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

传播是宿主-病原体系统的基本组成部分。尽管复杂的生物学 相互作用以确定病原体是否成功感染宿主的过程， 参数通常假定恒定的每次接触传输概率。可能影响风险的因素 感染包括暴露的频率，接触的持续时间，以及在接触期间获得的剂量。 相互作用，统称为传输决定因素。这些感染的决定因素 可以在宿主之间和传播途径之间（例如直接和间接）变化，并具有深刻的 对疾病动力学的影响。最终，一个关于异质性在传播中的机制性理解 暴露事件之间的概率对疾病动力学的贡献仍然是一个重要的突出问题， 传染病的生态学和进化问题。在这里，我们试图阐明如何因素 确定传播成功影响获得感染、流行病的概率 动力学和病原体进化。 具体而言，我们将调查传播决定因素（病原体剂量、接触时间和 接触频率）因接触途径（直接和间接）而异，并最终导致 一种新出现的多宿主蛇病的动态。蛇真菌病（SFD）是由， Ophidiomyces ophidiicola是一种环境持久性真菌病原体，迄今为止， 在三大洲超过42种野生蛇类中有记录，并导致了严重的 几个物种的灭绝。O. Ophidiicola通过直接和间接接触传播， 受SFD影响的蛇种的行为自然地随着暴露持续时间和接触强度而沿着变化 梯度，使其成为了解曝光事件变化对 疾病动态这项工作将突出的重要机制，有助于变异蛇 下降，更广泛地说，提供了深入了解的理论基础和深远的影响， 决定成功传播的因素可能对传染病爆发产生影响。 该提案将利用我们在此多主机系统中的最新进展，并结合使用 现场，实验和建模方法，以提供关键的洞察力如何暴露的动态 事件对传染病有连锁反应。

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.