Data from: Experimental investigation of alternative transmission functions: quantitative evidence for the importance of non-linear transmission dynamics in host-parasite systems

1. Understanding pathogen transmission is crucial for predicting and
managing disease. Nonetheless, experimental comparisons of alternative
functional forms of transmission remain rare, and those experiments that
are conducted are often not designed to test the full range of possible
forms. 2. To differentiate among ten candidate transmission functions, we
used a novel experimental design in which we independently varied four
factors—duration of exposure, numbers of parasites, numbers of hosts, and
parasite density—in laboratory infection experiments. 3. We used
interactions between amphibian hosts and trematode parasites as a model
system and all candidate models incorporated parasite depletion. An
additional manipulation involving anesthesia addressed the effects of host
behaviour on transmission form. 4. Across all experiments, non-linear
transmission forms involving either a power law or a negative binomial
function were the best-fitting models and consistently outperformed the
linear density-dependent and density-independent functions. By testing
previously published data for two other host-macroparasite systems, we
also found support for the same non-linear transmission forms. 5. Although
manipulations of parasite density are common in transmission studies, the
comprehensive set of variables tested in our experiments revealed that
variation in density alone was least likely to differentiate among
competing transmission functions. Across host-pathogen systems, non-linear
functions may often more accurately represent transmission dynamics and
thus provide more realistic predictions for infection.