Efficacy of chloroquine, amodiaquine and sulphadoxine-pyrimethamine for the treatment of uncomplicated falciparum malaria: revisiting molecular markers in an area of emerging AQ and SP resistance in Mali

<p>Abstract</p> <p>Background</p> <p>To update the National Malaria Control Programme of Mali on the efficacy of chloroquine, amodiaquine and sulphadoxine-pyrimethamine in the treatment of uncomplicated <it>falciparum </it>malaria.</p> <p>Methods</p> <p>During the malaria transmission seasons of 2002 and 2003, 455 children – between six and 59 months of age, with uncomplicated malaria in Kolle, Mali, were randomly assigned to one of three treatment arms. <it>In vivo </it>outcomes were assessed using WHO standard protocols. Genotyping of <it>msp1</it>, <it>msp2 </it>and CA1 polymorphisms were used to distinguish reinfection from recrudescent parasites (molecular correction).</p> <p>Results</p> <p>Day 28 adequate clinical and parasitological responses (ACPR) were 14.1%, 62.3% and 88.9% in 2002 and 18.2%, 60% and 85.2% in 2003 for chloroquine, amodiaquine and sulphadoxine-pyrimethamine, respectively. After molecular correction, ACPRs (cACPR) were 63.2%, 88.5% and 98.0% in 2002 and 75.5%, 85.2% and 96.6% in 2003 for CQ, AQ and SP, respectively. Amodiaquine was the most effective on fever. Amodiaquine therapy selected molecular markers for chloroquine resistance, while in the sulphadoxine-pyrimethamine arm the level of <it>dhfr </it>triple mutant and <it>dhfr</it>/<it>dhps </it>quadruple mutant increased from 31.5% and 3.8% in 2002 to 42.9% and 8.9% in 2003, respectively. No infection with <it>dhps </it>540E was found.</p> <p>Conclusion</p> <p>In this study, treatment with sulphadoxine-pyrimethamine emerged as the most efficacious on uncomplicated falciparum malaria followed by amodiaquine. The study demonstrated that sulphadoxine-pyrimethamine and amodiaquine were appropriate partner drugs that could be associated with artemisinin derivatives in an artemisinin-based combination therapy.</p

Differential infectivity of gametocytes after artemisinin-based combination therapy of uncomplicated falciparum malaria

Background: Most malaria-endemic countries use artemisinin-based combination therapy (ACT) as their first-line treatment. ACTs are known to be highly effective on asexual stages of the malaria parasite. Malaria transmission and the spread of resistant parasites depend on the infectivity of gametocytes. The effect of the current ACT regimens on gametocyte infectivity is unclear. Objectives: This study aimed to determine the infectivity of gametocytes to Anopheles gambiae following ACT treatment in the field. Methods: During a randomised controlled trial in Bougoula-Hameau, Mali, conducted from July 2005 to July 2007, volunteers with uncomplicated malaria were randomised to receive artemether-lumefantrine, artesunate-amodiaquine, or artesunate-sulfadoxine/pyrimethamine. Volunteers were followed for 28 days, and gametocyte carriage was assessed. Direct skin feeding assays were performed on gametocyte carriers before and after ACT administration. Results: Following artemether-lumefantrine treatment, gametocyte carriage decreased steadily from Day 0 to Day 21 post-treatment initiation. In contrast, for the artesunate-amodiaquine and artesunate-sulfadoxine/pyrimethamine arms, gametocyte carriage increased on Day 3 and remained constant until Day 7 before decreasing afterward. Mosquito feeding assays showed that artemether-lumefantrine and artesunate-amodiaquine significantly increased gametocyte infectivity to Anopheles gambiae sensu lato (s.l.) (p < 10−4), whereas artesunate-sulfadoxine/pyrimethamine decreased gametocyte infectivity in this setting (p = 0.03). Conclusion: Different ACT regimens could lead to gametocyte populations with different capacity to infect the Anopheles vector. Frequent assessment of the effect of antimalarials on gametocytogenesis and gametocyte infectivity may be required for the full assessment of treatment efficacy, the potential for spread of drug resistance and malaria transmission in the field

Uptake of plasmodium falciparum gametocytes during mosquito bloodmeal by direct and membrane feeding

