Bat flies (Diptera: Nycteribiidae and Streblidae) infesting cave-dwelling bats in Gabon: Diversity, dynamics and potential role in Polychromophilus melanipherus transmission

Background Evidence of haemosporidian infections in bats and bat flies has motivated a growing interest in characterizing their transmission cycles. In Gabon (Central Africa), many caves house massive colonies of bats that are known hosts of Polychromophilus Dionisi parasites, presumably transmitted by blood-sucking bat flies. However, the role of bat flies in bat malaria transmission remains under-documented. Methods An entomological survey was carried out in four caves in Gabon to investigate bat fly diversity, infestation rates and host preferences and to determine their role in Polychromophilus parasite transmission. Bat flies were sampled for 2–4 consecutive nights each month from February to April 2011 (Faucon and Zadie caves) and from May 2012 to April 2013 (Kessipoughou and Djibilong caves). Bat flies isolated from the fur of each captured bat were morphologically identified and screened for infection by haemosporidian parasites using primers targeting the mitochondrial cytochrome b gene. Results Among the 1,154 bats captured and identified as Miniopterus inflatus Thomas (n = 354), Hipposideros caffer Sundevall complex (n = 285), Hipposideros gigas Wagner (n = 317), Rousettus aegyptiacus Geoffroy (n = 157, and Coleura afra Peters (n = 41), 439 (38.0 %) were infested by bat flies. The 1,063 bat flies recovered from bats belonged to five taxa: Nycteribia schmidlii scotti Falcoz, Eucampsipoda africana Theodor, Penicillidia fulvida Bigot, Brachytarsina allaudi Falcoz and Raymondia huberi Frauenfeld group. The mean infestation rate varied significantly according to the bat species (ANOVA, F (4,75) = 13.15, P < 0.001) and a strong association effect between bat fly species and host bat species was observed. Polychromophilus melanipherus Dionisi was mainly detected in N. s. scotti and P. fulvida and less frequently in E. africana, R. huberi group and B. allaudi bat flies. These results suggest that N. s. scotti and P. fulvida could potentially be involved in P. melanipherus transmission among cave-dwelling bats. Sequence analysis revealed eight haplotypes of P. melanipherus. Conclusions This work represents the first documented record of the cave-dwelling bat fly fauna in Gabon and significantly contributes to our understanding of bat fly host-feeding behavior and their respective roles in Polychromophilus transmission. (Résumé d'auteur

Transports actifs et stratégies d'accès à l'emploi des populations des quartiers périphériques dans les villes africaines : le cas de Ouagadougou

