Sit-and-wait pathogens: Consequences of heterogeneity in pathogen exposure dynamics for environmentally persistent pathogens
NIH
VIRGINIA POLYTECHNIC INST AND ST UNIV
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. Our research will provide a framework for understanding the role of transmission determinates in infectious  disease dynamics across a broad array of infectious disease systems. Our work will therefore contribute to  the control of infectious diseases to enhance human health and reduce illness.
Non-SBIR/STTR