Spatial-temporal dynamics of yellow fever virus in the state of São Paulo, Brazil

Abstract

Yellow fever is a hemorrhagic fever that affects about 200,000 people annually in the endemic regions. It is transmitted in its wild cycle through the bite of infected Haemagogus spp. and Sabethes spp. mosquitos, which are arboreal and abundant in fragmented and degrades landscapes. Connectivity among habitats is important for a wide range of ecological processes, including disease transmission, once it describes the degree to which an environment´s spatial configuration facilitates or impedes vectors flows. However, our understanding of how landscape connectivity modulates yellow fever virus dispersion remains limited. To understand these effects, nonhuman primates constitute a privileged study element, once they are the main hosts of the virus and serve as an alert to the health agencies about the circulation of the agent. Here we will use circuit theory to model yellow fever virus flow in 30 municipalities of the state of São Paulo, Brazil. In the first step we will create a cost surface that represent permeability of the landscape to movement for yellow fever virus. For this we will use as basis the land use land cover map created by The Brazilian Sustainable Development Foundation, for the year of 2013, and which have six classes: water, urban, agricultural, forest, natural non-forest and forestry areas. Then we will use epizootic coordinates events through São Paulo state as nodes and circuit theory to connect pairs of nodes. The date of each event will be used in order to understand the temporality of the virus dispersal. With the resistance values generate by the Circuit Scape program, we will calculate the least expensive route between nodes, creating a map of connectivity. Evaluating contributions of these factors to yellow fever risk may enable predictions of future outbreaks and is critical to development of effective public health strategies. (AU)