Criblage Phytochimique et Activités Biologiques de Quatre Plantes Utilisées au Mali dans la Prise en Charge du Paludisme Chez les Enfants

Contexte : Selon les résultats d’une enquête menée dans différentes zones écologiques et culturelles au Sud du Mali, beaucoup de plantes médicinales sont utilisées dans la prise charge du paludisme chez les enfants, dont Annona senegalensis, Flueggea virosa, Gymnosporia senegalensis et Vitex doniana. Nous avons approfondi les études sur la composition phytochimique, la sécurité d’emplois et les activités contre les symptômes du paludisme. Objectifs : Caractériser les métabolites secondaires, déterminer la toxicité aiguë, vérifier l’activité hémolytique et évaluer les propriétés antalgiques, antipyrétiques et antiinflammatoires des quatre plantes. Méthodologie : La composition phytochimique a été déterminée par des réactions colorées en tube. L’activité hémolytique a été évaluée par CCM, révélée par le sang humain. La toxicité aigüe et les activités biologiques ont été déterminées in vivo chez les souris et les rats. Résultats : Les coumarines, stérols, tri terpènes, tanins et flavonoïdes ont été caractérisés dans les extraits aqueux des quatre plantes. Ces extraits n’ont pas présenté de constituants qui provoquent l’hémolyse. Les décoctés administrés par voie orale à la dose de 2000 mg /Kg chez des souris n’ont pas provoqués d’effets toxiques et de mortalité. Les décoctés administrés par voie orale à la dose de 100 et 200 mg /Kg chez des souris ont montré des remarquables activités antalgique, antiinflammatoire et chez les rats l’activité antipyrétique. Conclusion: Ces résultats préliminaires valident l’utilisation traditionnelle des quatre plantes dans la prise en charge des symptômes du paludisme chez les enfants.Introduction: According to the results of a survey conducted in different ecological and cultural areas in southern Mali, many medicinal plants are used by traditional paediatricians in taking charge of malaria in children. The survey highlighted the use of four plants, which we decided to carry out further study on phytochemical composition, safety of use and activity against symptoms of malaria. Objectives: To characterize secondary metabolites, to determine acute toxicity, to check haemolytic activity, and to evaluate the analgesic, antipyretic and anti-inflammatory properties of Annona senegalensis, Flueggea virosa, Gymnosporia senegalensis, and Vitex doniana. Methods: The phytochemical composition of the aqueous extracts of the leafy twigs of the four plants was determined by coloured tube reactions. Haemolytic activity was assessed by TLC and revealed by human blood. Acute toxicity and biological activities were determined in vivo in mice and rats. Results: Coumarins, sterols, tri-terpenes, tannins and flavonoids were characterized in the aqueous extracts of the leafy twigs of the four plants. These decocts did not show any constituents that cause haemolysis. Decoctions given orally at the dose of 2000 mg / kg in mice did not cause toxic effects and mortality. Decoctions administered orally at the dose of 100 and 200 mg / kg showed remarkable analgesic, anti-inflammatory (in mice), and antipyretic (in rat) activities. Conclusion: These preliminary results validate the traditional use of the four plants in the management of malaria symptoms in children

Population Size and Migration of Anopheles gambiae in the Bancoumana Region of Mali and Their Significance for Efficient Vector Control

We present results of two intensive mark-release-recapture surveys conducted during the wet and dry seasons of 2008 in the villages of Fourda and Kenieroba, Mali. The former is a small fishing village by the Niger River with a moderate to high densities of Anopheles gambiae Giles s.s. (Diptera: Culicidae) throughout the year, while the latter is a large agricultural community 2 km inland that experiences strong seasonal fluctuation in An. gambiae densities. We estimate the population size of female An. gambiae in Fourda to be in less than 3,000 during the dry season. We found evidence of large population size and migration from Fourda in Kenieroba during the wet season, but very low numbers and no sign of migrants during the dry season. We suggest that malaria vector control measures aimed at adult mosquitoes might be made more efficient in this region and other seasonal riparian habitats by targeting disruption of mosquito populations by the river during the dry season. This would decrease the size of an already small population, and would be likely to delay the explosive growth in vector numbers in the larger inland villages as rainfall increases

Spatial distribution of the chromosomal forms of anopheles gambiae in Mali

<p>Abstract</p> <p>Background</p> <p>Maps of the distribution of malaria vectors are useful tools for stratification of malaria risk and for selective vector control strategies. Although the distribution of members of the <it>Anopheles gambiae </it>complex is well documented in Africa, a continuous map of the spatial distribution of the chromosomal forms of <it>An. gambiae s.s. </it>is not yet available at country level to support control efforts.</p> <p>Methods</p> <p>Bayesian geostatistical methods were used to produce continuous maps of the spatial distribution of the chromosomal forms of <it>An. gambiae s.s</it>. (Mopti, Bamako, Savanna and their hybrids/recombinants) based on their relative frequencies in relation to climatic and environmental factors in Mali.</p> <p>Results</p> <p>The maps clearly show that each chromosomal form favours a particular defined eco-climatic zone. The Mopti form prefers the dryer northern Savanna and Sahel and the flooded/irrigated areas of the inner delta of the Niger River. The Savanna form favours the Sudan savanna areas, particularly the South and South-Eastern parts of the country (Kayes and Sikasso regions). The Bamako form has a strong preference for specific environmental conditions and it is confined to the Sudan savanna areas around urban Bamako and the Western part of Sikasso region. The hybrids/recombinants favour the Western part of the country (Kayes region) bordering the Republic of Guinea Conakry.</p> <p>Conclusion</p> <p>The maps provide valuable information for selective vector control in Mali (insecticide resistance management) and may serve as a decision support tool for the basis for future malaria control strategies including genetically manipulated mosquitoes.</p

