• A randomized open study to assess the efficacy and tolerability of dihydroartemisinin-piperaquine for the treatment of uncomplicated falciparum malaria in Cambodia.

      Janssens, B; Van Herp, M; Goubert, L; Chan, S; Uong, S; Nong, S; Socheat, D; Brockman, A; Ashley, E A; Van Damme, W; et al. (Wiley-Blackwell, 2007-02)
      OBJECTIVES: To compare the efficacy and tolerability of dihydroartemisinin-piperaquine (DHA-PQP) with that of a 3-day regimen of mefloquine and artesunate (MAS3) for the treatment of uncomplicated falciparum malaria in Cambodia. METHOD: Randomized open-label non-inferiority study over 64 days. RESULTS: Four hundred and sixty-four patients were included in the study. The polymerase chain reaction genotyping-adjusted cure rates on day 63 were 97.5% (95% confidence interval, CI, 93.8-99.3) for DHA-PQP and 97.5% (95% CI, 93.8-99.3) for MAS3, P = 1. There were no serious adverse events, but significantly more episodes of vomiting (P = 0.03), dizziness (P = 0.002), palpitations (P = 0.04), and sleep disorders (P = 0.03) reported in the MAS3 treatment group, consistent with the side-effect profile of mefloquine. CONCLUSIONS: DHA-PQP was as efficacious as MAS3, but much better tolerated, making it more appropriate for use in a routine programme setting. This highly efficacious, safe and more affordable fixed-dose combination could become the treatment of choice for Plasmodium falciparum malaria in Cambodia.
    • A randomized trial comparing the efficacy of four treatment regimens for uncomplicated falciparum malaria in Assam state, India.

      Campbell, P; Baruah, S; Narain, K; Rogers, C C; Medecins sans Frontieres-Holland, India Section, R.G. Baruah Road, Guwahati, Assam 781024, India. patricia10334@yahoo.com (Elsevier, 2006-02)
      A four-arm drug sensitivity study compared chloroquine, sulfadoxine-pyrimethamine (SP), mefloquine and mefloquine-artesunate in Sonitpur and Karbi Anglong districts in Assam state, India. Two criteria were used to ascertain outcome: success of clinical treatment and parasitologic cure. In Sonitpur, at 14 days, there were 36/56 early and late treatment failures plus late parasitologic failures to chloroquine and 16/56 for SP. In Karbi Anglong, combined treatment failure at 14 days was 16/56 to chloroquine and 8/60 to SP. Mefloquine and mefloquine-artesunate demonstrated 93.9% and 93.6% sustained responses respectively at 42 days. High failure rates to both chloroquine and SP preclude the use of these drugs as first-line treatment for uncomplicated falciparum malaria in this region. A mefloquine-artesunate combination presents an effective alternative utilizing the currently recommended higher dose of mefloquine.
    • Ranking malaria risk factors to guide malaria control efforts in African highlands

      Protopopoff, Natacha; Van Bortel, Wim; Speybroeck, Niko; Van Geertruyden, Jean-Pierre; Baza, Dismas; D'Alessandro, Umberto; Coosemans, Marc; Department of Parasitology, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium; Medecins Sans Frontieres Brussels, Belgium; Department of Animal Health, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium; School of Public Health, Universite Catholique de Louvain, Brussels, Belgium; Programme de Lutte contre les Maladies Transmissibles et Carentielles, Ministry of Health, Bujumbura, Burundi; Department of Biomedical Sciences, Faculty of Pharmaceutical, Veterinary and Biomedical Sciences, University of Antwerp, Antwerp, Belgium (2009-11-25)
      INTRODUCTION: Malaria is re-emerging in most of the African highlands exposing the non immune population to deadly epidemics. A better understanding of the factors impacting transmission in the highlands is crucial to improve well targeted malaria control strategies. METHODS AND FINDINGS: A conceptual model of potential malaria risk factors in the highlands was built based on the available literature. Furthermore, the relative importance of these factors on malaria can be estimated through "classification and regression trees", an unexploited statistical method in the malaria field. This CART method was used to analyse the malaria risk factors in the Burundi highlands. The results showed that Anopheles density was the best predictor for high malaria prevalence. Then lower rainfall, no vector control, higher minimum temperature and houses near breeding sites were associated by order of importance to higher Anopheles density. CONCLUSIONS: In Burundi highlands monitoring Anopheles densities when rainfall is low may be able to predict epidemics. The conceptual model combined with the CART analysis is a decision support tool that could provide an important contribution toward the prevention and control of malaria by identifying major risk factors.
    • Rapid malaria diagnostic tests vs. clinical management of malaria in rural Burkina Faso: safety and effect on clinical decisions. A randomized trial

