectively.
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Affiliation(s)
- Emelda A Okiro
- Malaria Public Health & Epidemiology Group, Centre for Geographic Medicine Research - Coast, Kenya Medical Research Institute/Wellcome Trust Research Programme, 00100 GPO, Nairobi, Kenya.
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Assessment of compliance to sulfadoxine–pyrimethamine 18 months after phasing out chloroquine in Mkuranga District, Coast region – Tanzania. ASIAN PAC J TROP MED 2010. [DOI: 10.1016/s1995-7645(10)60108-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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Dondorp AM, Yeung S, White L, Nguon C, Day NPJ, Socheat D, von Seidlein L. Artemisinin resistance: current status and scenarios for containment. Nat Rev Microbiol 2010; 8:272-80. [PMID: 20208550 DOI: 10.1038/nrmicro2331] [Citation(s) in RCA: 368] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Artemisinin combination therapies are the first-line treatments for uncomplicated Plasmodium falciparum malaria in most malaria-endemic countries. Recently, partial artemisinin-resistant P. falciparum malaria has emerged on the Cambodia-Thailand border. Exposure of the parasite population to artemisinin monotherapies in subtherapeutic doses for over 30 years, and the availability of substandard artemisinins, have probably been the main driving force in the selection of the resistant phenotype in the region. A multifaceted containment programme has recently been launched, including early diagnosis and appropriate treatment, decreasing drug pressure, optimising vector control, targeting the mobile population, strengthening management and surveillance systems, and operational research. Mathematical modelling can be a useful tool to evaluate possible strategies for containment.
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Affiliation(s)
- Arjen M Dondorp
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok10400, Thailand.
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Okara RM, Sinka ME, Minakawa N, Mbogo CM, Hay SI, Snow RW. Distribution of the main malaria vectors in Kenya. Malar J 2010; 9:69. [PMID: 20202199 PMCID: PMC2845185 DOI: 10.1186/1475-2875-9-69] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Accepted: 03/04/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A detailed knowledge of the distribution of the main Anopheles malaria vectors in Kenya should guide national vector control strategies. However, contemporary spatial distributions of the locally dominant Anopheles vectors including Anopheles gambiae, Anopheles arabiensis, Anopheles merus, Anopheles funestus, Anopheles pharoensis and Anopheles nili are lacking. The methods and approaches used to assemble contemporary available data on the present distribution of the dominant malaria vectors in Kenya are presented here. METHOD Primary empirical data from published and unpublished sources were identified for the period 1990 to 2009. Details recorded for each source included the first author, year of publication, report type, survey location name, month and year of survey, the main Anopheles species reported as present and the sampling and identification methods used. Survey locations were geo-positioned using national digital place name archives and on-line geo-referencing resources. The geo-located species-presence data were displayed and described administratively, using first-level administrative units (province), and biologically, based on the predicted spatial margins of Plasmodium falciparum transmission intensity in Kenya for the year 2009. Each geo-located survey site was assigned an urban or rural classification and attributed an altitude value. RESULTS A total of 498 spatially unique descriptions of Anopheles vector species across Kenya sampled between 1990 and 2009 were identified, 53% were obtained from published sources and further communications with authors. More than half (54%) of the sites surveyed were investigated since 2005. A total of 174 sites reported the presence of An. gambiae complex without identification of sibling species. Anopheles arabiensis and An. funestus were the most widely reported at 244 and 265 spatially unique sites respectively with the former showing the most ubiquitous distribution nationally. Anopheles gambiae, An. arabiensis, An. funestus and An. pharoensis were reported at sites located in all the transmission intensity classes with more reports of An. gambiae in the highest transmission intensity areas than the very low transmission areas. CONCLUSION A contemporary, spatially defined database of the main malaria vectors in Kenya provides a baseline for future compilations of data and helps identify areas where information is currently lacking. The data collated here are published alongside this paper where it may help guide future sampling location decisions, help with the planning of vector control suites nationally and encourage broader research inquiry into vector species niche modeling.
