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Subject: Malaria

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Now showing 1 - 10 of 29
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    PublicationOpen Access
    Ethical considerations in malaria research proposal review: empirical evidence from 114 proposals submitted to an Ethics Committee in Thailand
    (2015) Pornpimon Adams; Sukanya Prakobtham; Chanthima Limphattharacharoen; Pitchapa Vutikes; Srisin Khusmith; Krisana Pengsaa; Polrat Wilairatana; Jaranit Kaewkungwal; Mahidol University. Faculty of Tropical Medicine. Department of Tropical Hygiene
    for proposals involving new specimen collection. Studies involving stored data and specimens tended to attract more issues around privacy and confidentiality. Proposals involving minority populations were more likely to raise issues than those that did
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    PublicationOpen Access
    Efficacy and day 7 plasma piperaquine concentrations in African children treated for uncomplicated malaria with dihydroartemisinin-piperaquine.
    (2014-08-18) Zongo, Issaka; Some, Fabrice A.; Somda, Serge A. M.; Parikh, Sunil; Rouamba, Noel; Rosenthal, Philip J.; Tarning, Joel; Lindegardh, Niklas; Nosten, Franc¸ois; Oue´draogo, Jean Bosco; Oue´draogo, Jean Bosco; Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unit.; Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unit. Shoklo Malaria Research Unit.
    BACKGROUND: One promising new Artemisinin-based combination therapies (ACTs) is dihydroartemisinin-piperaquine (DHA-PQ). However, the pharmacokinetics of piperaquine and the relationship between drug levels and clinical efficacy are incompletely....001). CONCLUSION: DHA-PQ was effective for uncomplicated P. falciparum malaria treatment and offers an alternative to other ACTs. Recurrent malaria was mainly due to new infections after treatment and was correlated with low day 7 PQ concentration in the youngest
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    PublicationOpen Access
    FlexiChip package: an universal microarray with a dedicated analysis software for high-thoughput SNPs detection linked to anti-malarial drug resistance.
    (2009-10-15) Steenkeste, Nicolas; Dillies, Marie-Agnès; Khim, Nimol; Sismeiro, Odile; Chy, Sophy; Lim, Pharath; Crameri, Andreas; Bouchier, Christiane; Mercereau-Puijalon, Odile; Beck, Hans-Peter; Mallika Imwong; มัลลิกา อิ่มวงศ์; Dondorp, Arjen M.; Socheat, Duong; Rogier, Christophe; Coppée, Jean- Yves; Ariey, Frédéric; Steenkeste, Nicolas; Mahidol University. Faculty of Tropical Medicine
    of practical methods enabling high throughput analysis. Here a new Zip-code array is described, called FlexiChip, linked to a dedicated software program, which largely overcomes this problem. METHODS: Previously published microarray probes detecting single
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    PublicationOpen Access
    Introducing the concept of a new pre-referral treatment for severely ill febrile children at community level: a sociological approach in Guinea-Bissau.
    (2014-02-06) Vermeersch, Audrey; Libaud-Moal, Anaëlle; Rodrigues, Amabelia; White, Nicholas J; Olliaro, Piero; Gomes, Melba; Ashley, Elizabeth A; Millet, Pascal; Millet, Pascal; Mahidol University. Faculty of Tropical Medicine.
    treatment is not possible for several hours. Adding an antibacterial rectal drug would extend this strategy to treat non-malarial febrile illness as well. The objective of these studies was to assess acceptability of such a new pre-referral strategy.... RESULTS AND CONCLUSIONS: Up to 92% of health representatives were in favour of introducing a new pre-referral strategy to tackle both malaria and non-malaria related severe illnesses in Guinea-Bissau, provided it was endorsed by international health
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    PublicationOpen Access
    High-throughput ultrasensitive molecular techniques for quantifying low-density malaria parasitemias.
    (2014-09) Mallika Imwong; มัลลิกา อิ่มวงศ์; Sarun Hanchana; Malleret, Benoit; Rénia, Laurent; Day, Nicholas P. J.; Dondorp, Arjen; Nosten, Francois; Snounou, Georges; White, Nicholas J.; Mallika Imwong; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and Genetics.; Mahidol University. Faculty of Tropical Medicine. Mahidol Oxford Research Unit.; Mahidol University. Faculty of Tropical Medicine. Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit.