      Bisoffi, Zeno; Sirima, Bienvenu Sodiomon; Angheben, Andrea; Lodesani, Claudia; Gobbi, Federico; Tinto, Halidou; Van den Ende, Jef; Centre for Tropical Diseases, Sacro Cuore Hospital, Negrar (Verona), Italy; Centre National de Recherche et de Formation sur le Paludisme, Ministry of Health, Ouagadougou, Burkina Faso; Medecins sans Frontieres, Democratic Republic of Congo; Centre Muraz, Bobo Dioulasso, Burkina Faso; Projet AnKaHeresso, Bobo Dioulasso, Burkina Faso; Department of Clinical Sciences, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium (2009-02-15)
      OBJECTIVES: To assess if the clinical outcome of patients treated after performing a Rapid Diagnostic Test for malaria (RDT) is at least equivalent to that of controls (treated presumptively without test) and to determine the impact of the introduction of a malaria RDT on clinical decisions. METHODS: Randomized, multi-centre, open clinical trial in two arms in 2006 at the end of the dry and of the rainy season in 10 peripheral health centres in Burkina Faso: one arm with use of RDT before treatment decision, one arm managed clinically. Primary endpoint: persistence of fever at day 4. Secondary endpoints: frequency of malaria treatment and of antibiotic treatment. RESULTS: A total of 852 febrile patients were recruited in the dry season and 1317 febrile patients in the rainy season, and randomized either to be submitted to RDT (P_RTD) or to be managed presumptively (P_CLIN). In both seasons, no significant difference was found between the two randomized groups in the frequency of antimalarial treatment, nor of antibiotic prescription. In the dry season, 80.8% and 79.8% of patients with a negative RDT were nevertheless diagnosed and treated for malaria, and so were 85.0% and 82.6% negative patients in the rainy season. In the rainy season only, both diagnosis and treatment of other conditions were significantly less frequent in RDT positive vs. negative patients (48.3% vs. 61.4% and 46.2% vs. 59.9%, P = 0.00 and 0.00, respectively). CONCLUSION: Our study was inconclusive on RDT safety (clinical outcome in the two randomized groups), because of an exceedingly and unexpectedly low compliance with the negative test result. Further research is needed on best strategies to promote adherence and on the safety of a test based strategy compared with the current, presumptive treatment strategy.
    • Ready-to-use therapeutic food for Catch-up Growth in children after an episode of Plasmodium Falciparum Malaria: an open randomised controlled trial

      van der Kam, S; Swarthout, T; Niragira, O; Froud, A; Sompwe, E M; Mills, C; Roll, S; Tinnemann, P; Shanks, L; Médecins Sans Frontières, Amsterdam, The Netherlands. saskia.vd.kam@amsterdam.msf.org (2012-04-25)
      Catch-up growth after an infection is essential for children to maintain good nutritional status. To prevent malnutrition, WHO recommends that children are given one additional healthy meal per day during the 2 weeks after onset of illness. We investigated to what extent ready-to-use therapeutic food (RUTF) promotes catch-up growth in children after an acute, uncomplicated episode of Plasmodium falciparum malaria.
    • Real-time PCR/MCA assay using fluorescence resonance energy transfer for the genotyping of resistance related DHPS-540 mutations in Plasmodium falciparum

