Oumar Gaye

Seasonal intermittent preventive treatment with artesunate and sulfadoxine-pyrimethamine for prevention of malaria in Senegalese children: a randomised placebo-controlled double-blind trial.

BACKGROUND In the Sahel and sub-Sahelian regions of Africa, malaria transmission is highly seasonal. During a short period of high malaria transmission, mortality and morbidity are high in children under age 5 years. We assessed the efficacy of seasonal intermittent preventive treatment-a full dose of antimalarial treatment given at defined times without previous testing for malaria infection. METHODS We did a randomised, placebo-controlled, double-blind trial of the effect of intermittent preventive treatment on morbidity from malaria in three health-care centres in Niakhar, a rural area of Senegal. 1136 children aged 2-59 months received either one dose of artesunate plus one dose of sulfadoxine-pyrimethamine or two placebos on three occasions during the malaria transmission season. The primary outcome was a first or single episode of clinical malaria detected through active or passive case detection. Primary analysis was by intention-to-treat. This study is registered with , number NCT00132561. FINDINGS During 13 weeks of follow-up, the intervention led to an 86% (95% CI 80-90) reduction in the occurrence of clinical episodes of malaria. With passive case detection, protective efficacy against malaria was 86% (77-92), and when detected actively was 86% (78-91). The incidence of malaria in children on active drugs was 308 episodes per 1000 person-years at risk, whereas in those on placebo it was 2250 episodes per 1000 person-years at risk. 13 children were not included in the intention-to-treat analysis, which was restricted to children who received a first dose of antimalarial or placebo. There was an increase in vomiting in children who received the active drugs, but generally the intervention was well tolerated. INTERPRETATION Intermittent preventive treatment could be highly effective for prevention of malaria in children under 5 years of age living in areas of seasonal malaria infection.

Major Reduction in Anti-Malarial Drug Consumption in Senegal after Nation-Wide Introduction of Malaria Rapid Diagnostic Tests

Background While WHO recently recommended universal parasitological confirmation of suspected malaria prior to treatment, debate has continued as to whether wide-scale use of rapid diagnostic tests (RDTs) can achieve this goal. Adherence of health service personnel to RDT results has been poor in some settings, with little impact on anti-malarial drug consumption. The Senegal national malaria control programme introduced universal parasite-based diagnosis using malaria RDTs from late 2007 in all public health facilities. This paper assesses the impact of this programme on anti-malarial drug consumption and disease reporting. Methods and Findings Nationally-collated programme data from 2007 to 2009 including malaria diagnostic outcomes, prescription of artemisinin-based combination therapy (ACT) and consumption of RDTs in public health facilities, were reviewed and compared. Against a marked seasonal variation in all-cause out-patient visits, non-malarial fever and confirmed malaria, parasite-based diagnosis increased nationally from 3.9% of reported malaria-like febrile illness to 86.0% over a 3 year period. The prescription of ACT dropped throughout this period from 72.9% of malaria-like febrile illness to 31.5%, reaching close equivalence to confirmed malaria (29.9% of 584873 suspect fever cases). An estimated 516576 courses of inappropriate ACT prescription were averted. Conclusions The data indicate high adherence of anti-malarial prescribing practice to RDT results after an initial run-in period. The large reduction in ACT consumption enabled by the move from symptom-based to parasite-based diagnosis demonstrates that effective roll-out and use of malaria RDTs is achievable on a national scale through well planned and structured implementation. While more detailed information on management of parasite-negative cases is required at point of care level to assess overall cost-benefits to the health sector, considerable cost-savings were achieved in ACT procurement. Programmes need to be allowed flexibility in management of these funds to address increases in other programmatic costs that may accrue from improved diagnosis of febrile disease.

