Vector competence of Aedes vexans (Meigen), Culex poicilipes (Theobald) and Cx. quinquefasciatus Say from Senegal for West and East African lineages of Rift Valley fever virus

Background Rift Valley fever virus (RVFV; Phlebovirus, Bunyaviridae) is a mosquito–borne, zoonotic pathogen. In Senegal, RVFV was first isolated in 1974 from Aedes dalzieli (Theobald) and thereafter from Ae. fowleri (de Charmoy), Ae. ochraceus Theobald, Ae. vexans (Meigen), Culex poicilipes (Theobald), Mansonia africana (Theobald) and Ma. uniformis (Theobald). However, the vector competence of these local species has never been demonstrated making hypothetical the transmission cycle proposed for West Africa based on serological data and mosquito isolates. Methods Aedes vexans and Cx. poicilipes, two common mosquito species most frequently associated with RVFV in Senegal, and Cx. quinquefasciatus, the most common domestic species, were assessed after oral feeding with three RVFV strains of the West and East/central African lineages. Fully engorged mosquitoes (420 Ae. vexans, 563 Cx. quinquefasciatus and 380 Cx. poicilipes) were maintained at 27 ± 1 °C and 70–80 % relative humidity. The saliva, legs/wings and bodies were tested individually for the RVFV genome using real-time RT-PCR at 5, 10, 15 and 20 days post exposure (dpe) to estimate the infection, dissemination, and transmission rates. Genotypic characterisation of the 3 strains used were performed to identify factors underlying the different patterns of transmission. Results The infection rates varied between 30.0–85.0 % for Ae. vexans, 3.3–27 % for Cx. quinquefasciatus and 8.3–46.7 % for Cx. poicilipes, and the dissemination rates varied between 10.5–37 % for Ae. vexans, 9.5–28.6 % for Cx. quinquefasciatus and 3.0–40.9 % for Cx. poicilipes. However only the East African lineage was transmitted, with transmission rates varying between 13.3–33.3 % in Ae. vexans, 50 % in Cx. quinquefasciatus and 11.1 % in Cx. poicilipes. Culex mosquitoes were less susceptible to infection than Ae. vexans. Compared to other strains, amino acid variation in the NSs M segment proteins of the East African RVFV lineage human-derived strain SH172805, might explain the differences in transmission potential. Conclusion Our findings revealed that all the species tested were competent for RVFV with a significant more important role of Ae. vexans compared to Culex species and a highest potential of the East African lineage to be transmitted

Solanum cultivar responses to arbuscular mycorrhizal fungi: growth and mineral status

A greenhouse experiment was carried out in a sandy soil with a low available phosphorus to evaluate responsiveness of four Solanum aethiopicum cultivars to indigenous arbuscular mycorrhizal fungi. Results showed clear interaction between genetic variability of cultivars and fungal isolates on shoot biomass and on mineral status. Arbuscular mycorrhizal fungi can be ranked as Glomus aggregatum > Glomus mosseae > Glomus versiforme for improving yield as well as nitrogen, phosphorus, and potassium acquisition of Solanum cultivars. Key words: Arbuscular mycorrhizal fungi, Solanum aethiopicum, sterile soil, relative mycorrhizal dependency. African Journal of Biotechnology Vol.2(11) 2003: 429-43

Genetic Structure of the Western and Eastern African Sahel/Savannah Belt and the Role of Nomadic Pastoralists as Inferred from the Variation of D-loop mtDNA sequences