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Affiliation(s)
- Robi M Okara
- Malaria Public Health and Epidemiology Group, Centre for Geographic Medicine, KEMRI - University of Oxford - Wellcome Trust Collaborative Programme, Kenyatta National Hospital Grounds, PO Box 43640-00100, Nairobi, Kenya
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Knight SE, Anyachebelu EJ, Geddes R, Maharaj R. Impact of delayed introduction of sulfadoxine-pyrimethamine and arthemeter-lumefantrine on malaria epidemiology in KwaZulu-Natal, South Africa. Trop Med Int Health 2009; 14:1086-92. [PMID: 19624481 DOI: 10.1111/j.1365-3156.2009.02333.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVE To investigate how delayed introduction of sulfadoxine-pyrimethamine (Fansidar) and arthemeter-lumefantrine (Coartem) as first-line drugs for malaria in KwaZulu-Natal contributed to the reported epidemics of 1985-1988 and 1997-2001. METHODS Ecological study assessing the association between malaria incidence and the emergence and degree of resistance to chloroquine from 1982 to 1988 and to sulfadoxine-pyrimethamine from 1991 to 2001, when each was the first-line malaria treatment. RESULTS The relative risk for malaria infection after the level of drug resistance reached 10% was 4.5 (95% CI: 4.0-5.2) in the chloroquine period and 5.9 (95% CI: 5.7-6.1) in the sulfadoxine-pyrimethamine period. In the chloroquine period, the relative risk of death from malaria was tenfold (95% CI: 1.3-78.1) and the case fatality doubled after drug resistance had reached 10%. The risk of death during the sulfadoxine-pyrimethamine period was 10.8 (95% CI: 5.9-19.2) and case fatality 1.8 times higher after drug resistance had reached 10%, than before. CONCLUSION Malaria epidemics in KwaZulu-Natal, South Africa have been exacerbated by failing drug regimens. The establishment of sentinel sites for monitoring drug failure and the prompt adoption of guidelines based on World Health Organization standards in drug resistance should improve malaria control.
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Affiliation(s)
- S E Knight
- Department of Public Health Medicine, University KwaZulu-Natal, South Africa
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In vitro activity of antifolate and polymorphism in dihydrofolate reductase of Plasmodium falciparum isolates from the Kenyan coast: emergence of parasites with Ile-164-Leu mutation. Antimicrob Agents Chemother 2009; 53:3793-8. [PMID: 19528269 DOI: 10.1128/aac.00308-09] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have analyzed the activities of the antifolates pyrimethamine (PM), chlorcycloguanil (CCG), WR99210, trimethoprim (TMP), methotrexate (MTX), and trimetrexate (TMX) against Kenyan Plasmodium falciparum isolates adapted in vitro for long-term culture. We have also assessed the relationship between these drug activities and mutations in dihydrofolate reductase (dhfr), a domain of the gene associated with antifolate resistance. As expected, WR99210 was the most potent drug, with a median 50% inhibitory concentration (IC50) of <0.075 nM, followed by TMX, with a median IC50 of 30 nM. The median IC50 of CCG was 37.80 nM, and that of MTX was 83.60 nM. PM and TMP were the least active drugs, with median IC50s of 733.26 nM and 29,656.04 nM, respectively. We analyzed parasite dhfr genotypes by the PCR-enzyme restriction technique. No wild-type dhfr parasite was found. Twenty-four of 33 parasites were triple mutants (mutations at codons 108, 51, and 59), and only 8/33 were double mutants (mutations at codons 108 and 51 or at codons 108 and 59). IC50s were 2.1-fold (PM) and 3.6-fold (TMP) higher in triple than in double mutants, though these differences were not statistically significant. Interestingly, we have identified a parasite harboring a mutation at codon 164 (Ile-164-Leu) in addition to mutations at codons 108, 51, and 59. This quadruple mutant parasite had the highest TMP IC50 and was in the upper 10th percentile against PM and CCG. We confirmed the presence of this mutation by sequencing. Thus, TMX and MTX are potent against P. falciparum, and quadruple mutants are now emerging in Africa.