      Mens, Petra F; van Overmeir, Chantal; Bonnet, Maryline; Dujardin, Jean-Claude; d'Alessandro, Umberto; Prince Leopold Institute of Tropical Medicine, Department of Parasitology, Antwerp, Belgium; Koninklijk Instituut voor de Tropen/Royal Tropical Institute, KIT Biomedical Research, Amsterdam, The Netherlands; Epicentre, Paris, France (2008-03-17)
      BACKGROUND: Sulphadoxine-pyrimethamine has been abandoned as first- or second-line treatment by most African malaria endemic countries in favour of artemisinin-based combination treatments, but the drug is still used as intermittent preventive treatment during pregnancy. However, resistance to sulphadoxine-pyrimethamine has been increasing in the past few years and, although the link between molecular markers and treatment failure has not been firmly established, at least for pregnant women, it is important to monitor such markers. METHODS: This paper reports a novel sensitive, semi-quantitative and specific real-time PCR and melting curve analysis (MCA) assay using fluorescence resonance energy transfer (FRET) for the detection of DHPS-540, an important predictor for SP resistance. FRET/MCA was evaluated using 78 clinical samples from malaria patients and compared to PCR-RFLP. RESULTS: Sixty-two samples were in perfect agreement between both assays. One sample showed a small wild type signal with FRET/MCA that indicates a polyclonal infection. Four samples were not able to generate enough material in both assays to distinguish mutant from wild-type infection, six samples gave no signal in PCR-RFLP and five samples gave no amplification in FRET/MCA. CONCLUSION: FRET/MCA is an effective tool for the identification of SNPs in drug studies and epidemiological surveys on resistance markers in general and DHPS-540 mutation in particular.
    • Relapses of Plasmodium vivax infection usually result from activation of heterologous hypnozoites.

      Imwong, M; Snounou, G; Pukrittayakamee, S; Tanomsing, N; Kim, J R; Nandy, A; Guthmann, J P; Nosten, F; Carlton, J; Looareesuwan, S; et al. (Infectious Diseases Society of America and University of Chicago Press, 2007-04-01)
      BACKGROUND: Relapses originating from hypnozoites are characteristic of Plasmodium vivax infections. Thus, reappearance of parasitemia after treatment can result from relapse, recrudescence, or reinfection. It has been assumed that parasites causing relapse would be a subset of the parasites that caused the primary infection. METHODS: Paired samples were collected before initiation of antimalarial treatment and at recurrence of parasitemia from 149 patients with vivax malaria in Thailand (n=36), where reinfection could be excluded, and during field studies in Myanmar (n=75) and India (n=38). RESULTS: Combined genetic data from 2 genotyping approaches showed that novel P. vivax populations were present in the majority of patients with recurrent infection (107 [72%] of 149 patients overall [78% of patients in Thailand, 75% of patients in Myanmar {Burma}, and 63% of patients in India]). In 61% of the Thai and Burmese patients and in 55% of the Indian patients, the recurrent infections contained none of the parasite genotypes that caused the acute infection. CONCLUSIONS: The P. vivax populations emerging from hypnozoites commonly differ from the populations that caused the acute episode. Activation of heterologous hypnozoite populations is the most common cause of first relapse in patients with vivax malaria.
    • The relationship between the haemoglobin concentration and the haematocrit in Plasmodium falciparum malaria.

      Lee, S J; Stepniewska, K; Anstey, N; Ashley, E; Barnes, K; Binh, T Q; D'Alessandro, U; Day, N; de Vries, P J; Dorsey, G; et al. (BioMed Central, 2008-08)
      BACKGROUND: Malaria is a very important cause of anaemia in tropical countries. Anaemia is assessed either by measurement of the haematocrit or the haemoglobin concentration. For comparisons across studies, it is often necessary to derive one measure from the other. METHODS: Data on patients with slide-confirmed uncomplicated falciparum malaria were pooled from 85 antimalarial drug trials conducted in 25 different countries, to assess the haemoglobin/haematocrit relationship at different time points in malaria. Using a linear random effects model, a conversion equation for haematocrit was derived based on 3,254 measurements from various time points (ranging from day 0 to day 63) from 1,810 patients with simultaneous measurements of both parameters. Haemoglobin was also estimated from haematocrit with the commonly used threefold conversion. RESULTS: A good fit was obtained using Haematocrit = 5.62 + 2.60 * Haemoglobin. On average, haematocrit/3 levels were slightly higher than haemoglobin measurements with a mean difference (+/- SD) of -0.69 (+/- 1.3) for children under the age of 5 (n = 1,440 measurements from 449 patients). CONCLUSION: Based on this large data set, an accurate and robust conversion factor both in acute malaria and in convalescence was obtained. The commonly used threefold conversion is also valid.
    • Responding to the evidence for the management of severe malaria

      Ford, Nathan P.; de Smet, Martin; Kolappa, Kavitha; White, Nicholas J. (2011-09)
    • A review of the WHO malaria rapid diagnostic test product testing programme (2008–2018): performance, procurement and policy

