Emergence and Prevalence of Human Vector-Borne Diseases in Sink Vector Populations

Vector-borne diseases represent a major public health concern in most tropical and subtropical areas, and an emerging threat for more developed countries. Our understanding of the ecology, evolution and control of these diseases relies predominantly on theory and data on pathogen transmission in large self-sustaining ‘source’ populations of vectors representative of highly endemic areas. However, there are numerous places where environmental conditions are less favourable to vector populations, but where immigration allows them to persist. We built an epidemiological model to investigate the dynamics of six major human vector borne-diseases in such non self-sustaining ‘sink’ vector populations. The model was parameterized through a review of the literature, and we performed extensive sensitivity analysis to look at the emergence and prevalence of the pathogen that could be encountered in these populations. Despite the low vector abundance in typical sink populations, all six human diseases were able to spread in 15–55% of cases after accidental introduction. The rate of spread was much more strongly influenced by vector longevity, immigration and feeding rates, than by transmission and virulence of the pathogen. Prevalence in humans remained lower than 5% for dengue, leishmaniasis and Japanese encephalitis, but substantially higher for diseases with longer duration of infection; malaria and the American and African trypanosomiasis. Vector-related parameters were again the key factors, although their influence was lower than on pathogen emergence. Our results emphasize the need for ecology and evolution to be thought in the context of metapopulations made of a mosaic of sink and source habitats, and to design vector control program not only targeting areas of high vector density, but working at a larger spatial scale

Plasmodium falciparum Infection Significantly Impairs Placental Cytokine Profile in HIV Infected Cameroonian Women

BACKGROUND:Placental cytokines play crucial roles in the establishment and maintenance of pregnancy as well as protecting the foetus from infections. Previous studies have suggested the implication of infections such as P. falciparum and HIV in the stimulation of placental cytokines. This study assessed the impact of P. falciparum on placental cytokine profiles between HIV-1 positive and negative women. MATERIALS AND METHODS:P. falciparum infection was checked in peripheral and placental blood of HIV-1 negative and positive women by the thick blood smear test. Cytokines proteins and messenger RNAs were quantified by ELISA and real time PCR, respectively. Non-parametric tests were used for statistical analyses. RESULTS:Placental and peripheral P. falciparum infections were not significantly associated with HIV-1 infection (OR: 1.4; 95% confidence interval (95%CI): 0.5-4.2; p = 0.50 and OR: 0.6; 95%CI: 0.3-1.4; p = 0.26, respectively). Conversely, placental P. falciparum parasitemia was significantly higher in the HIV-1 positive group (p = 0.04). We observed an increase of TNF-alpha mRNA median levels (p = 0.02) and a trend towards a decrease of IL-10 mRNA (p = 0.07) in placenta from HIV-1 positive women compared to the HIV negative ones leading to a median TNF-alpha/IL-10 mRNA ratio significantly higher among HIV-1 positive than among HIV-1 negative placenta (p = 0.004; 1.5 and 0.8, respectively). Significant decrease in median secreted cytokine levels were observed in placenta from HIV-1 positive women as compared to the HIV negative however these results are somewhat indicative since it appears that differences in cytokine levels (protein or mRNA) between HIV-1 positive and negative women depend greatly on P.falciparum infection. Within the HIV-1 positive group, TNF-alpha was the only cytokine significantly associated with clinical parameters linked with HIV-1 MTCT such as premature rupture of membranes, CD4 T-cell number, plasma viral load and delay of NVP intake before delivery. CONCLUSIONS:These results show that P. falciparum infection profoundly modifies the placenta cytokine environment and acts as a confounding factor, masking the impact of HIV-1 in co-infected women. This interplay between the two infections might have implications in the in utero MTCT of HIV-1 in areas where HIV-1 and P. falciparum co-circulate

