Measles outbreak reveals measles susceptibility among adults in Namibia, 2009 - 2011

Background. The World Health Organization, African Region, set the goal of  achieving measles elimination by 2020. Namibia was one of seven African countries to implement an accelerated measles control strategy beginning in 1996. Following implementation of this strategy, measles incidence decreased; however, between 2009 and 2011 a major outbreak occurred in Namibia.Methods. Measles vaccination coverage data were analysed and a descriptive  epidemiological analysis of the measles outbreak was conducted using measles case-based surveillance and laboratory data.Results. During 1989 - 2008, MCV1 (the first routine dose of measles vaccine) coverage increased from 56% to 73% and five supplementary immunisation activities were implemented. During the outbreak (August 2009 - February 2011), 4 605 suspected measles cases were reported; of these, 3 256 were confirmed by laboratory testing or epidemiological linkage. Opuwo, a largely rural district in north-western Namibia with nomadic populations, had the highest confirmed measles incidence (16 427 cases per million). Infants aged ≤11 months had the highest cumulative age-specific incidence (9 252 cases per million) and comprised 22% of all confirmed cases; however, cases occurred across a wide age range, including adults aged ≥30 years. Among confirmed cases, 85% were unvaccinated or had unknown vaccination history. The predominantly detected measles virus genotype was B3, circulating in concurrent outbreaks in southern Africa, and B2, previously detected in Angola.Conclusion. A large-scale measles outbreak with sustained transmission over 18 months occurred in Namibia, probably caused by importation. The wide age distribution of cases indicated measles-susceptible individuals accumulated over several decades prior to the start of the outbreak

Agroforesterie et services écosystémiques en zone tropicale

Respectueux de l’environnement et garantissant une sécurité alimentaire soutenue par la diversification des productions et des revenus qu’ils procurent, les systèmes agroforestiers apparaissent comme un modèle prometteur d’agriculture durable dans les pays du Sud les plus vulnérables aux changements globaux. Cependant, ces systèmes agroforestiers ne peuvent être optimisés qu’à condition de mieux comprendre et de mieux maîtriser les facteurs de leurs productions. L’ouvrage présente un ensemble de connaissances récentes sur les mécanismes biophysiques et socio-économiques qui sous-tendent le fonctionnement et la dynamique des systèmes agroforestiers. Il concerne, d’une part les systèmes agroforestiers à base de cultures pérennes, telles que cacaoyers et caféiers, de régions tropicales humides en Amérique du Sud, en Afrique de l’Est et du Centre, d’autre part les parcs arborés et arbustifs à base de cultures vivrières, principalement de céréales, de la région semi-aride subsaharienne d’Afrique de l’Ouest. Il synthétise les dernières avancées acquises grâce à plusieurs projets associant le Cirad, l’IRD et leurs partenaires du Sud qui ont été conduits entre 2012 et 2016 dans ces régions. L’ensemble de ces projets s’articulent autour des dynamiques des systèmes agroforestiers et des compromis entre les services de production et les autres services socio-écosystémiques que ces systèmes fournissent

Estimation de l'évapotranspiration par télédétection spatiale : Enjeux et application en Afrique sahélienne

International audienc

Identification of a novel lymphoid population in the murine epidermis

10.1038/srep12554Scientific Reports51255

Estimating evapotranspiration from remote sensing in West Africa: application of S-SEBI and Ts-VI triangle methods

International audienc

Monitoring evapotranspiration from remote sensing data for groundwater resources evaluation.

