1,721,042 research outputs found
Entomological impact of complementary malaria control strategies in the context of insecticide resistance in vectors in Northern Côte d’Ivoire
No full textL’expansion de la résistance des vecteurs aux pyréthrinoïdes et le ralentissement des progrès obtenus récemment dans la lutte contre le paludisme en Afrique mettent en exergue le besoin urgent de déployer des stratégies complémentaires aux moustiquaires imprégnées d’insecticide à longue durée d’action (MILDA) pour accélérer la réduction du poids de la maladie. Les stratégies telles que le renforcement de l’Information, l’Education et la Communication (IEC), les pulvérisations intradomiciliaires (PID) et la lutte anti-larvaire (LAL) à base du Bacillus thuringiensis isralensis (Bti) sont disponibles mais le réel bénéfice de leur utilisation en combinaison aux MILDA reste à démontrer. L’objectif principal du présent travail a été de mesurer l’impact additionnel de ces trois stratégies sur la transmission des Plasmodium spp. à travers un essai contrôlé randomisé mené dans 28 villages du district sanitaire de Korhogo, au Nord de la Côte d’Ivoire, une zone de résistance des vecteurs aux pyréthrinoïdes. En amont du déploiement de ces interventions, mon travail de thèse a d’abord permis 1) l’étude de l’efficacité d’une nouvelle formulation de larvicide en conditions semi-contrôlées ; 2) l’étude de la bionomique des anophèles vecteurs, des mécanismes de résistance aux insecticides et de la transmission des Plasmodium spp et 3) l’identification et la caractérisation des gîtes larvaires d’anophèles dans la zone d’étude. Le suivi post-intervention a permis de montrer 1) une réduction de la densité agressive des vecteurs (69%) cinq mois après le démarrage de la stratégie IEC, de l’indice sporozoïtique (84%) et du TIE (86%) dans le bras MILDA + IEC par rapport au bras MILDA seules ; 2) une réduction de la densité agressive des vecteurs deux mois (72%) et quatre mois (69%) après la mise en place de la PID puis du TIE (62%) dans le bras MILDA + PID par rapport au bras MILDA seules ; 3) une réduction de la densité agressive des vecteurs (95%) trois mois après le démarrage de la LAL et du TIE (88%) dans le bras MILDA + LAL par rapport au bras MILDA seules. Ces résultats montrent que les stratégies IEC, PID et LAL sont des stratégies complémentaires efficaces pour réduire l’intensité de la transmission à Korhogo. L’analyse des données épidémiologiques de l’essai permettra de mieux apprécier le bénéfice additionnel de ces stratégies sur le poids du paludisme.The spread of pyrethroid resistance in malaria vectors and the stalling of recent progress in malaria control in Africa highlight the urgent need to deploy complementary strategies to long-lasting insecticidal nets (LLINs) to accelerate the reduction in the disease burden. Strategies such as strengthened Information, Education and Communication (IEC), Indoor Residual Spraying (IRS) and larviciding with Bacillus thuringiensis isralensis (Bti) are available but the actual benefit of their use in combination with LLINs remains to be demonstrated. The main objective of this work was to measure the additional impact of these three strategies on malaria transmission through a randomized controlled trial run in 28 villages in the health district of Korhogo, northern Côte d’Ivoire, an area of vector resistance to pyrethroids. Prior to the deployment of these strategies, my work allowed us to 1) assess the efficacy of a new larvicide formulation under semi-field conditions; 2) study vector bionomics, insecticide resistance mechanisms and malaria transmission; 3) identify and characterize Anopheles spp. breeding habitats in the study area. Data from post-intervention surveys showed 1) a reduction of vector density (69%) five months after the beginning of the IEC strategy, of sporozoïte rate (84%) and of IER (86%) in the LLIN+IEC arm relative to the LLIN alone arm; 2) a reduction of vector density at months two (72%) and four post-IRS (69%) and of EIR (62%) in the LLIN+IRS arm relative to the LLIN alone arm; 3) a reduction of vector density (95%) three months after the beginning of larviciding intervention and of IER (88%) in the LLIN + larviciding arm relative to the LLIN alone arm. These results provide evidence that IEC, IRS and larviciding are effective complementary strategies to reduce transmission intensity in Korhogo. Analysis of epidemiological data collected during the trial will allow a better understanding of the additional benefit of these strategies on the malaria burden
Effects of pesticide residues in soil substrates on the biology cycle of Aedes aegypti from three different setting zones in Benin