Plasmodium falciparum remains one of the leading causes of child mortality, and nearly half of the world’s population is at risk of contracting malaria. While pathogenesis results from replication of asexual forms in human red blood cells, it is the sexually differentiated forms, gametocytes, which are responsible for the spread of the disease. For transmission to succeed, both mature male and female gametocytes must be taken up by a female Anopheles mosquito during its blood meal for subsequent differentiation into gametes and mating inside the mosquito gut. Observed circulating numbers of gametocytes in the human host are often surprisingly low. A pre-fertilization behavior, such as skin sequestration, has been hypothesized to explain the efficiency of human-to-mosquito transmission but has not been sufficiently tested due to a lack of appropriate tools. In this study, we describe the optimization of a qPCR tool that enables the relative quantification of gametocytes within very small input samples. Such a tool allows for the quantification of gametocytes in different compartments of the host and the vector that could potentially unravel mechanisms that enable highly efficient malaria transmission. We demonstrate the use of our gametocyte quantification method in mosquito blood meals from both direct skin feeding on Plasmodium gametocyte carriers and standard membrane feeding assay. Relative gametocyte abundance was not different between mosquitoes fed through a membrane or directly on the skin suggesting that there is no systematic enrichment of gametocytes picked up in the skin

Population-specific variations in KCNH2 predispose patients to delayed ventricular repolarization upon dihydroartemisinin-piperaquine therapy

Funding Information: The study was supported by European and Developing Countries Clinical Trial Partnership (grant number RIA2017T-2018), Medicines for Malaria Venture (Geneva, Switzerland), UK Medical Research Council, Swedish International Development Cooperation Agency, German Ministry for Education and Research, University Claude Bernard (Lyon, France), Malaria Research and Training Centre (Bamako, Mali), Centre National de Recherche et de Formation sur le Paludisme (Burkina Faso), Institut de Recherche en Sciences de la Sant. (Bobo-Dioulasso, Burkina Faso), and Centre National de Formation et de Recherche en Sant. Rurale (Republic of Guinea). In addition, the authors received support from the Swedish Research Council (grant numbers 2019-01837, 2021-02801, 2021-05666, and 2021-06048), the Grants, Innovation and Product Development Unit of the South African Medical Research Council with funds received from Novartis and GSK R&D for Project Africa GRADIENT (grant numbers GSKNVS2/202101/004), the Robert Bosch Foundation, Stuttgart, Germany, and Conselho Nacional de Desenvolvimento Cient\u00EDfico e Tecnol\u00F3gico (CNPq), Brazil (grant number 200075/2022\u20135). T.N.S. is a CNPq Research Productivity Fellow. M.D.C. performed sequencing, analyzed the data, and conducted statistical analyses. Y.Z. conducted computational variant analyses. M.M.T. was involved in the acquisition of drug concentrations. A.D. and S.S. contributed to bioinformatics analyses. N.O. was the cardiologist responsible for cardiac toxicity assessment. A.H.T, M.L.A., B.F., and I.S. oversaw clinical patient recruitment and management. A.A.D. coordinated and oversaw the WANECAM study and critically reviewed the manuscript. P.J.G. and V.M.L designed and supervised the study. M.D.C. and V.M.L. wrote the manuscript. All authors read, reviewed, and approved of the final version of the manuscript. Funding Information: The study was supported by European and Developing Countries Clinical Trial Partnership (grant number RIA2017T-2018), Medicines for Malaria Venture (Geneva, Switzerland), UK Medical Research Council, Swedish International Development Cooperation Agency, German Ministry for Education and Research, University Claude Bernard (Lyon, France), Malaria Research and Training Centre (Bamako, Mali), Centre National de Recherche et de Formation sur le Paludisme (Burkina Faso), Institut de Recherche en Sciences de la Sant. (Bobo-Dioulasso, Burkina Faso), and Centre National de Formation et de Recherche en Sant. Rurale (Republic of Guinea). In addition, the authors received support from the Swedish Research Council (grant numbers 2019-01837, 2021-02801, 2021-05666, and 2021-06048), the Grants, Innovation and Product Development Unit of the South African Medical Research Council with funds received from Novartis and GSK R&D for Project Africa GRADIENT (grant numbers GSKNVS2/202101/004), the Robert Bosch Foundation, Stuttgart, Germany, and Conselho Nacional de Desenvolvimento e Tecnol\u00F3gico (CNPq), Brazil (grant number 200075/2022\u20135). T.N.S. is a CNPq Research Productivity Fellow. Publisher Copyright: Copyright © 2024 Camara et al.Dihydroartemisinin-piperaquine is efficacious for the treatment of uncomplicated malaria and its use is increasing globally. Despite the positive results in fighting malaria, inhibition of the Kv11.1 channel (hERG; encoded by the KCNH2 gene) by piperaquine has raised concerns about cardiac safety. Whether genetic factors could modulate the risk of piperaquine-mediated QT prolongations remained unclear. Here, we first profiled the genetic landscape of KCNH2 variability using data from 141,614 individuals. Overall, we found 1,007 exonic variants distributed over the entire gene body, 555 of which were missense. By optimizing the gene-specific parametrization of 16 partly orthogonal computational algorithms, we developed a KCNH2-specific ensemble classifier that identified a total of 116 putatively deleterious missense variations. To evaluate the clinical relevance of KCNH2 variability, we then sequenced 293 Malian patients with uncomplicated malaria and identified 13 variations within the voltage sensing and pore domains of Kv11.1 that directly interact with channel blockers. Cross-referencing of genetic and electrocardiographic data before and after piperaquine exposure revealed that carriers of two common variants, rs1805121 and rs41314375, experienced significantly higher QT prolongations (ΔQTc of 41.8 ms and 61 ms, respectively, vs 14.4 ms in controls) with more than 50% of carriers having increases in QTc >30 ms. Furthermore, we identified three carriers of rare population-specific variations who experienced clinically relevant delayed ventricular repolarization. Combined, our results map population-scale genetic variability of KCNH2 and identify genetic biomarkers for piperaquine-induced QT prolongation that could help to flag at-risk patients and optimize efficacy and adherence to antimalarial therapy.publishersversionpublishe

