Etude de l’effet d’une source d’inoculum externe sur la propagation du CABMV (Cowpea aphid – borne mosaic virus) selon la proximité des parcelles voisines et la variété de niébé

Un champ ensemencé avec des semences de qualité peut se retrouver voisin avec un autre ensemencé avec des semences infectées par le virus de la mosaïque du niébé. Ce virus est transmis par les semences à des taux de 0 à 40% selon les variétés. Ces semences infectées donnent des jeunes plantes virosées à partir desquelles les pucerons vont propager la maladie. Ce travail a été effectué pour déterminer la distance minimale permettant d’éviter des contaminations à partir d’inoculum externe suivant la sensibilité de la variété. Ainsi, deux parcelles centrales de 300 m2 ont été semées avec des graines de Gorom local contaminées à 0,5% par le virus. Autour de la première parcelle centrale, 4 parcelles de 200 m2 chacune ont été semées avec des graines de Gorom local indemnes de virus aux distances respectives de 10 m, 15 m, 20 m et 25 m. Autour de la deuxième parcelle centrale, des semences indemnes de virus de Kvx61-1 ont été utilisées. Un dispositif similaire a été constitué pour les parcelles témoins avec des semences indemnes de virus. La propagation de la maladie a montré qu’elle est liée à la variété, aux pucerons et à la distance avec la source d’inoculum.© 2015 International Formulae Group. All rights reserved.Mots clés: Semences indemnes de virus, semences contaminées, distance minimale, puceronsEnglish Title: Study of the effect of external inoculum source on CABMV (Cowpea aphid – borne mosaic virus) spread in relation to the proximity of neighboring plots and the cowpea varietyEnglish AbstractA field sown with quality seeds can be closed to another one sown with seeds infected by cowpea mosaic virus which is seed transmitted at rates ranging from 0 to 40% depending on cowpea varieties. Infected seeds germinate and grow into virus-infected seedlings from which aphids will spread the disease. This  research was carried out in order to determine the minimum distance needed for avoiding contaminations from external virus inoculum sources, in relation with the susceptibility of cowpea varieties. Thus, two central plots of 300 m² have been sown with contaminated seeds at 0.5% by CABMV of cowpea variety Gorom local. Around the first central plot, four plots of 200 m² each were sown with virus-free seeds of Gorom local at respective distances of 10 m, 15 m, 20 m and 25 m. Around the second central plot, virus-free seeds of Kvx61- 1 have been used. A similar layout was done for the control plots with virus-free seeds. It was found that the spread of the disease was related to the cowpea variety, the aphids and the distance from the inoculum source.© 2015 International Formulae Group. All rights reserved.Keywords: Virus-free seeds, contaminated seeds, minimum distance, aphid

Overall and Gender-Specific Effects of Intermittent Preventive Treatment of Malaria with Artemisinin-Based Combination Therapies among Schoolchildren in Mali: A Three-Group Open Label Randomized Controlled Trial.

Intermittent preventive treatment of malaria among schoolchildren (IPTsc) reduces clinical malaria, asymptomatic parasitemia, and anemia. The effects of IPTsc by gender have not been studied longitudinally. We investigated overall IPTsc efficacy and conducted a secondary analysis to explore gender-specific differences. We enrolled schoolchildren aged 6-13 years in an open-label, rolling-cohort randomized controlled trial between September 2007 and February 2013 in Kolle, Mali. Annually, schoolchildren received two full-treatment courses of sulfadoxine-pyrimethamine (SP) plus artesunate, or amodiaquine (AQ) plus artesunate, or no malaria treatment as control. We used mixed-effects generalized linear models to estimate differences in treatment outcomes across groups with interaction terms to explore gender-specific differences associated with Plasmodium falciparum infection, hemoglobin, and grade point averages (GPA) based on standardized testing. Overall, 305 students contributed 4,564 observations. Compared with the control, SP plus artesunate and AQ plus artesunate reduced the odds of P. falciparum infection (odds ratio [OR]: 0.33, 95% CI: 0.26-0.43; OR: 0.46, 95% CI: 0.36-0.59). We found strong evidence of increased mean hemoglobin concentrations (g/dL) in the SP plus artesunate group versus control (difference +0.37, 95% CI: 0.13-0.58). Collectively, schoolchildren given AQ plus artesunate had higher mean GPA (difference +0.36, 95% CI: 0.02-0.69) relative to control. Schoolgirls, compared with schoolboys, given SP plus artesunate had greater improvement in GPA (+0.50, 95% CI: -0.02 to 1.02 versus -0.27, 95% CI: -0.71 to 0.16); interaction P = 0.048, respectively. The IPTsc decreases P. falciparum infections in schoolchildren. Treatment regimens that include longer-acting drugs may be more effective at decreasing malaria-related anemia and improving educational outcomes as observed among girls in this setting