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Mwai L, Ochong E, Abdirahman A, Kiara SM, Ward S, Kokwaro G, Sasi P, Marsh K, Borrmann S, Mackinnon M, Nzila A. Chloroquine resistance before and after its withdrawal in Kenya. Malar J 2009; 8:106. [PMID: 19450282 PMCID: PMC2694831 DOI: 10.1186/1475-2875-8-106] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Accepted: 05/18/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The spread of resistance to chloroquine (CQ) led to its withdrawal from use in most countries in sub-Saharan Africa in the 1990s. In Malawi, this withdrawal was followed by a rapid reduction in the frequency of resistance to the point where the drug is now considered to be effective once again, just nine years after its withdrawal. In this report, the polymorphisms of markers associated with CQ-resistance against Plasmodium falciparum isolates from coastal Kenya (Kilifi) were investigated, from 1993, prior to the withdrawal of CQ, to 2006, seven years after its withdrawal. Changes to those that occurred in the dihydrofolate reductase gene (dhfr) that confers resistance to the replacement drug, pyrimethamine/sulphadoxine were also compared. METHODS Mutations associated with CQ resistance, at codons 76 of pfcrt, at 86 of pfmdr1, and at codons 51, 59 and 164 of dhfr were analysed using PCR-restriction enzyme methods. In total, 406, 240 and 323 isolates were genotyped for pfcrt-76, pfmdr1-86 and dhfr, respectively. RESULTS From 1993 to 2006, the frequency of the pfcrt-76 mutant significantly decreased from around 95% to 60%, while the frequency of pfmdr1-86 did not decline, remaining around 75%. Though the frequency of dhfr mutants was already high (around 80%) at the start of the study, this frequency increased to above 95% during the study period. Mutation at codon 164 of dhfr was analysed in 2006 samples, and none of them had this mutation. CONCLUSION In accord with the study in Malawi, a reduction in resistance to CQ following official withdrawal in 1999 was found, but unlike Malawi, the decline of resistance to CQ in Kilifi was much slower. It is estimated that, at current rates of decline, it will take 13 more years for the clinical efficacy of CQ to be restored in Kilifi. In addition, CQ resistance was declining before the drug's official withdrawal, suggesting that, prior to the official ban, the use of CQ had decreased, probably due to its poor clinical effectiveness.
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Affiliation(s)
- Leah Mwai
- Kenya Medical Research Institute/Wellcome Trust Collaborative Research Programme, Kilifi, Kenya.
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Williams HA, Vincent-Mark A, Herrera Y, Chang OJ. A retrospective analysis of the change in anti-malarial treatment policy: Peru. Malar J 2009; 8:85. [PMID: 19400953 PMCID: PMC2684118 DOI: 10.1186/1475-2875-8-85] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2008] [Accepted: 04/28/2009] [Indexed: 11/12/2022] Open
Abstract
Background National malaria control programmes must deal with the complex process of changing national malaria treatment guidelines, often without guidance on the process of change. Selecting a replacement drug is only one issue in this process. There is a paucity of literature describing successful malaria treatment policy changes to help guide control programs through this process. Objectives To understand the wider context in which national malaria treatment guidelines were formulated in a specific country (Peru). Methods Using qualitative methods (individual and focus group interviews, stakeholder analysis and a review of documents), a retrospective analysis of the process of change in Peru's anti-malarial treatment policy from the early 1990's to 2003 was completed. Results The decision to change Peru's policies resulted from increasing levels of anti-malarial drug resistance, as well as complaints from providers that the drugs were no longer working. The context of the change occurred in a time in which Peru was changing national governments, which created extreme challenges in moving the change process forward. Peru utilized a number of key strategies successfully to ensure that policy change would occur. This included a) having the process directed by a group who shared a common interest in malaria and who had long-established social and professional networks among themselves, b) engaging in collaborative teamwork among nationals and between nationals and international collaborators, c) respect for and inclusion of district-level staff in all phases of the process, d) reliance on high levels of technical and scientific knowledge, e) use of standardized protocols to collect data, and f) transparency. Conclusion Although not perfectly or fully implemented by 2003, the change in malaria treatment policy in Peru occurred very quickly, as compared to other countries. They identified a problem, collected the data necessary to justify the change, utilized political will to their favor, approved the policy, and moved to improve malaria control in their country. As such, they offer an excellent example for other countries as they contemplate or embark on policy changes.
