Diversité Et Dynamique Des Communautés De Vers De Terre De Trois Formations Végétales Dans Une Savane Humide De l’Afrique De l’Ouest (Lamto, Côte d’Ivoire)

The maintenance and stability of many terrestrial ecosystems are in part related to the ecosystem functions and services of soil organisms. The present study aims to evaluate the influence of litter biomass produced by three types of vegetation in the Lamto reserve on the dynamics of earthworm community. Each vegetation formations has been subdivided into 3 parcels. These parcels were geo-referenced using a GPS and mapped using QGIS software. For each plot, 25 points were randomly selected using their GPS coordinates. The litters were collected by manual collection to evaluate their biomass. Monoliths of the TSBF (Tropical Soil Biology) type were dug in order to collect the earthworms by direct manual sorting. Also, soil clumps were collected to determine the organic matter levels by the method of lossto-fire. In total, 12 species of earthworms belonging to 3 ecological categories were collected. The forest block had the highest density of earthworms with a predominance of epigeic earthworms followed by grassy savannah with a predominance of endogeic earthworms. The wooded savannah has the lowest density of earthworms with a predominance of anecic earthworms. In terms of species richness, the grassy savannah contained the greatest number of earthworm species followed by the wooded savannah and the forest block that had the same number of species. In the three vegetations formations, it was found that earthworm densities were correlated with litter biomass as well as organic matter levels (correlation between earthworm density and litter biomass: r 2 =0, 75; correlation between density of earthworms and the rate of organic matter: r 2 =0, 93)

Évaluation de la toxicité d'un herbicide à base de 2,4-D sur le ver de terre Eudrilus eugeniae Kinberg, 1867 (Oligochaeta, Eudrilidae)

2,4-D is commonly used in the world to control undesirable plant species in monocotyledonous fields. The massive use of this herbicide requires knowledge of its ecotoxicological spectrum for better regulation of its use. This study aimed to characterize acute toxicity and to determine the long-term effects of a 2,4-D herbicide on Eudrilus eugeniae. The tests were carried out in Azaguié (Côte d’Ivoire), on natural soil enriched with rabbit droppings. The lethal concentration (LC50) was 175.6±12.3 mg/kg. The exposure of earthworms to 20 mg/l of 2,4-D (9.2 mg/kg) reduced significantly cocoon production, hatching rate and juvenile’s number per cocoon. With regard to these results, we concluded that 2,4-D based herbicides are potential threat to earthworms because CL 50 was largely below concentrations of 1920 mg/l and 2880 mg/l of 2,4-D recommended by the manufacturer. Keywords: 2,4-D, Eudrilus eugeniae, formulation, acute toxicity, long-term effect.Le 2,4-D est un herbicide couramment utilisé dans le monde pour lutter contre les espèces de plantes indésirables du groupe des dicotylédones. L’emploi massif de cet herbicide nécessite la connaissance de son spectre écotoxicologique pour mieux réglementer son utilisation. Cette étude avait pour objet de caractériser la toxicité aiguë et de déterminer les effets à long terme d’un herbicide à base de 2,4-D sur Eudrilus eugeniae. Les essais ont été réalisés à Azaguié (Côte d’Ivoire), sur du sol naturel enrichi aux crottes de lapin. La concentration létale (CL50) du 2,4-D a été 175,6 ± 12,3 mg/kg. L’exposition des vers à 20 mg/l de 2,4-D soit 9,2 mg/kg, a réduit significativement la production de cocon, le taux d’éclosion et le nombre de juvéniles/cocon. Vue l’innocuité de cette formulation envers E. eugeniae, elle constitue une menace potentielle pour les vers de terre. La situation est inquiétante car la CL50 de l’herbicide a été inférieure à la dose recommandée par son fabricant (1920 mg/l et 2880 mg/l). Mots clés: 2,4-D, Eudrilus eugeniae, formulation, toxicité aiguë, effet à long terme. &nbsp

Field experiments of Anopheles gambiae attraction to local fruits/seedpods and flowering plants in Mali to optimize strategies for malaria vector control in Africa using attractive toxic sugar bait methods