Characterisation of camel breeding practices in the Ansongo Region, Mali

Despite its importance in Mali’s economy, camel breeding in the country remains poorly documented, impeding effective policy-making in this regard. This study consisted in a 3-month survey and aimed at characterising camel breeding systems in Ansongo, in the region of Gao, Mali. It highlights the diversity of strategies adopted by breeders and their evolutions. Supplementary feeding and veterinary care were seldom practised. In zones close to the Niger River, cattle were substituted to camels. Transhumance routes also are modified but mobility keeps its vital role in the breeding system. Important differences within the study region in the classification of camel breeds have been reported that will influence the implementation of a collective action for animal genetic improvement. The improvement goals should take the actual management, including mobility and the mixed nature of the herds into account

Pf Atlas of sexual development

&lt;p&gt;&lt;strong&gt;The datasets&nbsp;here are a key addition to the Malaria Cell Atlas, that include&nbsp;short and long read single cell RNA-sequencing profiles of i) over 37,000 &lt;em&gt;Plasmodium falciparum&lt;/em&gt; cells across intraerythrocytic asexual and sexual development of laboratory strains ii)&nbsp; ~8000 &lt;em&gt;P. falciparum&lt;/em&gt; parasites collected from four asymptomatic Malian individuals naturally infected with multiple strains. A single cell atlas comprising the laboratory dataset as well as an integrated atlas of both laboratory and field strains is generated and provided as a data resource to the malaria research community at malariacellatlas.org&lt;/strong&gt;&lt;/p&gt

Gametocyte clearance dynamics following oral artesunate treatment of uncomplicated falciparum malaria in Malian children

Artemisinin-based combination therapies decrease Plasmodium gametocyte carriage. However, the role of artesunate in monotherapy in vivo, the mechanisms involved, and the utility of gametocyte carriage as a potential tool for the surveillance of antimalarial resistance are poorly understood. In 2010–2011, we conducted an open-label, prospective efficacy study of artesunate as monotherapy in children 1–10 years of age with uncomplicated falciparum malaria in Bougoula-Hameau, Mali. Standard oral doses of artesunate were administered for 7 days and patients were followed up for 28 days. The data were compared to a similar study conducted in 2002–2004. Of 100 children enrolled in the 2010–2011 study, 92 were analyzed and compared to 217 children enrolled in the 2002–2004 study. The proportion of gametocyte carriers was unchanged at the end of treatment (23% at baseline vs. 24% on day 7, p = 1.0) and did not significantly decline until day 21 of follow-up (23% vs. 6%, p = 0.003). The mean gametocyte density at inclusion remained unchanged at the end of treatment (12 gametocytes/μL vs. 16 gametocytes/μL, p = 0.6). Overall, 46% of the 71 initial non-carriers had gametocytes detected by day 7. Similar results were found in the 2002–2004 study. In both studies, although gametocyte carriage significantly decreased by the end of the 28-day follow-up, artesunate did not clear mature gametocytes during treatment and did not prevent the appearance of new stage V gametocytes as assessed by light microscopy. Baseline gametocyte carriage was significantly higher 6 years after the deployment of artemisinin-based combination therapies in this setting

