Data for: Co-infection, but not infection intensity, increases shedding in a gastrointestinal helminth of gamebirds

Host heterogeneity in disease transmission is commonly seen across
host-pathogen systems and identifying individuals who contribute
disproportionately to pathogen transmission (i.e. superspreaders) is key
to understanding disease dynamics and managing outbreaks. It is often
assumed that shedding intensity is directly proportional to infection
intensity. However, theory predicts that co-infection might modulate the
relationship between infection intensity and shedding, promoting increased
onward transmission. Here we quantify the relative importance of infection
intensity and co-infection on shedding in Heterakis gallinarum, a
gastrointestinal helminth of gamebirds. We found that infection intensity
was a poor predictor of shedding intensity. Instead, increased shedding
was linked to co-infections with other endoparasites. Our results show
that shedding intensity is not simply explained by infection intensity,
but rather is the result of complex host-parasite and parasite-parasite
interactions. This highlights the importance of considering such
interactions in understanding disease emergence and persistence in natural
populations.