Human mobility patterns have a significant influence on the spreading of infectious disease. We will assume here that the coupling between patches is via migration, movement of individuals from one patch into another (as in Liebovitch and Schwartz 2004; Ruan et al. 2006; Sattenspiel and Dietz 1995; Grais et al. 2003 ). An alternative coupling strategy is mass action coupling, in which susceptibles in one patch are assumed to interact with infectives in another patch, introducing nonlinear coupling terms (Bolker and Grenfell 1995; Lloyd and May 1996; Rohani et al. 1999) . Stochastic coupling can be modeled (see Keeling and Rohani 2002 and references therein, and Colizza and Vespignani 2008) .