Although parasite probability of infection and intensity are central to understanding parasite distributions and their ecological and evolutionary impacts, the drivers of these parameters remain poorly understood. At a local scale, we examined how host dietary niche partitioning and river landscape processes influence infections of the trematode Renifer aniarum in a community of watersnakes (Nerodia spp.). Host-specific dietary preferences and body size (SVL) were associated with infection probability among sympatric congeners. However, contrary to predictions of the stream drift hypothesis, infection probability increased with distance upstream. These results highlight that, even at local scales, multiple factors can distinctly shape the infection dynamics of a generalist parasite across closely related, co-occurring hosts.