# A general framework for modeling pathogen transmission in co‐roosting host communities

## TL;DR

This paper presents a framework to model how pathogens spread among co-roosting wildlife species, showing that relatedness between species can influence infection rates.

## Contribution

The study introduces a generalizable modeling framework to assess cross-species pathogen transmission in co-roosting host communities.

## Key findings

- Relatedness between co-roosting hosts facilitates pathogen invasion, especially for poorly transmissible pathogens.
- Roost-level infection prevalence is highest when hosts are closely related, but can also increase with distant relations under certain conditions.
- The models are adaptable to other co-roosting systems with directly transmitted, low-virulence pathogens.

## Abstract

Cross‐species transmission of pathogens can be facilitated by frequent contact among wildlife. Cross‐species transmission is often driven by phylogenetic similarity between host species, but the role this plays when multiple host species co‐roost is unknown. We developed a generalizable framework for understanding how cross‐species transmission is driven by contact among co‐roosting species spanning evolutionary similarities and the net impact on roost‐level infection prevalence. We developed ordinary differential equation models describing population and infection dynamics between two and three co‐roosting species. We derived conditions for pathogen invasion and parameterized models using co‐roosting Neotropical bat systems, with interspecific transmission exponentially declining with phylogenetic distance. To assess the relative contribution of contact rates and phylogenetic similarity, we co‐varied intraspecific transmission rates and phylogenetic distances while considering sensitivity to epidemiological structure and pathogen traits. For both susceptible–infected–recovered–susceptible and susceptible–infected–latent–infected models, we show that relatedness between co‐roosting hosts facilitates pathogen invasion, particularly for poorly transmissible pathogens with short durations of infection and immunity or latency. These models converged on similar equilibria, and roost‐level prevalence was greatest when hosts were most closely related. However, we also identified regions of parameter space where roost‐level prevalence increased when hosts were distantly related. Our generalizable models are adaptable to other co‐roosting systems with low‐virulence pathogens that are directly transmitted and inform our understanding of pathogen spillover.