International audienceEvapotranspiration (ET) is a fundamental variable of the hydrological cycle which plays a major role on surface water balance and surface energy balance. At local scale ET can be estimated from detailed ground observations (eddy covariance towers), but these measurements are only representative of very limited homogeneous area. When regional information is required, e.g. for monitoring ground water resources, the flux tower measurements cannot be used directly and estimation of ET often relies on estimation from meteorological data through potential evapotranspiration formulas. At regional scale remote sensing provides spatially distributed information for mapping and monitoring ET, but this information is still rarely used for ground water assessment. Indeed, remote sensing estimation of ET suffers several drawbacks. In particular, remote sensing information by itself cannot provide a continuous monitoring of ET because of the presence of clouds and the revisit period of the sensor. Another difficulty originates in the lack of exhaustive evaluation of remote sensed ET since accurate ground measurements are scarce and representative of a limited number of homogeneous areas. This has also for consequence that a large number of methodologies to derive ET were developed with no real possibility of a consistent evaluation. We have developed the EVASPA (EVapotranspiration Assessment from SPAce) tool to monitor ET on a daily basis, together with an evaluation of the associated uncertainties, from remote sensing data in the thermal and the solar domains (Gallego Elvira et al. 2013). This tool combines the estimation of ET from various models and various sources of data, including MODIS sensors, LANDSAT-borne sensors and meteorological information. EVASPA was applied to estimate evapotranspiration over several areas in the products such as MOD16 or analysis of atmospheric-hydrological modeling such as the operational Safran-Isba-Modcou application). The results highlight the potential use of the retrieved ET for calibrating groundwater models (e.g. for estimating aquifer parameters…) or evaluating model inputs (e.g. determination of effective rainfall, identification of irrigated areas…). We also evaluated the impact of the uncertainties in the estimation of ET in the monitoring of ground water. We showed that the main sources of ET uncertainty were related to the uncertainties in incident radiations and surface temperature together with the diversity of ET models. When forced in ground water models, the uncertainties in ET had an impact almost equivalent to the impact of uncertainties in rain inputs. South of France to help in monitoring the water budget of different hydrosystems: superficial aquifer in the Rhône river delta (Camargue), karstic aquifer of the Fontaine de Vaucluse spring system and alluvial aquifer in Limagne with increasing water withdrawing for irrigation. The method was first evaluated against flux tower measurements of evapotranspiration (RMSE between 0.5 and 1 mm/day depending on the ecosystems). When integrated over watershed, ET retrievals were also compared to indirect estimates of evapotranspiration from either water balance and stream flow monitoring or other modelling approaches for time period of more than a decade (these include remote sensing operationa

Monitoring evapotranspiration from remote sensing data for groundwater resources evaluation

International audienceEvapotranspiration (ET) is a fundamental variable of the hydrological cycle which plays a major role on surface water balance and surface energy balance. At local scale ET can be estimated from detailed ground observations (eddy covariance towers), but these measurements are only representative of very limited homogeneous area. When regional information is required, e.g. for monitoring ground water resources, the flux tower measurements cannot be used directly and estimation of ET often relies on estimation from meteorological data through potential evapotranspiration formulas. At regional scale remote sensing provides spatially distributed information for mapping and monitoring ET, but this information is still rarely used for ground water assessment. Indeed, remote sensing estimation of ET suffers several drawbacks. In particular, remote sensing information by itself cannot provide a continuous monitoring of ET because of the presence of clouds and the revisit period of the sensor. Another difficulty originates in the lack of exhaustive evaluation of remote sensed ET since accurate ground measurements are scarce and representative of a limited number of homogeneous areas. This has also for consequence that a large number of methodologies to derive ET were developed with no real possibility of a consistent evaluation. We have developed the EVASPA (EVapotranspiration Assessment from SPAce) tool to monitor ET on a daily basis, together with an evaluation of the associated uncertainties, from remote sensing data in the thermal and the solar domains (Gallego Elvira et al. 2013). This tool combines the estimation of ET from various models and various sources of data, including MODIS sensors, LANDSAT-borne sensors and meteorological information. EVASPA was applied to estimate evapotranspiration over several areas in the products such as MOD16 or analysis of atmospheric-hydrological modeling such as the operational Safran-Isba-Modcou application). The results highlight the potential use of the retrieved ET for calibrating groundwater models (e.g. for estimating aquifer parameters…) or evaluating model inputs (e.g. determination of effective rainfall, identification of irrigated areas…). We also evaluated the impact of the uncertainties in the estimation of ET in the monitoring of ground water. We showed that the main sources of ET uncertainty were related to the uncertainties in incident radiations and surface temperature together with the diversity of ET models. When forced in ground water models, the uncertainties in ET had an impact almost equivalent to the impact of uncertainties in rain inputs. South of France to help in monitoring the water budget of different hydrosystems: superficial aquifer in the Rhône river delta (Camargue), karstic aquifer of the Fontaine de Vaucluse spring system and alluvial aquifer in Limagne with increasing water withdrawing for irrigation. The method was first evaluated against flux tower measurements of evapotranspiration (RMSE between 0.5 and 1 mm/day depending on the ecosystems). When integrated over watershed, ET retrievals were also compared to indirect estimates of evapotranspiration from either water balance and stream flow monitoring or other modelling approaches for time period of more than a decade (these include remote sensing operationa