Cette thèse interroge la mobilité des populations précaires qui se déplacent pour le motif de l'emploi, entre les quartiers périphériques considérés comme étant des zones de génération des déplacements et les autres quartiers ainsi que les quartiers centraux, qui sont des zones d'attraction ou de destination des mobilités domicile-travail. Pour se rendre à leur lieu d'emploi, ces populations adoptent une mobilité active et se déplacent à pied ou à vélo. L'approche proposée dans notre thèse s'articule sur l'analyse des différentes stratégies adoptées par ces populations précaires, sachant que ces stratégies ne sont pas exclusives, mais se complètent, il s'agit de l'intermodalité, le recours aux réseaux sociaux et le choix des emplois de proximité/éloignement. Dans le cas des villes du Sud, il est nécessaire de redéfinir la mobilité des actifs précaires comme étant une « mobilité de survie ». Ils sont « mobiles malgré tout » à cause de l'adaptabilité de leurs pratiques de mobilité, dont la pénibilité est caractérisée selon notre approche par les seuils de mobilité et dépend finalement d'une combinaison de facteurs centrés sur les conditions de déplacement qui sont marquées par les contraintes extérieures sociales, politiques, économiques et environnementales. La question des mobilités éprouvantes dans notre approche confirme l'étroitesse du lien qui se dégage entre « pratiques de mobilité » et « survie des actifs précaires ». Ce lien mérite d'être analysé et nous abordons cette question à la fois sous l'angle des stratégies de mobilité et sous l'angle de la pénibilité en lien avec la mobilité de survie. L'objectif de notre thèse consiste à explorer et à documenter les différentes stratégies de mobilité adoptées par les actifs précaires à Ouagadougou au Burkina Faso en tenant compte du contexte de leur ancrage résidentiel dans les quartiers périphériques. Notre population cible est constituée par les actifs précaires âgés de 40 à 55 ans. Pour réaliser cette exploration, nous utilisons l'approche espace-temps-activités, car les besoins de déplacement s'expriment à la fois dans le temps et dans l'espace et varient selon : la position sociale de l'individu, l'âge et les modes de vie. Aussi, la mobilité des populations précaires peut être vécue de manière différente suivant le niveau de pénibilité, le contexte professionnel et le niveau des revenus. Nos hypothèses de travail prennent en compte les effets induits par les amplitudes de déplacement qui sont de proximité ou d'éloignement, sur les stratégies de mobilité. Ensuite, nous abordons la question des réseaux sociaux d'entraide qui sont « des refuges ou des exutoires » dans les pratiques de mobilité et face aux situations imprévues que nous qualifions « d'amplificateurs de pénibilité ». Le capital social constitué par ces réseaux sociaux représente un facteur décisif à la pérennisation de la situation de mobilité. Il se dégage que l'apport des réseaux sociaux d'amis et de voisinage présente un enjeu aussi considérable que celui des réseaux de famille. Nous explorons enfin la manière dont les stratégies adoptées améliorent les conditions de vie des populations. Cette thèse a également pour but d'éclairer la relation entre deux quartiers périphériques situés à des distances différentes, mais qui vivent une même intensité quant à leurs flux de mobilité par rapport aux quartiers centraux. L'un des apports majeurs de notre thèse a été l'analyse des trajectoires de vie des actifs précaires et à travers nos analyses, il se dégage qu'un événement ou une situation imprévue peuvent reconfigurer les conditions de vie et les seuils de mobilité d'un individu ou d'un ménage qui sont : la mobilité de survie, la mobilité de subsistance, la mobilité d'épargne et la mobilité d'investissement. Les différents facteurs qui peuvent contribuer à fragiliser les stratégies de mobilité sont : les facteurs de motilité (accessibilité, compétences, appréhension des opportunités) ainsi que d'autres facteurs tels que la distance des déplacements et les emplois occupés, les situations imprévues, l'aspect genre et l'aspect institutionnel à travers les politiques publiques mises en place. Nos résultats montrent qu'une harmonisation entre les stratégies et les facteurs de mobilité favorise l'amélioration des conditions de vie des ménages.\ud ______________________________________________________________________________ \ud MOTS-CLÉS DE L’AUTEUR : Mobilités urbaines, mobilités actives, mobilité de survie, trajectoires de vie, quartiers périphériques, stratégies de mobilité et seuils de mobilité

A cross-sectional study of malaria transmission in suggests the existence of a potential bridge vector susceptible of ensuring the transfer of simian malaria parasites to humans

Introduction: Despite all the efforts made to control or even eliminate malaria, the disease continues to claim the highest number of victims of vector-borne pathogens in the world and Sub-Saharan countries bear the heaviest burden. The lack of knowledge of the role of various protagonists involved in the transmission of this parasitic disease, such as mosquito vectors and the plasmodial species they transmit as well as the host species they infect in a locality, constitutes one of the main causes of the persistence of malaria. In Gabon, in several areas, entomological data on malaria transmission remain poorly known. Thus, this study aimed to determine the diversity of Anopheles involved in malaria transmission in different environments of the province of Nyanga in southwest Gabon.Methods: For this, an entomological study was carried out in the four main localities of the province of Nyanga to provide answers to these shortcomings. Mosquitoes were collected over several nights using the human landing catch method. The identification of Anopheles and malaria parasites circulating in the different sites was achieved by combining morphological and molecular analysis tools.Results: A total of five hundred and ninety-one (591) mosquitoes belonging to the Culicidae family were collected. From this collection of adult mosquitoes, nine species of Anopheles mosquitoes notably species of the Anopheles nili complex (53.46%) followed by those of Anopheles gambiae complex (22.01%), Anopheles funestus group (18.24%), Anopheles moucheti complex (5.66%) and Anopheles hancocki (0.63%). Approximately 18 percent of these Anopheles species were infected with Plasmodium spp. Anopheles funestus, known to be involved in malaria transmission to humans, and An. moucheti-like, recently discovered in Gabon, and whose status in Plasmodium transmission is not yet elucidated, were found to be infected with great ape Plasmodium.Discussion: Our results raise the question of the potential switch of simian malaria parasites to humans. If these observations are confirmed in the future, and the infective capacity of the bridge vectors is demonstrated, this new situation could ultimately constitute an obstacle to progress in the fight against malaria