Artemisinin-based combinations versus amodiaquine plus sulphadoxine-pyrimethamine for the treatment of uncomplicated malaria in Faladje, Mali

<p>Abstract</p> <p>Background</p> <p>Because of the emergence of chloroquine resistance in Mali, artemether-lumefantrine (AL) or artesunate-amodiaquine (AS+AQ) are recommended as first-line therapy for uncomplicated malaria, but have not been available in Mali until recently because of high costs.</p> <p>Methods</p> <p>From July 2005 to January 2006, a randomized open-label trial of three oral antimalarial combinations, namely AS+AQ, artesunate plus sulphadoxine-pyrimethamine (AS+SP), and amodiaquine plus sulphadoxine-pyrimethamine (AQ+SP), was conducted in Faladje, Mali. Parasite genotyping by polymerase chain reaction (PCR) was used to distinguish new from recrudescent <it>Plasmodium falciparum </it>infections.</p> <p>Results</p> <p>397 children 6 to 59 months of age with uncomplicated <it>Plasmodium falciparum </it>malaria were enrolled, and followed for 28 days to assess treatment efficacy. Baseline characteristics were similar in all three treatment groups. The uncorrected rates of adequate clinical and parasitologic response (ACPR) were 55.7%, 90.8%, and 97.7% in AS+AQ, AS+SP, and AQ+SP respectively (p < 0.001); after PCR correction ACPR rates were similar among treatment groups: 95.4%, 96.9%, and 99.2% respectively (p = 0.17). Mean haemoglobin concentration increased across all treatment groups from Day 0 (9.82 ± 1.68 g/dL) to Day 28 (10.78 ± 1.49 g/dL) (p < 0.001), with the greatest improvement occurring in children treated with AQ+SP. On Day 2, the prevalence of parasitaemia was significantly greater among children treated with AQ+SP (50.8%) than in children treated with AS+AQ (10.5%) or AS+SP (10.8%) (p < 0.001). No significant difference in gametocyte carriage was found between groups during the follow-up period.</p> <p>Conclusion</p> <p>The combination of AQ+SP provides a potentially low cost alternative for treatment of uncomplicated <it>P. falciparum </it>infection in Mali and appears to have the added value of longer protective effect against new infection.</p

Historical Contingencies Modulate the Adaptability of Rice Yellow Mottle Virus

The rymv1-2 and rymv1-3 alleles of the RYMV1 resistance to Rice yellow mottle virus (RYMV), coded by an eIF(iso)4G1 gene, occur in a few cultivars of the Asiatic (Oryza sativa) and African (O. glaberrima) rice species, respectively. The most salient feature of the resistance breaking (RB) process is the converse genetic barrier to rymv1-2 and rymv1-3 resistance breakdown. This specificity is modulated by the amino acid (glutamic acid vs. threonine) at codon 49 of the Viral Protein genome-linked (VPg), a position which is adjacent to the virulence codons 48 and 52. Isolates with a glutamic acid (E) do not overcome rymv1-3 whereas those with a threonine (T) rarely overcome rymv1-2. We found that isolates with T49 had a strong selective advantage over isolates with E49 in O. glaberrima susceptible cultivars. This explains the fixation of the mutation T49 during RYMV evolution and accounts for the diversifying selection estimated at codon 49. Better adapted to O. glaberrima, isolates with T49 are also more prone than isolates with E49 to fix rymv1-3 RB mutations at codon 52 in resistant O. glaberrima cultivars. However, subsequent genetic constraints impaired the ability of isolates with T49 to fix rymv1-2 RB mutations at codons 48 and 52 in resistant O. sativa cultivars. The origin and role of the amino acid at codon 49 of the VPg exemplifies the importance of historical contingencies in the ability of RYMV to overcome RYMV1 resistance

