In vitro delayed response to dihydroartemisinin of malaria parasites infecting sickle cell erythocytes.

BACKGROUND: Decreased efficacy of artemisinin-based combination therapy (ACT) for Plasmodium falciparum malaria has been previously reported in patients with sickle cell disease (SCD). The main purpose of this study was to investigate the in vitro susceptibility of isolates to dihydro-artemisinin (DHA) to provide a hypothesis to explain this treatment failure. METHODS: Isolates were collected from patients attending health centres in Abidjan with uncomplicated P. falciparum malaria. The haemoglobin type has been identified and in vitro drug sensitivity tests were conducted with the ring stage assay and maturation inhibition assay. RESULTS: 134 isolates were obtained. Parasitaemia and haemoglobin levels at inclusion were lower in patients with haemoglobin HbSS and HbSC than in patients with normal HbAA. After ex vivo RSA and drug inhibition assays, the lowest rate of parasitic growth was found with isolates from HbAS red cells. Conversely, a significantly higher survival rate of parasites ranging from 15 to 34% were observed in isolates from HbSS. Isolates with in vitro reduced DHA sensitivity correlate with lower RBC count and haematocrit and higher parasitaemia at inclusion compared to those with isolates with normal DHA sensitivity. However, this decrease of in vitro sensitivity to DHA was not associated with Kelch 13-Propeller gene polymorphism. CONCLUSION: This study highlights an in vitro decreased sensitivity to DHA, for isolates collected from HbSS patients, not related to the Pfkelch13 gene mutations. These results are in line with recent studies pointing out the role of the redox context in the efficacy of the drug. Indeed, SCD red cells harbour a highly different ionic and redox context in comparison with normal red cells. This study offers new insights into the understanding of artemisinin selective pressure on the malaria parasite in the context of haemoglobinopathies in Africa.

Influence of Host-Related Factors and Exposure to Mosquito Bites on the Dynamics of Antibody Response to Plasmodium falciparum Antigens.

Humoral immunity to Plasmodium falciparum is acquired after repeated infections, and can lead to clinical protection. This study aimed to evaluate how human-, parasite-, and environment-related determinants can modulate the dynamics of IgG responses to Plasmodium falciparum after an infection. Individuals (n = 68, average age = 8.2 years) with uncomplicated malaria were treated with ACT and followed up for 42 days. IgG responses to P. falciparum merozoite antigens (PfMSP1, PfMSP3, PfAMA1, PfGLURP-R0), to whole schizont extract (PfSchz), and to Anopheles gSG6-P1 and Aedes Nterm-34 kDa salivary peptides were measured. Regression analyses were used to identify factors that influence the dynamics of IgG response to P. falciparum antigen between D0 and D42, including demographic and biological factors and the level of exposure to mosquito bites. The dynamics of IgG response to P. falciparum differed according to the antigen. According to multivariate analysis, IgG responses to PfSchz and to PfGLURP-R0 appear to be affected by exposure to Aedes saliva and are associated with age, parasite density, and anti-Plasmodium pre-existing immune response at study inclusion. The present work shows that human exposure to Aedes saliva may contribute, in addition to other factors, to the regulation of anti-Plasmodium immune responses during a natural infection.

Artemisinin derivative-containing therapies and abnormal hemoglobin: Do we need to adapt the treatment?

BACKGROUND: Artemisinin-based treatment in malaria patients with abnormal hemoglobin may be ineffective because of their genetic particularity, which could lead to resistance. The main purpose of this study was to assess the effect of artemisinin derivatives on in vivo parasite clearance according to erythrocyte variants. In vivo response was investigated through retrospective data obtained over a 42-day artemether-lumefantrine/artesunate amodiaquine efficacy protocol conducted from 2012 to 2016. RESULTS: A total of 770 patients in Côte d'Ivoire attending the hospitals of Anonkoua-koute (Abidjan), Petit Paris (Korhogo), Libreville (Man), Dar es salam (Bouaké), Ayamé and Yamoussoukro with acute uncomplicated falciparum malaria were selected for successful hemoglobin typing. HbAS, HbSS, HbAC, and HbSC genotypes were found. Parasite clearance time was obtained for 414 patients. In the population with abnormal hemoglobin, parasite densities on admission and parasite clearance rates were significantly lower in the HbSC group compared to HbAA (p = 0.02 and p = 0.007, respectively). After PCR correction on day 42, the acute treatment rate was 100% for each group. Parasite half-life and time for initial parasitaemia to decline by 50 and 99% were longer for the HbSC group (p < 0.05). The study also investigated the prevalence of K13-propeller polymorphisms across different hemoglobin genotype groups. A total of 185 and 63 samples were sequenced in the HbAA group and patients with abnormal Hb, respectively. Only two nonsynonymous mutations D559N and V510M were found in the HbAA group. CONCLUSION: Although this study proved good efficacy of artemether-lumefantrine and artesunate amodiaquine in the treatment of uncomplicated Plasmodium falciparum malaria in patients with abnormal hemoglobin, the increased delay of parasite clearance may represent a threat to health in these patients in relation with sickle cell crisis, which could support selection of parasites resistant to artemisinin.