The objective of this study is to provide deeper knowledge of the maternal genetic structure and demographic history of the human population of the dynamic Sahel/Savannah belt, the extensive region lying between the Sahara and tropical rainforests, spanning from the Atlantic Ocean to the Red Sea coast. The study aims to confirm or disconfirm archaeological and linguistic data indicating that the region’s populations underwent diversification as a result of the spread of agropastoral food-producing subsistence lifestyles, over time dividing the region into separate areas of nomadic pastoralism on the one hand, and sedentary farming on the other. In order to perform both descriptive and coalescence analyses from the Sahel/Savannah belt’s entire region, including western and eastern rather than just central populations studied previously, we generated a new mtDNA dataset not only having almost 2,000 samples (875 of which were newly collected); but also encompassing whole mtDNA D-loop segment rather than only the previously studied HVS-1. While comparing our analyses with previous results from the Lake Chad Basin (central Sahel/Savannah Belt) we revealed similar intra-population diversity measures (i.e., lower values of measures in pastoralists than farmers). However, the new dataset pointed to significant differences in mating strategies between western as compared to the eastern pastoralists: our results suggest higher gene flow between the Arabic pastoralists and neighboring farmers in the eastern than between the Fulani pastoralists and their sedentary neighbors in the western part of the Sahel/Savannah Belt. The findings are discussed in the light of archaeological and linguistic data, allowing us to postulate that the genetic differentiation of Fulani pastoralists from the common western African agropastoral gene pool occurred at around the same time as the arrival of the Arabic pastoralists to eastern Africa. However, it seems that while the process of divergence of the Fulani pastoralists in the west was accompanied by a loss of Fulani females to other populations, the Arab pastoralists’ immigration to the Sahel/Savannah belt conversely resulted in some gain of local females into this Arab population

Prevalence and awareness of diabetes in Guinea: findings from a WHO STEPS

Aims: The aim of the present study was to determine the prevalence of diabetes, and to assess its awareness and related risk factors among adult Guineans.Methods: A population-based cross-sectional survey was conducted on 1 100  adults (46.6% women) aged 35–64 years from Lower Guinea, during September to December 2009, using the WHO STEPwise approach of surveillance of chronic  disease risk factors. Data were collected in three steps: demographic and  behavioural risk factors, blood pressure and anthropometric measurements, and fasting blood cholesterol and glucose testing. A multi-stage cluster sample design was applied to generate nationwide representative data.Results: The mean age of all participants was 47.3 years (SD 8.8), similarly in  Conakry, rural Lower Guinea and urban Lower Guinea. The prevalence of diabetes was 5.7% (95% CI 4.0–8.1). Among participants with diabetes, only 44.0% were aware of their status. In multivariable logistic regression analysis, determinants of diabetes prevalence were urban residency, male sex, age group 45–64 years, increased waist circumference, hypertension and hypercholesterolemia. Male sex, rural residency, age group 45–54 years, no formal education, waist circumference, hypertension and hypercholesterolemia were independent predictors of screen-detected diabetes.Conclusion: The present study found a high prevalence and low awareness of  diabetes, suggesting the need for appropriate actions to strengthen primary  healthcare approaches towards non-communicable diseases in Guinea.Keywords: Diabetes, epidemiology, Guine

Gene expression profiling in blood from cerebral malaria patients and mild malaria patients living in Senegal

International audienceBACKGROUND:Plasmodium falciparum malaria remains a major health problem in Africa. The mechanisms of pathogenesis are not fully understood. Transcriptomic studies may provide new insights into molecular pathways involved in the severe form of the disease.METHODS:Blood transcriptional levels were assessed in patients with cerebral malaria, non-cerebral malaria, or mild malaria by using microarray technology to look for gene expression profiles associated with clinical status. Multi-way ANOVA was used to extract differentially expressed genes. Network and pathways analyses were used to detect enrichment for biological pathways.RESULTS:We identified a set of 443 genes that were differentially expressed in the three patient groups after applying a false discovery rate of 10%. Since the cerebral patients displayed a particular transcriptional pattern, we focused our analysis on the differences between cerebral malaria patients and mild malaria patients. We further found 842 differentially expressed genes after applying a false discovery rate of 10%. Unsupervised hierarchical clustering of cerebral malaria-informative genes led to clustering of the cerebral malaria patients. The support vector machine method allowed us to correctly classify five out of six cerebral malaria patients and six of six mild malaria patients. Furthermore, the products of the differentially expressed genes were mapped onto a human protein-protein network. This led to the identification of the proteins with the highest number of interactions, including GSK3B, RELA, and APP. The enrichment analysis of the gene functional annotation indicates that genes involved in immune signalling pathways play a role in the occurrence of cerebral malaria. These include BCR-, TCR-, TLR-, cytokine-, FcεRI-, and FCGR- signalling pathways and natural killer cell cytotoxicity pathways, which are involved in the activation of immune cells. In addition, our results revealed an enrichment of genes involved in Alzheimer's disease.CONCLUSIONS:In the present study, we examine a set of genes whose expression differed in cerebral malaria patients and mild malaria patients. Moreover, our results provide new insights into the potential effect of the dysregulation of gene expression in immune pathways. Host genetic variation may partly explain such alteration of gene expression. Further studies are required to investigate this in African populations