      Cunningham, J; Jones, S; Gatton, M; Barnwell, J; Cheng, Q; Chiodini, P; Glenn, J; Gonzalez, I; Kosack, C; Nhem, S; et al. (Springer Science and Business Media LLC, 2019-12-02)
      Malaria rapid diagnostic tests (RDTs) emerged in the early 1990s into largely unregulated markets, and uncertain field performance was a major concern for the acceptance of tests for malaria case management. This, combined with the need to guide procurement decisions of UN agencies and WHO Member States, led to the creation of an independent, internationally coordinated RDT evaluation programme aiming to provide comparative performance data of commercially available RDTs. Products were assessed against Plasmodium falciparum and Plasmodium vivax samples diluted to two densities, along with malaria-negative samples from healthy individuals, and from people with immunological abnormalities or non-malarial infections. Three measures were established as indicators of performance, (i) panel detection score (PDS) determined against low density panels prepared from P. falciparum and P. vivax wild-type samples, (ii) false positive rate, and (iii) invalid rate, and minimum criteria defined. Over eight rounds of the programme, 332 products were tested. Between Rounds 1 and 8, substantial improvements were seen in all performance measures. The number of products meeting all criteria increased from 26.8% (11/41) in Round 1, to 79.4% (27/34) in Round 8. While products submitted to further evaluation rounds under compulsory re-testing did not show improvement, those voluntarily resubmitted showed significant increases in P. falciparum (p = 0.002) and P. vivax PDS (p < 0.001), with more products meeting the criteria upon re-testing. Through this programme, the differentiation of products based on comparative performance, combined with policy changes has been influential in the acceptance of malaria RDTs as a case-management tool, enabling a policy of parasite-based diagnosis prior to treatment. Publication of product testing results has produced a transparent market allowing users and procurers to clearly identify appropriate products for their situation, and could form a model for introduction of other, broad-scale diagnostics.
    • Risk associated with asymptomatic parasitaemia occurring post-antimalarial treatment

      Olliaro, P; Pinoges, L; Checchi, F; Vaillant, M; Guthmann, J P; UNICEF/UNDP/World Bank/WHO Special Programme on Research and Training in Tropical Diseases (TDR), Geneva, Switzerland. Centre for Tropical Medicine and Vaccinology, University of Oxford, Oxford, UK. Epicentre, Paris, France. Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK. Centre de Recherches Publiques (CRP)-Santé, Luxembourg. (2008-01)
      OBJECTIVE: Parasites may recur asymptomatically after initial clearance by antimalarial treatment. Current guidelines recommend treatment only when patients develop symptoms or at the end of follow-up. We wanted to assess prospectively the probability of becoming symptomatic and the risks of this practice. METHODS: We analysed data collected in 13 trials of uncomplicated paediatric malaria conducted in eight sub-Saharan African countries. These studies followed all cases of post-treatment asymptomatic parasitaemia until they developed symptoms or to the end of the 28-day follow-up period, at which time parasite genotypes were compared to pre-treatment isolates to distinguish between recrudescences and new infections. RESULTS: There were 425 asymptomatic recurrences after 2576 treatments with either chloroquine, sulfadoxine/pyrimethamine or amodiaquine, of which 225 occurred by day 14 and 200 between day 15 and day 28. By day 28, 42% developed fever (median time to fever = 5 days) and 30% remained parasitaemic but afebrile, while 23% cleared their parasites (outcome unknown in 4%). Young age, parasitaemia >/=500 parasites/microl; onset of parasitaemia after day 14, and treatment with amodiaquine were the main variables associated with higher risk of developing fever. CONCLUSION: In areas of moderate to intense transmission, asymptomatic recurrences of malaria after treatment carry a substantial risk of becoming ill within a few days and should be treated as discovered. Young children are at higher risk. The higher risk carried by cases occurring in the second half of follow-up may be explained by falling residual drug levels.
    • Safety and efficacy of dihydroartemisinin-piperaquine in falciparum malaria: a prospective multi-centre individual patient data analysis.

