70 research outputs found
Epidemiology and diagnosis of schistosomiasis in preschool-aged children in Azaguié, south Côte d'Ivoire
Get PDFBackground: Classified among the neglected tropical diseases (NTDs), schistosomiasis remains one of the most important parasitic diseases in the tropics and subtropics, and constitutes a major public health problem. Following World Health Assembly (WHA) resolution 54.19, put forth in May 2001, several control programmes have emerged in schistosomiasis-endemic countries with the objective to reduce morbidity due to schistosomiasis and soil-transmitted helminthiasis by regularly treating at least 75% and up to 100% of all school-aged children who are at risk by 2010. By focusing treatment upon the school-aged population, WHA resolution 54.19 neglects preschool-aged children, thus preventing them from benefiting from preventive chemotherapy targeted to their older peers, and hence creating a potential health inequity. Root causes include the belief that very young children would not yet be exposed to infected freshwater bodies, thus an insufficient understanding and documentation of the extent and severity of schistosomiasis in this age class, and a paucity of pharmacokinetic safety data of praziquantel among young children. However, in endemic zones, women are frequently accompanied by their children, even at young age, when they go to ponds, rivers or irrigation canals, all of which may be contaminated with cercariae, the infective stage to humans. Recent studies carried out in East and West Africa showed that intestinal and urogenital schistosomiasis can indeed occur in very early childhood. Pathology due to chronic infection with Schistosoma mansoni includes hepatic perisinusoidal egg granulomas, Symmers’ pipe-stem periportal fibrosis, portal hypertension and, occasionally, embolic egg granulomas in the brain or spinal cord. Schistosoma haematobium infection may cause haematuria, scarring, calcification, squamous cell carcinoma and, occasionally, embolic egg granulomas in the brain or spinal cord.
Goal and specific objectives: The overarching goal of this Ph.D. thesis is to deepen our understanding of the epidemiology of schistosomiasis in preschool-aged children. The thesis pursued five specific objectives in Azaguié district, south Côte d’Ivoire. First, to characterize intestinal parasitic infections at the Azaguié district level. Second, to assess the accuracy of a commercially available urine circulating cathodic antigen (CCA) cassette test (CCA-A) and an experimental formulation (CCA-B) for the diagnosis of S. mansoni among school-aged children in different endemicity settings. Third, to assess the accuracy of CCA-A for the diagnosis of S. mansoni in preschool-aged children before and after praziquantel administration. Fourth, to study the epidemiology and risk factors for schistosomiasis in preschool-aged children. Fifth, to assess the efficacy and safety of crushed praziquantel tablets in preschool-aged children in a co-endemic setting of S. mansoni and S. haematobium.
Methods: The fieldwork for this Ph.D. thesis was split into two parts. In order to address the first two objectives, in mid-2010, a cross-sectional study was carried out in seven schools from four locations of Azaguié district, including more than 600 schoolchildren. Multiple stool and urine samples were collected from each schoolchild over three consecutive days. Stool samples were examined with the Kato-Katz technique for the diagnosis of S. mansoni and soil-transmitted helminths (Trichuris trichiura, Ascaris lumbricoides and hookworm). Stool samples from the first day of collection were preserved in sodium acetate-acetic acid-formalin (SAF) and examined one month later using an ether-concentration method for the diagnosis of intestinal protozoa. Urine samples were examined with CCA tests (CCA-A on three days and CCA-B once) for the diagnosis of S. mansoni. In addition, urine samples were analysed with the urine filtration technique and reagent strips for the diagnosis of S. haematobium.
In order to address objectives 3-5, a cross-sectional study was implemented as a baseline survey in 2011 in two villages of Azaguié district, namely Azaguié Makouguié and Azaguié M’Bromé, where S. mansoni and S. haematobium coexist. About 300 preschool-aged children (<6 years) were involved in this study. Multiple stool and urine samples were collected over two consecutive days and subjected to the same laboratory procedures as the samples of the schoolchildren in 2010. Anthropometric measures (weight, height and arm circumference) and clinical features (temperature, haemoglobin level) from each preschool-aged child were recorded. Focus group discussions were performed with the mothers of the preschool-aged children and questionnaires administered for a risk factor assessment. Subsequently, preschool-aged children were treated with crushed praziquantel tablets and three weeks posttreatment, drug efficacy was determined following the same field and laboratory procedures as during the baseline study. Adverse events (within 3 and 24 hours posttreatment were recorded by interviewing the mothers of the preschoolers.
