Stochastic Modelling of the Spatial Spread of Influenza in Germany

Abstract

In geographical epidemiology, disease counts are typically available in discrete spatial units and at discrete time-points. For example, surveillance data on infectious diseases usually consists of weekly counts of new infections in pre-defined geographical areas. Similarly, but on a different timescale, cancer registries typically report yearly incidence or mortality counts in administrative regions.A major methodological challenge lies in building realistic models for spacetime interactions on discrete irregular spatial graphs. In this paper we will discuss an observation-driven approach, where past observed counts in neighboring areas enter directly as explanatory variables, in contrast to the parameterdriven approach through latent Gaussian Markov random fields (Rue and Held, 2005) with spatio-temporal structure. The main focus will lie on the demonstration of the spread of influenza in Germany, obtained through the design and simulation of a spatial extension of the classical SIR model (Hufnagel et al., 2004).