TITLE: Thérapies contenant des dérivés de l'artémisinine et hémoglobine anormale : faut-il adapter le traitement ? ABSTRACT: Contexte : Le traitement à base d'artémisinine chez les patients atteints de paludisme et présentant une hémoglobine anormale peut être inefficace en raison de leur particularité génétique, ce qui pourrait entraîner une résistance. L'objectif principal de cette étude était d'évaluer in vivo l'effet des dérivés de l'artémisinine sur la clairance du parasite en fonction des variantes érythrocytaires. La réponse in vivo a été étudiée à travers des données rétrospectives obtenues au cours d'un protocole d'efficacité de 42 jours artéméther-luméfantrine/artésunate-amodiaquine mené dans les années 2012 à 2016. Résultats : Un total de 770 patients en Côte d'Ivoire fréquentant les hôpitaux d'Anonkoua-koute (Abidjan), Petit Paris (Korhogo), Libreville (Man), Dar es salam (Bouaké), Ayamé et Yamoussoukro, présentant un paludisme aigu non compliqué à falciparum ont été sélectionnés pour un typage réussi de l'hémoglobine. Les génotypes HbAS, HbSS, HbAC et HbSC ont été trouvés. Le temps de clairance du parasite a été obtenu pour 414 patients. Dans la population avec une hémoglobine anormale, les densités parasitaires à l'admission et le taux de clairance parasitaire étaient significativement plus faibles dans le groupe HbSC par rapport au groupe HbAA (respectivement, p = 0,02 et p = 0,007). Le RCPA était de 100 % pour chaque groupe après correction par PCR au jour 42. La demi-vie du parasite et le temps nécessaire pour que la parasitémie initiale diminue de 50 et 99 % étaient plus longs pour le groupe HbSC (p < 0,05). L'étude a également examiné la prévalence des polymorphismes du gène K13 dans différents groupes de génotype d'hémoglobine. Un total de 185 et 63 échantillons ont été séquencés respectivement dans le groupe HbAA et chez les patients présentant une Hb anormale. Seules deux mutations non synonymes D559N et V510M ont été trouvées dans le groupe HbAA. Conclusion : Bien que cette étude ait prouvé la bonne efficacité de l'artéméther-luméfantrine et de l'artésunate amodiaquine dans le traitement du paludisme simple à Plasmodium falciparum chez les patients présentant une hémoglobine anormale, le retard accru de clairance parasitaire peut représenter une menace pour la santé de ces patients en relation avec la crise drépanocytaire, et peut favoriser la sélection de parasites résistants à l'artémisinine.

Efficacy and safety of artesuante-amodiaquine and artemether lumefantrine, the first line malaria treatment in six sentinel's sites of Côte d'Ivoire, West Africa.

The purpose of this study was to update efficacy data of Artesunate-Amodiaquine (AS+AQ) and Artemether-Lumefantrine (AL) used as first-line malaria treatment in Côte d'Ivoire since 2005. This was an open-label, randomized trial conducted in patients older than 6 months with uncomplicated P. falciparum malaria at six sentinel sites. The WHO 2009 protocol on surveillance of anti-malaria drug efficacy was used with primary outcomes as ACPR corrected by PCR at day 42. Secondary endpoints were parasite and fever clearance times and safety. From January to July 2016, 712 patients were included in the trial. 353 and 359 patients were randomly assigned respectively to the AS+AQ and AL arm. Day 42 PCR-adjusted ACPR in the per-protocol analysis was 99.4% and 98.8% in AS+AQ and AL arm respectively. Delayed parasite clearance was observed in six patients at Abidjan and Yamousssoukro sites. Both ACTs were well tolerated. Both ACTs remain efficacious for uncomplicated P. falciparum malaria treatment in Côte d'Ivoire. But regarding delayed parasite clearance observed in this study, a close monitoring and supervision for ACT resistance are essential for future malaria treatment and control strategies in Côte d'Ivoire.

Open-label, randomized, non-inferiority clinical trial of artesunate-amodiaquine versus artemether-lumefantrine fixed-dose combinations in children and adults with uncomplicated falciparum malaria in Côte d'Ivoire.