      Zwang, Julien; Ashley, Elizabeth A; Karema, Corine; D'Alessandro, Umberto; Smithuis, Frank; Dorsey, Grant; Janssens, Bart; Mayxay, Mayfong; Newton, Paul; Singhasivanon, Pratap; et al. (2009-07-15)
      BACKGROUND: The fixed dose antimalarial combination of dihydroartemisinin-piperaquine (DP) is a promising new artemisinin-based combination therapy (ACT). We present an individual patient data analysis of efficacy and tolerability in acute uncomplicated falciparum malaria, from seven published randomized clinical trials conducted in Africa and South East Asia using a predefined in-vivo protocol. Comparator drugs were mefloquine-artesunate (MAS3) in Thailand, Myanmar, Laos and Cambodia; artemether-lumefantrine in Uganda; and amodiaquine+sulfadoxine-pyrimethamine and artesunate+amodiaquine in Rwanda. METHODS AND FINDINGS: In total 3,547 patients were enrolled: 1,814 patients (32% children under five years) received DP and 1,733 received a comparator antimalarial at 12 different sites and were followed for 28-63 days. There was no significant heterogeneity between trials. DP was well tolerated with 1.7% early vomiting. There were less adverse events with DP in children and adults compared to MAS3 except for diarrhea; ORs (95%CI) 2.74 (2.13 to 3.51) and 3.11 (2.31 to 4.18), respectively. DP treatment resulted in a rapid clearance of fever and parasitaemia. The PCR genotype corrected efficacy at Day 28 of DP assessed by survival analysis was 98.7% (95%CI 97.6-99.8). DP was superior to the comparator drugs in protecting against both P.falciparum recurrence and recrudescence (P = 0.001, weighted by site). There was no difference between DP and MAS3 in treating P. vivax co-infections and in suppressing the first relapse (median interval to P. vivax recurrence: 6 weeks). Children under 5 y were at higher risk of recurrence for both infections. The proportion of patients developing gametocytaemia (P = 0.002, weighted by site) and the subsequent gametocyte carriage rates were higher with DP (11/1000 person gametocyte week, PGW) than MAS3 (6/1000 PGW, P = 0.001, weighted by site). CONCLUSIONS: DP proved a safe, well tolerated, and highly effective treatment of P.falciparum malaria in Asia and Africa, but the effect on gametocyte carriage was inferior to that of MAS3.
    • Seasonal Malaria Chemoprevention with Sulphadoxine-Pyrimethamine and Amodiaquine Selects Pfdhfr-dhps Quintuple Mutant Genotype in Mali

      Maiga, H; Lasry, E; Diarra, M; Sagara, I; Bamadio, A; Traore, A; Coumare, S; Bahonan, S; Sangare, B; Dicko, Y; et al. (Public Library of Science, 2016-09-23)
      Seasonal malaria chemoprevention (SMC) with sulphadoxine-pyrimethamine (SP) plus amodiaquine (AQ) is being scaled up in Sahelian countries of West Africa. However, the potential development of Plasmodium falciparum resistance to the respective component drugs is a major concern.
    • Seasonal Malaria Chemoprevention: successes and missed opportunities

      Coldiron, ME; Von Seidlein, L; Grais, RF (BioMed Central, 2017-11-28)
      Seasonal malaria chemoprevention (SMC) was recommended in 2012 for young children in the Sahel during the peak malaria transmission season. Children are given a single dose of sulfadoxine/pyrimethamine combined with a 3-day course of amodiaquine, once a month for up to 4 months. Roll-out and scale-up of SMC has been impressive, with 12 million children receiving the intervention in 2016. There is evidence of its overall benefit in routine implementation settings, and a meta-analysis of clinical trial data showed a 75% decrease in clinical malaria compared to placebo. SMC is not free of shortcomings. Its target zone includes many hard-to-reach areas, both because of poor infrastructure and because of political instability. Treatment adherence to a 3-day course of preventive treatment has not been fully documented, and could prove challenging. As SMC is scaled up, integration into a broader, community-based paradigm which includes other preventive and curative activities may prove beneficial, both for health systems and for recipients.
    • Selection of Plasmodium Falciparum pfcrt and pfmdr1 Polymorphisms After Treatment with Artesunate-Amodiaquine Fixed Dose Combination or Artemether-Lumefantrine in Liberia

      Otienoburu, SD; Maïga-Ascofaré, O; Schramm, B; Jullien, V; Jones, JJ; Zolia, YM; Houzé, P; Ashley, EA; Kiechel, JR; Guérin, PJ; et al. (BioMed Central (Springer Science), 2016-09-05)
      Plasmodium falciparum uncomplicated malaria can successfully be treated with an artemisinin-based combination therapy (ACT). However resistance is spreading to the different ACT compounds; the artemisinin derivative and the partner drug. Studies of P. falciparum polymorphisms associated with drug resistance can provide a useful tool to track resistance and guide treatment policy as well as an in-depth understanding of the development and spread of resistance.
    • Selection strength and hitchhiking around two anti-malarial resistance genes.

