Serological follow up of rift valley fever in a sahelian ecosystem 2004

In 2003, a serological study performed in the Ferlo area (northern Senegal), showed that (i) Rift valley fever was endemic; (ii) the risk of transmission depended on the pond type (Chevalier, et al. 2005). In 2004, a serological longitudinal survey was undertaken in the same area. A total of 260 sheep were sampled three times: starting, middle and end of the rainy season. Sera were tested for anti-RVF immunoglobulin G (IgG) using a seroneutralization test. Statistical analyses were performed using a generalized linear model, with the incidence as the response and the period as the explanatory variable. The overall incidence rate was lower than in 2003 (1.7% vs 5.4%). The observed incidence rate was 3% (n= 166) from August till early October. It was 5.10-3 % (n = 177) from early October till the end of November. These results associated with entomological knowledge suggested that the main period of transmission is the middle of the rainy season. Ponds infected in 2003 remained infected in 2004. Rift Valley fever is endemic in this area but the way the virus is maintained in the field remains unknown. Assumptions on the persistence mechanisms are formulated. The relevance of vaccination is discussed

Rift Valley Fever : processes of emergeance and dissemination

Risk factors of Rift Valley fever (RVF) emergence remain partially unknown [1]. RVF is endemic in the Ferlo area (northern Senegal).A serological study performed in this region in small ruminants associated with an entomological study showed that the risk of RVF transmission, was spatially heterogeneous [2, 3] and linked to the pond structure. In the same area, we identified from satellite images three main landscape indexes potentially linked with the vector dynamic. These indexes were included as explanatory variables in a logistic regression mixed model. The 500-m landscape closure index was significantly correlated with higher serologic incidence. These results highlight the potential of high resolution remote sensing to characterize the landscape structure at a relevant scale to describe RVF risk areas [4]. The re-emergence of the virus during rainy season in this very dry area may be explained by two processes: transovarial transmission within the vector, or introduction of the virus by nomadic ruminants coming from endemic areas. A quantitative risk assessment indicates that the risk of introduction of the virus by nomadic herds is very low. Thus, it is likely that RVF is endemic in this area as a result of transovarial transmission within the vector population. Globalisation of legal and illegal trade and travel may increase the risk of the large scale spread of the virus and introduction from endemic into disease-free areas. Assuming the virus has not survived in Yemen, data from field studies and literature was used to qualitatively assess the likelihood of ¿re-introduction¿ of RVF into Yemen through the legal and illegal importation of small ruminants from the Horn of Africa. After developing the different pathways and the matrix of likelihood combinations, first results were an overall probability of introduction assessed low outside the rainy season, medium in summer and most likely to occur via ovine males exported during festival periods. Finally, we modelled and estimated the basic reproduction number (R0) for RVF in the Ferlo region using serological data (2003-2004) with two methods: the first based on an ordinary differential equation model fitted to serological test data and the based catalytic models' theory. With the first method, the value of R0 (which gave a root mean square value of 1and and was therefore considered to be the most accurate estimate) was 1.5. With the second method, R0 values were 2.84 for young sheep and 1.69 for adults. A regional project (Indian Ocean-Southern Africa) will be implemented in the next years to test main persistence and emergence assumptions and propose control recommendations. (Texte intégral

Protective effect of a Protein Epitope Mimetic CCR10 antagonist, POL7085, in a model of allergic eosinophilic airway inflammation

BACKGROUND: Potential involvement of the CCR10/CCL28 axis was recently reported in murine models of allergic asthma. If confirmed, blockade of the CCR10 receptor would represent an alternative to current asthma therapies. We evaluated the effect of a novel Protein Epitope Mimetic CCR10 antagonist, POL7085, in a murine model of allergic eosinophilic airway inflammation. METHODS: Mice were sensitized and challenged to ovalbumin. POL7085, a CCR10 antagonist (7.5 and 15 mg/kg), dexamethasone (1 mg/kg) or vehicle were administered intranasally once daily 1h before each allergen challenge. On day 21, airway hyperresponsiveness, bronchoalveolar lavage inflammatory cells and Th2 cytokines, and lung tissue mucus and collagen were measured. RESULTS: Allergen challenge induced airway hyperresponsiveness in vehicle-treated animals as measured by whole body barometric plethysmography, and eosinophilia in bronchoalveolar lavage. POL7085 dose-dependently and significantly decreased airway hyperresponsiveness (34 ± 16 %) and eosinophil numbers in bronchoalveolar lavage (66 ± 6 %). In addition, the highest dose of POL7085 used significantly inhibited lung IL-4 (85 ± 4 %), IL-5 (87 ± 2 %) and IL-13 (190 ± 19 %) levels, and lung collagen (43 ± 11 %). CONCLUSIONS: The Protein Epitope Mimetic CCR10 antagonist, POL7085, significantly and dose-dependently decreased allergen-induced airway hyperresponsiveness and airway inflammation after once daily local treatment. Our data give strong support for further investigations with CCR10 antagonists in asthmatic disease. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12931-015-0231-5) contains supplementary material, which is available to authorized users

New bonded assembly configuration for dynamic mechanical analysis of adhesives

A new sample configuration has been developed in order to study molecular mobility of an adhesive in a bonded assembly configuration by dynamic mechanical analysis. The torsional rectangular mode is used to provide a shear solicitation all along the adherend/adhesive interface. The initial mechanical properties of each assembly's constituent are first investigated as reference. The modulus of aluminum foils used as substrates exhibits a classic elastic component and a slight viscous part due to microstructural changes or stress relaxation. Four relaxation modes are highlighted and identified for epoxy adhesive tested as a bulk material. Its viscoelastic behavior is compared to the one of adhesive tested in assembly configuration. The relaxation modes of the adhesive remain visible in spite of the sample stiffening by aluminum foils. Relaxation modes comparison shows that the temperature of loss modulus associated with the mechanical manifestation of glass transition slightly increases for the assembly configuration. Energy losses during this relaxation are much higher in the assembly configuration. Influence of rigid aluminum substrates is discussed in terms of the adhesively bonded joint solicitation mode