Anesthesie au cours des ventriculocisternostomies au Mali : Une serie de 31 cas

Introduction La ventriculocisternostomie est une technique moderne du traitement des hydrocéphalies. Elle est peu fréquente en Afrique. Objectif:  Décrire la prise en charge anesthésique et l’évolution des patients opérés par ventriculocisternostomie. Patients et Méthode: Etude de cohorte prospective de 15 mois de janvier 2014 au 31 mars 2015. La saisie et l’analyse des données ont été effectuées par Microsoft word 2010 Epi info 3.5.3.fr. Résultats:  Les nourrissons prédominaient avec un sexe ratio de 1,81 en faveur du sexe masculin. Un antécédent de méningite ou d’infection respiratoire à répétition a été retrouvé chez 10 patients (32,2%). L’indication de la ventriculocisternostomie était une hydrocéphalie chez 30 patients (96, 8%). La classe ASA était II chez 19 patients (61,3%). L’intubation était prévue difficile chez 28 patients (90,3%).Tous les patients ont été opérés sous anesthésie générale. Une antibioprophylaxie a été faite chez tous les patients. La tachycardie isolée a été le seul évènement indésirable per opératoire observé chez 13 patients (41,9%). La durée de la chirurgie était de 62, 25 ± 20,9 minutes celle de l’anesthésie était de 93,5 ± 25,4 minutes. En postopératoire, une complication a été observée chez 7 patients (22,6%). Il s’agissait d’une méningite chez 3 patients (42,9%), d’une souffrance cérébrale, d’une obstruction de la stomie, d’un abcès cérébral et une paralysie du nerf III dans 14,3% chacune (1 patient). L’évolution était favorable chez 29 patients (93,5%). La durée médiane d’hospitalisation était de 3 jours. Conclusion:  Au Mali, la prise en charge anesthésique au cours de la ventriculocisternostomie s’adresse à une population pédiatrique avec un terrain précaire.   English title: Anesthesia during endoscopic third ventriculostomy in Mali: A series of 31 cases Introduction: Endoscopic Third Ventriculostomy (ETV) is a modern technique for the treatment of hydrocephalus. It is uncommon in Africa. Objective To describe ananesthesic management and the outcome of patients operated on by ETV. Patients and Methods Prospective cohort study over 15 months to January 2014 at 31 march 2015. The data entry and analysis were done by word office, Epi info 3.5.3.fr. Results: Infants predominated with a sex ratio of 1.81 in favor of men. A history of meningitis or recurrent respiratory infection was found in 10 patients (32.2%). The indication of ETV was hydrocephalus in 30 patients (96.8%). The ASA class was II in 19 patients (61.3%).  Intubation was expected to be difficult in 28 patients (90.3%). All patients were operated on under general anesthesia. Antibiotic  prophylaxis was done in all patients. Isolated tachycardia was the only peroperative adverse event observed in 13 patients (41.9%). The duration of the surgery was 62.25 ± 20.9 minutes that of the anesthesia was 93.5 ± 25.4 minutes. Postoperatively, a complication was observed in 7 patients (22.6%). It was meningitis in 3 patients (42.9%), brain pain, obstruction of the stoma, brain abscess and nerve III paralysis in 14.3% each (1 patient). The outcome was favorable in 29 patients (93.5%). The median hospital stay was 3 days. Conclusion:  In Mali, anesthetic management during ETV is aimed at a pediatric population with precarious terrain

