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 intera..., Study system and sample collection Ring-necked pheasants (Phasianus colchicus) were collected postmortem between November and December 2023 from 8 recreational pheasant shoots across south-west England. Pheasants were sexed and body size (beak - cloaca length, to the nearest 0.5cm) and body mass (to the nearest 0.5g) were recorded. Scaled mass index (SMI) was calculated as a measure of body condition following (Peig and Green, 2009). We calculated SMI separately for males and females to account for sexual size dimorphism. A faecal sample was collected directly from the cloaca and refrigerated at 4°C within 10 hours of collection. The lower digestive tract (small intestine, large intestine, and caeca) was removed and immediately stored in 10% formalin. In total, faecal samples and intestines from 58 pheasants were obtained. This research was conducted under the approval of the Ethical Committee of the University of Exeter (ethical approval number 513904). The study was conducted in accor..., , # Data for: Co-infection, but not infection intensity, increases shedding in a gastrointestinal helminth of gamebirds [https://doi.org/10.5061/dryad.sqv9s4ndd](https://doi.org/10.5061/dryad.sqv9s4ndd) ## Description of the data and file structure This dataset accompanies the manuscript **\"Co-infection, but not infection intensity, increases shedding in a gastrointestinal helminth of gamebirds.\"** It includes infection and co-infection data for *Phasianus colchicus*, collected from dissections, faecal egg counts, and intestinal examinations. ### Files and variables #### File: supershedder_co_infection_data.csv **Description:** This file contains data associated with infection, co-infection, and variables related to host traits. Data collected from, dissections, faecal egg counts, and internal intestinal examination of *Phasianus colchicus*. Abbreviations in the site variable match those used in the manuscript.  ##### Variables * code: Unique identification code given to each *Ph..., ,