La population active selon les diplômes et les secteurs d'activité

Dominique Menu und Martine Möbus, Die Verteilung der Erwerbsbevölkerung nach der Ausbildung und dem Wirtschaftszweig. Die Bevölkerung eines Landes ändert sich ständig. Die Zahl der Erwerbspersonen nimmt durch die jugendlichen Schulabsolventen zu, die öfters ein besseres Ausbildungsniveau als ihre Vorgänger haben. Im Gegensatz dazu, verlassen ältere und oft weniger lang ausgebildete Beschäftigte ihre Tätigkeit, und die Massnahmen zur Förderung der vorgezogenen Rente haben im Laufe der letzten Jahre zu einem starken Zuwachs dieser Abgänge aus dem Erwerbsleben geführt. Schliesslich unterbrechen andere Personen, vor allem Frauen, vorübergehend ihre Beschäftigung, oder sie nehmen nach einer mehr oder weniger langen Unterbrechung eine Tätigkeit wieder auf. Aus diesen unterschiedlichen Bewegungen ergibt sich, dass der Anteil der diplomierten Beschäftigten allmählich zunimmt, im Gegensatz zu den Nichtdiplomierten. Der Aufsatz zeigt, dass diese Entwicklung sich zwischen 1975 und 1981 ziemlich schnell vollzogen hat. Die Verteilung der Beschäftigten nach dem Bildungsniveau auf die Wirtschaftszweige ist jedoch sehr unterschiedlich. Im Jahre 1981 hatten zum Beispiel mehr als 40 % der Beschäftigten in der Verwaltung mindestens das Abitur, während der Prozentsatz der Abiturienten nur 5 % in der Landwirtschaft beträgt, 16 % im Handel und 23 % in der Energiebranche. Im Aufsatz werden diese Unterschiede kommentiert, und deren Bedeutung hinterfragt : gibt es eine Beziehung zwischen der Arbeitsplatz- (bzw. Berufs-) -struktur und der Verteilung der Beschäftigten nach ihrem Ausbildungsniveau in einem Wirtschaftszweig ? Anscheinend sind in jeder Branche historische Entwicklungen oder bestimmte Praktiken bezuglich der Arbeitsverteilung und der Einstellung vorhanden, die dazu führen, die sehr starke Stabilität der Rangordnungen in den verschiedenen Wirtschaftszweigen zu erhalten. In der Tat waren die Bewegungen auf globaler Ebene stark, sie waren jedoch zu wenig unterschiedlich zwischen den einzelnen Wirtschaftszweigen, um deren Hierarchie zu ändern : so bleibt die Verwaltung der Sektor, der am meisten Hochschulabsolventen beschäftigt — dagegen die Landwirtschaft am wenigsten und in der Mitte dazwischen das Baugewerbe und der Handel. Im Aufsatz werden auch die Beschäftigtenstruktur nach Ausbildung in jedem Wirtschaftszweig und ihre wichtigsten Entwicklungen dargestellt : z.B., wie die Beschäftigten, die mindestens das Abitur haben, in wenigen Zweigen des Dienstieistungssektors sich stark konzentrieren.Dominique Menu, with the collaboration of Martine Möbus, The active population according to qualifications and sectors of activity. The population of a country is constantly changing. Young people finishing their studies swell the active population, and today they are far more frequently in possession of a diploma than their elders. On the contrary, older workers, often with few qualifications, are leaving professional activity, and in the course of the past few years early retirement schemes have led to a substantial increase in this outward flow. Others, especially women, leave professional activity temporarily, or return to it after interruptions of various lengths. The result of these different movements is that the proportion of qualified workers in the active population tends to increase, and that of unqualified ones to decrease. This article shows that during the years 1975/1981 these changes were relatively rapid. However, the distribution of qualified and unqualified workers varies greatly from one sector to another. For example, in the administration, in 1983, over 40 % of salaried workers had at least a « baccalauréat » (high-school leaving diploma), compared to only 5 % of workers in agriculture, 16 % in commerce and 23 % in the energy sector. This article comments on these differences, and examines their significance : is there a relationship between job structures (or professional categories) and the distribution of active workers in a given sector according to their qualifications ? It appears that in each main sector there is a history or a series of practices in the organization of work and in recruitment that allows the tremendous stability of sectorial situations to be understood. In fact, changes over the period 1975/1981 are considerable at a global level, but the differentiation between sectors is too slight for the hierarchy to be modified : in this way, the administration is still the sector employing the greatest number of workers with higher education, and agriculture the least, while BTP and commerce remain in intermediate positions. This article also shows the distribution of the different categories of qualifications by sectors, and the main developments. It shows the massive concentration of active workers with at least a high-school diploma in some tertiary sectors.La population d'un pays se transforme en permanence. Des jeunes terminant leurs études viennent augmenter le nombre des actifs et ils sont, actuellement, beaucoup plus fréquemment diplômés que leurs aînés. À l'inverse, des travailleurs âgés, souvent peu diplômés, quittent l'activité, et au cours des dernières années les systèmes de retraite anticipée ont provoqué une forte augmentation de ce flux de départ. Enfin, d'autres personnes, surtout des femmes, arrêtent momentanément leur activité, ou reprennent une activité après une interruption plus ou moins longue. Il résulte de ces différents mouvements que la proportion de diplômés dans la population active tend à augmenter et celle des non-diplômés, au contraire, à diminuer. L'article montre qu'au cours des années 1975/1981 ces évolutions ont été relativement rapides. Cependant, la répartition des actifs diplômés et non diplômés est très variable d'un secteur à l'autre. Par exemple, dans l'Administration, en 1981, plus de 40% des salariés ont au moins le baccalauréat, alors que la proportion de bacheliers n'est que de 5 % dans l'Agriculture, de 16 % dans le Commerce et de 23 % dans le secteur de l'Energie. L'article commente ces différences et s'interroge sur leur signification : existe-t-il une relation entre la structure des emplois (ou des professions) et la répartition par diplômes des actifs d'un secteur. Il semble qu'il y ait dans chaque grand secteur une histoire ou une série de pratiques dans l'organisation du travail comme dans les recrutements qui permet de comprendre la très grande stabilité des situations sectorielles. Pratiquement, les évolutions sur la période 1975/1981 sont fortes au niveau global mais trop peu différenciées entre les secteurs pour modifier la hiérarchie : ainsi l'Administration reste le secteur qui emploie le plus de diplômés de l'enseignement supérieur et l'Agriculture le moins, le BTP et le Commerce restant en position intermédiaire. L'article présente aussi la répartition des différentes catégories de diplômés par secteurs et les évolutions principales. Il montre la concentration massive des actifs ayant au moins le baccalauréat dans quelques secteurs tertiaires.Menu Dominique, Möbus Martine. La population active selon les diplômes et les secteurs d'activité. In: Formation Emploi. N.4, 1983. pp. 16-28