      Nash, D; Nair, S; Mayxay, M; Newton, P N; Guthmann, J P; Nosten, F; Anderson, T J C; Southwest Foundation for Biomedical Research (SFBR), San Antonio, TX 78245, USA. (2005-06-07)
      Neutral mutations may hitchhike to high frequency when they are situated close to sites under positive selection, generating local reductions in genetic diversity. This process is thought to be an important determinant of levels of genomic variation in natural populations. The size of genome regions affected by genetic hitchhiking is expected to be dependent on the strength of selection, but there is little empirical data supporting this prediction. Here, we compare microsatellite variation around two drug resistance genes (chloroquine resistance transporter (pfcrt), chromosome 7, and dihydrofolate reductase (dhfr), chromosome 4) in malaria parasite populations exposed to strong (Thailand) or weak selection (Laos) by anti-malarial drugs. In each population, we examined the point mutations underlying resistance and length variation at 22 (chromosome 4) or 25 (chromosome 7) microsatellite markers across these chromosomes. All parasites from Thailand carried the K76T mutation in pfcrt conferring resistance to chloroquine (CQ) and 2-4 mutations in dhfr conferring resistance to pyrimethamine. By contrast, we found both wild-type and resistant alleles at both genes in Laos. There were dramatic differences in the extent of hitchhiking in the two countries. The size of genome regions affected was smaller in Laos than in Thailand. We observed significant reduction in variation relative to sensitive parasites for 34-64 kb (2-4 cM) in Laos on chromosome 4, compared with 98-137 kb (6-8 cM) in Thailand. Similarly, on chromosome 7, we observed reduced variation for 34-69 kb (2-4 cM) around pfcrt in Laos, but for 195-268 kb (11-16 cM) in Thailand. Reduction in genetic variation was also less extreme in Laos than in Thailand. Most loci were monomorphic in a 12 kb region surrounding both genes on resistant chromosomes from Thailand, whereas in Laos, even loci immediately proximal to selective sites showed some variation on resistant chromosomes. Finally, linkage disequilibrium (LD) decayed more rapidly around resistant pfcrt and dhfr alleles from Laos than from Thailand. These results demonstrate that different realizations of the same selective sweeps may vary considerably in size and shape, in a manner broadly consistent with selection history. From a practical perspective, genomic regions containing resistance genes may be most effectively located by genome-wide association in populations exposed to strong drug selection. However, the lower levels of LD surrounding resistance alleles in populations under weak selection may simplify identification of functional mutations.
    • Severe acute malnutrition results in lower lumefantrine exposure in children treated with artemether-lumefantrine for uncomplicated malaria

      Chotsiri, P; Denoeud-Ndam, L; Baudin, E; Guindo, O; Diawara, H; Attaher, O; Smit, M; Guerin, PJ; Duombo, OK; Weisner, L; et al. (American Society for Clinical Pharmacology and Therapeutics, 2019-06-01)
      Severe acute malnutrition (SAM) has been reported to be associated with increased malaria morbidity in Sub‐Saharan African children and may affect the pharmacology of antimalarial drugs. This population pharmacokinetic‐pharmacodynamic study included 131 SAM and 266 non‐SAM children administered artemether‐lumefantrine twice daily for 3 days. Lumefantrine capillary plasma concentrations were adequately described by two transit‐absorption compartments followed by two distribution compartments. Allometrically scaled body weight and an enzymatic maturation effect were included in the pharmacokinetic model. Mid‐upper arm circumference (MUAC) was associated with decreased absorption of lumefantrine (25.4% decrease per 1 cm reduction). Risk of recurrent malaria episodes (i.e. reinfection) were characterised by an interval‐censored time‐to‐event model with a sigmoid EMAX‐model describing the effect of lumefantrine. SAM children were at risk of under‐exposure to lumefantrine and an increased risk of malaria reinfection compared to well‐nourished children. Research on optimised regimens should be considered for malaria treatment in malnourished children.
    • Short Report: Association Between Chloroquine and Amodiaquine Resistance and Allelic Variation in the Plasmodium Falciparum Multiple Drug Resistance 1 Gene and the Chloroquine Resistance Transporter Gene in Isolates from the Upper Nile in Southern Sudan.