Efficacy and safety of a fixed-dose oral combination of pyronaridine-artesunate compared with artemether-lumefantrine in children and adults with uncomplicated Plasmodium falciparum malaria: a randomised non-inferiority trial

BACKGROUND There is a need for new artemisinin-based combination therapies that are convenient, effective, and safe. We compared the efficacy and safety of pyronaridine-artesunate with that of artemether-lumefantrine for treatment of uncomplicated P falciparum malaria. METHODS This phase 3, parallel-group, double-blind, randomised, non-inferiority trial was undertaken in seven sites in Africa and three sites in southeast Asia. In a double-dummy design, patients aged 3-60 years with uncomplicated P falciparum malaria were randomly assigned in a 2:1 ratio to receive pyronaridine-artesunate once a day or artemether-lumefantrine twice a day, orally for 3 days, plus respective placebo. Randomisation was done by computer-generated randomisation sequence in blocks of nine by study centre. Intervention tablets contained 180 mg pyronaridine and 60 mg artesunate; control tablets contained 20 mg artemether and 120 mg lumefantrine. Both treatments were given according to bodyweight. The primary efficacy outcome was PCR-corrected adequate clinical and parasitological response (ACPR) rate at day 28 in the per-protocol population. Non-inferiority was shown if the lower limit of the two-sided 95% CI for the difference between groups was greater than -5%. This study is registered with ClinicalTrials.gov, number NCT00422084. FINDINGS 1272 patients were randomly assigned to treatment (pyronaridine-artesunate, n=849; artemether-lumefantrine, n=423). The per-protocol population consisted of 784 patients in the pyronaridine-artesunate group and 386 patients in the artemether-lumefantrine group. PCR-corrected ACPR rate at day 28 was 99.5% (780 patients; 95% CI 98.7-99.9) in the pyronaridine-artesunate group and 99.2% (383 patients; 95% CI 97.7-99.8) in the artemether-lumefantrine group (treatment difference 0.3%, 95% CI -0.7 to 1.8; p=0.578). There were 509 (60.0%) adverse events in 849 patients assigned to pyronaridine-artesunate and 241 (57.0%) in 423 patients assigned to artemether-lumefantrine. The most frequent drug-related adverse event was eosinophilia (pyronaridine-artesunate, 53 events [6.2%]; artemether-lumefantrine 24 events [5.7%]). 21 (2.5%) patients in the pyronaridine-artesunate group and seven (1.7%) in the artemether-lumefantrine group discontinued study drugs or were withdrawn from the study. Mild and transient increases in alanine aminotransferase and aspartate aminotransferase concentrations were seen in the pyronaridine-artesunate group but not in the artemether-lumefantrine group. INTERPRETATION Efficacy of pyronaridine-artesunate was non-inferior to that of artemether-lumefantrine for treatment of uncomplicated falciparum malaria. Pyronaridine-artesunate should be considered for inclusion in malaria treatment programmes. FUNDING Shin Poong Pharmaceutical and the Medicines for Malaria Venture.

Long-Term Asymptomatic Carriage of Plasmodium falciparum Protects from Malaria Attacks: a Prospective Study among Senegalese Children

BACKGROUND In areas of seasonal malaria transmission, long-term asymptomatic carriage of Plasmodium falciparum throughout the dry season has been primarily studied in terms of the parasites, and the clinical consequences of persistent parasite carriage are unknown. METHODS A prospective study was conducted in Senegal, from 2001 through 2003 among 1356 children living in areas where malaria is endemic, with seasonal transmission occurring from August through December. Cross-sectional parasitological measurements and detection of active malaria attacks were performed. A malaria attack was defined as an axillary temperature > or =37.5 degrees C, associated with a parasite density >2500 trophozoites/microL. Children harboring P. falciparum in June who did not have clinical signs were defined as asymptomatic carriers. The association of asymptomatic carriage with parasite densities and with the occurrence of malaria attacks during the rainy season were analyzed separately for the years 2002 and 2003, taking into account potential confounding covariates and use of antimalarial drugs. RESULTS The prevalence of asymptomatic carriage was 32% (332 of 1025 persons) in June 2002 and 23% (208 of 912 persons) in June 2003. Asymptomatic P. falciparum carriers had a significantly higher mean parasite density and a significantly lower probability of developing a malaria attack during the subsequent rainy season than did noncarriers (adjusted odds ratio in 2002, 0.56; P = .01; adjusted odds ratio in 2003, 0.50; P = .01). CONCLUSIONS These results suggest that in areas of seasonal transmission, asymptomatic carriage of P. falciparum may protect against clinical malaria. Further studies are needed to understand the immune effectors and host susceptibility that could be involved in this phenomenon.

