Éditeur(s) : HAL CCSD Public Library of Science
Résumé : We examined tree-soil habitat associations in lowland forest communities at Paracou, French Guiana. We analyzed a large dataset assembling six permanent plots totaling 37.5 ha, in which extensive LIDAR-derived topographical data and soil chemical and physical data have been integrated with precise botanical determinations. Map of relative elevation from the nearest stream summarized both soil fertility and hydromorphic characteristics, with seasonally inundated bottomlands having higher soil phosphate content and base saturation, and plateaus having higher soil carbon, nitrogen and aluminum contents. We employed a statistical test of correlations between tree species density and environmental maps, by generating Monte Carlo simulations of random raster images that preserve autocorrelation of the original maps. Nearly three fourths of the 94 taxa with at least one stem per ha showed a significant correlation between tree density and relative elevation, revealing contrasted species-habitat associations in term of abundance, with seasonally inundated bottomlands (24.5% of species) and well-drained plateaus (48.9% of species). We also observed species preferences for environments with or without steep slopes (13.8% and 10.6%, respectively). We observed that closely-related species were frequently associated with different soil habitats in this region (70% of the 14 genera with congeneric species that have a significant association test) suggesting species-habitat associations have arisen multiple times in this tree community. We also tested if species with similar habitat preferences shared functional strategies. We found that seasonally inundated forest specialists tended to have smaller stature (maximum diameter) than species found on plateaus. Our results underline the importance of tree-soil habitat associations in structuring diverse communities at fine spatial scales and suggest that additional studies are needed to disentangle community assembly mechanisms related to dispersal limitation, biotic interactions and environmental filtering from species-habitat associations. Moreover, they provide a framework to generalize across tropical forest sites.
ISSN: 1932-6203

hal-01260289
https://hal.archives-ouvertes.fr/hal-01260289
PRODINRA : 342930
DOI : 10.1371/journal.pone.0141488

Éditeur(s) : HAL CCSD MDPI
Résumé : International audience
Canopy height is a key variable in tropical forest functioning and for regional carbon inventories. We investigate the spatial structure of the canopy height of a tropical forest, its relationship with environmental physical covariates, and the implication for tropical forest height variation mapping. Making use of high-resolution maps of LiDAR-derived Digital Canopy Model (DCM) and environmental covariates from a Digital Elevation Model (DEM) acquired over 30,000 ha of tropical forest in French Guiana, we first show that forest canopy height is spatially correlated up to 2500 m. Forest canopy height is significantly associated with environmental variables, but the degree of correlation varies strongly with pixel resolution. On the whole, bottomland forests generally have lower canopy heights than hillslope or hilltop forests. However, this global picture is very noisy at local scale likely because of the endogenous gap-phase forest dynamic processes. Forest canopy height has been predictively mapped across a pixel resolution going from 6 m to 384 m mimicking a low resolution case of 3 points·km −2. Results of canopy height mapping indicated that the error for spatial model with environment effects decrease from 8.7 m to 0.91 m, depending of the pixel resolution. Results suggest that, outside the calibration plots, the contribution of environment in shaping the global canopy height distribution is quite limited. This prevents accurate canopy height mapping based only on environmental information, and suggests that precise canopy height maps, for local management purposes, can only be obtained with direct LiDAR monitoring.
ISSN: 2072-4292

hal-01590726
https://hal-univ-guyane.archives-ouvertes.fr/hal-01590726
https://hal-univ-guyane.archives-ouvertes.fr/hal-01590726/document
https://hal-univ-guyane.archives-ouvertes.fr/hal-01590726/file/remotesensing-08-00747.pdf
DOI : 10.3390/rs8090747

Éditeur(s) : HAL CCSD
Résumé : The relation between primary and secondary growth has been traditionally studied in terms of growth units and has always being assumed as closely correlated. Pluviometric variation directly affects growth patterns in the neotropical pioneer species Jacaranda copaia. In French Guiana this species produces annual growth rings in the dry season that can be seen with the naked eye.The morphological and anatomical description of three monocaulous individuals was made node by node. The trees where felled at a roadside locality close to the city of Kourou, French Guiana. The comparison of intermodal distance, pith transversal area and wood ring area variation within an individual elucidates the origin of well-known problems in dendrochronological analysis of tropical trees.The wood found close to the pith, known as young wood, always has false wood rings; the production of these rings is correlated with short intermodal distances and small pith transversal area. This phenomenon seems to be caused by minor intrannual pluviometric variation that affects both primary and secondary growth. This new methodological approach helps morphologists and anatomists interpret growth patterns in tropical trees in a more holistic way.
Botany 2010
Rhode Island, United States