Results: The results of this PhD thesis can be structured as follows:
Intestinal parasitic infections in Azaguié: We showed that the selection of intervention settings by control programmes based on a single stool sample examined with duplicate Kato-Katz thick smears or a single urine sample subjected to a standard urine filtration method considerably underestimate the prevalence of Schistosoma infection. This led to a misclassification of intervention settings as defined by the World Health Organization (WHO) guidelines. Hence, in such a context, more sensitive diagnostic tools are needed to select the intervention settings with high accuracy. In addition, we found a small-scale heterogeneity in the distribution of helminth and intestinal protozoa infections. We also confirmed that polyparasitism is common in the Azaguié district.
Accuracy of urine CCA tests in different endemicity settings in schoolchildren: The prevalence of S. mansoni in the three different endemicity settings was 32.9%, 53.1% and 91.8%, respectively. In all three settings, the sensitivity of a single CCA-A test was similar to triplicate Kato-Katz thick smears and was 56.3% and 47.9% in setting A (S. mansoni prevalence, 32.9%), 69.6% and 73.9% in setting B (S. mansoni prevalence, 53.1%), and 89.6% and 94.2% in setting C (S. mansoni prevalence, 91.8%). The specificity of the CCA-A test was moderate (76.9–84.2%). The likelihood of a CCA-A test color reaction increased with higher S. mansoni faecal egg counts (odds ratio = 1.07, p <0.001). A concurrent S. haematobium infection or the presence of microhaematuria did not influence the CCA test results for S. mansoni diagnosis.
Accuracy of the urine CCA test in preschool-aged children: Before treatment, the prevalence of S. mansoni, as determined by quadruplicate Kato-Katz thick smears, duplicate CCA(t-) test considering “trace” as negative results, and CCA(t+) test with “trace” as positive, was 23.1%, 45.0% and 76.5%, respectively. Irrespectiv of the ‘gold’ standard, a single CCA test (CCA(t+) or CCA(t-)) was more sensitive than quadruplicate Kato-Katz thick smears before and after treatment. The specificity of a single CCA test ranged between 59.3% and 100% before and after treatment. The intensity of the CCA test band reaction was correlated with S. mansoni egg burden (odds ratio = 1.2, p = 0.04).
Epidemiology and risk factors of schistosomiasis in preschoolers: The prevalence of S. mansoni in preschool-aged children was 25.5% in Azaguié Makouguié and 21.6% in Azaguié M’Bromé and the prevalence of S. haematobium 17.3% and 5.9%, respectively. Most infections were of light intensity. Mothers’ occupation and older siblings played important roles in the epidemiology of schistosomiasis in preschool-aged children.
Efficacy and safety of crushed praziquantel in preschoolers: According to the Kato-Katz and urine filtration results, we found high efficacy of crushed praziquantel against S. mansoni (cure rate (CR) = 88.6%, egg reduction rate (ERR) = 96.7%) and S. haematobium (CR = 88.9%, ERR = 98.0%). Treatment was generally well tolerated, but moderate adverse events (i.e. body and face inflammation), which required close supervision by the study physician, were observed in four non-infected children.
