Scott Duke-Sylvester
Friday, October 17, 2008 - 2:00-2:30
We present results from a spatial model of raccoon rabies in which a latitudinal gradient in the seasonal reproduction of the host leads to an unexpected trend in the spatial synchronization of epidemics. Disease models often assume spatially constant host demographic processes. However, as a disease spreads it may encounter host populations governed by different demographic processes. Using our model, we consider a north-south gradient in the length of the seasonal parturition period of raccoons (Procyon lotor). Our ecological intuition was that the short northern birth pulse would tend to entrain local host dynamics and consequently produce spatially synchronized epidemics. In the absence of strong seasonal forcing we expected southern populations to proceed along locally determined trajectories resulting in spatially asynchronous epidemics. Contrary to intuition and previous results from childhood diseases, the short northern birth pulse resulted in spatially asynchronous epidemics while weak seasonal forcing resulted in epidemics that were spatially synchronized. Differences in the synchronization of epidemics can have important consequences for the allocation of public health resources to the surveillance of wildlife diseases. In the case of rabies, surveillance in a northern population will require sampling at most locations to detect local epidemics. In southern populations, the epidemiological dynamics for an entire region can be assessed through surveillance at a few locations.
Keywords: SPATIAL MODELING, RABIES, RACCOONS (PROCYON LOTOR)