Aestivation of the African Malaria Mosquito, Anopheles gambiae in the Sahel

The African malaria mosquito, Anopheles gambiae, inhabits diverse environments including dry savannas, where surface waters required for larval development are absent for 4–8 months per year. Under such conditions, An. gambiae virtually disappears. Whether populations survive the long dry season by aestivation (a dormant state promoting extended longevity during the summer) or are reestablished by migrants from distant locations where larval sites persist has remained an enigma for over 60 years. Resolving this question is important, because fragile dry season populations may be more susceptible to control. Here, we show unequivocally that An. gambiae aestivates based on a demographic study and a mark release–recapture experiment spanning the period from the end of one wet season to the beginning of the next. During the dry season, An. gambiae was barely detectable in Sahelian villages of Mali. Five days after the first rain, before a new generation of adults could be produced, mosquito abundance surged 10-fold, implying that most mosquitoes were concealed locally until the rain. Four days after the first rain, a marked female An. gambiae s.s. was recaptured. Initially captured, marked, and released at the end of the previous wet season, she has survived the 7-month-long dry season. These results provide evidence that An. gambiae persists throughout the dry season by aestivation and open new questions for mosquito and parasite research. Improved malaria control by targeting aestivating mosquitoes using existing or novel strategies may be possible

A comprehensive analysis of drug resistance molecular markers and Plasmodium falciparum genetic diversity in two malaria endemic sites in Mali.

BACKGROUND: Drug resistance is one of the greatest challenges of malaria control programme in Mali. Recent advances in next-generation sequencing (NGS) technologies provide new and effective ways of tracking drug-resistant malaria parasites in Africa. The diversity and the prevalence of Plasmodium falciparum drug-resistance molecular markers were assessed in Dangassa and Nioro-du-Sahel in Mali, two sites with distinct malaria transmission patterns. Dangassa has an intense seasonal malaria transmission, whereas Nioro-du-Sahel has an unstable and short seasonal malaria transmission. METHODS: Up to 270 dried blood spot samples (214 in Dangassa and 56 in Nioro-du-Sahel) were collected from P. falciparum positive patients in 2016. Samples were analysed on the Agena MassARRAY® iPLEX platform. Specific codons were targeted in Pfcrt, Pfmdr1, Pfdhfr, and Pfdhps, Pfarps10, Pfferredoxin, Pfexonuclease and Pfmdr2 genes. The Sanger's 101-SNPs-barcode method was used to assess the genetic diversity of P. falciparum and to determine the parasite species. RESULTS: The Pfcrt_76T chloroquine-resistance genotype was found at a rate of 64.4% in Dangassa and 45.2% in Nioro-du-Sahel (p = 0.025). The Pfdhfr_51I-59R-108N pyrimethamine-resistance genotype was 14.1% and 19.6%, respectively in Dangassa and Nioro-du-Sahel. Mutations in the Pfdhps_S436-A437-K540-A581-613A sulfadoxine-resistance gene was significantly more prevalent in Dangassa as compared to Nioro-du-Sahel (p = 0.035). Up to 17.8% of the isolates from Dangassa vs 7% from Nioro-du-Sahel harboured at least two codon substitutions in this haplotype. The amodiaquine-resistance Pfmdr1_N86Y mutation was identified in only three samples (two in Dangassa and one in Nioro-du-Sahel). The lumefantrine-reduced susceptibility Pfmdr1_Y184F mutation was found in 39.9% and 48.2% of samples in Dangassa and Nioro-du-Sahel, respectively. One piperaquine-resistance Exo_E415G mutation was found in Dangassa, while no artemisinin resistance genetic-background were identified. A high P. falciparum diversity was observed, but no clear genetic aggregation was found at either study sites. Higher multiplicity of infection was observed in Dangassa with both COIL (p = 0.04) and Real McCOIL (p = 0.02) methods relative to Nioro-du-Sahel. CONCLUSIONS: This study reveals high prevalence of chloroquine and pyrimethamine-resistance markers as well as high codon substitution rate in the sulfadoxine-resistance gene. High genetic diversity of P. falciparum was observed. These observations suggest that the use of artemisinins is relevant in both Dangassa and Nioro-du-Sahel

Successful field trial of attractive toxic sugar bait (ATSB) plant-spraying methods against malaria vectors in the Anopheles gambiae complex in Mali, West Africa