hal-01032389
https://hal.archives-ouvertes.fr/hal-01032389

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Introduction: Most studies on nematode-malaria interactions were conducted outside of the Americas. The objective of the present study was thus to study the relation between malaria and nematodes in a cohort of children in an Amazonian village. Methods: Odds ratios for intestinal nematode infections as an explanatory variable to malaria resistant vs. malaria sensitive were computed. Results: Ascaris lumbricoides was significantly more frequent in the ‘resistant’ malaria group than in the ‘sensitive’ one. Conclusions: Despite its low statistical power, the present results find that Ascaris was associated with less malaria, as observed by a number of studies.
ISSN: 0142-6338

inserm-01410100
http://www.hal.inserm.fr/inserm-01410100
http://www.hal.inserm.fr/inserm-01410100/document
http://www.hal.inserm.fr/inserm-01410100/file/worms%20malaria%20camopi%20j%20trop%20pediatrics.pdf
http://www.hal.inserm.fr/inserm-01410100/file/GI%20nematodes%20tab%20aurelia%29.pdf

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Mapping forest aboveground biomass (AGB) has become an important task, particularly for the reporting of carbon stocks and changes. AGB can be mapped using synthetic aperture radar data (SAR) or passive optical data. However, these data are insensitive to high AGB levels (>150 Mg/ha, and >300 Mg/ha for P-band), which are commonly found in tropical forests. Studies have mapped the rough variations in AGB by combining optical and environmental data at regional and global scales. Nevertheless, these maps cannot represent local variations in AGB in tropical forests. In this paper, we hypothesize that the problem of misrepresenting local variations in AGB and AGB estimation with good precision occurs because of both methodological limits (signal saturation or dilution bias) and a lack of adequate calibration data in this range of AGB values. We test this hypothesis by developing a calibrated regression model to predict variations in high AGB values (mean >300 Mg/ha) in French Guiana by a methodological approach for spatial extrapolation with data from the optical geoscience laser altimeter system (GLAS), forest inventories, radar, optics, and environmental variables for spatial inter-and extrapolation. Given their higher point count, GLAS data allow a wider coverage of AGB values. We find that the metrics from GLAS footprints are correlated with field AGB estimations (R 2 =0.54, RMSE=48.3 Mg/ha) with no bias for high values. First, predictive models, including remote-sensing, environmental variables and spatial correlation functions, allow us to obtain "wall-to-wall" AGB maps over French Guiana with an RMSE for the in situ AGB estimates of ~51 Mg/ha and R²=0.48 at a 1-km grid size. We conclude that a calibrated regression model based on GLAS with dependent environmental data can produce good AGB predictions even for high AGB values if the calibration data fit the AGB range. We also demonstrate that small temporal and spatial mismatches between field data and GLAS footprints are not a problem for regional and global calibrated regression models because field data aim to predict large and deep tendencies in AGB variations from environmental gradients and do not aim to represent high but stochastic and temporally limited variations from forest dynamics. Thus, we advocate including a greater variety of data, even if less precise and shifted, to better represent high AGB values in global models and to improve the fitting of these models for high values.
ISSN: 0303-2434

Droits : http://creativecommons.org/licenses/by/
hal-01381116
https://hal.archives-ouvertes.fr/hal-01381116
https://hal.archives-ouvertes.fr/hal-01381116/document
https://hal.archives-ouvertes.fr/hal-01381116/file/Fayad2016a.pdf
DOI : 10.1016/j.jag.2016.07.015

Éditeur(s) : HAL CCSD Elsevier
Résumé : Eperua falcata (Aublet), a late-successional species in tropical rainforest and one of the most abundant tree in French Guiana, has developed an original strategy concerning N-acquisition by largely preferring nitrate, rather than ammonium (H. Schimann, S. Ponton, S. Hattenschwiler, B. Ferry, R. Lensi, A.M. Domenach, J.C. Roggy, Differing nitrogen use strategies of two tropical rainforest tree species in French Guiana: evidence from N-15 natural abundance and microbial activities, Soil Biol, Biochem. 40 (2008) 487-494). Given the preference of this species for nitrate, we hypothesized that root exudates would promote nitrate availability by (a) enhancing nitrate production by stimulating ammonium oxidation or (b) minimizing nitrate losses by inhibiting denitrification. Root exudates were collected in situ in monospecific planted plots. The phytochemical analysis of these exudates and of several of their corresponding root extracts was achieved using UHPLC/DAD/ESI-QTOF and allowed the identification of diverse secondary metabolites belonging to the flavonoid family. Our results show that (i) the distinct exudation patterns observed are related to distinct root morphologies, and this was associated with a shift in the root flavonoid content, (ii) a root extract representative of the diverse compounds detected in roots showed a significant and selective metabolic inhibition of isolated denitrifiers in vitro, and (iii) in soil plots the abundance of nirK-type denitrifiers was negatively affected in rhizosphere soil compared to bulk. Altogether this led us to formulate hypothesis concerning the ecological role of the identified compounds in relation to N-acquisition strategy of this species. (C) 2013 Elsevier Masson SAS. All rights reserved.
ISSN: 0981-9428

