Disentangling the role of parasite infectivity and environmental density in infection development and parasite proliferation

Understanding the environmental drivers of host-parasite interactions is a major concern for human health and conservation, particularly in the context of emerging infectious diseases. The likelihood of contracting an infection can be related to both the rate of contact between host and parasite, as well as innate features of hosts (susceptibility/resistance) and parasites (infectivity, virulence, within-host proliferation rate). This study uses a host-parasite system with a matching allele model for host susceptibility and parasite infectivity to disentangle contact rate from parasite infectivity while accounting for the effects of host susceptibility. Using three exposure doses from several parasite isolates to hosts with known susceptibility, we find significant differences in parasite infectivity (in terms of number of successful infections) and proliferation rate inside the host among parasite isolates, after controlling for exposure rate and host genotype. Exposure dose did not im..., , # Data from: Disentangling the role of parasite infectivity and environmental density in infection development and parasite proliferation

Dataset DOI: [10.5061/dryad.7wm37pw5z](10.5061/dryad.7wm37pw5z)

## Description of the data and file structure

Nine clones of *Daphnia magna* were exposed to three calculated doses of six isolates of their parasite, *Pasteuria ramosa,* in a full factorial design, replicated at the individual level ten times for a total of 1620 individuals in isolated jars. Individuals were then monitored three times per week for 28 days, and at the end of the experiment, all individuals showing any signs of infection (no eggs, reddish colour, large size) were frozen in Eppendorf tubes with 1 mL of water. Tubes were then defrosted, their contents crushed with a pestle, and shaken at 4500 rpm for 2 hours to separate parasite spores, and a sample was placed in a hemocytomer. This was used to 1: confirm the presence of parasite spores to determine that the individual ha...,