Acute dengue virus 2 infection in Gabonese patients is associated with an early innate immune response, including strong interferon alpha production

<p>Abstract</p> <p>Background</p> <p>Dengue is now a leading cause of morbidity and mortality throughout the tropics. We conducted the first <it>ex vivo </it>study of dengue fever (DF) in African patients infected during the first Gabonese dengue virus 2 (DENV-2) outbreak in 2007, in order to investigate cytokine production, including the antiviral cytokine IFN-α, reported to be a potent inhibitor of DENV replication <it>in vitro</it>.</p> <p>Methods</p> <p>Levels of 50 cytokines, chemokines and growth factors were measured in plasma from 36 patients with DENV-2 infection, and in uninfected controls, using Luminex multiplex technology. The results were interpreted according to the day of sampling after symptom onset. PBMC from six patients were also studied for T lymphocyte cell surface marker expression by flow cytometry.</p> <p>Results</p> <p>Acute DENV-2 infection elicited high levels of several pro-inflammatory cytokines (IL-6 and IL-17), chemokines (MIF, RANTES, IP-10 and MCP-1) and growth factors (G-CSF, GM-CSF and VEGF-A). We also observed high levels of IFN-α for the first time in adult DF patients, and CD4+ and CD8+ T cell activation at symptom onset.</p> <p>Conclusion</p> <p>Acute DENV-2 infection in African patients elicits a strong innate response involving IFN-α production, as well as an adaptive immune response.</p

Zika virus in Gabon (Central Africa) - 2007 : a new threat from Aedes albopictus ?

Background Chikungunya and dengue viruses emerged in Gabon in 2007, with large outbreaks primarily affecting the capital Libreville and several northern towns. Both viruses subsequently spread to the south-east of the country, with new outbreaks occurring in 2010. The mosquito species Aedes albopictus, that was known as a secondary vector for both viruses, recently invaded the country and was the primary vector involved in the Gabonese outbreaks. We conducted a retrospective study of human sera and mosquitoes collected in Gabon from 2007 to 2010, in order to identify other circulating arboviruses. Methodology/Principal Findings Sample collections, including 4312 sera from patients presenting with painful febrile disease, and 4665 mosquitoes belonging to 9 species, split into 247 pools (including 137 pools of Aedes albopictus), were screened with molecular biology methods. Five human sera and two Aedes albopictus pools, all sampled in an urban setting during the 2007 outbreak, were positive for the flavivirus Zika (ZIKV). The ratio of Aedes albopictus pools positive for ZIKV was similar to that positive for dengue virus during the concomitant dengue outbreak suggesting similar mosquito infection rates and, presumably, underlying a human ZIKV outbreak. ZIKV sequences from the envelope and NS3 genes were amplified from a human serum sample. Phylogenetic analysis placed the Gabonese ZIKV at a basal position in the African lineage, pointing to ancestral genetic diversification and spread. Conclusions/Significance We provide the first direct evidence of human ZIKV infections in Gabon, and its first occurrence in the Asian tiger mosquito, Aedes albopictus. These data reveal an unusual natural life cycle for this virus, occurring in an urban environment, and potentially representing a new emerging threat due to this novel association with a highly invasive vector whose geographic range is still expanding across the globe. Author Summary Not previously considered an important human arboviral pathogen, the epidemic capacity of Zika virus (ZIKV, a dengue-related flavivirus) was revealed by the Micronesia outbreak in 2007, which affected about 5000 persons. Widely distributed throughout tropical areas of Asia and Africa, ZIKV is transmitted by a broad range of mosquito species, most of which are sylvatic or rural, Aedes aegypti, an anthropophilic and urban species, being considered the main ZIKV epidemic vector. In a context of emerging arbovirus infections (chikungunya (CHIKV) and dengue (DENV)) in Gabon since 2007, we conducted a retrospective study to detect other, related viruses. In samples collected during the concurrent CHIKV/DENV outbreaks that occurred in the capital city in 2007, we detected ZIKV in both humans and mosquitoes, and notably the Asian mosquito Aedes albopictus that recently invaded the country and was the main vector responsible for these outbreaks. We found that the Gabonese ZIKV strain belonged to the African lineage, and phylogenetic analysis suggested ancestral diversification and spread rather than recent introduction. These findings, showing for the first time epidemic ZIKV activity in an urban environment in Central Africa and the presence of ZIKV in the invasive mosquito Aedes albopictus, raise the possibility of a new emerging threat to human health

