HOST SPATIAL HETEROGENEITY AND EXTINCTION OF AN SIS EPIDEMIC

Spatially explicit epidemic models explore population-level consequenc es of interactions between neighboring infectious and susceptible indi viduals. Most such models equate local and global host density, so tha t each individual interacts with the same number of neighbors. But man y natural populations exhibit heterogeneity in local abundance. Theref ore, we let host dispersion vary from uniform to clumped in a spatial epidemic with recovery. We analytically approximated the epidemic with a branching process to show how the probability of pathogen extinctio n could depend on the degree of host clumping. We then simulated the d etailed model across a range of parameter combinations. Both approache s to the problem indicate that host spatial aggregation strongly incre ases the chance of pathogen extinction. (C) 1998 Academic Press Limite d.