No full text<p>In order to evaluate the effects of insecticides residues in soil substrates on the biology cycle of <i>Aedes aegypti</i>, we conducted a study in three ecological zones: urban areas (Dandji, southern Benin with few agriculture activities), peri urban areas (Awaya, central of Benin with agriculture practices), and forests (Kaoura, northern Benin with few agriculture activities). These areas were chosen because they provided an ideal environment for the development of <i>Aedes aegypti</i>. The purpose of this study is to look for insecticide residues that may have detrimental impacts on the biology cycle of <i>A. aegypti</i>. Indirect bioassays were used to investigate the factors affecting mosquito larvae's ability to develop normally at breeding sites, their rate of growth, and their ability to produce an adequate number of larvae. Due to the absence of an HPLC equipment for the direct detection of pesticide residues in samples, <i>A. aegypti</i> larvae at breeding sites were reconstituted using water and soil samples obtained at each study site. A comparison of the larval growth in test breeding locations was made using the reference strain SBE as a control. The different bioassays demonstrate the existence of inhibitory elements on test materials. In control samples, larval development was observed to be normal. However, when the breeding sites were established with just a few grams of soil samples from the three study sites, it was found that the <i>A. aegypti</i> eggs had a poor hatching rate, along with sluggish larval development and a low production of adult mosquitoes from hatched eggs. The findings of this study indicate that toxic substances that prevent <i>A. aegypti</i> eggs from hatching and larvae from growing are most likely leftover pesticides from agricultural operations. In order to quantify the toxic factors likely to affect the biology parameters of <i>A. aegypti</i> cited above, these results must be validated using HPLC techniques.</p><p>published by the <a href="https://innspub.net/journal-of-biodiversity-and-environmental-sciences/"><strong>Journal of Biodiversity and Environmental Sciences (JBES)</strong></a></p><p><br> </p>
Importance of coagulase-negative staphylococci in severe primitive infections : research of novel virulence factors
No full textLes staphylocoques à coagulase négative (SCN) sont généralement considérés comme des pathogènes opportunistes à faible virulence. Cependant, des études antérieures ont rapporté une pathogénicité de certaines souches similaire à celle observée chez S. aureus ce qui laisse supposer l’expression de facteurs de virulence. Cette thèse vise à contribuer à l’importance des SCN dans les infections primitives sévères. Nous avons évalué le potentiel pathogène de souches cliniques de SCN au Bénin. Pour atteindre cet objectif, des SCN associés à diverses infections cliniques sévères ont été collectés sur une période de 10 mois au Centre National Hospitalier et Universitaire Hubert Koutoukou Maga à Cotonou. Ces souches sont identifiées d’abord par la galerie API® Staph, puis par la spectrométrie de masse MALDI-TOF et analysées pour leur susceptibilité aux antibiotiques et leur capacité à produire des facteurs de virulence. Cette partie de l’étude a montré que les espèces les plus impliquées dans les infections à SCN au Bénin sont : S. haemolyticus et S. epidermidis suivi d’autres espèces comme S. cohnii, S. sciuri, S. arlettae, S. capitis. Nous avons aussi apporté la preuve de la multi-résistance des souches aux antibiotiques, ainsi que de la présence d’au moins un, voire plusieurs facteurs de virulence tels que la protéase, l’estérase, l’hémolysine, la leucotoxine et l’entérotoxine staphylococcique C chez 44% des souches testées particulièrement dans les souches hospitalières isolées d’hémocultures. Ensuite, nous avons caractérisé un nouveau facteur de virulence identifié chez deux souches de S. epidermidis : l’entérotoxine staphylococcique C nommée SECepi qui a été dosée à environ 100 µg/mL dans les surnageants de culture bactérienne. Le gène secepi est constitué de 801 pb correspondant à 266 acides aminés. Sur la base des résultats de la comparaison d'homologie entre la chaîne peptidique de SECepi et les séquences déjà connues, nous avons constaté que SECepi est proche de SEC3 de la souche de S. aureus Mu3, avec trois substitutions d'acides aminés dans le peptide signal et neuf substitutions d'acides aminés dans la protéine mature. Cependant, plusieurs résidus qui sont impliqués dans la formation du complexe trimoléculaire