      Ochong, E; van den Broek, I; Keus, K; Nzila, A; Kenya Medical Research Institute, Wellcome Trust Collaborative Program, Médecins sans Frontières-Holland, South Sudan Section, Nairobi, Kenya. (Published by: American Society of Tropical Medicine and Hygiene, 2003-08)
      Amodiaquine, a 4-aminoquinoline compound, is being considered as an alternative to chloroquine and pyrimethamine/sulfadoxine where resistance in Plasmodium falciparum to both drugs has been selected. Although amodiaquine is more potent than chloroquine, its effectiveness is reduced in areas where chloroquine resistance is high. We report an association of the P. falciparum chloroquine resistance transporter (pfcrt) gene and the P. falciparum multiple drug resistance 1 (pfmdr1) gene, two chloroquine resistance markers, with chloroquine and amodiaquine efficacy in vivo in southern Sudan. The data show that the allele of the pfcrt gene with a lysine to threonine change at codon 76 is strongly associated with both chloroquine and amodiaquine resistance. No such association was observed with the pfmdr1 gene.
    • Short report: molecular markers associated with Plasmodium falciparum resistance to sulfadoxine-pyrimethamine in the Democratic Republic of Congo.

      Cohuet, S; Bonnet, M; Van Herp, M; Van Overmeir, C; D'Alessandro, U; Guthmann, J P; Epicentre, Paris, France; Médecins Sans Frontières, Brussels, Belgium; Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium. (2006-07)
      Sulfadoxine-pyrimethamine (SP) is the first line antimalarial treatment in the Democratic Republic of Congo. Using polymerase chain reaction, we assessed the prevalence of mutations in the dihydrofolate reductase (dhfr) (codons 108, 51, 59) and dihydropteroate synthase (dhps) (codons 437, 540) genes of Plasmodium falciparum, which have been associated with resistance to pyrimethamine and sulfadoxine, respectively. Four hundred seventy-four patients were sampled in Kilwa (N = 138), Kisangani (N = 112), Boende (N = 106), and Basankusu (N = 118). The proportion of triple mutations dhfr varied between sites but was always > 50%. The proportion of dhps double mutations was < 20%, with some sites as low as 0.9%. A quintuple mutation was present in 12.8% (16/125) samples in Kilwa; 11.9% (13/109) in Kisangani, 2.9% (3/102) in Boende, and 0.9% (1/112) in Basankusu. These results suggest high resistance to pyrimethamine alone or combined with sulfadoxine. Adding artesunate to SP does not seem a valid alternative to the current monotherapy.
    • A significant increase in kdr in Anopheles gambiae is associated with an intensive vector control intervention in Burundi highlands.

      Protopopoff, N; Verhaeghen, K; Van Bortel, W; Roelants, P; Marcotty, T; Baza, D; D'Alessandro, U; Coosemans, M; Department of Parasitology, Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium. nprotopopoff@itg.be (2008-12)
      OBJECTIVES AND METHODS: In Burundi, the occurrence of the knock down resistance (kdr) mutation in Anopheles gambiae sensu lato (s.l.) was determined for six consecutive years within the framework of a vector control programme. Findings were also linked with the insecticide resistance status observed with bioassay in An. gambiae s.l. and An. funestus. RESULTS: The proportion of An. gambiae s.l. carrying the East Leu-Ser kdr mutation was 1% before the spraying intervention in 2002; by 2007 it was 86% in sprayed valleys and 67% in untreated valleys. Multivariate analysis showed that increased risk of carrying the kdr mutation is associated with spraying interventions, location and time. In bioassays conducted between 2005 and 2007 at five sites, An. funestus was susceptible to permethrin, deltamethrin and DDT. Anopheles gambiae s.l. remained susceptible or tolerant to deltamethrin and resistant to DDT and permethrin, but only when kdr allele carriers reached 90% of the population. CONCLUSIONS: The cross-resistance against DDT and permethrin in Karuzi suggests a possible kdr resistance mechanism. Nevertheless, the homozygous resistant genotype alone does not entirely explain the bioassay results, and other mechanisms conferring resistance cannot be ruled out. After exposure to all three insecticides, homozygote individuals for the kdr allele dominate among the surviving An. gambiae s.l. This confirms the potential selection pressure of pyrethroids on kdr mutation. However, the high occurrence of the kdr mutation, even at sites far from the sprayed areas, suggests a selection pressure other than that exerted by the vector control programme.