# Sit-and-wait pathogens: Consequences of heterogeneity in pathogen exposure dynamics for environmentally persistent pathogens

> **NIH NIH R01** · VIRGINIA POLYTECHNIC INST AND ST UNIV · 2024 · $588,814

## Abstract

Transmission is a fundamental component of host-pathogen systems. Despite complex biological 
processes interacting to determine whether a pathogen successfully infects a host, transmission 
parameters often assume a constant per-contact transmission probability. Factors that can influence risk of 
infection include the frequency of exposures, duration of a contact, and dose acquired during an 
interaction, which are collectively referred to as transmission determinants. These determinants of infection 
can vary among hosts and between routes of transmission (e.g. direct and indirect) and have profound 
effects on disease dynamics. Ultimately, a mechanistic understanding of how heterogeneity in transmission 
probabilities among exposure events contributes to disease dynamics remains an important outstanding 
question in the ecology and evolution of infectious diseases. Here we seek to elucidate how factors 
determining transmission success influence the probability of acquiring infection, epidemic 
dynamics, and pathogen evolution.
Specifically, we will investigate how transmission determinants (pathogen dose, contact duration, and 
contact frequency) vary among exposure routes (direct and indirect) and ultimately contribute to the 
dynamics of an emerging multi-host disease of snakes. Snake fungal disease (SFD) is caused by, 
Ophidiomyces ophidiicola, which is an environmentally persistent fungal pathogen that, to date, has been 
documented in more than 42 species of wild snakes on three continents, and has contributed to the severe 
declines of several species. O. ophidiicola is transmitted through direct and indirect contacts, and the 
behavior of snake species affected by SFD naturally vary along an exposure duration and contact intensity 
gradient, making this an ideal system for understanding the effects of variation in exposure events on 
disease dynamics. This work will highlight important mechanisms that contribute to variation in snake 
declines, and more broadly, provide insight into the theoretical underpinnings and profound effects that 
factors determining successful transmission can have on infectious disease outbreaks.
This proposal will leverage our recent advances in this multi-host system and use a combination of 
field, experimental, and modeling approaches to provide critical insight into how the dynamics of exposure 
events have cascading effects on infectious disease.

## Key facts

- **NIH application ID:** 10912819
- **Project number:** 5R01GM152978-02
- **Recipient organization:** VIRGINIA POLYTECHNIC INST AND ST UNIV
- **Principal Investigator:** Joseph Ryan Hoyt
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $588,814
- **Award type:** 5
- **Project period:** 2023-09-01 → 2028-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10912819

## Citation

> US National Institutes of Health, RePORTER application 10912819, Sit-and-wait pathogens: Consequences of heterogeneity in pathogen exposure dynamics for environmentally persistent pathogens (5R01GM152978-02). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10912819. Licensed CC0.

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