Efficacy and tolerability of four antimalarial combinations in the treatment of uncomplicated Plasmodium falciparum malaria in Senegal

BackgroundIn view of the high level of chloroquine resistance in many countries, WHO has recommended the use of combination therapy with artemisinin derivatives in the treatment of uncomplicated malaria due to Plasmodium falciparum. Four antimalarial drug combinations, artesunate plus amodiaquine (Arsucam®), artesunate plus mefloquine (Artequin®), artemether plus lumefantrine (Coartem®; four doses and six doses), and amodiaquine plus sulphadoxine-pyrimethamine, were studied in five health districts in Senegal.MethodsThis is a descriptive, analytical, open, randomized study to evaluate the efficacy and tolerability of these four antimalarial combinations in the treatment of uncomplicated falciparum malaria using the 2002 WHO protocol.ResultsAll drug combinations demonstrated good efficacy. On day 28, all combinations resulted in an excellent clinical and parasitological response rate of 100% after correction for PCR results, except for the four-dose artemether-lumefantrine regimen (96.4%). Follow-up of approximately 10% of each treatment group on day 42 demonstrated an efficacy of 100%.The combinations were well tolerated clinically and biologically. No unexpected side-effect was observed and all side-effects disappeared at the end of treatment. No serious side-effect requiring premature termination of treatment was observed.ConclusionThe four combinations are effective and well-tolerated.

Randomized, multicentre assessment of the efficacy and safety of ASAQ – a fixed-dose artesunate-amodiaquine combination therapy in the treatment of uncomplicated Plasmodium falciparum malaria

BackgroundThe use of artemisinin derivative-based combination therapy (ACT) such as artesunate plus amodiaquine is currently recommended for the treatment of uncomplicated Plasmodium falciparum malaria. Fixed-dose combinations are more adapted to patients than regimens involving multiple tablets and improve treatment compliance. A fixed-dose combination of artesunate + amodiaquine (ASAQ) was recently developed. To assess the efficacy and safety of this new combination and to define its optimum dosage regimen (once or twice daily) in the treatment of uncomplicated P. falciparum malaria, a multicentre clinical study was conducted.MethodsA multicentre, randomized, controlled, investigator-blinded, parallel-group study was conducted in five African centers in Cameroon, Madagascar, Mali and Senegal from March to December 2006. Efficacy and safety of ASAQ were assessed compared to those of artemether + lumefantrine (AL). The WHO protocol with a 28-day follow-up for assessing the drug therapeutic efficacy was used. Patients suffering from uncomplicated P. falciparum malaria were randomized to receive ASAQ orally once daily (ASAQ1), ASAQ twice daily (ASAQ2) or AL twice daily (AL) for three days. The primary outcome was PCR-corrected parasitological cure rate and clinical response.ResultsOf 941 patients initially randomized and stratified into two age groups (<5 years, and ≥5 years), 936 (99.5%) were retained for the intent to treat (ITT) analysis, and 859 (91.3%) patients for the per protocol (PP) analysis. Among ITT population, up to D28, PCR-corrected adequate parasitological and clinical response rates were 95.2% in the ASAQ1 group, 94.9% in the ASAQ2 group and 95.5% in the AL group. Moreover, the cure rate evaluated among PP population was ≥98.5% in both ASAQ therapeutic arms. Therapeutic response rates did not display any significant differences between age groups or between one geographical site and another. Altogether, this demonstrates the non-inferiority of ASAQ1 regimen compared to both ASAQ2 and AL regimens. During follow-up mild and moderate adverse events including gastrointestinal and/or nervous disorders were reported in 29.3% of patients, with no difference between groups in the nature, frequency or intensity of adverse events.ConclusionThe non-inferiority of ASAQ compared with AL was demonstrated. The fixed-dose combination artesunate + amodiaquine (ASAQ) is safe and efficacious even in young children under 5 years of age. Whilst administration on a twice-a-day basis does not improve the efficacy of ASAQ significantly, a once-a-day intake of this new combination clearly appears as an effective and safe therapy in the treatment of uncomplicated P. falciparum malaria both in adults and children. Implications of such findings are of primary importance in terms of public health especially in African countries. As most national policies plan to strengthen malaria control to reach the elimination of this disease, anti-malarial drugs such as the artesunate + amodiaquine fixed-dose ACT will play a pivotal role in this process.Trial registrationThe protocol was registered with the www.clinicaltrials.gov open clinical trial registry under the identifier number NCT00316329.

