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DY: Fachverband Dynamik und Statistische Physik

DY 9: Statistical physics in biological systems

DY 9.5: Vortrag

Montag, 26. März 2007, 17:30–17:45, H3

The role of heterogeneity in the dynamics of infectious diseases — •Alejandro Morales Gallardo, Dirk Brockmann, and Theo Geisel — MPI for Dynamics and Self-organization, Göttingen, Germany

Most sexually transmitted diseases cannot be understood without the strong variability of sexual activity within human populations. Furthermore, emergent infectious diseases such as SARS showed that social heterogeneities play a vital role in the spread and prevalence of some diseases. It is commonly believed that inhomogeneities, for instance the existence of superspreaders can lead to a larger basic reproduction number R₀. We examined the role of heterogeneities in a SIS model with variable contact rates. The time between infections as well as the time of being infectious are considered as Poisson processes. The heterogeneity is introduced by variable individual contact rates. Our results show that the degree of fluctuation increases as a function of contact rate variability around the SIS endemic state. Moreover, fluctuations tend to be asymmetric in strongly heterogeneous systems. Although heterogeneities lead to more explosive outbreaks, the number of infected individuals in the endemic state is smaller than predicted for homogeneous populations. Both results indicate that epidemiological data could be misleading when estimating the basic reproduction number R₀, a key epidemiological parameter, and in consequence erroneous measures would be adopted in diseases where heterogeneities dominate.