hal-01032437
https://hal.archives-ouvertes.fr/hal-01032437
DOI : 10.1016/j.plaphy.2013.05.003

Éditeur(s) : HAL CCSD European Geosciences Union
Résumé : Xylem density is a physical property of wood that varies between individuals, species and environments. It reflects the physiological strategies of trees that lead to growth, survival and reproduction. Measurements of branch xylem density, ρx, were made for 1653 trees representing 598 species, sampled from 87 sites across the Amazon basin. Measured values ranged from 218 kg m−3 for a Cordia sagotii (Boraginaceae) from Mountagne de Tortue, French Guiana to 1130 kg m−3 for an Aiouea sp. (Lauraceae) from Caxiuana, Central Pará, Brazil. Analysis of variance showed significant differences in average ρx across regions and sampled plots as well as significant differences between families, genera and species. A partitioning of the total variance in the dataset showed that species identity (family, genera and species) accounted for 33% with environment (geographic location and plot) accounting for an additional 26%; the remaining "residual" variance accounted for 41% of the total variance. Variations in plot means, were, however, not only accountable by differences in species composition because xylem density of the most widely distributed species in our dataset varied systematically from plot to plot. Thus, as well as having a genetic component, branch xylem density is a plastic trait that, for any given species, varies according to where the tree is growing in a predictable manner. Within the analysed taxa, exceptions to this general rule seem to be pioneer species belonging for example to the Urticaceae whose branch xylem density is more constrained than most species sampled in this study. These patterns of variation of branch xylem density across Amazonia suggest a large functional diversity amongst Amazonian trees which is not well understood.
ISSN: 1726-4170

hal-01032137
https://hal.archives-ouvertes.fr/hal-01032137

Résumé : Le Brésil et la France partagent une frontière commune sur plus de 700 kilomètres, via la Guyane, région monodépartementale d’Outre-Mer française, et l’Amapá, Etat de la République fédérative du Brésil. Réalité socio-spatiale en marges à toutes les échelles malgré le différentiel socio-économique fort qu’elle marque, la frontière franco-brésilienne est devenue, depuis les années 1990, une interface politique, support de la relance des relations internationales franco-brésiliennes et des relations entre Guyane et Amapá.La thèse pose la question de cet écart en se concentrant sur la partie estuarienne de la frontière fluviale de l’Oyapock, autour des bourgs riverains de Saint-Georges (Guyane française) et d’Oiapoque (Brésil), entre lesquels un pont binational d’envergure est en construction, malgré leur rattachement routier à la marge aux polarités régionales de Cayenne et de Macapá.
Brazil and France share a common border of over 700 km via French Guiana, a French Overseas monodepartmental region, and Amapá, State of the Federal Republic of Brazil. Socio-spatial margin at all scales despite the strong socio-economic differential it marks, the Franco-Brazilian border has become since the 1990s a political interface, support for the revival of the Franco-Brazilian international relations and of the relations between French Guiana and Amapá. The thesis raises the question of this gap, focusing on the estuarine portion of the border river of the Oyapock, around the towns of Saint-Georges (French Guiana) and Oiapoque (Brazil) ; a significant bi-national bridge is under construction between these two towns, despite their road connection as margins to the regional polarities of Cayenne and Macapá.
Brasil e França compartilham uma fronteira comum com mais de 700 km através da Guiana Francesa, Região monodepartamental ultramarina francesa, e do Amapá, Estado da República Federativa do Brasil. Realidade sócio-espacial à margem a todas as escalas, apesar do forte diferencial sócio-econômico que a marca, a fronteira franco-brasileira tornou-se, desde os anos 90, uma interface política, suporte para a retomada das relações internacionais franco-brasileiras e das relações entre a Guiana Francesa e o Amapá. A tese expõe a questão deste desnível, centrando-se na porção estuarina da fronteira fluvial do Oiapoque, ao redor das pequenas cidades de Saint-Georges (Guiana Francesa) e de Oiapoque (Brasil), entre as quais uma ponte binacional de grande porte está em construção, apesar da ligação rodoviária delas como margens aos pólos regionais de Caiena e Macapá.