A trial of the efficacy, safety and impact on drug resistance of four drug regimens for seasonal intermittent preventive treatment for malaria in Senegalese children.

Summary In the Sahel, most malaria deaths occur among children 1–4 years old during a short transmission season. A trial of seasonal intermittent preventive treatment (IPT) with sulfadoxine-pyrimethamine (SP) and a single dose of artesunate (AS) showed an 86% reduction in the incidence of malaria in Senegal but this may not be the optimum regimen. We compared this regimen with three alternatives. Methods 2102 children aged 6–59 months received either one dose of SP plus one dose of AS (SP+1AS) (the previous regimen), one dose of SP plus 3 daily doses of AS (SP+3AS), one dose of SP plus three daily doses of amodiaquine (AQ) (SP+3AQ) or 3 daily doses of AQ and AS (3AQ+3AS). Treatments were given once a month on three occasions during the malaria transmission season. The primary end point was incidence of clinical malaria. Secondary end-points were incidence of adverse events, mean haemoglobin concentration and prevalence of parasites carrying markers of resistance to SP. Findings The incidence of malaria, and the prevalence of parasitaemia at the end of the transmission season, were lowest in the group that received SP+3AQ: 10% of children in the group that received SP+1AS had malaria, compared to 9% in the SP+3AS group (hazard ratio HR 0.90, 95%CI 0.60, 1.36); 11% in the 3AQ+3AS group, HR 1.1 (0.76–1.7); and 5% in the SP+3AQ group, HR 0.50 (0.30–0.81). Mutations associated with resistance to SP were present in almost all parasites detected at the end of the transmission season, but the prevalence of Plasmodium falciparum was very low in the SP+3AQ group. Conclusions Monthly treatment with SP+3AQ is a highly effective regimen for seasonal IPT. Choice of this regimen would minimise the spread of drug resistance and allow artemisinins to be reserved for the treatment of acute clinical malaria. Trial Registration Clinicaltrials.gov NCT00132548

The Quantity and Quality of African Children's IgG Responses to Merozoite Surface Antigens Reflect Protection against Plasmodium falciparum Malaria

Background Antibodies, particularly cytophilic IgG subclasses, with specificity for asexual blood stage antigens of Plasmodium falciparum, are thought to play an important role in acquired immunity to malaria. Evaluating such responses in longitudinal sero-epidemiological field studies, allied to increasing knowledge of the immunological mechanisms associated with anti-malarial protection, will help in the development of malaria vaccines. Methods and Findings We conducted a 1-year follow-up study of 305 Senegalese children and identified those resistant or susceptible to malaria. In retrospective analyses we then compared post-follow-up IgG responses to six asexual-stage candidate malaria vaccine antigens in groups of individuals with clearly defined clinical and parasitological histories of infection with P. falciparum. In age-adjusted analyses, children resistant to malaria as well as to high-density parasitemia, had significantly higher IgG1 responses to GLURP and IgG3 responses to MSP2 than their susceptible counterparts. Among those resistant to malaria, high anti-MSP1 IgG1 levels were associated with protection against high-density parasitemia. To assess functional attributes, we used an in vitro parasite growth inhibition assay with purified IgG. Samples from individuals with high levels of IgG directed to MSP1, MSP2 and AMA1 gave the strongest parasite growth inhibition, but a marked age-related decline was observed in these effects. Conclusion Our data are consistent with the idea that protection against P. falciparum malaria in children depends on acquisition of a constellation of appropriate, functionally active IgG subclass responses directed to multiple asexual stage antigens. Our results suggest at least two distinct mechanisms via which antibodies may exert protective effects. Although declining with age, the growth inhibitory effects of purified IgG measurable in vitro reflected levels of anti-AMA1, -MSP1 and -MSP2, but not of anti-GLURP IgG. The latter could act on parasite growth via indirect parasiticidal pathways.

