Estimating Chikungunya prevalence in La Réunion Island outbreak by serosurveys: Two methods for two critical times of the epidemic

<p>Abstract</p> <p>Background</p> <p>Chikungunya virus (CHIKV) caused a major two-wave seventeen-month-long outbreak in La Réunion Island in 2005–2006. The aim of this study was to refine clinical estimates provided by a regional surveillance-system using a two-stage serological assessment as gold standard.</p> <p>Methods</p> <p>Two serosurveys were implemented: first, a rapid survey using stored sera of pregnant women, in order to assess the attack rate at the epidemic upsurge (s1, February 2006; n = 888); second, a population-based survey among a random sample of the community, to assess the herd immunity in the post-epidemic era (s2, October 2006; n = 2442). Sera were screened for anti-CHIKV specific antibodies (IgM and IgG in s1, IgG only in s2) using enzyme-linked immunosorbent assays. Seroprevalence rates were compared to clinical estimates of attack rates.</p> <p>Results</p> <p>In s1, 18.2% of the pregnant women were tested positive for CHIKV specific antibodies (13.8% for both IgM and IgG, 4.3% for IgM, 0.1% for IgG only) which provided a congruent estimate with the 16.5% attack rate calculated from the surveillance-system. In s2, the seroprevalence in community was estimated to 38.2% (95% CI, 35.9 to 40.6%). Extrapolations of seroprevalence rates led to estimate, at 143,000 and at 300,000 (95% CI, 283,000 to 320,000), the number of people infected in s1 and in s2, respectively. In comparison, the surveillance-system estimated at 130,000 and 266,000 the number of people infected for the same periods.</p> <p>Conclusion</p> <p>A rapid serosurvey in pregnant women can be helpful to assess the attack rate when large seroprevalence studies cannot be done. On the other hand, a population-based serosurvey is useful to refine the estimate when clinical diagnosis underestimates it. Our findings give valuable insights to assess the herd immunity along the course of epidemics.</p

Systemic Maternal Inflammation and Neonatal Hyperoxia Induces Remodeling and Left Ventricular Dysfunction in Mice

The impact of the neonatal environment on the development of adult cardiovascular disease is poorly understood. Systemic maternal inflammation is linked to growth retardation, preterm birth, and maturation deficits in the developing fetus. Often preterm or small-for-gestational age infants require medical interventions such as oxygen therapy. The long-term pathological consequences of medical interventions on an immature physiology remain unknown. In the present study, we hypothesized that systemic maternal inflammation and neonatal hyperoxia exposure compromise cardiac structure, resulting in LV dysfunction during adulthood.Pregnant C3H/HeN mice were injected on embryonic day 16 (E16) with LPS (80 µg/kg; i.p.) or saline. Offspring were placed in room air (RA) or 85% O(2) for 14 days and subsequently maintained in RA. Cardiac echocardiography, cardiomyocyte contractility, and molecular analyses were performed. Echocardiography revealed persistent lower left ventricular fractional shortening with greater left ventricular end systolic diameter at 8 weeks in LPS/O(2) than in saline/RA mice. Isolated cardiomyocytes from LPS/O(2) mice had slower rates of contraction and relaxation, and a slower return to baseline length than cardiomyocytes isolated from saline/RA controls. α-/β-MHC ratio was increased and Connexin-43 levels decreased in LPS/O(2) mice at 8 weeks. Nox4 was reduced between day 3 and 14 and capillary density was lower at 8 weeks of life in LPS/O(2) mice.These results demonstrate that systemic maternal inflammation combined with neonatal hyperoxia exposure induces alterations in cardiac structure and function leading to cardiac failure in adulthood and supports the importance of the intrauterine and neonatal milieu on adult health

Développement d'un dispositif expérimental de surmoulage permettant la mesure de la résistance thermique de contact pièce polymère/pièce polymère en conditions industrielles

International audienceDans l'industrie automobile, les joints d'étanchéité sont fabriqués par surmoulage de profils en élastomères extrudés. Les élastomères thermoplastiques vulcanisés (TPV) constituent un des types d'élastomères utilisés. Lors du procédé de surmoulage, la qualité du contact thermique est essentielle pour développer la résistance mécanique de l'assemblage. Cet article vise à évaluer, pour la première fois, la qualité du contact thermique entre le TPV extrudé et le TPV injecté pendant les phases de maintien et de refroidissement en conditions procédé. A cette fin, un moule expérimental instrumenté a été conçu, permettant de mesurer les champs de température dans chaque polymère pendant le cycle de surmoulage. Les relevés de température ainsi que les positions des thermocouples servent alors de données d’entrée à la méthode séquentielle inverse de Beck. Les informations quantitatives non intrusives de température de surface et de flux de chaleur ainsi obtenues, permettent d’identifier la Résistance Thermique de Contact (RTC) sur le cycle d’élaboration complet. Il a été observé que les variations de la RTC à l’interface polymère semblent être liées au déséquilibre thermique engendré lors du procédé qui génère un champ de transformation hétérogène

Thermal and mechanical interface behaviour of overmoulded vulcanized thermoplastic elastomers

International audienceVulcanized thermoplastic elastomers (TPV) are widely used in the automotive industry for the manufacturing of weather seals by overmoulding a TPV on an extrudate TPV. This process is assumed to be a fusion bonding in which the quality of the thermal contact is essential to develop the mechanical strength of the assembly. From a thermal point of view, the contact can be quantified by a thermal contact resistance (TCR) which consider the flux lines constriction and their lengthening. From a mechanical point of view, the contact can be qualified by Double Cantilever Beam tests through the calculation of the critical energy restitution rate. The influence of the overmoulding conditions on the contact thermal resistance value and on the critical energy restitution rate is discussed. A correlation was found between these two quantities