Università degli studi di Napoli Federico II; Global Network of Geospatial Health (GnosisGIS)
Doi
Abstract
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. Additional data on ponds and
rainfall events from the Tropical Rainfall Measuring Mission were combined with in-situ entomological and limnimetric
measurements, and the localization of vulnerable ruminant hosts (data derived from QuickBird satellite). Since
“Ae. vexans productive events” are dependent on the timing of rainfall for their embryogenesis (six days without rain
are necessary to trigger hatching), the dynamic spatio-temporal distribution of Ae. vexans density was based on the
total rainfall amount and pond dynamics. Detailed ZPOM mapping was obtained on a daily basis and combined with
aggressiveness temporal profiles. Risks zones, i.e. zones where hazards and vulnerability are combined, are expressed
by the percentages of parks where animals are potentially exposed to mosquito bites. This new approach, simply relying
upon rainfall distribution evaluated from space, is meant to contribute to the implementation of a new, operational
early warning system for RVF based on environmental risks linked to climatic and environmental conditions