    The epidemiology of malaria in "low-transmission" areas has been underestimated. Molecular detection methods have revealed higher prevalences of malaria than conventional microscopy or rapid diagnostic tests, but these typically evaluate finger-prick capillary blood samples (∼5 μl) and therefore cannot detect parasite densities of <200/ml. Their use underestimates true parasite carriage rates. To characterize the epidemiology of malaria in low-transmission settings and plan elimination strategies, more sensitive quantitative PCR (qPCR) is needed to identify and quantify low-density malaria parasitemias. A highly sensitive "high-volume" quantitative PCR (qPCR) method based on Plasmodium sp. 18S RNA was adapted for blood sample volumes of ≥250 μl and scaled for high throughput. The methods were validated by assessment of the analytical sensitivity and specificity, diagnostic sensitivity, and specificity, efficiency, precision, analytical and diagnostic accuracies, limit of detection, root cause analysis of false positives, and robustness. The high-volume qPCR method based on Plasmodium sp. 18S RNA gave high PCR efficiency of 90 to 105%. Concentrations of parasite DNA from large volumes of blood gave a consistent analytical detection limit (LOD) of 22 parasites/ml (95% CI, 21.79 to 74.9), which is some 2,500 times more sensitive than conventional microscopy and 50 times more sensitive than currently used PCR methods from filter paper blood spots. The diagnostic specificity was 99.75%. Using automated procedures it was possible to process 700 blood samples per week. A very sensitive and specific high-throughput high-volume qPCR method for the detection of low-density parasitemias (>20 parasites/ml) was developed and validated.
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    PublicationOpen Access
    Effect of malaria in pregnancy on foetal cortical brain development: a longitudinal observational study
    (2012) Rijken, Marcus J; Merel Charlotte de Wit; Mulder, Eduard JH; Suporn Kiricharoen; Noaeni Karunkonkowit; Tamalar Paw; Visser, Gerard HA; McGready, Rose; Nosten, François H; Pistorius, Lourens R; Mahidol University. Faculty of Tropical Medicine
    Background: Malaria in pregnancy has a negative impact on foetal growth, but it is not known whether this also affects the foetal nervous system. The aim of this study was to examine the effects of malaria on foetal cortex development by three-dimensional ultrasound. Methods: Brain images were acquired using a portable ultrasound machine and a 3D ultrasound transducer. All recordings were analysed, blinded to clinical data, using the 4D view software package. The foetal supra-tentorial brain volume was determined and cortical development was qualitatively followed by scoring the appearance and development of six sulci. Multilevel analysis was used to study brain volume and cortical development in individual foetuses. Results: Cortical grading was possible in 161 out of 223 (72%) serial foetal brain images in pregnant women living in a malaria endemic area. There was no difference between foetal cortical development or brain volumes at any time in pregnancy between women with immediately treated malaria infections and non-infected pregnancies. Conclusion: The percentage of images that could be graded was similar to other neuro-sonographic studies. Maternal malaria does not have a gross effect on foetal brain development, at least in this population, which had access to early detection and effective treatment of malaria.
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    PublicationOpen Access
    Efficacy of artemether-lumefantrine, the nationally-recommended artemisinin combination for the treatment of uncomplicated falciparum malaria, in southern Laos.
    (2012-06-8) Mayfong Mayxay; Maniphone Khanthavong; Odai Chanthongthip; Mallika Imwong; มัลลิกา อิ่มวงศ์; Tiengkham Pongvongsa; Bouasy Hongvanthong; Samalane Phompida; Viengxay Vanisaveth; White, Nicholas J.; Newton, Paul N; Mayfong Mayxay; Mahidol University. Faculty of Tropical Medicine. Department of Molecular Tropical Medicine and Genetics
    malaria. RESULTS: Of 630 patients with P. falciparum enrolled in the trial of thiamin treatment, 549 (87%, 357 children ≤15 years and 192 adults) were included in this study. The per protocol 42-day cure rates were 97% (524/541) [96% (337/352
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    PublicationOpen Access
    Investigations on anopheline mosquitoes close to the nest sites of chimpanzees subject to malaria infection in Ugandan highlands
    (2012-04-17) Krief, Sabrina; Levrero, Florence; Krief, Jean-Michel; Supinya Thanapongpichat; สุภิญญา ธนาพงษ์ภิชาติ; Mallika Imwong; มัลลิกา อิ่มวงศ์; Snounou, Georges; Kasenene, John M.; Cibot, Marie; Gantier, Jean-Charles; Krief, Sabrina; Mahidol University. Faculty of Tropical Medicine
    BACKGROUND: Malaria parasites (Plasmodium sp.), including new species, have recently been discovered as low grade mixed infections in three wild chimpanzees (Pan troglodytes schweinfurthii) sampled randomly in Kibale National Park, Uganda