http://www.theses.fr/2012AGUY0504/document

Éditeur(s) : HAL CCSD American Society of Tropical Medicine and Hygiene
Résumé : International audience
French Guiana, the French territory most affected by human immunodeficiency virus (HIV) (1.3% of pregnant women), is also endemic for human T lymphotropic virus 1 (HTLV1). The objective of this study was to determine if the HTLV1/HIV coinfected patients had particular characteristics. All HIV-infected patients having a computerized medical file containing an HTLV1 serology were included: there were 1,333 HIV monoinfections and 76 HTLV1/VIH coinfections. The prevalence of HTLV1/HIV coinfections was 5.39%. Women (odds ratio [OR] = 1.91[1.13-3.24]), subjects > 40 years of age, and patients of Surinamese origin (OR = 2.65 [1.25-5.61]) were overrepresented among the coinfected. CD4 count at the time of diagnosis and viral loads were higher among coinfected patients. The clinical stage was not significantly different between the two groups. The number of CD4 cells was not higher among the coinfected, unlike most reports from the literature. Prevalence of HTLV1 among HIV-infected patients is high in French Guiana, and physicians seem to omit the prescription of serology for this potentially serious coinfection.
ISSN: 0002-9637

inserm-00913990
http://www.hal.inserm.fr/inserm-00913990
http://www.hal.inserm.fr/inserm-00913990/document
http://www.hal.inserm.fr/inserm-00913990/file/2013_Gouhier_-_Predictive_factorssur HTLV1-HIV.pdf
DOI : 10.4269/ajtmh.12-0769

Éditeur(s) : HAL CCSD Wiley
Résumé : Seasonal variations in environmental conditions influence the functioning of the whole ecosystem of tropical rain forests, but as yet little is known about how such variations directly influence the leaf gas exchange and transpiration of individual canopy tree species. We examined the influence of seasonal variations in relative extractable water in the upper soil layers on predawn leaf water potential, saturated net photosynthesis, leaf dark respiration, stomatal conductance, and tree transpiration of 13 tropical rain forest canopy trees (eight species) over 2yr in French Guiana. The canopies were accessed by climbing ropes attached to the trees and to a tower. Our results indicate that a small proportion of the studied trees were unaffected by soil water depletion during seasonal dry periods, probably thanks to efficient deep root systems. The trees showing decreased tree water status (i.e., predawn leaf water potential) displayed a wide range of leaf gas exchange responses. Some trees strongly regulated photosynthesis and transpiration when relative extractable water decreased drastically. In contrast, other trees showed little variation, thus indicating good adaptation to soil drought conditions. These results have important applications to modeling approaches: indeed, precise evaluation and grouping of these response patterns are required before any tree-based functional models can efficiently describe the response of tropical rain forest ecosystems to future changes in environmental conditions.
ISSN: 0006-3606

hal-01032411
https://hal.archives-ouvertes.fr/hal-01032411
DOI : 10.1111/j.1744-7429.2012.00902.x

Éditeur(s) : HAL CCSD Elsevier
Résumé : URL de l'article : http://www.sciencedirect.com/science/article/B6WPN-4XY3KDK-2/2/fd8508af63d82e29b4f9829c65194e26
The impact of climatic changes that occurred during the last glacial maximum and the Holocene on vegetation changes in the Amazon Basin and the Guiana Shield are still widely debated. The aim of our study was to investigate whether major changes in vegetation (i.e. transitions between rainforests and C4 savannas) occurred in northern French Guiana during the Holocene. We measured variations in the δ13C of soil organic matter at eight sites now occupied by forest or savannah. The forest sites were selected to cover two regions (forest refugia and peneplains) which are thought to have experienced different intensities of disturbance during the latest Pleistocene and the Holocene. We found that none of the forest sites underwent major disturbances during the Holocene, i.e. they were not replaced by C4 savannahs or C4 forest savannahs for long periods. Our results thus suggest that tropical rainforests in northern French Guiana were resilient to drier climatic conditions during the Holocene. Nevertheless, geographical and vertical variations in the 13C of SOM were compatible with minor changes in vegetation, variations in soil processes or in soil physical properties.
ISSN: 0033-5894

halshs-00551758
https://halshs.archives-ouvertes.fr/halshs-00551758
DOI : 10.1016/j.yqres.2009.11.007