Development of a generic model of a ruthenium reactor

A mathematical first-principle model (FPM) of a ruthenium reactor was developed, implemented and successfully validated against a set of measurements of the real reactor of a precious metal refinery (PMR). The model describes the dynamic behavior of a process involving two exothermic reactions, occurring simultaneously in a semi-batch reactor equipped with a jacket. The reactions describe the dissolution of solid ruthenium (Ru) to produce liquid ruthenium trichloride (RuCl3), which is then evaporated into ruthenium tetroxide gas (RuO4). This paper presents a lumped model of the process whose main objective was to achieve satisfactory tracking of temperature and pressure data sets of the real reactor. The model was written as an explicit system of ordinary differential equations (ODEs), and has demonstrated satisfactory predictions of temperature and pressure dynamics. However, more work aiming at achieving better validation of the model is still in progress. This involves using nonlinear optimization techniques to find optimum parameter estimates of reaction kinetics constants, together with some heat and mass transfer coefficients, only obtained by trial-and-error at this point.Conference paper : 12th International Symposium on Process Systems Engineering and 25th European Symposium on Computer Aided Process Engineering, 31-4 June 2015, Copenhagen, Denmark.http://www.sciencedirect.com/science/bookseries/157079462016-05-31hb201

Still's disease in the adult

editorial reviewedThe Adult Onset Still's Disease (AOSD) is an entity of unknown origin characterised by fever, polyarthralgias or polyarthritis, a pharyngitis, a cutaneous eruption and elevation of leucocytes. We present observations of 17 patients diagnosed during the last thirteen years. Files of hospitalized patients with suspected AOSD have been examined in a retrospective study and Yamaguchi and Kahn's criterias applied in order to confirm the diagnosis. Treatments undertaken and the evolution have been noted. The sex ratio is 1.83; the middle age of intervening from 42 to 45 years. The middle delay for the diagnosis is 3 to 8 weeks. Fever, eruption and polyarthralgias are the most frequent clinical signs. Elevation of leucocytes, hepatic cytolysis and hyperferritinemia are usual. Constantly, inflammatory tests are increased and the rheumatoid factor and the antinuclear antibodies are negative. Yamaguchi's criterias have been met by all patients. The non steroïd anti-inflammatory drugs and corticoïds constituted the main treatment. In the evolutionary shield, 6 cases of remission have been noted. The other patients evolved toward the chronicity with either a systemic or an articular shape. In the two situations, a state of corticodependance got settled with necessity of association to immunosuppressive drugs. The diagnosis of AOSD is easily done on basis of Yamaguchi's criterias. Corticoïds can permit to control the bouts. There are 3 types of evolution: remission, chronic systemic or chronic articular shape