Rift Valley fever dynamics in Senegal: a project for pro-active adaptation and improvement of livestock raising management.

The multi-disciplinary French project "Adaptation à la Fiévre de la Vallée du Rift" (AdaptFVR) has concluded a 10-year constructive interaction between many scientists/partners involved with the Rift Valley fever (RVF) dynamics in Senegal. The three targeted objectives reached were (i) to produce--in near real-time--validated risk maps for parked livestock exposed to RVF mosquitoes/vectors bites; (ii) to assess the impacts on RVF vectors from climate variability at different time-scales including climate change; and (iii) to isolate processes improving local livestock management and animal health. Based on these results, concrete, pro-active adaptive actions were taken on site, which led to the establishment of a RVF early warning system (RVFews).

TerraSAR-X high-resolution radar remote sensing: an operational warning system for Rift Valley fever risk.

In the vicinity of the Barkedji village (in the Ferlo region of Senegal), the abundance and aggressiveness of the vector mosquitoes for Rift Valley fever (RVF) are strongly linked to rainfall events and associated ponds dynamics. Initially, these results were obtained from spectral analysis of high-resolution (~10 m) Spot-5 images, but, as a part of the French AdaptFVR project, identification of the free water dynamics within ponds was made with the new high-resolution (down to 3-meter pixels), Synthetic Aperture Radar satellite (TerraSAR-X) produced by Infoterra GmbH, Friedrichshafen/Potsdam, Germany. During summer 2008, within a 30 x 50 km radar image, it was found that identified free water fell well within the footprints of ponds localized by optical data (i.

Climate impacts on environmental risks evaluated from space: a conceptual approach to the case of Rift Valley Fever in Senegal.

Background: Climate and environment vary across many spatio-temporal scales, including the concept of climate change, which impact on ecosystems, vector-borne diseases and public health worldwide.

Objectives: To develop a conceptual approach by mapping climatic and environmental conditions from space and studying their linkages with Rift Valley Fever (RVF) epidemics in Senegal.

Design: Ponds in which mosquitoes could thrive were identified from remote sensing using high-resolution SPOT-5 satellite images.

Rift Valley fever in a zone potentially occupied by Aedes vexans in Senegal: dynamics and risk mapping.

This paper presents an analysis of the interaction between the various variables associated with Rift Valley fever (RVF) such as the mosquito vector, available hosts and rainfall distribution. To that end, the varying zones potentially occupied by mosquitoes (ZPOM), rainfall events and pond dynamics, and the associated exposure of hosts to the RVF virus by Aedes vexans, were analyzed in the Barkedji area of the Ferlo, Senegal, during the 2003 rainy season. Ponds were identified by remote sensing using a high-resolution SPOT-5 satellite image.

Mapping of zones potentially occupied by Aedes vexans and Culex poicilipes mosquitoes, the main vectors of Rift Valley fever in Senegal.

A necessary condition for Rift Valley fever (RVF) emergence is the presence of Aedes (Aedimorphus) vexans and Culex (Culex) poicilipes mosquitoes carrying the arbovirus and responsible for the infection. This paper presents a detailed mapping in the Sahelian region of Senegal of zones potentially occupied by these mosquitoes (ZPOMs) whose population density is directly linked to ecozones in the vicinity of small ponds. The vectors habitats and breeding sites have been characterized through an integrated approach combining remote sensing technology, geographical information systems, geographical positioning systems and field observations for proper geo-referencing.

Satellite imaging and vector-borne diseases: the approach of the French National Space Agency (CNES).

Tele-epidemiology consists in studying human and animal epidemic, the spread of which is closely tied to environmental factors, using data from earth-orbiting satellites. By combining various data originated from satellites such as SPOT (vegetation indexes), Meteosat (winds and cloud masses) and other Earth observation data from Topex/Poseidon and Envisat (wave height, ocean temperature and colour) with hydrology data (number and distribution of lakes, water levels in rivers and reservoirs) and clinical data from humans and animals (clinical cases and serum use), predictive mathematical models can be constructed. A number of such approaches have been tested in the last three years.

Prevalence of West Nile virus neutralizing antibodies in wild birds from the Camargue area, southern France.

The Camargue area of southern France experienced the re-emergence of West Nile Virus (WNV) in the late summer of 2000 and 2004. Immediately preceding the 2004 outbreak, samples were collected from 432 birds of 32 different species captured in mist nets and from 201 Cattle Egret (Bubulcus ibis) nestlings sampled in their nests between 1 April and 12 June 2004. West Nile virus neutralizing titers of >/=40 were detected in 4.

Application of space technologies to the surveillance and modelling of waterborne diseases.

Earth observing satellites, global positioning and geographic information systems are new tools that currently enable the scientific community to integrate ecological, environmental and medical data to develop predictive models for disease surveillance and modelling. A number of investigators have explored remotely sensed environmental factors that might be associated with waterborne disease ecology and human transmission risk. However, health specialists have not been fully familiarized with the capabilities of space technology, and in some cases it has not proved to be the wonder tool that scientists expected.

Magpies as hosts for West Nile virus, southern France.

European magpies (Pica pica) from southern France were tested for antibodies to West Nile virus (WNV) and viral shedding in feces during spring-autumn 2005. Results suggest that this peridomestic species may be a suitable sentinel species and a relevant target for additional investigations on WNV ecology in Europe.