BACKGROUND: Emergence of artemisinin resistance has raised concerns that the most potent anti-malarial drug may be under threat. Artesunate-amodiaquine (AS-AQ) and artemether-lumefantrine (AL) are, respectively, the first- and second-line treatments for uncomplicated falciparum malaria in Côte d'Ivoire. Constant monitoring by National Malaria Control Programme (NMCP) of drug efficacy is an important tool in establishing rational anti-malarial drug policies in Côte d'Ivoire. METHODS: In an open label, randomized controlled clinical trial, children and adults were randomized to receive AS-AQ or AL. Both drug regimens were given for three days, and follow-up was for 42 days. The primary endpoint was the 42-day cure rate and was defined as proportion of patients with PCR-corrected cure rate after 42 days of follow-up. RESULTS: A total of 383 patients who were attending the Anonkoua-koute (Abidjan), Petit Paris (Korhogo) and Libreville (Man) hospitals and presenting with symptomatic acute uncomplicated falciparum malaria were randomized to receive AS-AQ (188) and AL (195). The intention-to-treat analysis showed effectiveness rates of 94.7% and 96.4% for AS-AQ and AL, respectively on day 42. After adjustment for PCR, these rates were 96.8% and 99%, respectively. At day 42, in per-protocol analysis, Adequate clinical and parasitological response (ACPR) PCR uncorrected was 97.8% and 97.4% for AS-AQ and AL, respectively. The PCR adjusted ACPR was 100% for each combination and both regimens were well tolerated. CONCLUSIONS: This study has shown the high efficacy of AS-AQ in patients of all ages with acute uncomplicated falciparum malaria and AS-AQ was non-inferior to AL. Continuous efficacy monitoring is recommended.

Coverage and efficacy of intermittent preventive treatment with sulphadoxine pyrimethamine against malaria in pregnancy in Côte d'Ivoire five years after its implementation.

BACKGROUND: The World Health Organization (WHO) recommends for sub-Saharan Africa a package of prompt and effective case-management combined with the delivery of insecticide-treated nets (ITN) and intermittent preventive treatment during pregnancy (IPTp) with sulphadoxine-pyrimethamine (SP) through the national antenatal care (ANC) programs. Implemented in Côte d'Ivoire around 2005, few Data on IPTp coverage and efficacy in the country are available. METHODS: A multicentre, cross-sectional survey was conducted in Côte d'Ivoire from September 2009 to May 2010 at six urban and rural antenatal clinics. IPTp-sp coverage, Socio-economic and obstetrical data of mothers and neonate birth weights were documented. Peripheral blood as well as placental and cord blood were used to prepare thick and thin blood films. In addition, pieces of placental tissues were used to prepare impression smears and maternal haemoglobin concentration was measured. Regression logistics were used to study factors associated with placental malaria and LBW (<2.500 grams). RESULTS: A total of 1317 delivered women were enrolled with a median age of 26 years. A proportion of 43.28% of the women had received at least two doses of IPTsp during the current pregnancy although a high proportion (90.4%) of women received antenatal care and made enough visits (≥2). Variability in the results was observed depending on the type of area (rural/urban). Plasmodium falciparum was detected in the peripheral blood of 97 women (7.3%) and in the placenta of 119 women (9%). LBW infants were born to 18.8% (22/107) of women with placental malaria and 8.5% (103/1097) of women without placental malaria. LBW was associated with placental malaria. CONCLUSIONS: This study found relative low coverage of IPTp in the study areas which supported findings that high ANC attendance does not guarantee high IPTp coverage. Urgent efforts are required to improve service delivery of this important intervention.

Artesunate/mefloquine paediatric formulation vs. artemether/lumefantrine for the treatment of uncomplicated Plasmodium falciparum in Anonkoua kouté, Côte d'Ivoire.

OBJECTIVES: To test the hypothesis that Artesunate-mefloquine paediatric (AS+MEF) is as effective as Artemether-lumefantrine (AL) in treating acute uncomplicated malaria in children. METHODS: In an open label, randomized controlled clinical trial, children aged 6-59 months were randomized to receive AS+MEF or AL. Both drug regimens were given for 3 days, and follow-up was for 28 days. The primary endpoint was the 28-day cure rate and was defined as proportion of patients with PCR-corrected cure rate after 28 days of follow-up. RESULTS: One hundred and fifty-six patients with confirmed uncomplicated P. falciparum malaria were randomly assigned to receive AS+MEF (n = 77) or AL (n = 79). PCR-corrected day 28 cure rates for per protocol (PP) populations were 99% for AS+MEF and 97% (P = 1) for AL. For the intention to treat (ITT) population, cure rates were 96% for AS+MEF and 92% (P = 0.49) for AL. Both regimens were well tolerated. CONCLUSION: AS+MEF is as effective as AL, and both combinations were efficacious and safe.

A comparative, randomized clinical trial of artemisinin/naphtoquine twice daily one day versus artemether/lumefantrine six doses regimen in children and adults with uncomplicated falciparum malaria in Côte d'Ivoire.