Conclusions: More sensitive diagnostic tools and rigorous sampling approaches are needed to select schistosomiasis-endemicity settings with high accuracy. The observed small-scale heterogeneity of helminth and intestinal protozoa infections should be carefully considered by control programmes. A single urine CCA test is more sensitive than multiple Kato-Katz thick smears in school-aged as well as in preschool-aged children. The urine CCA test can be recommended for rapid identification of high risk communities. However, its application for monitoring the impact of control interventions needs further investigation. In our study settings, preschool-aged children are at risk of schistosomiasis and can be infected very early in childhood. Integrated control approaches including improvement of safe water supply, sanitation, health facilities, and health education are needed in our study communities. Crushed praziquantel is efficacious against S. mansoni and S. haematobium and can be recommended for the treatment of infected children at young age, but only if they are unambiguously diagnosed. Nevertheless, further research is needed to deepen our understanding on the safety of praziquantel in this age group
Petrographie Des Volcanites Et Plutonites De La Partie Sud Du Sillon Volcano-Sedimentaire De Toumodi-Fetekro (Cote D’ivoire)
Get PDFThe southern part of Toumodi-Fètêkro greenstone belt is located in the Center - Southeast of Ivory Coast. Petrographic study of volcanic and plutonic rocks shows three units. The first unit is composed of basaltic to rhyolitic lavas which imply effusive character. Then we have volcanosedimentary unit composed of pyroclastic formations (lapilli tuff, breccia, ash deposit and ignimbrites) and the pillow-lavas. Indeed, the presence of this last shows clearly that an explosive volcanism and a submarine effusive volcanism have occurred during during the setting of Toumodi-Fètêkro belt. Plutonic unit is constituted of gabbroic to granitic rocks. Sericite, chlorite, epidote observed in these rocks are consistent with the impacts of greenschist facies metamorphism. The rocks of the southern part of the Toumodi-Fètêkro greenstone belt are formed in a subduction context rather than in oceanic plateaus context because of the old inheritance, sometimes of Archean age, found somewhere in theBirimiandomain. The lithologies of the southern part of Toumodi-Fètêkro meet elsewhere in the other Birimian greenstone belts. Also, these lithologies are affected by a hydrothermal alteration due to the abundant veins of quartz, carbonates, sericite, chlorite, epidote, sulphides and oxides. However, volcanic show in some places amphibolit facies metamorphism
Survival Analysis of Canadian Oil and Gas Firms
Get PDFIn the context of oil price fluctuations inducing boom and bust cycles, this empirical study is a survival analysis of the Canadian oil and gas exploration and production (E&P) industry. The population includes 540 public Canadian E&P firms that have their headquarters and production activity in Canada, and the data covers the periods of Q1-2002 to Q1-2016 representing over 15,850 firm-quarter observations. The method is an extended Cox model with repeating events, allowing for the use of time-varying predictor variables and the analysis is executed in R, a free statistical software. The study introduces a new definition of financial distress as two consecutive quarters of negative operating cash flow to total assets ratio, develops a baseline model with financial ratios and industry-specific covariates and tests three hypotheses. The first two hypotheses examine the extent to which hedging and company size respectively correlate to the state of financial distress, and the third hypothesis explores how being financially distressed contributes to being a target in a merger and acquisitions (M&A) transaction. The findings show that a hedging firm is 18.5 times less exposed to the hazard of financial distress than a non-hedging firm; and with each unit size increase, a firm is 1.18 times less likely to experience financial distress, but financial distress is not a valid predictor of the hazard of being an M&A target. This study provides a new perspective supporting the use of hedging and size increase for increasing corporate resilience in Canadian oil and gas firms
Petrography and Geochemistry of the Dabakala’ Region Volcanites (Northeastern Côte d’Ivoire)
