Browsing by Author "Nosten, F."
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Item Author Correction: The temporal dynamics and infectiousness of subpatent Plasmodium falciparum infections in relation to parasite density(Nature communications, 2019-06-11) Koram, K.; Slater, H.C.; Ross, A.; Felger, I.; Hofmann, N.E.; Robinson, L.; Cook, J.; Gonçalves, B.P.; Björkman, A.; Ouedraogo, A.L.; Morris, U.; Msellem, M.; Koepfli, C.; Mueller, I.; Tadesse, F.; Gadisa, E.; Das, S.; Domingo, G.; Kapulu, M.; Midega, J.; Owusu-Agyei, S.; Nabet, C.; Piarroux, R.; Doumbo, O.; Doumbo, S.N.; Koram, K.; Lucchi, N.; Udhayakumar, V.; Mosha, J.; Tiono, A.; Chandramohan, D.; Gosling, R.; Mwingira, F.; Sauerwein, R.; Paul, R.; Riley, E.M.; White, N.J.; Nosten, F.; Imwong, M.; Bousema, T.; Drakeley, C.; Okell, L.C.Item High-throughput analysis of antimalarial susceptibility data by the worldwide antimalarial resistance network (WWARN) In Vitro analysis and reporting tool(Antimicrobial Agents and Chemotherapy, 2013-07) Woodrow, C.J.; Dahlström, S.; Cooksey, R.; Flegg, J.A.; Le Nagard, H.; Mentré, F.; Murillo, C.; Ménard, D.; Nosten, F.; Sriprawat, K.; Musset, L.; Quashie, N.B.; Lim, P.; Fairhurst, R.M.; Nsobya, S.L.; Sinou, V.; Noedl, H.; Pradines, B.; Johnson, J.D.; Guerin, P.J.; Sibley, C.H.; Le Bras, J.Assessment of in vitro susceptibility is a fundamental component of antimalarial surveillance studies, but wide variations in the measurement of parasite growth and the calculation of inhibitory constants make comparisons of data from different laboratories difficult. Here we describe a Web-based, high-throughput in vitro analysis and reporting tool (IVART) generating inhibitory constants for large data sets. Fourteen primary data sets examining laboratory-determined susceptibility to artemisinin derivatives and artemisinin combination therapy partner drugs were collated from 11 laboratories. Drug concentrations associated with half-maximal inhibition of growth (IC 50s) were determined by a modified sigmoid Emax model-fitting algorithm, allowing standardized analysis of 7,350 concentration-inhibition assays involving 1,592 isolates. Examination of concentration-inhibition data revealed evidence of apparent paradoxical growth at high concentrations of nonartemisinin drugs, supporting amendment of the method for calculating the maximal drug effect in each assay. Criteria for defining more-reliable IC50s based on estimated confidence intervals and growth ratios improved correlation coefficients for the drug pairs mefloquine-quinine and chloroquine-desethylamodiaquine in 9 of 11 and 8 of 8 data sets, respectively. Further analysis showed that maximal drug inhibition was higher for artemisinins than for other drugs, particularly in ELISA (enzyme-linked immunosorbent assay)-based assays, a finding consistent with the earlier onset of action of these drugs in the parasite life cycle. This is the first high-throughput analytical approach to apply consistent constraints and reliability criteria to large, diverse antimalarial susceptibility data sets. The data also illustrate the distinct biological properties of artemisinins and underline the need to apply more sensitive approaches to assessing in vitro susceptibility to these drugs. Copyright © 2013, American Society for Microbiology.Item Malaria: Current status of control, diagnosis, treatment, and a proposed agenda for research and development(Lancet Infectious Diseases, 2002-09) Guerin, P.J.; Olliaro, P.; Nosten, F.; Druilhe, P.; Laxminarayan, R.; Binka, F.; Kilama, W.L.; Ford, N.; White, N.J.Rolling back malaria is possible. Tools are available but they are not used. Several countries deploy, as their national malaria control treatment policy, drugs that are no longer effective. New and innovative methods of vector control, diagnosis, and treatment should be developed, and work towards development of new drugs and a vaccine should receive much greater support. But the pressing need, in the face of increasing global mortality and general lack of progress in malaria control, is research into the best methods of deploying and using existing approaches, particularly insecticide-treated mosquito nets, rapid methods of diagnosis, and artemisinin-based combination treatments. Evidence on these approaches should provide national governments and international donors with the cost-benefit information that would justify much-needed increases in global support for appropriate and effective malaria control.Item An open dataset of Plasmodium falciparum genome variation in 7,000 worldwide