Éditeur(s) : HAL CCSD American Society of Tropical Medicine and Hygiene
Résumé : International audience
Anti-leishmaniasis drug resistance is a common problem worldwide. The aim of this study was to inventory the general in vitro level of sensitivity of Leishmania isolates circulating in French Guiana and to highlight potential in vitro pentamidine-resistant isolates. This sensitivity study was conducted on 36 patient-promastigote isolates for seven drugs (amphotericin B, azithromycin, fluconazole, meglumine antimoniate, miltefosine, paromomycin, and pentamidine) using the Cell Counting Kit-8 viability test. The IC50 values obtained were heterogeneous. One isolate exhibited high IC50 values for almost all drugs tested. Pentamidine, which is the first-line treatment in French Guiana, showed efficacy at very low doses (mean of 0.0038 μg/mL). The concordance of the in vitro pentamidine results with the patients' clinical outcomes was 94% (K = 0.82).
ISSN: 0002-9637

inserm-01481512
http://www.hal.inserm.fr/inserm-01481512
http://www.hal.inserm.fr/inserm-01481512/document
http://www.hal.inserm.fr/inserm-01481512/file/2017%2C%20Ginouves%20-%20In%20vitro%20sensitivity%20of%20cutaneous%20leishmania.pdf
DOI : 10.4269/ajtmh.16-0373

Éditeur(s) : HAL CCSD
Résumé : International audience
Suriname is the smallest country in South America. However, in regional academic literature, it has been repeatedly considered one of the largest Caribbean territories for many years (Best 1967; Granger 2008). This territory is generally included in the socio-historical group of the three Guianas (Lézy 2000), or the bio-geographical group of the Guiana Plateau. Additionally, Suriname is frequently considered part of the insular Caribbean (Girvan 2005). The latter consideration implies a geographical paradox that is twofold. In fact, Suriname, French Guiana and Guyana are not directly bordered by the Caribbean Sea. Moreover, like Belize, which is also commonly included in the Caribbean island group, Suriname is not an island in the strict sense of the word, i.e. land surrounded by water, based on the restricted definition of the term. Nevertheless, the Caribbean cannot be defined today on the sole basis of a deterministic relationship with the sea bearing the same name. Further, research conducted on insularity increasingly demonstrates the limitations of the physical nature of the island, in favour of feelings of belonging, alienation, etc. (Taglioni 2003).
Caribbean Atlas

hal-00875566
https://hal.archives-ouvertes.fr/hal-00875566

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : The patterns of the distribution of fungal species and their potential interactions with trees remain understudied in Neotropical rainforests, which harbor more than 16,000 tree species, mostly dominated by endomycorrhizal trees. Our hypothesis was that tree species shape the non-mycorrhizal fungal assemblages in soil and litter and that the diversity of fungal communities in these two compartments is partly dependent on the coverage of trees in the Neotropical rainforest. In French Guiana, a long-term plantation and a natural forest were selected to test this hypothesis. Fungal ITS1 regions were sequenced from soil and litter samples from within the vicinity of tree species. A broad range of fungal taxa was found, with 42 orders and 14 classes.Significant spatial heterogeneity in the fungal communities was found without strong variation in the species richness and evenness among the tree plots. However, tree species shaped the fungal assemblages in the soil and litter, explaining up to 18 % of the variation among the communities in the natural forest.These results demonstrate that vegetation cover has an important effect on the structure of fungal assemblages inhabiting the soil and litter in Amazonian forests, illustrating the relative impact of deterministic processes on fungal community structures in these highly diverse ecosystems.
ISSN: 0095-3628

hal-01595373
https://hal.archives-ouvertes.fr/hal-01595373
DOI : 10.1007/s00248-016-0839-0
PRODINRA : 395655
PUBMED : 27645139