<p>Abstract</p> <p>Background</p> <p>Based on highly successful demonstrations in Israel that attractive toxic sugar bait (ATSB) methods can decimate local populations of mosquitoes, this study determined the effectiveness of ATSB methods for malaria vector control in the semi-arid Bandiagara District of Mali, West Africa.</p> <p>Methods</p> <p>Control and treatment sites, selected along a road that connects villages, contained man-made ponds that were the primary larval habitats of <it>Anopheles gambiae </it>and <it>Anopheles arabiensis</it>. Guava and honey melons, two local fruits shown to be attractive to <it>An. gambiae </it>s.l., were used to prepare solutions of Attractive Sugar Bait (ASB) and ATSB that additionally contained boric acid as an oral insecticide. Both included a color dye marker to facilitate determination of mosquitoes feeding on the solutions. The trial was conducted over a 38-day period, using CDC light traps to monitor mosquito populations. On day 8, ASB solution in the control site and ATSB solution in the treatment site were sprayed using a hand-pump on patches of vegetation. Samples of female mosquitoes were age-graded to determine the impact of ATSB treatment on vector longevity.</p> <p>Results</p> <p>Immediately after spraying ATSB in the treatment site, the relative abundance of female and male <it>An. gambiae </it>s.l. declined about 90% from pre-treatment levels and remained low. In the treatment site, most females remaining after ATSB treatment had not completed a single gonotrophic cycle, and only 6% had completed three or more gonotrophic cycles compared with 37% pre-treatment. In the control site sprayed with ASB (without toxin), the proportion of females completing three or more gonotrophic cycles increased from 28.5% pre-treatment to 47.5% post-treatment. In the control site, detection of dye marker in over half of the females and males provided direct evidence that the mosquitoes were feeding on the sprayed solutions.</p> <p>Conclusion</p> <p>This study in Mali shows that even a single application of ATSB can substantially decrease malaria vector population densities and longevity. It is likely that ATSB methods can be used as a new powerful tool for the control of malaria vectors, particularly since this approach is highly effective for mosquito control, technologically simple, inexpensive, and environmentally safe.</p

Pronostic maternel et périnatal de l'éclampsie à l'hôpital de Tombouctou au Mali

L´éclampsie représente l´une des principales causes de décès maternels dans le monde. Notre objectif était de déterminer le pronostic maternel et périnatal de l´éclampsie à l´hôpital de Tombouctou, Mali. L´étude a été descriptive, rétrospective du 1er&nbsp;janvier 2013 au 31 décembre 2017, incluant les cas d´éclampsies survenues au cours de la grossesse ou l´accouchement à l´hôpital de Tombouctou. Nous avons retrouvé 116 cas sur 4951 accouchements soit un taux d´incidence de 2,3%. Il s´agissait essentiellement de femmes de moins de 26 ans (85,3%), primipare (81%), admise en moyenne 8 heures après la première crise. La césarienne était pratiquée dans 77,6% des cas. Le Sulfate de magnésium a été utilisé dans 75% des cas. Les létalités maternelle et périnatale étaient respectivement à 4,3% et 21,5%. Le facteur de mauvais pronostic maternel était un score Glasgow ≤ 8 à l´admission (p: 0,004). Les facteurs de mauvais pronostic périnatal étaient la résidence hors de la ville de Tombouctou (p: 0,000), l´absence de consultation prénatale (p: 0,020) et l´accouchement par voie basse (p: 0,012). Ainsi, l´amélioration du pronostic maternel et périnatal nécessite un suivi correct des grossesses, la réduction des retards dans l´accès à des soins adéquats

Resurgence of Malaria Transmission and Incidence after Withdrawal of Indoor Residual Spraying in the District of Koulikoro, Mali

In Mali, malaria vector control relies mostly on long-lasting insecticidal nets and indoor residual spraying (IRS). From 2008 to 2016, an IRS program was implemented in the district of Koulikoro. After a significant reduction in malaria indicators, IRS was stopped in 2016. This study evaluated the effect of IRS withdrawal on entomological parameters of malaria transmission and incidence in children aged 6 months to 10 years in the district of Koulikoro. Entomological parameters of malaria transmission during the last year of IRS implementation in 2016 were compared with those obtained 2 years after IRS withdrawal in 2018 in two villages of Koulikoro. Mosquito vectors were collected by mouth aspiration and pyrethrum spray catches in the villages to monitor these transmission parameters. A sharp increase (10.8 times higher) in vector abundance after IRS withdrawal was observed. The infection rate of Anopheles gambiae sensu lato to Plasmodium falciparum increased from zero during IRS implementation to 14.8% after IRS withdrawal. The average entomological inoculation rate, which was undetectable before, was 1.22 infected bites per person per month 2 years after IRS was withdrawn, and the cumulative malaria incidence rate observed after IRS was 4.12 times (15.2% versus 3.7%) higher than that observed in 2016 in the villages before IRS withdrawal. This study showed a resurgence of malaria transmission and incidence in the Koulikoro health district after IRS was withdrawn. Thus, to manage the potential consequences of malaria transmission resurgence, alternative approaches are needed when stopping successful malaria control interventions