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Affiliation(s)
- Holly Ann Williams
- Malaria Branch, Centers for Disease Control and Prevention (CDC), Mail Stop F-60, 4770 Buford Hwy NE, Atlanta, Georgia 30341, USA.
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Warsame M, Atta H, Klena JD, Waqar BA, Elmi HH, Jibril AM, Hassan HM, Hassan AM. Efficacy of monotherapies and artesunate-based combination therapies in children with uncomplicated malaria in Somalia. Acta Trop 2009; 109:146-51. [PMID: 19026606 DOI: 10.1016/j.actatropica.2008.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 10/09/2008] [Accepted: 10/24/2008] [Indexed: 11/17/2022]
Abstract
In order to guide the antimalarial treatment policy of Somalia, we conducted therapeutic efficacy studies of routinely used antimalarial monotherapies as well as artemisinin-based combination therapies (ACTs) for uncomplicated malaria in three sentinel sites during 2003-2006. Therapeutic efficacy of chloroquine (CQ), amodiaquine (AQ) and sulfadoxine/pyrimetahmine (SP) monotherapies, and artesunate plus SP (AS+SP) or AQ (AS+AQ) were evaluated in children 6 months to 10 years old with uncomplicated malaria. For the assessment of the monotherapies, 2003 WHO protocol with 14-day follow-up was used while the 2005 WHO protocol with 28-day follow-up was used for testing the ACTs. Of the monotherapies, CQ performed very poorly with treatment failures varying from 76.5% to 88% between the sites. AQ treatment failure was low except for Janale site with treatment failure of 23.4% compared to 2.8% and 8% in Jamame and Jowhar, respectively. For SP, treatment failures from 7.8% to 12.2% were observed. A 28-day test of artemisinin-based combinations, AS+SP and AS+AQ, proved to be highly efficacious with cure rates of 98-100% supporting the choice of AS+SP combination as first line treatment for uncomplicated malaria for Somalia.
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Affiliation(s)
- Marian Warsame
- Division of International Health, Karolinska Institutet, Stockholm, Sweden.
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Vinayak S, Rathore D, Kariuki S, Slutsker L, Shi YP, Villegas L, Escalante AA, Udhayakumar V. Limited genetic variation in the Plasmodium falciparum heme detoxification protein (HDP). INFECTION GENETICS AND EVOLUTION 2008; 9:286-9. [PMID: 19135554 DOI: 10.1016/j.meegid.2008.12.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2008] [Revised: 12/04/2008] [Accepted: 12/09/2008] [Indexed: 10/21/2022]
Abstract
Malaria parasites infecting host red blood cells degrade hemoglobin by detoxifying heme into hemozoin. This conversion of heme to hemozoin is performed by a potent protein called heme detoxification protein (HDP), making HDP an attractive target for antimalarial drug development. We studied the genetic variation in Plasmodium falciparum HDP and also investigated if HDP due to its involvement in the heme detoxification pathway is under any potential chloroquine (CQ) selection pressure. We sequenced the complete HDP gene encompassing three exons and two introns (AT and ATTT repeats in intron 1; AT repeats in intron 2) from five P. falciparum laboratory strains with known CQ sensitivity and 50 field isolates from Venezuela (n=26) and Kenya (n=24), with high levels of CQ resistance. Sequencing revealed two mutations, C41F and F91L in exon 1 and exon 2, respectively. The F41 mutation was present only in the CQ sensitive (CQS) HB3 strain. However, all the isolates harbored the 91L mutation, except for the CQS 3D7 strain. The sequencing of the intron 2 region revealed no variation in the number of AT repeats. In contrast, there was a wide variation in the AT and ATTT repeats in intron 1. Overall with respect to the intron 1 repeats, the Venezuelan isolates (Expected heterozygosity, He=0.685) showed less genetic variation as compared to the Kenyan isolates (He=0.986). Furthermore, we also genotyped the 72-76 codons of the pfcrt gene but did not observe any correlation of the pfcrt CQ resistant genotypes (SVMNT or CVIET) with variation in the HDP, thus indicating HDP not to be under any CQ selection pressure. In conclusion, HDP is a conserved target for future antimalarial development.
