In the context of climate change and the rapidly increasing population, some epidemics are emerging or re-emerging such as the Rift Valley Fever in West Africa.
The French Spatial Agency (CNES) has thus developed a concept based on a deterministic approach of the relations climate-environment-health and on an original and really adapted space offer (Lacaux et al., 2007 ; CNES, 2008).
It aims to monitor and study the spread of human and animal infectious diseases which are closely tied to climate and environmental changes. By combining satellite-originated data on vegetation (SPOT), meteorology (Meteosat, TRMM), oceanography (Topex/Poseidon ; ENVISAT, JASON) with hydrology data (distribution of lakes, water levels in rivers, ponds and reservoirs), with clinical data from humans and animals (clinical cases and serum use), predictive mathematical models can be constructed. Lately as a part of the French Ministry of Research’s Earth-Space Network, a pilot sentinel network has been deployed in Niger and Burkina Faso for monitoring infectious diseases such as malaria, which is also tied to changing environmental factors. This integrated and multidisciplinary approach of tele-epidemiology includes : (1) monitoring and assembling multidisciplinary in-situ datasets to extract and identify physical and biological mechanisms at stake ;
(2) remote-sensing monitoring of climate and environment, linking epidemics with ‘confounding factors’ such as rainfall, vegetation, hydrology and population dynamics ; and
(3) use of bio-mathematical models for epidemic dynamics, vector aggressiveness and associated risks.
In AdaptFVR project, the interactions between climatic and environmental variables associated with Rift Valley Fever (RVF) epidemics are evaluated from space. Ponds were identified by remote sensing using a high-resolution SPOT-5 satellite images. Data on ponds and rainfall events obtained from the Tropical Rainfall Measuring Mission were combined with in-situ data. Localization of vulnerable hosts (from QuickBird satellite) are also used.
The dynamic spatio-temporal distribution of Aedes vexans density (one of the main RVF vectors) was based on the total rainfall amount and pond dynamics. Detailed risks zones, i.e. zones where hazards and vulnerability are combined, are expressed by percentages of parks where animals are potentially exposed to mosquito bites.
This new conceptual approach, simply relies upon rainfall distribution evaluated from space. It is meant to contribute to the implementation of operational early warning system for RVF based on environmental risks linked to climatic and environmental changing conditions: natural and anthropogenic. In a climate change context, this approach is also to be applied to other diseases and places worldwide.