Meeting Abstract
Urbanization can have interacting and complex effects on wildlife immunology, behavior, and demography with important consequences for exposure to pathogens and sustained transmission. Predicting how urban habituation influences the transmission of multi-host pathogens in a single host species requires a mechanistic understanding of transmission pathways and within-species versus extrinsic sources of infectious propagules. Here we develop a mathematical model for the transmission dynamics of the enteric pathogen Salmonella spp. in urban-feeding white ibis (Eudocimus albus) to determine (i) the relative importance of close contact versus environmental transmission and (ii) whether sustained transmission can be supported by ibis alone or requires additional non-ibis sources of environmental pathogen stages. Using data on infection prevalence in urban ibis flocks and detections of Salmonella in soil and water from the same urban sites within South Florida, we assess support for various transmission routes and sources of infection using Latin hypercube sampling. Across all possible regions of parameter space, simulations that assume low effective contact between ibis, high exposure through environmental uptake, a prevalent non-ibis source of Salmonella input into the environment, and high rates of shedding by ibis into the environmental pathogen pool provide the most plausible explanations for the observed temporal patterns in infection prevalence. Our sensitivity analysis therefore suggests that urban white ibis are capable of sustaining seasonal transmission of Salmonella in the absence of other environmental sources.