A Multilevel Core Sampler Device to Directly Estimate Food Supply Accessible to Waders

International audienceTo understand food webs functioning in intertidal soft-sediments, it is critical to assess the macrobenthic prey fraction accessible to waders. Here we describe a simple core sampler device allowing to directly relating the vertical distribu- tion of macrozoobenthos to waders bill length. Bill length measurements were used as a proxy of probing depth to esti- mate the amount of food supply accessible. Several metal plates can be inserted in the core sampler at different heights according to the bill length data of the studied species. These data are provided in a literature survey. For each species, the bill length variability is then explicitly taken into account in the estimation of food accessibility. The core is trans- parent to check for the quality of the sample. It could also be used to estimate a Benthic Habitat Quality index (BHQ) based on characteristics of the vertical structure of the sediment. This multilevel core is easy to build and to adapt to any studied wader species of the intertidal zone, floodplains or other wetlands. The samples are obtained with the same ef-fort as with usual circular cores leading to the possibility to survey large area. With one core sample, the ecological in-formation that can be achieved at once is threefold: 1) benthic community structure (partitioned in several depths), 2) estimate of the accessible food fraction to waders (range of values) and 3) habitat quality index assessmen

Photosynthetic activity and productivity of intertidal macroalgae: in situ measurements, from thallus to community scale

International audienceThe photosynthetic activity and productivity of four dominant canopy intertidal macroalgae were measured under emersion and immersion, at saturating light levels (PAR > 300 μmol photons m−2 s−1), and compared at two sites (eastern and western English Channel) in spring and summer. The photosynthetic activity of thalli was measured by the electron transport rate (ETR) using pulse-amplitude modulated (PAM) fluorescence and the productivity of individuals and of communities was measured by carbon fluxes in closed chambers. Under emersion, when thalli were still hydrated, the uppermost species Pelvetia canaliculata had higher photosynthetic activity (mean ETR between 327 and 460 μmol e− m−2 s−1) and individual gross productivity (between 60 and 212 μmol C gDW−1 h−1) than the lowermost species Laminaria digitata (mean ETR between 24 and 53 μmol e− m−2 s−1 and gross productivity between 2 and 38 μmol C gDW−1 h−1), whatever the site and season. P. canaliculata had higher ETR in air than underwater (averaged 146 μmol e− m−2 s−1) and L. digitata had lower ETR in air than underwater (averaged 112 μmol e− m−2 s−1), while they exhibited respectively 3 and 5 times higher gross productivity underwater. At the community scale, the low mid-shore zone of Fucus serratus had the highest mean gross productivity under emersion (47 mmol C m−2 h−1) while rates were higher for the uppermost than lowermost zone at the eastern site (average 20 and 6 mmol C m−2 h−1 respectively) and of the same order of magnitude for both zones at the western site (about 30 mmol C m−2 h−1). Finally, the variability of under emersion primary productivity among sites and seasons was reduced when the measurements were performed on entire communities compared to isolated individuals of the dominant species