Éditeur(s) : HAL CCSD
Résumé : International audience
In French Guiana, located on the northeastern coast of South America, bats of different species are very numerous. The infection of bats and their ticks with zoonotic bacteria, especially Rickettsia species, is so far unknown. In order to improve knowledge of these zoonotic pathogens in this French overseas department, the presence and diversity of tick-borne bacteria was investigated with molecular tools in bat ticks. In the beginning of 2013, 32 bats were caught in Saint-Jean-du-Maroni, an area close to the coast of French Guiana, and the ticks of these animals were collected. A total of 354 larvae of Argasidae soft ticks (Ornithodoros hasei) from 12 bats (Noctilio albiventris) were collected and 107 of them were analysed. DNA was extracted from the samples and quantitative real-time PCR was carried out to detect Rickettsia spp., Bartonella spp., Borrelia spp. and Coxiella burnetii. All tested samples were negative for Bartonella spp., Borrelia spp. and Coxiella burnetii. Rickettsia DNA was detected in 31 (28.9%) ticks. An almost entire (1118 base pairs long) sequence of the gltA gene was obtained after the amplification of some positive samples on conventional PCR and sequencing. A Bayesian tree was constructed using concatenated rrs, gltA, ompA, ompB, and gene D sequences. The study of characteristic sequences shows that this Rickettsia species is very close (98.3-99.8%) genetically to R. peacockii. Nevertheless, the comparative analysis of sequences obtained from gltA, ompA, ompB, rrs and gene D fragments demonstrated that this Rickettsia is different from the other members of the spotted fever group. The sequences of this new species were deposited in GenBank as Candidatus Rickettsia wissemanii. This is the first report showing the presence of nucleic acid of Rickettsia in Ornithodoros hasei ticks from South American bats. (C) 2016 Elsevier GmbH. All rights reserved.
TICKS AND TICK-BORNE DISEASES

hal-01459758
https://hal.archives-ouvertes.fr/hal-01459758
DOI : 10.1016/j.ttbdis.2016.09.004

Éditeur(s) : HAL CCSD American Society of Tropical Medicine and Hygiene
Résumé : International audience
These authors contributed equally to this work. Abstract. Human behaviors are increasingly recognized to play a key role in the spread of infectious diseases. Although a set of social and cognitive determinants has been consistently found to affect the adoption of health protective behaviors aiming to control and prevent a variety of infections, little is currently known about the ecological drivers of these behaviors in epidemic settings. In this article, we took advantage of the outbreak of chikungunya, a reemerging mosquito-borne disease, that occurred in French Guiana in 2014–15 to test empirically the assumption proposed by Zielinski-Gutierrez and Hayden that the proximity of the disease and perceptions of the natural environment may considerably shape public response to an emerging health threat. To achieve this, a cross-sectional survey was conducted among high school students of the region (N = 1462) at an early stage of the epidemic. Surprisingly, spatial analysis of the collected data leads to counterintuitive results as the participants who lived in the most affected area expressed less concern about the disease and practiced preventive behaviors less frequently than did other participants. These paradoxical results may be attributed to the possible activation of risk denial processes which have previously been observed in the risk perception literature, and described by several social and psychological defensiveness theories.
ISSN: 0002-9637

hal-01589232
http://hal.univ-reunion.fr/hal-01589232
http://hal.univ-reunion.fr/hal-01589232/document
http://hal.univ-reunion.fr/hal-01589232/file/Flamand%20...Raude%202017%20%28CHIKV%20French%20Guiana%29.pdf
DOI : 10.4269/ajtmh.16-1028

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Local variation in the density of Anopheles mosquitoes and the risk of exposure to bites are essential to explain the spatial and temporal heterogeneities in the transmission of malaria. Vector distribution is driven by environmental factors. Based on variables derived from satellite imagery and meteorological observations, this study aimed to dynamically model and map the densities of Anopheles darlingi in the municipality of Saint-Georges de l’Oyapock (French Guiana). Longitudinal sampling sessions of An. darlingi densities were conducted between September 2012 and October 2014. Landscape and meteorological data were collected and processed to extract a panel of variables that were potentially related to An. darlingi ecology. Based on these data, a robust methodology was formed to estimate a statistical predictive model of the spatial-temporal variations in the densities of An. darlingi in Saint-Georges de l’Oyapock. The final cross-validated model integrated two landscape variables—dense forest surface and built surface—together with four meteorological variables related to rainfall, evapotranspiration, and the minimal and maximal temperatures. Extrapolation of the model allowed the generation of predictive weekly maps of An. darlingi densities at a resolution of 10-m. Our results supported the use of satellite imagery and meteorological data to predict malaria vector densities. Such fine-scale modeling approach might be a useful tool for health authorities to plan control strategies and social communication in a cost-effective, targeted, and timely manner.
ISSN: 1932-6203

hal-01383486
https://hal.archives-ouvertes.fr/hal-01383486
https://hal.archives-ouvertes.fr/hal-01383486/document
https://hal.archives-ouvertes.fr/hal-01383486/file/Adde_et_al_PlosONE_2016.pdf
DOI : 10.1371/journal.pone.0164685