Gametocyte clearance dynamics following oral artesunate treatment of uncomplicated

Artemisinin-based combination therapies decrease Plasmodium gametocyte carriage. However, the role of artesunate in monotherapy in vivo, the mechanisms involved, and the utility of gametocyte carriage as a potential tool for the surveillance of antimalarial resistance are poorly understood. In 2010–2011, we conducted an open-label, prospective efficacy study of artesunate as monotherapy in children 1–10 years of age with uncomplicated falciparum malaria in Bougoula-Hameau, Mali. Standard oral doses of artesunate were administered for 7 days and patients were followed up for 28 days. The data were compared to a similar study conducted in 2002–2004. Of 100 children enrolled in the 2010–2011 study, 92 were analyzed and compared to 217 children enrolled in the 2002–2004 study. The proportion of gametocyte carriers was unchanged at the end of treatment (23% at baseline vs. 24% on day 7, p = 1.0) and did not significantly decline until day 21 of follow-up (23% vs. 6%, p = 0.003). The mean gametocyte density at inclusion remained unchanged at the end of treatment (12 gametocytes/μL vs. 16 gametocytes/μL, p = 0.6). Overall, 46% of the 71 initial non-carriers had gametocytes detected by day 7. Similar results were found in the 2002–2004 study. In both studies, although gametocyte carriage significantly decreased by the end of the 28-day follow-up, artesunate did not clear mature gametocytes during treatment and did not prevent the appearance of new stage V gametocytes as assessed by light microscopy. Baseline gametocyte carriage was significantly higher 6 years after the deployment of artemisinin-based combination therapies in this setting

Evaluation of the effects on the QT-interval of 4 artemisinin-based combination therapies with a correction-free and heart rate-free method

Abstract Several antimalarial drugs are known to prolong ventricular repolarization as evidenced by QT/QTc interval prolongation. This can lead to Torsades de Pointes, a potentially lethal ventricular arrhythmia. Whether this is the case with artemisinin-based combination therapies (ACTs) remains uncertain. Assessment of the extent of QTc prolongation with antimalarials is hampered by important variations of heart rate during malaria crises and previous studies have reported highly variable values of QTc prolongations with ACTs. We assessed QTc prolongation with four ACTs, using high quality ECG recording and measurement techniques, during the first episode of malaria in 2,091 African patients enrolled in the WANECAM study which also monitored clinical safety. Using an original and robust method of QTc assessment, independent from heart rate changes and from the method of QT correction, we were able to accurately assess the extent of mean maximum QTc prolongation with the four ACTs tested. There was no evidence of proarrhythmia with any treatment during the study although dihydroartemisinin-piperaquine, artesunate-amodiaquine and artemether-lumefantrine significantly prolonged QTc. The extent of prolongation of ventricular repolarization can be accurately assessed in studies where heart rate changes impede QTc assessment

Stratification at the health district level for targeting malaria control interventions in Mali

International audienceMalaria is the leading cause of morbidity and mortality in Mali. Between 2017 and 2020, the number of cases increased in the country, with 2,884,827 confirmed cases and 1454 reported deaths in 2020. We performed a malaria risk stratification at the health district level in Mali with a view to proposing targeted control interventions. Data on confirmed malaria cases were obtained from the District Health Information Software 2, data on malaria prevalence and mortality in children aged 6-59 months from the 2018 Demographic and Health Survey, entomological data from Malian research institutions working on malaria in the sentinel sites of the National Malaria Control Program (NMCP), and environmental data from the National Aeronautics and Space Administration. A stratification of malaria risk was performed. Targeted malaria control interventions were selected based on spatial heterogeneity of malaria incidence, malaria prevalence in children, vector resistance distribution, health facility usage, child mortality, and seasonality of transmission. These interventions were discussed with the NMCP and the different funding partners. In 2017-2019, median incidence across the 75 health districts was 129.34 cases per 1000 person-years (standard deviation = 86.48). Risk stratification identified 12 health districts in very low transmission areas, 19 in low transmission areas, 20 in moderate transmission areas, and 24 in high transmission areas. Low health facility usage and increased vector resistance were observed in high transmission areas. Eight intervention combinations were selected for implementation. Our work provides an updated risk stratification using advanced statistical methods to inform the targeting of malaria control interventions in Mali. This stratification can serve as a template for continuous malaria risk stratifications in Mali and other countries