Les objets colorés du Paléolithique supérieur : cas de la grotte de La Vache (Ariège)

ABSTRACT La Vache cave (near Alliât, Ariege, south of France) presented many bone art objects. They are engraved and colored, several alternatively in red and black. Examinations and analysis have been undertaken with a Scanning Electron Microscope in order to characterise prehistoric paint. The red (hematite) and black (manganese oxide) pigments are without any single exception associated with biotite. This study let us rediscover the « receipes » used by the artists of the Final Magdalenian Period.RESUME Le mobilier osseux de la grotte de La Vache (Commune d'Alliat, Ariège) offre un ensemble de pièces gravées et colorées, dont certaines alternativement en rouge et en noir. Des observations et des analyses physico-chimiques ont été effectuées au microscope électronique à balayage pour mieux caractériser la nature des colorants. Les pigments rouge (hématite) et noir (oxyde de manganèse) sont associés systématiquement à de la biotite, jouant le rôle de charge. Cette étude a montré l'existence d'une « recette » utilisée par les artistes du Magdalénien final.Buisson Dominique, Menu M., Pinçon Geneviève, Walter Ph. Les objets colorés du Paléolithique supérieur : cas de la grotte de La Vache (Ariège). In: Bulletin de la Société préhistorique française, tome 86, n°6, 1989. pp. 183-192

Influence of local environmental conditions on the seasonal acclimation process and the daily integrated production rates of Laminaria digitata (Phaeophyta) in the English Channel

International audienceTwo populations of Laminaria digitata (Hudson) Lamouroux (Ann Mus Hist Nat Paris 20:21-47, 1813) were examined for their seasonal photosynthetic acclimation to clear and turbid-light environments along the French coast of the English Channel. Photosynthesis-irradiance curves, pigment concentrations and the daily in situ integrated oxygen production rates were measured in both populations. Despite the great differences in light attenuation between the sites, the two populations achieved similar oxygen production rates in the field, in relation to high maximal photosynthetic rates, total pigment concentrations and antenna (fucoxanthin + chlorophyll c)/chl a pigment ratios in sporophytes from the turbid environment. Environmental conditions (i.e. light, temperature and nitrogen availability) changed throughout the year in both sites. While the seasonal acclimation trends were evident in the clear-light environment, the strategy in the turbid-light environment differed, tending to maximize light capture throughout the year. This study highlights the diversity of the response of a single species to contrasted light environments

Photosynthesis of Laminaria digitata during the immersion and emersion periods of spring tidal cycles during hot, sunny weather

The boreal kelp Laminaria digitata dominates the low intertidal and upper subtidal zones of moderately exposed rocky shores in north-western Europe. Due to ocean warming, this foundation species is predicted to disappear from French coasts in the near future. Photosynthesis of L. digitata sporophytes was surveyed in situ during spring and summer tidal cycles with emersion periods around midday during hot, sunny weather. The net production (NP) of whole individuals (i.e. the difference between their gross primary production and respiration) was assessed by measuring carbon fluxes inside a closed chamber. Photosynthetic performance of thalli was assessed using pulse-amplitude modulated (PAM) fluorescence parameters, the effective (ΦPSII) and optimal (Fv/Fm) quantum yields of photosystem II. Content in pigments involved in the xanthophyll cycle, a photoprotective mechanism, was measured in thalli to evaluate the de-epoxidation ratio (DR). NP shifted from positive values (reaching 140 μmol C gDW-1 h-1) during morning immersion to negative values uduring emersion (reaching -37 μmol C gDW-1 h-1), and did not return to positive values during the following immersion period when respiration was exacerbated. ΦPSII decreased during emersion (down to 0.01), but recovered during afternoon immersion. Fv/Fm decreased during emersion (down to 0.18) indicating severe photoinhibition. High DR values (up to 0.70) showed the effectiveness of the photoprotective mechanism, which appeared nevertheless insufficient to prevent photodamage during emersion stress. Among the environmental factors contributing to this emersion stress, repeated heat shocks over consecutive tide cycles likely play a leading role. These repeated heat shocks appear to further exacerbate the detrimental effects of warming events on this marginal population of L. digitata