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    PublicationOpen Access
    Persistent Plasmodium falciparum and Plasmodium vivax infections in a western Cambodian population: implications for prevention, treatment and elimination strategies
    (2016) Rupam Tripura; Peto, Thomas J.; Jeremy Chalk; Lee, Sue J.; Pasathorn Sirithiranont; Chea Nguon; Mehul Dhorda; Seidlein, Lorenz von; Maude, Richard J.; Day, Nicholas P. J.; Mallika Imwong; White, Nicholas J.; Dondorp, Arjen M.; Mahidol University. Faculty of Tropical Medicine. Mahidol-Oxford Tropical Medicine Research Unit
    Background: Subclinical Plasmodium parasitaemia is an important reservoir for the transmission and persistence of malaria, particularly in low transmission areas. Methods: Using ultrasensitive quantitative PCR (uPCR) for the detection of parasitaemia, the entire population of three Cambodian villages in Pailin province were followed for 1 year at three-monthly intervals. A cohort of adult participants found initially to have asymptomatic malaria parasitaemia was followed monthly over the same period. Results: The initial cross sectional survey in June 2013 (M0) of 1447 asymptomatic residents found that 32 (2.2 %) had Plasmodium falciparum, 48 (3.3 %) had P. vivax, 4 (0.3 %) had mixed infections and in 142/1447 (9.8 %) malaria was detected but there was insufficient DNA to identify the species (Plasmodium. species). Polymorphisms in the ‘K13-propeller’ associated with reduced susceptibility to artemisinin derivatives (C580Y) were found in 17/32 (51 %) P. falciparum strains. Monthly follow-up without treatment of 24 adult participants with asymptomatic mono or mixed P. falciparum infections found that 3/24 (13 %) remained parasitaemic for 2–4 months, whereas the remaining 21/24 (87 %) participants had cleared their parasitaemia after 1 month. In contrast, 12/34 (35 %) adult participants with P. vivax mono-infection at M0 had malaria parasites (P. vivax or P. sp.) during four or more of the following 11 monthly surveys. Conclusions: This longitudinal survey in a low transmission setting shows limited duration of P. falciparum carriage, but prolonged carriage of P. vivax infections. Radical treatment of P. vivax infections by 8-aminoquinoline regimens may be required to eliminate all malaria from Cambodia. Trial registration ClinicalTrials.gov NCT01872702
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    PublicationOpen Access
    World Antimalarial Resistance Network (WARN) IV: clinical pharmacology
    (2007-09-06) Barnes, Karen I.; Lindegardh, Niklas; Ogundahunsi, Olumide; Olliaro, Piero; Plowe, Christopher V.; Randrianarivelojosia, Milijaona; Gbotosho, Grace O; Watkins, William M.; Sibley, Carol H.; White, Nicholas J.; Barnes, Karen I.; Mahidol University. Faculty of Tropical Medicine. Mahidol Oxford Tropical Medicine Research Unit (MORU).
    A World Antimalarial Resistance Network (WARN) database has the potential to improve the treatment of malaria, through informing current drug selection and use and providing a prompt warning of when treatment policies need changing. This manuscript outlines the contribution and structure of the clinical pharmacology component of this database. The determinants of treatment response are multi-factorial, but clearly providing adequate blood concentrations is pivotal to curing malaria. The ability of available antimalarial pharmacokinetic data to inform optimal dosing is constrained by the small number of patients studied, with even fewer (if any) studies conducted in the most vulnerable populations. There are even less data relating blood concentration data to the therapeutic response (pharmacodynamics). By pooling all available pharmacokinetic data, while paying careful attention to the analytical methodologies used, the limitations of small (and thus underpowered) individual studies may be overcome and factors that contribute to inter-individual variability in pharmacokinetic parameters defined. Key variables for pharmacokinetic studies are defined in terms of patient (or study subject) characteristics, the formulation and route of administration of the antimalarial studied, the sampling and assay methodology, and the approach taken to data analysis. Better defining these information needs and criteria of acceptability of pharmacokinetic-pharmacodynamic (PK-PD) studies should contribute to improving the quantity, relevance and quality of these studies. A better understanding of the pharmacokinetic properties of antimalarials and a more clear definition of what constitutes "therapeutic drug levels" would allow more precise use of the term "antimalarial resistance", as it would indicate when treatment failure is not caused by intrinsic parasite resistance but is instead the result of inadequate drug levels. The clinical pharmacology component of the WARN database can play a pivotal role in monitoring accurately for true antimalarial drug resistance and promptly correcting sub-optimal dosage regimens to prevent these contributing to the emergence and spread of antimalarial resistance.