BACKGROUND: Drug resistance in Plasmodium falciparum poses a major threat to malaria control. Combination anti-malarial therapy, including artemisinins, has been advocated to improve efficacy and limit the spread of resistance. The fixed combination of oral artemether-lumefantrine (AL) is highly effective and well-tolerated. Artemisinin/naphtoquine (AN) is a fixed-dose ACT that has recently become available in Africa. The objectives of the study were to compare the efficacy and safety of AN and AL for the treatment of uncomplicated falciparum malaria in a high transmission-intensity site in Ivory Coast. METHODS: We enrolled 122 participants aged 6 months or more with uncomplicated falciparum malaria. Participants were randomized to receive either artemisinin/naphtoquine or artemether/lumefantrine with variable dose according to their weight. Primary endpoints were the risks of treatment failure within 28 days, either unadjusted or adjusted by genotyping to distinguish recrudescence from new infection. RESULTS: Among 125 participants enrolled, 123 (98.4%) completed follow-up. Clinical evaluation of the 123 participants showed that cumulative PCR-uncorrected cure rate on day 28 was 100% for artemisinin/naphtoquine and 98.4% for artemether/lumefantrine. Both artemisinin-based combinations effected rapid fever and parasite clearance. INTERPRETATION: These data suggest that Arco could prove to be suitable for use as combination antimalarial therapy. Meanwhile, pharmacokinetic studies and further efficacy assessment should be conducted before its widespread use can be supported.

Etude comparative de l'efficacite et de la tolerance de l'association sulfadoxine-pyrimethamine versus l'association sulfadoxine-pyrimethamine dans le traitement du paludisme simple en zone d'endemie

En depit des efforts deployes a travers plusieurs initiatives internationales; le paludisme constitue toujours un veritable probleme de sante publique. La prise en charge des cas de la maladie s'est compliquee avec l'emergence et l'extension des resistances de plasmodium Falciparum aux antipaludiques usuels. Parmi les strategies de lutte; outre la prise en charge des cas; la prevention reste l'element majeur. La moustiquaire impregnee d'insecticides est une composante de la strategie de lutte antivectorielle. La chloroquine; utilisee il y a quelques annees dans la chimioprophylaxie chez la femme enceinte a ete abandonnee du fait de niveaux de resistance devenus trop eleves. Elle est desormais remplacee par l'association sulfadoxine-pyrimethamine en traitement preventif intermittent (TPI).Cependant; il est urgent aujourd'hui de trouver une alternative a cet antipaludique; en raison de taux de resistances de Plasmodium Falciparum en augmentation. Aussi; avons-nous juge opportun de mettre en ouvre une etude comparee de l'efficacite et de la tolerance de l'association sulfalene-pyrimethamine ou metakelfin (MK) et de l'association sulfadoxine-pyrimethamine (SP); molecule de reference dans le TPI de la femme en ceinte. L'etude; multicentrique; randomisee; comparative; s'est deroulee simultanement au Cameroun; en Cote d'Ivoire et au Senegal durant la seconde semestre de l'annee 2005. La methodologie OMS d'etude de l'efficacite des antipaludiques a ete utilisee. Au total; 444 patients ont ete inclus dans cette etude. L'efficacite des deux medicaments etaient comparable; avec des taux de reponses cliniques et parasitologiques adequat respectifs de 92pour l'association sulfalene-pyrimethamine et 92;1pour l'association sulfadoxine-pyrimethamine apres correction PCR. La tolerance dans les deux groupes de traitement etait egalement comparable. L'association sulfalene-pyrimethamine pourrait etre utilisee dans le TPI chez les femmes enceinte; ce qui pourrait diminuer la pression exercee sur l'association sulfadoxine-pyrimethamine

Comparaison of Clinical and Parasitological Responses to Sulfalene-Pyrimethamine plus Amodiaquine versus Amodiaquine plus Artesunate in the Treatment of Uncomplicated Malaria in Endemic Areas in Africa

Despite all the effort expended in the context of diverse international programmes; malaria still represents a massive public health problem. The treatment of patients has been complicated by the emergence and spread of Plasmodium Falciparum resistant to the regular antimalarial drugs. Thus research has focused on the identification of more effective but safe treatment modalities; notably drug combination. In this context; we have investigated the efficacy and safety of a novel combination; namely sulfalene/ pyrimethamine plus amodiaquine; by comparing it to amodiaquine plus artesunate (a combination recently adopted as first-line treatment in many countries). The randomized; multicentre; comparative study was conducted simultaneously in Cameroon and Cote d'Ivoire in the first six months of 2005. WHO methods for the evaluation of the efficacy of antimalarial drugs was used and a total of 467 patients were included. The two regime comparably effective with a clinical and parasitologic response rate of 97for sulfalene/pyrimethamine plus amodiaquine compared with 98.1for artesunate plus amodiaquine after PCR correction. Tolerance was also comparable in both groups