No full textSpontaneous Calcium Release in Cardiac Myocytes: Store Overload and Electrical Dynamics
No full textHeart disease is the leading cause of mortality in the United States. One cause of heart arrhythmia is calcium (Ca²⁺) mishandling in cardiac muscle cells. We adapt Izu's et al. mathematical reaction-diffusion model of calcium in cardiac muscle cells, or cardiomyocytes, [14], implemented by Gobbert [12], and analyzed in Coulibaly et al. [8] to include calcium being released from the sarcoplasmic reticulum (SR), the effects of buffers in the SR, particularly calsequestrin, and the effects of Ca²⁺ influx due to voltage across the cell membrane. Based on simulations of the model implemented in parallel using MPI, our findings aligned with
known biological models and principles, giving us a thorough understanding of several factors that influence Ca²⁺ dynamics in cardiac myocytes. Speci cally, dynamic calcium store will cap previous calcium blow-up seen in the model. Calcium channels located in spatial opposition of calcium release units produce more predictable intracellular calcium propagation. And we used multi-parametric calcium dynamics tables, which act as a multidimensional bifurcation diagram, to visualize parameter boundaries between different biophysical dynamics.These results were obtained as part of the REU Site: Interdisciplinary Program in High Performance Computing
(hpcreu.umbc.edu) in the Department of Mathematics and Statistics at the University of Maryland, Baltimore County (UMBC) in Summer 2015. This program is funded by the National Science Foundation (NSF), the National Security Agency (NSA), and the Department of Defense (DOD), with additional support from UMBC, the Department of Mathematics and Statistics, the Center for Interdisciplinary Research and Consulting (CIRC), and the UMBC High Performance Computing Facility (HPCF). HPCF is supported by the U.S. National Science Foundation through the MRI program (grant nos. CNS{0821258 and CNS{1228778) and the SCREMS program (grant no. DMS{0821311), with additional substantial support from UMBC. Co-author Michael Mc-Cauley was supported, in part, by the UMBC National Security Agency (NSA) Scholars Program through a contract with the NSA. Graduate assistant Zana Coulibaly was supported during Summer 2015 by UMBC.https://ir.library.illinoisstate.edu/spora/vol1/iss1/6
Signature Geochimique des Granitoides de la Branche Est du Sillon de Boundiali-Korhogo (Nord de la Cote D’ivoire)
Get PDFCet article résume les données relatives à la pétrographie et aux compositions en éléments majeurs et en traces des granitoïdes du sillon de Korhogo. Le sillon de Korhogo est situé au Nord de la Côte d’Ivoire, dans le domaine birimien. Ce sillon qui constitue la branche Est du sillon de Boundiali-Korhogo est à cheval sur les régions du Poro et du Tchologo. La méthodologie employée a permis à l’issue des observations macroscopiques, de recueillir des échantillons pour les études microscopiques et géochimiques. Les études pétrographiques indiquent que les granitoïdes du sillon de Korhogo sont des granodiorites et granites. Ces granitoïdes ont été affectés par une intense altération pervasive et fissurale témoignant ainsi de l’intensité de l’altération hydrothermale dans le sillon de Korhogo. Ces roches ont été affectées par un le métamorphisme de faciès schiste vert. Les données géochimiques montrent que les granitoïdes sont calco-alcalins, potassiques, métalumineux à peralumineux et de Type « I ». Ces roches sont enrichies en LREE [Granodiorite ((La/Sm)N = 3,36 – 4,45 ; (Gd/Yb)N = 1,56 – 2,51 ; et (La/Yb)N = 7,29 – 20,92) ; Granite ((La/Sm)N = 4,51 - 4,69 ; (Gd/Yb)N = 1,00– 3,13 et (La/Yb)N = 7,63 - 26,53] et présentent des anomalies négatives à quasiment nulles en cérium [Granite (Ce/Ce*= 0,60 -0,92) ; Granodiorite (Ce/Ce* = 0,80 -1,01)]. Les anomalies en europium varient des granodiorites [(Eu/Eu* = 0,81 – 1,53)] aux granites [(Eu/Eu*= 0,90 - 1,11)]. Ces granitoïdes ont de faibles taux de TiO2 (<2 %). Les arachnogrammes des éléments en trace normalisés au manteau primitif sont généralement enrichis en LILE (Cs, Ba, Rb, K) associés à une anomalie négative en Nb-Ta. Les tendances géochimiques indiquent que les granitoïdes du sillon de Korhogo proviendraient d’un mélange crustal et mantellique et se seraient mis en place dans un contexte de subduction.