CMH-SEC-TCR sont conservés dans SECepi. L’analyse de la protéine recombinante (rSECepi) révèle une parenté antigénique et une forte homologie structurale prédite avec SECaureus. De plus, cette toxine présente les activités biologiques caractéristiques d'un superantigène (SAg) incluant la stimulation de la mitogénicité et de la production concomitante de fortes doses de cytokines pro-inflammatoires et suppressives chez des lymphocytes T humains activés. Par ailleurs, SECepi résiste assez bien au chauffage à 100°C et à la digestion par les enzymes gastro-intestinales telles que la pepsine et la trypsine. Ces résultats fournissent la preuve que SECepi peut agir comme un superantigène chez l'hôte humain bien que le type sauvage comporte plusieurs mutations chez S. epidermidis. L’étude du dossier médical de l’un des patients a montré que l’entérotoxine produite par la souche de S. epidermidis a bien pu être à l’origine d’éléments de gravité du tableau clinique présenté par ce dernier à son admission en hospitalisation. Enfin, l’analyse génomique des deux souches toxinogènes de S. epidermidis, ainsi que leur aptitude à former du biofilm, confirment les possibilités variées d’échanges génétiques entre cette espèce et S. aureus. Cette thèse souligne l'importance de la surveillance des infections à SCN chez l’homme parce que certaines souches, à l’instar de S. aureus, produisent des facteurs de virulence pouvant aggraver l’état générale l’hôte.Coagulase-negative staphylococci (CNS) are generally considered as opportunistic pathogens with low virulence. However, previous studies have reported pathogenicity of some strains similar to that observed in S. aureus. This thesis aims to contribute to the importance of SCN in severe primitive infections. First, we evaluated the pathogenic potential of clinical CNS strains in Benin. To achieve this objective, CNS associated with various severe clinical infections were collected over at the Hubert Koutoukou Maga National Hospital and University Center in Cotonou. These strains are identified as well as their susceptibility to antibiotics and their ability to produce virulence factors. This part of the study showed that the most involved species in Benin are: S. haemolyticus and S. epidermidis followed by other species such as S. cohnii, S. sciuri, S. arlettae, S. capitis. We also demonstrated the multi-resistance of strains to antibiotics, as well as the presence of potential virulence factors such as protease, esterase, hemolysin, leukotoxin and, enterotoxin Staphylococcal C in 44% of strains tested particularly in hospital strains isolated from blood cultures. We, then, characterized a new virulence factor identified in two strains of S. epidermidis: staphylococcal enterotoxin C called SECepi, which was secreted at ~100 μg/mL in bacterial culture supernatants. The secepi gene consists of 801 bp corresponding to 266 amino acids. On the basis of the comparison between the peptide chain of SECepi and the already known peptide sequences of the SEC, we found that SECepi is close to SEC3 of S. aureus Mu3 strain with three amino acids substitutions in the signal peptide and nine amino acid substitutions in the mature protein. However, most residues involved in formation of the tri-molecular complex CMH-SEC-TCR are conserved in SECepi. Analysis of the recombinant protein (rSECepi) revealed antigenic relationships and a strong structural homology is predicted with SECaureus. Moreover, this toxin exhibits the biological activities characteristic of a SAg including the stimulation of the mitogenicity and the concomitant production of high doses of pro-inflammatory and suppressive cytokines in activated human T lymphocytes. Moreover, SECepi is resistant to heating at 100 °C and digestion by gastrointestinal enzymes such as pepsin and trypsin. These results provide evidence that SECepi can act as a superantigen in humans although the wild type has several mutations in S. epidermidis. The study of the medical record of one of the patients showed that the enterotoxin produced by the strain of S. epidermidis might be at the origin of severity of the clinics presented at hospital admission. Finally, genomic analysis of the two toxigenic S. epidermidis strains confirms the varied possibilities of genetic exchange between this species and S. aureus. This thesis underscores the importance of monitoring CNS infections in humans because some strains, like S. aureus, produce virulence factors that can aggravate the overall host condition
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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