Expanding Research Capacity in Sub-Saharan Africa Through Informatics, Bioinformatics, and Data Science Training Programs in Mali

Bioinformatics and data science research have boundless potential across Africa due to its high levels of genetic diversity and disproportionate burden of infectious diseases, including malaria, tuberculosis, HIV and AIDS, Ebola virus disease, and Lassa fever. This work lays out an incremental approach for reaching underserved countries in bioinformatics and data science research through a progression of capacity building, training, and research efforts. Two global health informatics training programs sponsored by the Fogarty International Center (FIC) were carried out at the University of Sciences, Techniques and Technologies of Bamako, Mali (USTTB) between 1999 and 2011. Together with capacity building efforts through the West Africa International Centers of Excellence in Malaria Research (ICEMR), this progress laid the groundwork for a bioinformatics and data science training program launched at USTTB as part of the Human Heredity and Health in Africa (H3Africa) initiative. Prior to the global health informatics training, its trainees published first or second authorship and third or higher authorship manuscripts at rates of 0.40 and 0.10 per year, respectively. Following the training, these rates increased to 0.70 and 1.23 per year, respectively, which was a statistically significant increase (p &lt; 0.001). The bioinformatics and data science training program at USTTB commenced in 2017 focusing on student, faculty, and curriculum tiers of enhancement. The program’s sustainable measures included institutional support for core elements, university tuition and fees, resource sharing and coordination with local research projects and companion training programs, increased student and faculty publication rates, and increased research proposal submissions. Challenges reliance of high-speed bandwidth availability on short-term funding, lack of a discounted software portal for basic software applications, protracted application processes for United States visas, lack of industry job positions, and low publication rates in the areas of bioinformatics and data science. Long-term, incremental processes are necessary for engaging historically underserved countries in bioinformatics and data science research. The multi-tiered enhancement approach laid out here provides a platform for generating bioinformatics and data science technicians, teachers, researchers, and program managers. Increased literature on bioinformatics and data science training approaches and progress is needed to provide a framework for establishing benchmarks on the topics

Persistent Submicroscopic Plasmodium falciparum Parasitemia 72 Hours after Treatment with Artemether-Lumefantrine Predicts 42-Day Treatment Failure in Mali and Burkina Faso.

A recent randomized controlled trial, the WANECAM (West African Network for Clinical Trials of Antimalarial Drugs) trial, conducted at seven centers in West Africa, found that artemether-lumefantrine, artesunate-amodiaquine, pyronaridine-artesunate, and dihydroartemisinin-piperaquine all displayed good efficacy. However, artemether-lumefantrine was associated with a shorter interval between clinical episodes than the other regimens. In a further comparison of these therapies, we identified cases of persisting submicroscopic parasitemia by quantitative PCR (qPCR) at 72 h posttreatment among WANECAM participants from 5 sites in Mali and Burkina Faso, and we compared treatment outcomes for this group to those with complete parasite clearance by 72 h. Among 552 evaluable patients, 17.7% had qPCR-detectable parasitemia at 72 h during their first treatment episode. This proportion varied among sites, reflecting differences in malaria transmission intensity, but did not differ among pooled drug treatment groups. However, patients who received artemether-lumefantrine and were qPCR positive at 72 h were significantly more likely to have microscopically detectable recurrent Plasmodium falciparum parasitemia by day 42 than those receiving other regimens and experienced, on average, a shorter interval before the next clinical episode. Haplotypes of pfcrt and pfmdr1 were also evaluated in persisting parasites. These data identify a possible threat to the parasitological efficacy of artemether-lumefantrine in West Africa, over a decade since it was first introduced on a large scale

Landscape Ecology of Sylvatic Chikungunya Virus and Mosquito Vectors in Southeastern Senegal

