One of the fundamental challenges in contemporary disease ecology involves understanding infection dynamics within complex communities composed of multiple hosts and multiple pathogens. Hosts in nature are exposed to a 'cocktail'of different pathogens, therefore a central question concerns how interactions between co-occurring pathogens affect disease severity and pathogen transmission in host communities. Most research to date has been focused at a single level, examining either how multiple infections influence individual host pathology or using population surveys to identify correlations in pathogen co-occurrence within a host population. This focus on single scales (i.e., within-host vs. between- host) neglects a critically important question - namely, how do pathogen interactions within hosts 'scale up'to influence between- host processes, such as transmission and disease dynamics? The primary goal of this project is to understand how interactions among three virulent pathogens at different scales of biological complexity, including within hosts, between species, and among communities, combine to influence disease dynamics in amphibians, a group of globally threatened vertebrates. This project combines cross-sectional field surveys of wetland communities with controlled laboratory and mesocosm experiments to determine (1) how amphibian pathogens co-vary in occurrence and intensity across multiple spatial scales (individual hosts, host species, wetland communities), (2) the individual and combined effects of each pathogen on host pathology and pathogen infection success, and (3) the net effects of variation in host and pathogen community structure for pathogen transmission and host-pathogen dynamics. A stochastic, simulation-based modeling framework, uniquely focused on individual hosts, will be used to interpret experimental results and link field distributions of pathogens with underlying mechanisms. This project focuses on three pathogens that have been widely implicated in causing amphibian pathology: the chytrid fungus Batrachochytrium dendrobatidis, the trematode Ribeiroia ondatrae, and the viral genus Ranavirus.

Public Health Relevance

Results from this work will build toward a more mechanistic understanding of how changes in complex ecological communities - including both hosts and pathogens - interact to influence disease risk, laying a foundation to develop effective tools for forecasting epidemics and improving our understanding of disease emergence in both humans and wildlife. A broader understanding of the conditions in which pathogens interact to affect disease patterns has immediate relevance for public health, conservation, and wildlife management.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
Project #
Application #
Study Section
Special Emphasis Panel (ZRG1-IDM-U (55))
Program Officer
Eckstrand, Irene A
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of California Santa Barbara
Organized Research Units
Santa Barbara
United States
Zip Code
Wilber, Mark Q; Weinstein, Sara B; Briggs, Cheryl J (2016) Detecting and quantifying parasite-induced host mortality from intensity data: method comparisons and limitations. Int J Parasitol 46:59-66
Calhoun, Dana M; Woodhams, Doug; Howard, Cierra et al. (2016) Role of Antimicrobial Peptides in Amphibian Defense Against Trematode Infection. Ecohealth 13:383-91
Jayawardena, Uthpala A; Rohr, Jason R; Navaratne, Ayanthi N et al. (2016) Combined Effects of Pesticides and Trematode Infections on Hourglass Tree Frog Polypedates cruciger. Ecohealth 13:111-22
Hannon, Emily R; Kinsella, John M; Calhoun, Dana M et al. (2016) Endohelminths in Bird Hosts from Northern California and an Analysis of the Role of Life History Traits on Parasite Richness. J Parasitol 102:199-207
Rohr, Jason R; Farag, Aïda M; Cadotte, Marc W et al. (2016) Transforming ecosystems: When, where, and how to restore contaminated sites. Integr Environ Assess Manag 12:273-83
Jennings, David E; Krupa, James J; Rohr, Jason R (2016) Foraging modality and plasticity in foraging traits determine the strength of competitive interactions among carnivorous plants, spiders, and toads. J Anim Ecol :
De Laender, Frederik; Rohr, Jason R; Ashauer, Roman et al. (2016) Reintroducing Environmental Change Drivers in Biodiversity-Ecosystem Functioning Research. Trends Ecol Evol 31:905-915
Johnson, Pieter T J; Wood, Chelsea L; Joseph, Maxwell B et al. (2016) Habitat heterogeneity drives the host-diversity-begets-parasite-diversity relationship: evidence from experimental and field studies. Ecol Lett 19:752-61
Sauer, Erin L; Sperry, Jinelle H; Rohr, Jason R (2016) An efficient and inexpensive method for measuring long-term thermoregulatory behavior. J Therm Biol 60:231-6
Joseph, Maxwell B; Preston, Daniel L; Johnson, Pieter T J (2016) Integrating occupancy models and structural equation models to understand species occurrence. Ecology 97:765-75

Showing the most recent 10 out of 22 publications