<p>Abstract</p> <p>Background</p> <p>Based on recent studies in Israel demonstrating that attractive toxic sugar bait (ATSB) methods can be used to decimate local anopheline and culicine mosquito populations, an important consideration is whether the same methods can be adapted and improved to attract and kill malaria vectors in Africa. The ATSB approach uses fruit or flower scent as an attractant, sugar solution as a feeding stimulant, and an oral toxin. The ATSB solutions are either sprayed on vegetation or suspended in simple bait stations, and the mosquitoes ingesting the toxic solutions are killed. As such, this approach targets sugar-feeding female and male mosquitoes. This study examines the attractiveness of African malaria vectors to local fruits/seedpods and flowering plants, key biological elements of the ATSB approach for mosquito control.</p> <p>Methods</p> <p>Three field experiments were conducted at sites in Mali. The attraction of <it>Anopheles gambiae </it>s.l. to 26 different local fruits and seedpods was determined at a site in the semi-arid Bandiagara District of Mali. Wire mesh glue traps with fruits/seedpods suspended on skewers inside were set along a seasonal lagoon. Seven replicates of each fruit/seedpod species were tested, with a water-soaked sponge and a sugar-soaked sponge as controls. The attraction of <it>An. gambiae </it>s.l. to 26 different types of flowering plants was determined at a site near Mopti in Mali. The flowering plants held in a water-filled buried container were tested using the same glue traps, with controls including water only and sugar solution. Six replicates of each selected plant type were tested on transects between rice paddies. Additional studies using CDC light traps were done to determine the relative densities and periodicity of <it>An. gambiae </it>s.l. attraction to branches of the most highly attractive flowering plant, branches without flowers, human odor, and candescent light.</p> <p>Results</p> <p>Of the 26 fruits and seedpods tested, 6 were attractive to <it>An. gambiae </it>s.l. females and males, respectively. Guava (<it>Psidium guajava</it>) and honey melon (<it>Cucumis melo</it>) were the two most attractive fruits for both females and males. Of the 26 flowering plants tested, 9 were significantly attractive for females, and 8 were attractive for males. <it>Acacia macrostachya </it>was the most attractive flowering plant. Periodicity studies using this plant showed peaks of <it>An. gambiae </it>s.l. attraction between 1930 and 2200 h and 0400-0500 h, which differed considerably from the response to human odors, which expectedly peaked at around midnight.</p> <p>Conclusion</p> <p>These field experiments in Mali highlight that female and male <it>An. gambiae </it>s.l. have pronounced differences in attraction for diverse types of indigenous fruits/seedpods and flowering plants. The identification of attractive fruits and seedpods shows that a variety of indigenous and locally abundant natural products could potentially be used as juices to make ATSB solution for mosquito control. As well, the simple methods used to identify the most attractive flowering plants provide valuable insights into the natural history of sugar feeding for <it>An. gambiae </it>s.l. These observations can be used to guide future strategies for employing ATSB methods for malaria vector control in Africa. They also provide a basis for subsequent chemical analysis and development of attractive baits for mosquito control.</p

Apport des moyens endoscopiques dans la dilatation des sténoses caustiques de l’oesophage

Introduction: The aim of this work was to present the contribution of the endoscopy in the management of esophageal dilatation for caustic esophageal stenosis (CES). Methods: This was a descriptive and prospective study in the thoracic surgery department at the Hospital of Mali. A total of 46 cases of CES is recorded and divided into 4 groups according to the topography of the esophageal lesions. For the different methods of dilatation the number of performed endoscopic support was determined to understand the contribution of endoscopic means in the success of dilatation for CES. The outcome, complications and mortality in the two methods were compared. Results: Fibroscopy was used in 41.30% of patients with Savary Guillard dilators and in 47.82% of patients with Lerut dilators. Video laryngoscopy was used in 58.69% of patients who underwent dilatation with Lerut dilators. The passage of the guide wire was performed in 39.13% under video laryngoscopy and 58.68% under fibroscopy. In comparison of the two methods, there is a significant difference in the occurrence of complications (p = 0.04075), general anesthesia (p = 0.02287), accessibility (p = 0.04805) and mortality (p = 0.00402). Conclusion: The CES is a serious disease and under evaluated in Mali. The endoscopies contribute significantly to the success of esophageal dilatation for caustic stenosis in the different methods we used.Keywords: Esophagus, caustic stenosis, dilatation, endoscopicPan African Medical Journal 2016; 2

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

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

Health facility-based prevalence and potential risk factors of autism spectrum disorders in Mali

Background: The prevalence of autism spectrum disorders (ASD) is 1-2% worldwide, 1 in 68 in the U.S, and unknown in Africa. ASD is under-diagnosed in Mali due to stigma and the lack of appropriate human resources and infrastructure.Objective: To determine the ASD frequency and potential risk factors in Mali.Methods: We identified all the health facilities and community-based organizations involved in the ASD diagnosis and management in Bamako. We established an ASD research and awareness platform in Mali, which encompasses community-based organizations and a multidisciplinary team including psychiatrists, psychologists, pediatricians, geneticists, and public health and social science specialists. Through this platform, we performed a survey in health facilities and organizations where patients with ASD are likely to seek care in Bamako. We reviewed the psychiatric patient registry to obtain basic epidemiological profiles of children with ASD, epilepsy and other psychiatric disorders.Results: We found a health facility-based prevalence of ASD of 4.5% (105/2,343) in Bamako. The mean age at the first outpatient visit was 7.64 ± 3.85 years old. First degree consanguinity of 29.5% (31/105) was more frequent in parents of ASD children versus age and sex matched controls OR= 4.37 [1.96-9.76] p=0.0001.Conclusion: Our data suggest that ASD is more common than expected in Mali. The established ASD awareness and research platform may improve the diagnosis and management of ASD by raising ASD awareness, training of Malian clinicians and researchers in early ASD screening and diagnosis, and strengthening research capacity in genomics of ASD and other mental disorders.Keywords: ASD, prevalence, consanguinity, health facilit

Estimation of changes in the force of infection for intestinal and urogenital schistosomiasis in countries with Schistosomiasis Control Initiative-assisted programmes

The last decade has seen an expansion of national schistosomiasis control programmes in Africa based on large-scale preventative chemotherapy. In many areas this has resulted in considerable reductions in infection and morbidity levels in treated individuals. In this paper, we quantify changes in the force of infection (FOI), defined here as the per (human) host parasite establishment rate, to ascertain the impact on transmission of some of these programmes under the umbrella of the Schistosomiasis Control Initiative (SCI)

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