Randomized trial of piperaquine with sulfadoxine-pyrimethamine or dihydroartemisinin for malaria intermittent preventive treatment in children.

Background The long terminal half life of piperaquine makes it suitable for intermittent preventive treatment for malaria but no studies of its use for prevention have been done in Africa. We did a cluster randomized trial to determine whether piperaquine in combination with either dihydroartemisin (DHA) or sulfadoxine-pyrimethamine (SP) is as effective, and better tolerated, than SP plus amodiaquine (AQ), when used for intermittent preventive treatment in children delivered by community health workers in a rural area of Senegal. Methods Treatments were delivered to children 3–59 months of age in their homes once per month during the transmission season by community health workers. 33 health workers, each covering about 60 children, were randomized to deliver either SP+AQ, DHA+PQ or SP+PQ. Primary endpoints were the incidence of attacks of clinical malaria, and the incidence of adverse events. Results 1893 children were enrolled. Coverage of monthly rounds and compliance with daily doses was similar in all groups; 90% of children received at least 2 monthly doses. Piperaquine combinations were better tolerated than SP+AQ with a significantly lower risk of common, mild adverse events. 103 episodes of clinical malaria were recorded during the course of the trial. 68 children had malaria with parasitaemia >3000/µL, 29/671 (4.3%) in the SP+AQ group, compared with 22/604 (3.6%) in the DHA+PQ group (risk difference 0.47%, 95%CI −2.3%,+3.3%), and 17/618 (2.8%) in the SP+PQ group (risk difference 1.2%, 95%CI −1.3%,+3.6%). Prevalences of parasitaemia and the proportion of children carrying Pfdhfr and Pfdhps mutations associated with resistance to SP were very low in all groups at the end of the transmission season. Conclusions Seasonal IPT with SP+PQ in children is highly effective and well tolerated; the combination of two long-acting drugs is likely to impede the emergence of resistant parasites. Trial Registration ClinicalTrials.gov NCT00529620

Community screening and treatment of asymptomatic carriers of Plasmodium falciparum with artemether-lumefantrine to reduce malaria disease burden: a modelling and simulation analysis

BackgroundAsymptomatic carriers of Plasmodium falciparum serve as a reservoir of parasites for malaria transmission. Identification and treatment of asymptomatic carriers within a region may reduce the parasite reservoir and influence malaria transmission in that area.MethodsUsing computer simulation, this analysis explored the impact of community screening campaigns (CSC) followed by systematic treatment of P. falciparum asymptomatic carriers (AC) with artemether-lumefantrine (AL) on disease transmission. The model created by Okell et al (originally designed to explore the impact of the introduction of treatment with artemisinin-based combination therapy on malaria endemicity) was modified to represent CSC and treatment of AC with AL, with the addition of malaria vector seasonality. The age grouping, relative distribution of age in a region, and degree of heterogeneity in disease transmission were maintained. The number and frequency of CSC and their relative timing were explored in terms of their effect on malaria incidence. A sensitivity analysis was conducted to determine the factors with the greatest impact on the model predictions.ResultsThe simulation showed that the intervention that had the largest effect was performed in an area with high endemicity (entomological inoculation rate, EIR > 200); however, the rate of infection returned to its normal level in the subsequent year, unless the intervention was repeated. In areas with low disease burden (EIR < 10), the reduction was sustained for over three years after a single intervention. Three CSC scheduled in close succession (monthly intervals) at the start of the dry season had the greatest impact on the success of the intervention.ConclusionsCommunity screening and treatment of asymptomatic carriers with AL may reduce malaria transmission significantly. The initial level of disease intensity has the greatest impact on the potential magnitude and duration of malaria reduction. When combined with other interventions (e.g. long-lasting insecticide-treated nets, rapid diagnostic tests, prompt diagnosis and treatment, and, where appropriate, indoor residual spraying) the effect of this intervention can be sustained for many years, and it could become a tool to accelerate the reduction in transmission intensity to pre-elimination levels. Repeated interventions at least every other year may help to prolong the effect. The use of an effective diagnostic tool and a highly effective ACT, such as AL, is also vital. The modelling supports the evaluation of this approach in a prospective clinical trial to reduce the pool of infective vectors for malaria transmission in an area with marked seasonality.