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Affiliation(s)
- Sumiti Vinayak
- Atlanta Research and Education Foundation, Atlanta, GA, USA
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Van Hemelrijck MJJ, Lindblade KA, Kubaje A, Hamel MJ, Odhiambo F, Phillips-Howard PA, Laserson KF, Slutsker L, Feikin DR. Trends observed during a decade of paediatric sick visits to peripheral health facilities in rural western Kenya, 1997-2006. Trop Med Int Health 2008; 14:62-9. [PMID: 19017311 DOI: 10.1111/j.1365-3156.2008.02184.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
OBJECTIVES To assess whether longitudinal surveillance in peripheral health facilities could document trends in disease burden, healthcare practice and utilization resulting from large-scale public health interventions made in the decade 1997-2006. METHODS Data were collected from sick child visits (SCVs) among children <5 years attending 14 outpatient facilities in Asembo, rural western Kenya, during 1997-2006. Changes in proportions, and counts and rates were evaluated using chi-square and Poisson regression respectively. RESULTS During the decade, 64 394 SCVs were made, yielding an average rate of 0.70 SCVs per child-year. The annual number of SCVs stayed constant during 1997-2003, then increased by 74% between 2003 and 2006 (P < 0.01). The time between symptom onset and SCV shortened from 5.6 days in 1997 to 4.4 days in 2006 (P < 0.01). Malaria and upper respiratory tract infection (URTI) were most commonly diagnosed (69% and 36% of SCVs respectively). Between 2003 and 2006, the proportion of SCVs with a malaria diagnosis fell from 77% to 48%, although the rate of malaria SCVs did not. URTI visits increased in 2004-2006. The most frequently prescribed antimalarials changed three times, lagging 1-2 years behind changes in national policy. Treatment of pneumonia with antibiotics varied by year, ranging from 19% to 89%. CONCLUSION Surveillance of paediatric SCVs at peripheral health facilities was useful in documenting the timing and penetration of changes in national policies and clinical patterns of drug use for common infections. The surveillance data suggested that improved access to care, rather than disease burden changes, likely led to greater healthcare utilization after 2003.