This paper summarizes the data available on petrography and the concentrations of major and trace elements in granitoids from Korhogo greenstone belt province. The Korhogo greenstone belt is localed in the north of Côte d’Ivoire, in the birimian domain. This belt which constitutes the eastern branch of the Boundiali-Korhogo greenstone belt straddles the Poro and Tchologo areas. The methodology started by the macroscopic to microscopic observations then it continued to the geochemical studies. Petrographic studies indicate that the granitoids of Korhogo greenstone belt are granodiorites and granites. These granitoids were affected by intense pervasive and fissural alteration thus testifying the intensity of hydrothermal alteration in the Korhogo greenstone belt. These rocks were affected by regional greenschist facies. Geochemical datas show that the granitoids are calc-alkaline, potassic, metaluminous to peraluminous and “I” Type. These rocks are enriched in LREE [Granodiorite (La/Sm)N = 3,36 – 4,45 ; (Gd/Yb)N = 1,56 – 2,51 ; et (La/Yb)N = 7,29 – 20,92) ; Granite (La/Sm)N = 4,51 - 4,69 ; (Gd/Yb)N = 1,00 – 3,13 et (La/Yb)N = 7,63 - 26,53] and present negative to non-exixting cerium anomalies [Granite (Ce / Ce * = 0.60 -0.92); Granodiorite (Ce/Ce * = 0.80 -1.01)]. The europium anomalies vary from granodiorites [(Eu/Eu * = 0.81 - 1.53)] to granites [(Eu/ Eu * = 0.90 - 1.11)]. These granitoids have low levels of TiO2 (<2%). Primitive mantle normalized, trace element patterns show that granitoids have geochemical patterns characterized by enrichment in LILE (Cs, Ba, Rb, K) associated with negative Nb –Ta anomalies. Geochemical trends indicate that the granitoids of Korhogo greenstone belt originate from a crustal and mantle mixture and were set up in a context of subduction
Conte romanesque, chant-roman: postures de la figure auctoriale chez Maurice Bandaman et Werewere Liking
Get PDFWhat is the connection between the author figure and the genre? Contrary to a widespread idea, the generic mention is not a petrified venue. Indeed, from the mention of song-novel in Elle sera de jaspe et de corail and La mémoire amputée by Werewere Liking to that of novelistic tale in Le fi/s de-la-femme-male or that of the novel in L\u27État Z\u27héros by Maurice Bandaman, this study shows that, by a play of permanent negotiation of the limits of their fictional status, the writer and the storyteller, figures of the author, produce hybrid genres. The practice summons a kind of autogenre which raises the question of all the profusion of energy put by the authors in achieving an autonomous status for their fiction writing
Apport de la Cartographie du Régolithe dans la Connaissance de la Géologie de la Zone Nord de Toumodi (Centre de la Côte d’Ivoire)
Get PDFLa zone nord de Toumodi est située dans la partie sud du sillon de Toumodi-Fètêkro, au centre de la Côte d’Ivoire. Cette zone étant fortement latéritisée, une cartographie à partir du régolithe en vue de l’amélioration des connaissances de la géologie de la partie sud du sillon de Toumodi-Fètêkro a été initiée. Elle s’est faite grâce à la télédétection et aux données de sondage réalisés dans la zone. Ainsi, il ressort de cette étude que le régolithe de la zone d’étude provient de l’altération supergène des différentes formations géologiques observées et se caractérise par un profond profil d'altération d’épaisseur moyenne d’environ 18 m avec une distribution spatiale de régolithe relique, d'érosion, de dépôt ainsi que des surfaces affectées par une latéritisation généralisée.
The northern area of Toumodi is located in the southern part of the Toumodi-Fètêkro Trench in central Côte d'Ivoire. In order to improve knowledge of the regolith and geology of the southern part of the Toumodi-Fètêkro Trench, a regolith mapping study was initiated. This was done using remote sensing and borehole data from the area. Thus, it appears from this study that the regolith in the study area comes from the supergene alteration of the different geological units observed and is characterized by a deep alteration profile with an average thickness of about 18 m with a spatial distribution of relict regolith, erosion, deposition as well as surfaces affected by a generalized lateritization
Etude Métallogénique du Prospect Aurifère de Woulo-Woulo (Zone d'Afema, sud-est de la Côte d'Ivoire)
Get PDFLe prospect de Woulo-Woulo est situé au sud-est de la Côte d’Ivoire précisément dans la zone de Maféré, à environ 8 km à l’ouest du couloir de cisaillement d’Aféma. Le prospect Woulo-Woulo est constitué de métasédiments (métagrauwackes et métaargilites), de métavolcanites (laves andésitiques et brèches) et d’intrusions de métarhyolites porphyriques et de métagabbros. Ces différentes lithologies ont été affectées par une importante activité hydrothermale matérialisée par des veines et veinules de quartz, carbonates (calcite ± dolomie), ± tourmaline, ± sulfures. La minéralisation aurifère du prospect de Woulo-Woulo est encaissée préférentiellement dans la métarhyolite porphyrique déformée et hydrothermalisée. Cependant, cette minéralisation apparait principalement liée aux veines et veinules de quartz et carbonates et présente donc un contrôle structural. C’est une minéralisation de type filonien et hydrothermale donc épigénétique. Cette activité hydrothermale a induit une altération pervasive des encaissants entrainant une carbonatation, une silicification, une chloritisation, une séricitisation et une épidotisation. La paragenèse métallifère est constituée de pyrite (sulfure principal), blende ou sphalérite et or natif.