Résumé : L'objectif du registre des cancers de Guyane est de collecter l ensemble des tumeurs invasives et/ou in situ survenues depuis le 1er janvier 2003 chez des patients vivant en Guyane, quels que soient la localisation de la tumeur, le lieu de diagnostic et de traitement. Cette thèse a pour but de décrire la population atteinte d un cancer afin d améliorer les connaissances sur cette maladie et ainsi de permettre aux actions de santé publique d être plus efficaces.De 2003 à 2009, le taux d incidence des cancers standardisé sur l âge était, dans les deux sexes, 30% inférieur en Guyane par rapport à la France métropolitaine et n était pas différent de celui d Amérique du Sud.Nous avons comparé l incidence, la mortalité et la survie relative des patientes atteintes d un cancer invasif du sein (CIS) et des patientes atteintes d un cancer invasif du col de l utérus (CIC) entre la Guyane et la métropole.Le ratio incidence/mortalité indiquait que les cancers du sein étaient de plus mauvais pronostic en Guyane par rapport à la métropole.La survie relative des femmes atteintes d un CIS était inférieure en Guyane par rapport à la France métropolitaine.En Guyane, le taux standardisé d incidence du cancer du col de l utérus était 4 fois plus élevé qu en métropole. Les femmes vivant dans l intérieur de la Guyane semblaient être diagnostiquées à un stade plus tardif et plus souvent sur symptômes que les femmes du littoral. L accès aux soins des migrants est un challenge et une source d inégalité de santé. La détection précoce des cancers à travers des programmes de prévention est cruciale pour améliorer la survie par cancer et notamment chez les patients étrangers.
The objective of the cancer registry of French Guiana is to compile all patients living in French Guiana with malignant invasive pathology and/or in situ lesions starting January 1st 2003 in persons living in French Guiana, whatever the tumoral location and the place of diagnosis and care. This study aimed to describe the population with invasive cancer to improve the knowledge about this disease in order to target public health interventions more effectively.The age standardised incidence rate was 30% times lower than in France in both sexes and the same than in South America.We compared incidence and relative survival of patients with invasive breast cancer (IBC) and patients with invasive cervical cancer (ICC) between women from French Guiana and metropolitan France.The ratio between incidence and mortality showed that the prognosis of IBC in French Guiana was worse than in metropolitan France.The relative survival rate among women with IBC in French Guiana was lower than among women in metropolitan France.In French Guiana, the age-standardized incidence rate of cervical cancer was four times higher than in France. Women living in remote areas seemed to be diagnosed later and more often following symptoms.Access to care for migrants is challenging and sustains health inequalities. Early detection through prevention programs is crucial for increasing cancer survival notably for foreign-born patients. Further studies with more patients and other variables could improve the knowledge about these diseases