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O'Meara WP, Bejon P, Mwangi TW, Okiro EA, Peshu N, Snow RW, Newton CRJC, Marsh K. Effect of a fall in malaria transmission on morbidity and mortality in Kilifi, Kenya. Lancet 2008; 372:1555-62. [PMID: 18984188 PMCID: PMC2607008 DOI: 10.1016/s0140-6736(08)61655-4] [Citation(s) in RCA: 339] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND As efforts to control malaria are expanded across the world, understanding the role of transmission intensity in determining the burden of clinical malaria is crucial to the prediction and measurement of the effectiveness of interventions to reduce transmission. Furthermore, studies comparing several endemic sites led to speculation that as transmission decreases morbidity and mortality caused by severe malaria might increase. We aimed to assess the epidemiological characteristics of malaria in Kilifi, Kenya, during a period of decreasing transmission intensity. METHODS We analyse 18 years (1990-2007) of surveillance data from a paediatric ward in a malaria-endemic region of Kenya. The hospital has a catchment area of 250 000 people. Clinical data and blood-film results for more than 61 000 admissions are reported. FINDINGS Hospital admissions for malaria decreased from 18.43 per 1000 children in 2003 to 3.42 in 2007. Over 18 years of surveillance, the incidence of cerebral malaria initially increased; however, malaria mortality decreased overall because of a decrease in incidence of severe malarial anaemia since 1997 (4.75 to 0.37 per 1000 children) and improved survival among children admitted with non-severe malaria. Parasite prevalence, the mean age of children admitted with malaria, and the proportion of children with cerebral malaria began to change 10 years before hospitalisation for malaria started to fall. INTERPRETATION Sustained reduction in exposure to infection leads to changes in mean age and presentation of disease similar to those described in multisite studies. Changes in transmission might not lead to immediate reductions in incidence of clinical disease. However, longitudinal data do not indicate that reductions in transmission intensity lead to transient increases in morbidity and mortality.
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Affiliation(s)
- Wendy P O'Meara
- Kenya Medical Research Institute, Centre for Geographic Medicine Research–Wellcome Trust Collaborative Program, Kilifi, Kenya
- Fogarty International Center, National Institutes of Health, Bethesda, MD, USA
- Correspondence to: Dr Wendy Prudhomme O'Meara, Fogarty International Center, National Institutes of Health, 16 Center Drive, Bethesda, MD 20892, USA
| | - Phillip Bejon
- Kenya Medical Research Institute, Centre for Geographic Medicine Research–Wellcome Trust Collaborative Program, Kilifi, Kenya
- Centre of Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Tabitha W Mwangi
- Kenya Medical Research Institute, Centre for Geographic Medicine Research–Wellcome Trust Collaborative Program, Kilifi, Kenya
| | - Emelda A Okiro
- Kenya Medical Research Institute–Wellcome Trust Collaborative Program, Nairobi, Kenya
| | - Norbert Peshu
- Kenya Medical Research Institute, Centre for Geographic Medicine Research–Wellcome Trust Collaborative Program, Kilifi, Kenya
| | - Robert W Snow
- Kenya Medical Research Institute–Wellcome Trust Collaborative Program, Nairobi, Kenya
- Centre of Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Charles RJC Newton
- Kenya Medical Research Institute, Centre for Geographic Medicine Research–Wellcome Trust Collaborative Program, Kilifi, Kenya
- Institute of Child Health, University College London, UK
| | - Kevin Marsh
- Kenya Medical Research Institute, Centre for Geographic Medicine Research–Wellcome Trust Collaborative Program, Kilifi, Kenya
- Centre of Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
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Ogungbamigbe TO, Ojurongbe O, Ogunro PS, Okanlawon BM, Kolawole SO. Chloroquine resistant Plasmodium falciparum malaria in Osogbo Nigeria: efficacy of amodiaquine + sulfadoxine-pyrimethamine and chloroquine + chlorpheniramine for treatment. Mem Inst Oswaldo Cruz 2008; 103:79-84. [PMID: 18368238 DOI: 10.1590/s0074-02762008000100012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 02/18/2008] [Indexed: 11/22/2022] Open
Abstract
Chloroquine (CQ) resistance in Plasmodium falciparum contributes to increasing malaria-attributable morbidity and mortality in Sub-Saharan Africa. Despite a change in drug policy, continued prescription of CQ did not abate. Therefore the therapeutic efficacy of CQ in uncomplicated falciparum malaria patients was assessed in a standard 28-day protocol in 116 children aged between six and 120 months in Osogbo, Southwest Nigeria. Parasitological and clinical assessments of response to treatment showed that 72 (62.1%) of the patients were cured and 44 (37.9%) failed the CQ treatment. High initial parasite density and young age were independent predictors for early treatment failure. Out of the 44 patients that failed CQ, 24 received amodiaquine + sulphadoxine/pyrimethamine (AQ+SP) and 20 received chlorpheniramine + chloroquine (CH+CQ) combinations. Mean fever clearance time in those treated with AQ+SP was not significantly different from those treated with CH+CQ (p = 0.05). There was no significant difference in the mean parasite density of the two groups. The cure rate for AQ+SP group was 92% while those of CH+CQ was 85%. There was a significant difference in parasite clearance time (p = 0.01) between the two groups. The 38% treatment failure for CQ reported in this study is higher than the 10% recommended by World Health Organization in other to effect change in antimalarial treatment policy. Hence we conclude that CQ can no more be solely relied upon for the treatment of falciparum malaria in Osogbo, Nigeria. AQ+SP and CH+CQ are effective in the treatment of acute uncomplicated malaria and may be considered as useful alternative drugs in the absence of artemisinin-based combination therapies.
