The amphibian parasite Batrachochytrium dendrobatidis (Bd) is regarded as an extreme generalist,
infecting over 500 species, but amongst these hosts there exists a great deal of variation in the
susceptibility to and the costs of parasite exposure. We use two infection experiments to determine
whether inter-specific variation in the sublethal and lethal effects of parasite exposure exist in two
host species. We then tested the relative roles of host density and diversity on infection probability
of a focal susceptible host. Our results show significant heterogeneity in host species response to
parasite exposure, and that both lethal and sub-lethal costs exist in individuals that are able to
resist infection, indicating that successful immune response to infection comes at a cost. Further,
we show that increasing host density significantly increased the likelihood of susceptible individuals
becoming infected with Bd irrespective of host diversity and variation in host susceptibility. These
results suggest that populations of resistant species are likely to suffer ill-effects of exposure to Bd
regardless of their infection status, and that at the stage of initial infection there was no support
for the dilution of transmission events, in contrast to other studies that focus on subsequent
transmission of infection.