Data from: Why is sterility virulence most common in sexually transmitted infections? examining the role of epidemiology

Sterility virulence, or the reduction in host fecundity due to infection,
occurs in many host-pathogen systems. Notably, sterility virulence is more
common for sexually-transmitted infections (STIs) than for
directly-transmitted pathogens, while other forms of virulence tend to be
limited in STIs. This has led to the suggestion that sterility virulence
may have an adaptive explanation. By focusing upon finite population
models, we show that the observed patterns of sterility virulence can be
explained by consideration of the epidemiological differences between STIs
and directly-transmitted pathogens. In particular, when pathogen
transmission is predominantly density-invariant (as for STIs), and
mortality is density-dependent, sterility virulence can be favoured by
demographic stochasticity, whereas if pathogen transmission is
predominantly density-dependent, as is common for most
directly-transmitted pathogens, sterility virulence is disfavoured. We
show these conclusions can hold even if there is a weak selective
advantage to sterilizing.