The Woulo-Woulo prospect is located in the south-east of Côte d'Ivoire, precisely in the Maféré area, approximately 8 km west of the Aféma shear corridor. The Woulo-Woulo prospect consists of metasediments (metagrauwackes and metaargilites), metavolcanites (andesitic lavas and breccias) and intrusions of porphyry metarhyolites and metagabbros. These different lithologies have been affected by significant hydrothermal activity materialized by quartz, carbonates (calcite ± dolomite), ± tourmaline, ± sulphide veins and veinlets. Gold mineralization at the Woulo-Woulo prospect is hosted preferentially in the deformed and hydrothermalized porphyry metarhyolite. However, this mineralization appears to be mainly related to quartz and carbonate veins and veinlets and is therefore structurally controlled. It is a vein-type and hydrothermal mineralization and therefore epigenetic. This hydrothermal activity has induced a pervasive alteration of the host rock leading to carbonation, silicification, chloritization, sericitization and epidotization. The metalliferous paragenesis consists of pyrite (principal sulfide), blende or sphalerite and native gold
Etude Metallogenique du Prospect Aurifere de Woulo-Woulo (Zone d’Afema, Sud-est de la Cote d’Ivore)
Get PDFLe prospect de Woulo-Woulo est situé au sud-est de la Côte d’Ivoire, précisément dans la zone de Maféré, à environ 8 km à l’ouest du couloir de cisaillement d’Aféma. Les activités de terrain et de forage ont montré que certaines formations observées sur le prospect de Woulo-Woulo contiennent de la minéralisation aurifère. L’objectif général de cette étude est de déterminer les caractéristiques pétrographiques et structurales de ces roches et la minéralisation aurifère associée. Ainsi, l’acquisition des données a consisté au prélèvement d’échantillons de roches de terrain et de forage carotté, suivi de leur caractérisation macroscopique et microscopique. Le prospect de Woulo-Woulo est constitué de métasédiments (métagrauwackes et métaargilites), de métavolcanites (laves andésitiques et brèches), de filons acides (métarhyolite à porphyre de quartz) et d’intrusions de métagabbros, tousp affectées par une importante activité hydrothermale, filonienne, qui a induit une altération pervasive des encaissants. La minéralisation aurifère du prospect de Woulo-Woulo est de type filonien et hydrothermal épigénétique liée aux veines et veinules de quartz et carbonates, encaissée préférentiellement dans la métarhyolite porphyrique déformée et hydrothermalisée. Elle présente donc un contrôle structural. La paragenèse de cette minéralisation est constituée de pyrite (sulfure principal), sphalérite et or natif.
The Woulo-Woulo prospect is located in south-eastern Côte d'Ivoire, precisely in the Maféré zone, approximately 8 km west from the Aféma shear zone. Field and drilling activities have shown that certain formations observed at the Woulo-Woulo prospect contain gold mineralization. The overall objective of this study is to determine the petrographic and structural characteristics of these rocks and the associated gold mineralization. Thus, data acquisition consisted of field and core sampling followed by macroscopic and microscopic characterization. The Woulo-Woulo prospect consists of metasediments (metagrauwackes and metaargilites), metavolcanites (andesitic lavas and breccias), felsic veins (quartz porphyry metarhyolite) and metagabbro intrusions, all affected by significant hydrothermal and vein activity, which induced pervasive alteration of host rocks. The gold mineralization at the Woulo-Woulo prospect is vein-type and epigenetic hydrothermal type related to quartz and carbonate veins and veinlets, hosted preferentially in the deformed and hydrothermalized porphyry metarhyolite. It is therefore structurally controlled. The paragenesis of this mineralization consists of pyrite (main sulfide), sphalerite and native gold
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