The risk of human infection with sylvatic chikungunya (CHIKV) virus was assessed in a focus of sylvatic arbovirus circulation in Senegal by investigating distribution and abundance of anthropophilic Aedes mosquitoes, as well as the abundance and distribution of CHIKV in these mosquitoes. A 1650 km2 area was classified into five land cover classes: forest, barren, savanna, agriculture and village. A total of 39,799 mosquitoes was sampled from all classes using human landing collections between June 2009 and January 2010. Mosquito diversity was extremely high, and overall vector abundance peaked at the start of the rainy season. CHIKV was detected in 42 mosquito pools. Our data suggest that Aedes furcifer, which occurred abundantly in all land cover classes and landed frequently on humans in villages outside of houses, is probably the major bridge vector responsible for the spillover of sylvatic CHIKV to humans

Quinine Treatment Selects the pfnhe-1 ms4760-1 Polymorphism in Malian Patients with Falciparum Malaria

Background. The mechanism of Plasmodium falciparum resistance to quinine is not known. In vitro quantitative trait loci mapping suggests involvement of a predicted P. falciparum sodium-hydrogen exchanger (pfnhe-1) on chromosome 13. Methods. We conducted prospective quinine efficacy studies in 2 villages, Kolle and Faladie, Mali. Cases of clinical malaria requiring intravenous therapy were treated with standard doses of quinine and followed for 28 days. Treatment outcomes were classified using modified World Health Organization protocols. Molecular markers of parasite polymorphisms were used to distinguish recrudescent parasites from new infections. The prevalence of pfnhe-1 ms4760-1 among parasites before versus after quinine treatment was determined by direct sequencing. Results. Overall, 163 patients were enrolled and successfully followed. Without molecular correction, the mean adequate clinical and parasitological response (ACPR) was 50.3% (n = 163). After polymerase chain reaction correction to account for new infections, the corrected ACPR was 100%. The prevalence of ms4760-1 increased significantly, from 26.2% (n = 107) before quinine treatment to 46.3% (n = 54) after therapy (P = .01). In a control sulfadoxine-pyrimethamine study, the prevalence of ms4760-1 was similar before and after treatment. Conclusions. This study supports a role for pfnhe-1 in decreased susceptibility of P. falciparum to quinine in the field.Howard Hughes Medical Institute [55005502]; Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health; European and Developing Countries Clinical Trials Partnership [EDCTP IP_07_31060_002]info:eu-repo/semantics/publishedVersio

Efficacy and safety of a fixed dose artesunate-sulphamethoxypyrazine-pyrimethamine compared to artemether-lumefantrine for the treatment of uncomplicated falciparum malaria across Africa: a randomized multi-centre trial

<p>Abstract</p> <p>Background</p> <p>The efficacy of artemisinin-based combination therapy has already been demonstrated in a number of studies all over the world, and some of them can be regarded as comparably effective. Ease of administration of anti-malarial treatments with shorter courses and fewer tablets may be key determinant of compliance.</p> <p>Methods</p> <p>Patients with uncomplicated falciparum malaria and over six months of age were recruited in Cameroon, Mali, Rwanda and Sudan. 1,384 patients were randomly assigned to receive artesunate-sulphamethoxypyrazine-pyrimethamine (AS-SMP) three-day (once daily for 3 days) regimen (N = 476) or AS-SMP 24-hour (0 h, 12 h, 24 h) regimen (N = 458) or artemether-lumefantrine (AL), the regular 6 doses regimen (N = 450). The primary objective was to demonstrate non-inferiority (using a margin of -6%) of AS-SMP 24 hours or AS-SMP three days versus AL on the PCR-corrected 28-day cure rate.</p> <p>Results</p> <p>The PCR corrected 28-day cure rate on the intention to treat (ITT) analysis population were: 96.0%(457/476) in the AS-SMP three-day group, 93.7%(429/458) in the AS-SMP 24-hour group and 92.0%(414/450) in the AL group. Likewise, the cure rates on the PP analysis population were high: 99.3%(432/437) in the AS-SMP three-day group, 99.5%(416/419) in the AS-SMP 24-hour group and 99.7(391/394)% in the AL group. Most common drug-related adverse events were gastrointestinal symptoms (such as vomiting and diarrhea) which were slightly higher in the AS-SMP 24-hour group.</p> <p>Conclusion</p> <p>AS-SMP three days or AS-SMP 24 hours are safe, are as efficacious as AL, and are well tolerated.</p> <p>Trial registration</p> <p>NCT00484900 <url>http://www.clinicaltrials.gov</url>.</p