samples(2021) MalariaGEN; Ahouidi, A.; Ali, M.; Almagro-Garcia, J.; Amambua-Ngwa, A.; Amaratunga, C.; Amato, R.; Amenga-Etego, L.; Andagalu, B.; Anderson, T.J.C.; Andrianaranjaka, V.; Apinjoh, T.; Ariani, C.; Ashley, E.A.; Auburn, S.; Awandare, G.A.; Ba, H.; Baraka, V.; Barry, A.E.; Bejon, P.; Bertin, G.I.; Boni, M.F.; Borrmann, S.; Bousema, T.; Branch, O.; Bull, P.C.; Busby, G.B.J.; Chookajorn, T.; Chotivanich, K.; Claessens, A.; Conway, D.; Craig, A.; D'Alessandro, U.; Dama, S.; Day, N.P.J.; Denis, B.; Diakite, M.; Djimdé, A.; Dolecek, C.; Dondorp, A.M.; Drakeley, C.; Drury, E.; Duffy, P.; Echeverry, D.F.; Egwang, T.G.; Erko, B.; Fairhurst, R.M.; Faiz, A.; Fanello, C.A.; Fukuda, M.M.; Gamboa, D.; Ghansah, A.; Golassa, L.; Goncalves, S.; Hamilton, W.L.; Harrison, G.L.A.; Hart, L.; Henrichs, C.; Hien, T.T.; Hill, C.A.; Hodgson, A.; Hubbart, C.; Imwong, M.; Ishengoma, D.S.; Jackson, S.A.; Jacob, C.G.; Jeffery, B.; Jeffreys, A.E.; Johnson, K.J.; Jyothi, D.; Kamaliddin, C.; Kamau, E.; Kekre, M.; Kluczynski, K.; Kochakarn, T.; Konaté, A.; Kwiatkowski, D.P.; Kyaw, M.P.; Lim, P.; Lon, C.; Loua, K.M.; Maïga-Ascofaré, O.; Malangone, C.; Manske, M.; Marfurt, J.; Marsh, K.; Mayxay, M.; Miles, A.; Miotto, O.; Mobegi, V.; Mokuolu, O.A.; Montgomery, J.; Mueller, I.; Newton, P.N.; Nguyen, T.; Nguyen, T.; Noedl, H.; Nosten, F.; Noviyanti, R.; Nzila, A.; Ochola-Oyier, L.I.; Ocholla, H.; Oduro, A.; Omedo, I.; Onyamboko, M.A.; Ouedraogo, J.; Oyebola, K.; Pearson, R.D.; Peshu, N.; Phyo, A.P.; Plowe, C.V.; Price, R.N.; Pukrittayakamee, S.; Randrianarivelojosia, M.; Rayner, J.C.; Ringwald, P.; Rockett, K.A.; Rowlands, K.; Ruiz, L.; Saunders, D.; Shayo, A.; Siba, P.; Simpson, V.J.; Stalker, J.; Su, X.; Sutherland, C.; Takala-Harrison, S.; Tavul, L.; Thathy, V.; Tshefu, A.; Verra, F.; Vinetz, J.; Wellems, T.E.; Wendler, J.; White, N.J.; Wright, I.; Yavo, W.; Ye, H.MalariaGEN is a data-sharing network that enables groups around the world to work together on the genomic epidemiology of malaria. Here we describe a new release of curated genome variation data on 7,000 Plasmodium falciparum samples from MalariaGEN partner studies in 28 malaria-endemic countries. High-quality genotype calls on 3 million single nucleotide polymorphisms (SNPs) and short indels were produced using a standardised analysis pipeline. Copy number variants associated with drug resistance and structural variants that cause failure of rapid diagnostic tests were also analysed. Almost all samples showed genetic evidence of resistance to at least one antimalarial drug, and some samples from Southeast Asia carried markers of resistance to six commonly-used drugs. Genes expressed during the mosquito stage of the parasite life-cycle are prominent among loci that show strong geographic differentiation. By continuing to enlarge this open data resource we aim to facilitate research into the evolutionary processes affecting malaria control and to accelerate development of the surveillance toolkit required for malaria elimination.Item The temporal dynamics and infectiousness of subpatent Plasmodium falciparum infections in relation to parasite density(Nature Communications, 2019) Slater, H.C.; Ross, A.; Felge, I.; Hofmann, N.E.; Robinson, L.; Cook, J.; Gonçalves, B.P.; Björkman, A.; Ouedraogo, A.L.; Morris, U.; Msellem, M.; Koepfli, C.; Mueller, I.; Tadesse, F.; Gadisa, E.; Das, S.; Domingo, G.; Kapulu, M.; Midega, J.; Owusu-Agyei, S.; Nabet, C.; Piarroux, R.; Doumbo, O.; Doumbo, S.N.; Koram, K.; Lucchi, N.; Udhayakumar, V.; Mosha, J.; Tiono, A.; Chandramohan, D.; Gosling, R.; Mwingira, F.; Sauerwein, R.; Riley, E.M.; White, N.J.; Nosten, F.; Imwong, M.; Bousema, T.; Drakeley, C.; Okell, L.C.Malaria infections occurring below the limit of detection of standard diagnostics are common in all endemic settings. However, key questions remain surrounding their contribution to sustaining transmission and whether they need to be detected and targeted to achieve malaria elimination. In this study we analyse a range of malaria datasets to quantify the density, detectability, course of infection and infectiousness of subpatent infections. Asymptomatically infected individuals have lower parasite densities on average in low transmission settings compared to individuals in higher transmission settings. In cohort studies, subpatent infections are found to be predictive of future periods of patent infection and in membrane feeding studies, individuals infected with subpatent asexual parasite densities are found to be approximately a third as infectious to mosquitoes as individuals with patent (asexual parasite) infection. These results indicate that subpatent infections contribute to the infectious reservoir, may be long lasting, and require more sensitive diagnostics to detect them in lower transmission settings. © 2019, The Author(s).