An agile electronically scanned EBG matrix antenna for monitoring target activity

International audienceTelecommunications, civil and military radars, RFID (Radio Frequency IDentification) and all the radiating systems are evolving towards the spatial agility that associates « range » and « coverage ». In this context, this article describes and demonstrates an experimental prototype to show the reliability and efficiency of the EBG matrix antenna theoretical aspect, for beam forming and beam steering applications

Aligned carbon nanotube based ultrasonic microtransducers for durability monitoring in civil engineering

International audienceStructural health monitoring of porous materials such as concrete is becoming a major component in our resource-limited economy, as it conditions durable exploitation of existing facilities. Durability in porous materials depends on nanoscale features which need to be monitored in situ with nanometric resolution. To address this problem, we put forward an approach based on the development of a new nanosensor, namely a capacitive micrometric ultrasonic transducer whose vibrating membrane is made of aligned single-walled carbon nanotubes (SWNT). Such sensors are meant to be embedded in large numbers within a porous material in order to provide information on its durability by monitoring in situ neighboring individual micropores. In the present paper, we report on the feasibility of the key building block of the proposed sensor: we have fabricated well-aligned, ultra-thin, dense SWNT membranes that show above-nanometer amplitudes of vibration over a large range of frequencies spanning from 100 kHz to 5 MHz

Enthalpy relaxation phenomena of epoxy adhesive in operational configuration: Thermal, mechanical and dielectric analyses

Thermal cycling in space environment can cause physical aging of polymers used in structural adhesive bonded joint. Later, they can initiate failure. A methodology to follow physical aging effects on their thermal, mechanical and dielectric properties is applied to a commercial epoxy adhesive. The analytic description, using Tool, Narayanaswamy and Moynihan model gives a good description of the enthalpy relaxation. It is completed by a phenomenological analysis of the evolution of the adhesive thermal transitions, mechanical properties and molecular mobility. Testedsamples with bondedassembly are representative ofin service configurations. The influence of physical aging on the adhesive and the associated bonded assemblies is analyzed

Time-Dependence of the Mass Accretion Rate in Cluster Cooling Flows

We analyze two time-dependent cluster cooling flow models in spherical symmetry. The first assumes that the intracluster gas resides in a static external potential, and includes the effects of optically thin radiative cooling and mass deposition. This corresponds to previous steady-state cooling flow models calculated by White & Sarazin (1987). Detailed agreement is found between steady-state models and time-dependent models at fixed times in the simulations. The mass accretion rate is found either to increase or remain nearly constant once flows reach a steady state. The time rate of change of the accretion rate is strongly sensitive to the value of the mass deposition parameter q, but only mildly sensitive to the ratio beta of gravitational binding energy to gas temperature. We show that previous scaling arguments presented by Bertschinger (1988) and White (1988) are valid only for mature cooling flows with weak mass deposition (q ~< 1). The second set of models includes the effects of a secularly deepening cluster potential and secondary infall of gas from the Hubble flow. We find that such heating effects do not prevent the flows from reaching a steady state within an initial central cooling time.Comment: 22 pages (AASTeX) with 16 EPS figures; accepted for publication in The Astrophysical Journa

Bird flu, avian influenza : the H5N1 virus, poultry, other animals, and people here and elsewhere, from Asia to Africa

Illustré d'une trentaine de photographies originales issues des missions de terrain des vétérinaires et ornithologues du Cirad dans les pays du Sud, le livret fait le point sur ce fléau qui a d'abord frappé les pays du Sud-Est asiatique depuis 1997, avant de gagner l'Europe puis l'Afrique au début 2006. La version anglaise apporte plusieurs éléments nouveaux. L'Inra s'ajoute aux neuf institutions partenaires de l'édition française. Les recherches, conduites dans ce domaine par l'institut, sont mentionnées en page 41 du livret. On trouve également, en page 42, le bilan des opérations de surveillance menées au cours de l'année 2006 dans diverses zones d'implantation des oiseaux sauvages. En pages 33 et 34, les cartes des pays touchés par le virus H5N1 ont été actualisées. Il en est de même concernant la rubrique " Pour en savoir beaucoup plus ", fournissant, en fin de livret, de nouvelles sources d'information accessibles sur le web

Towards a better understanding of Rift Valley fever epidemiology in the south-west of the Indian Ocean.

International audience: Rift Valley fever virus (Phlebovirus, Bunyaviridae) is an arbovirus causing intermittent epizootics and sporadic epidemics primarily in East Africa. Infection causes severe and often fatal illness in young sheep, goats and cattle. Domestic animals and humans can be contaminated by close contact with infectious tissues or through mosquito infectious bites. Rift Valley fever virus was historically restricted to sub-Saharan countries. The probability of Rift Valley fever emerging in virgin areas is likely to be increasing. Its geographical range has extended over the past years. As a recent example, autochthonous cases of Rift Valley fever were recorded in 2007--2008 in Mayotte in the Indian Ocean. It has been proposed that a single infected animal that enters a naive country is sufficient to initiate a major outbreak before Rift Valley fever virus would ever be detected. Unless vaccines are available and widely used to limit its expansion, Rift Valley fever will continue to be a critical issue for human and animal health in the region of the Indian Ocean