Spatial and temporal dynamics of West Nile virus between Africa and Europe

It is unclear whether West Nile virus (WNV) circulates between Africa and Europe, despite numerous studies supporting an African origin and high transmission in Europe. We integrated genomic data with geographic observations and phylogenetic and phylogeographic inferences to uncover the spatial and temporal viral dynamics of WNV between these two continents. We focused our analysis towards WNV lineages 1 (L1) and 2 (L2), the most spatially widespread and pathogenic WNV lineages. Our study shows a Northern-Western African origin of L1, with back-and-forth exchanges between West Africa and Southern-Western Europe; and a Southern African origin of L2, with one main introduction from South Africa to Europe, and no back introductions observed. We also noticed a potential overlap between L1 and L2 Eastern and Western phylogeography and two Afro-Palearctic bird migratory flyways. Future studies linking avian and mosquito species susceptibility, migratory connectivity patterns, and phylogeographic inference are suggested to elucidate the dynamics of emerging viruse

NCR3 polymorphism, haematological parameters, and severe malaria in Senegalese patients

Background Host factors, including host genetic variation, have been shown to influence the outcome of Plasmodium falciparum infection. Genome-wide linkage studies have mapped mild malaria resistance genes on chromosome 6p21, whereas NCR3-412 polymorphism (rs2736191) lying within this region was found to be associated with mild malaria. Methods Blood samples were taken from 188 Plasmodium falciparum malaria patients (76 mild malaria patients, 85 cerebral malaria patients, and 27 severe non-cerebral malaria patients). NCR3-412 (rs2736191) was analysed by sequencing, and haematological parameters were measured. Finally, their association with clinical phenotypes was assessed. Results We evidenced an association of thrombocytopenia with both cerebral malaria and severe non-cerebral malaria, and of an association of high leukocyte count with cerebral malaria. Additionally, we found no association of NCR3-412 with either cerebral malaria, severe non-cerebral malaria, or severe malaria after grouping cerebral malaria and severe non-cerebral malaria patients. Conclusions Our results suggest that NCR3 genetic variation has no effect, or only a small effect on the occurrence of severe malaria, although it has been strongly associated with mild malaria. We discuss the biological meaning of these results. Besides, we confirmed the association of thrombocytopenia and high leukocyte count with severe malaria phenotypes

A New High-Throughput Tool to Screen Mosquito-Borne Viruses in Zika Virus Endemic/Epidemic Areas

International audienceMosquitoes are vectors of arboviruses affecting animal and human health. Arboviruses circulate primarily within an enzootic cycle and recurrent spillovers contribute to the emergence of human-adapted viruses able to initiate an urban cycle involving anthropophilic mosquitoes. The increasing volume of travel and trade offers multiple opportunities for arbovirus introduction in new regions. This scenario has been exemplified recently with the Zika pandemic. To incriminate a mosquito as vector of a pathogen, several criteria are required such as the detection of natural infections in mosquitoes. In this study, we used a high-throughput chip based on the BioMark™ Dynamic arrays system capable of detecting 64 arboviruses in a single experiment. A total of 17,958 mosquitoes collected in Zika-endemic/epidemic countries (Brazil, French Guiana, Guadeloupe, Suriname, Senegal, and Cambodia) were analyzed. Here we show that this new tool can detect endemic and epidemic viruses in different mosquito species in an epidemic context. Thus, this fast and low-cost method can be suggested as a novel epidemiological surveillance tool to identify circulating arboviruses