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Affiliation(s)
- T O Ogungbamigbe
- Malaria Research Clinic & Laboratory, College of Health Sciences, Ladoke Akintola University Teaching Hospital, Osogbo, Nigeria
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Abstract
Despite the availability of many drugs and therapies to treat malaria, many countries' national policies recommend using a single first-line therapy for most clinical malaria cases. To assess whether this is the best strategy for the population as a whole, we designed an evolutionary-epidemiological modeling framework for malaria and compared the benefits of different treatment strategies in the context of resistance evolution. Our results show that the population-wide use of multiple first-line therapies (MFT) against malaria yields a better clinical outcome than using a single therapy or a cycling strategy where therapies are rotated, either on a fixed cycling schedule or when resistance levels or treatment failure become too high. MFT strategies also delay the emergence and slow the fixation of resistant strains (phenotypes), and they allow a larger fraction of the population to be treated without trading off future treatment of cases that may be untreatable because of high resistance levels. Earlier papers have noted that cycling strategies have the disadvantage of creating a less temporally variable environment than MFT strategies, making resistance evolution easier for the parasite. Here, we illustrate a second feature of parasite ecology that impairs the performance of cycling policies, namely, that cycling policies degrade the mean fitness of the parasite population more quickly than MFT policies, making it easier for new resistant types to invade and spread. The clinical benefits of using multiple first-line therapies against malaria suggest that MFT policies should play a key role in malaria elimination and control programs.
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Zhong D, Afrane Y, Githeko A, Cui L, Menge DM, Yan G. Molecular epidemiology of drug-resistant malaria in western Kenya highlands. BMC Infect Dis 2008; 8:105. [PMID: 18671871 PMCID: PMC2533336 DOI: 10.1186/1471-2334-8-105] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 07/31/2008] [Indexed: 11/18/2022] Open
Abstract
Background Since the late 1980s a series of malaria epidemics has occurred in western Kenya highlands. Among the possible factors that may contribute to the highland malaria epidemics, parasite resistance to antimalarials has not been well investigated. Methods Using parasites from highland and lowland areas of western Kenya, we examined key mutations associated with Plasmodium falciparum resistance to sulfadoxine – pyrimethamine and chloroquine, including dihydrofolate reductase (pfdhfr) and dihydropteroate synthetase (pfdhps), chloroquine resistance transporter gene (pfcrt), and multi-drug resistance gene 1 (pfmdr1). Results We found that >70% of samples harbored 76T pfcrt mutations and over 80% of samples harbored quintuple mutations (51I/59R/108N pfdhfr and 437G/540E pfdhps) in both highland and lowland samples. Further, we did not detect significant difference in the frequencies of these mutations between symptomatic and asymptomatic malaria volunteers, and between highland and lowland samples. Conclusion These findings suggest that drug resistance of malaria parasites in the highlands could be contributed by the mutations and their high frequencies as found in the lowland. The results are discussed in terms of the role of drug resistance as a driving force for malaria outbreaks in the highlands.
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Affiliation(s)
- Daibin Zhong
- Program in Public Health, College of Health Sciences, University of California at Irvine, Irvine, CA 92697, USA.
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