http://www.theses.fr/2014AGUY0743/document

Éditeur(s) : HAL CCSD
Résumé : The forests of French Guiana occupy a central part of the region’s potential resource base, but as yet remain almost completely unexploited. This stems from the forestry industry struggling to valorize wood stocks of a high diversity with an extremely heterogeneous distribution. Indeed, identifying essences for future propagation is an issue of both environmental and socio-economic importance for the region. Bagassa guianensis Aubl. and Cordia alliodora (Ruiz & Pav.) Oken. go against conventional models, in that they display the life history characteristics of rapid growth and wood of high quality, and thus are species of high potential for future plantations. Firstly, our study of growth characteristics reveals a defined strategy half way between long-lived species and pioneer species. It is the variability of basic density of wood which is a key trait allowing for such a development, favoring rapid growth in initial years whilst allowing for tree longevity. Secondly, the analysis of a range of wood properties (shrinkage, modulus of elasticity, durability) in relation to tree growth confirms the technologic quality of the two species. It also enables the emergence of new results like the effect of extractives on wood stability, the control of growth as a result of basic density variation, the evolution of leaf traits throughout tree development or the improvement of trunk maintenance thanks to interlocked grain. The knowledge gained in relation to the developmental traits of these two species, and to the quality of their wood allows for the elaboration of plantation projects and what will be required for their success. The results of this study can orientate future studies on novel species for commercialization in French Guiana.
La ressource forestière en Guyane occupe une place maîtresse au sein de la région et est encore majoritairement préservée, mais la filière bois parvient difficilement à valoriser la biodiversité locale en raison de l’hétérogénéité de la ressource. Identifier les essences à planter demain représente aujourd’hui un enjeu à la fois environnemental, économique et social pour la Guyane. Bagassa guianensis Aubl. et Cordia alliodora (Ruiz & Pav.) Oken. vont à l’encontre des modèles usuels en associant vitesse de croissance et qualité du bois et sont identifiées comme prometteuses pour la plantation. Dans un premier temps, l’étude de la dynamique de croissance des deux espèces révèle un modèle écologique singulier, à la fois pionnières et longévives. La variabilité de l’infradensité dans l’arbre est l’élément clé qui permet un tel développement, favorisant une croissance rapide dans les premières années tout en assurant la longévité de l’individu. Dans une seconde partie, l’analyse d’un large panel de propriétés du bois (retrait, module, durabilité) en lien avec le développement de l’arbre confirme les qualités technologiques des deux espèces et permet l’émergence de résultats novateurs tels que le rôle des extractibles sur le retrait, le contrôle de la croissance grâce aux variations d’infradensité, l’évolution des traits foliaires au cours de l’ontogénie ou encore la mise en place de contrefil dans l’arbre pour assurer son maintien. La connaissance acquise vis-à-vis du mode de développement de ces deux espèces et des facteurs influençant la qualité de leur bois permet aujourd’hui de définir avec plus de précision le cadre d’un projet de plantation et les conditions de son succès. Les résultats de cette étude permettent finalement d’orienter la recherche de nouvelles espèces d’avenir pour la plantation en Guyane.
https://tel.archives-ouvertes.fr/tel-01430243

Droits : info:eu-repo/semantics/OpenAccess
NNT : 2015YANE0002
tel-01430243
https://tel.archives-ouvertes.fr/tel-01430243
https://tel.archives-ouvertes.fr/tel-01430243/document
https://tel.archives-ouvertes.fr/tel-01430243/file/julie-bossu.pdf

Éditeur(s) : HAL CCSD
Résumé : International audience
Background Mycobacterium ulcerans infection is the third most common mycobacterial disease in the world after tuberculosis and leprosy. To date, transmission pathways from its environmental reservoir to humans are still unknown. In South America, French Guiana has the highest reported number of M ulcerans infections across the continent. This empirical study aimed to characterise the epidemiology of M ulcerans infection in French Guiana between 1969 and 2013.MethodsData were collected prospectively mainly by two dermatologists at Cayenne Hospital’s dermatologydepartment between Jan 1, 1969, and Dec 31, 2013, for age, date of diagnosis, sex, residence, location of the lesion,type of lesion, associated symptoms, and diagnostic method (smear, culture, PCR, or histology) for all confirmed andsuspected cases of M ulcerans. We obtained population data from censuses. We calculated mean M ulcerans infectionincidences, presented as the number of cases per 100 000 person-years.Findings 245 patients with M ulcerans infections were reported at Cayenne Hospital’s dermatology department duringthe study period. M ulcerans infection incidence decreased over time, from 6·07 infections per 100 000 person-years(95% CI 4·46–7·67) in 1969–83 to 4·77 infections per 100 000 person-years (3·75–5·79) in 1984–98 and to3·49 infections per 100 000 person-years (2·83–4·16) in 1999–2013. The proportion of children with infections alsodeclined with time, from 42 (76%) of 55 patients in 1969–83 to 26 (31%) of 84 in 1984–98 and to 22 (21%) of 106 in1999–2013. Most cases occurred in coastal areas surrounded by marshy savannah (incidence of 21·08 per100 000 person-years in Sinnamary and 21·18 per 100 000 person-years in Mana). Lesions mainly affected limbs (lowerlimbs 161 [66%] patients; upper limbs 60 [24%] patients). We diagnosed no bone infections.Interpretation The decrease of M ulcerans infection incidence and the proportion of children with infections over a45 year period in this ultra-peripheral French territory might have been mostly driven by improving living conditions,prophylactic recommendations, and access to health care.
The Lancet Planetary Health

inserm-01545603
http://www.hal.inserm.fr/inserm-01545603
http://www.hal.inserm.fr/inserm-01545603/document
http://www.hal.inserm.fr/inserm-01545603/file/2017%2C%20Douine%20-%20Mycobacterium%20ulcerans%20infection%20%28Buruli%20ulcer%29.pdf
http://www.hal.inserm.fr/inserm-01545603/file/Comments.pdf