How do disease hotspots move in time and space?
Ongoing emergence of infectious diseases has prompted heightened interest in understanding the ecological drivers of infection. In wildlife, for instance, infections ranging from salmonid whirling disease to crayfish plague have had devastating effects in managed and wild populations of aquatic organisms. Often a major impediment to developing better models for forecasting patterns of emergence and disease spread is the relative rarity of multi-scale databases on parasites, particularly for infections of non-human hosts. Currently our group is exploring several questions related to disease macroecology, including the spread of infections from human to wildlife hosts, the large-scale drivers of bird mortality events, mechanisms underlying the relationship between the logmean and logvariance of infection, and spatiotemporal patterns in parasite richness and disease hotspots in aquatic ecosystems.
A major effort over the past 15 years has been compilation and development of the Aquatic Parasite Observatory (APO, www.aquaticparasites.org). The purpose behind the APO is to investigate infections and their consequences for freshwater taxa, with a focus on amphibians, birds, snails, and fishes. This effort was initially launched to examine the role of infectious agents for amphibians, which have become the most threatened class of vertebrates worldwide due, in part, to infectious disease threats. In cooperation with the US Fish and Wildlife Service, we are examining parasites of amphibians collected from National Wildlife Refuges across the United States. This work has subsequently been extended to explore patterns of infection in other aquatic hosts, such as fishes, invertebrates, and water-associated birds. These data will be invaluable toward understanding (i) how community interactions among parasites affect the abundance of pathogenic species, (ii) exploring how parasite abundance and richness covary in response to latitudinal, longitudinal and land-use gradients, and (iii) evaluating whether aquatic parasites can be used as indicators of environmental condition, including free-living diversity.
Stephens, P. E., Altizer, S., Smith, K. F., Aguirre, A. A., Brown, J. H., Budischak, S., Byers, J. E., Dallas, T., Davies, J. T., Drake, J. M., Ezenwa, V., Farrel, M., Gittleman, J. L., Han, B., Huang, S., Hutchinson, R. A., Johnson, P. T. J., Nunn, C. L., Onstad, D., Park, A., Vazquez-Prokopec, G. M., Schmidt, J. P. and R. Poulin (2016). The macroecology of infectious diseases: a new perspective on global-scale drivers of pathogen distributions and impacts. Ecology Letters (in press). PDF
Wood, C. L. and P. T. J. Johnson (2016). How does space influence the relationship between host and parasite diversity? Journal of Parasitology (in press). PDF
Johnson P. T. J., Wood, C. L., Joseph, M. B., Preston, D. L., Haas, S. E., and Y. P. Springer (2016). Habitat heterogeneity drives the host diversity begets-parasite diversity relationship: evidence from experimental and field studies. Ecology Letters 19: 752-761. PDF
Mihaljevic, J. R., Joseph, M. B., and P. T. J. Johnson (2015). Using multi-species occupancy models to improve the characterization and understanding of metacommunity structure. Ecology 96: 1783-1792. PDF
Johnson, P. T. J. and J. T. Hoverman (2014). Heterogeneous hosts: how variation in host size, behaviour and immunity affect parasite aggregation. Journal of Animal Ecology 83: 1103-1112. PDF
Richgels, K. L. D., Hoverman, J. T., and P. T. J. Johnson (2013). Evaluating the role of regional and local processes in structuring a larval trematode metacommunity of Helisoma trivolvis. Ecography 36: 854-863. PDF
Paull, S. H., Song, S. J., McClure, K. M., Sackett, L. C., Kilpatrick, A. M. and P. T. J. Johnson (2012). From superspreaders to disease hotspots: linking transmission across hosts and space. Frontiers in Ecology and the Environment 10: 75-82. PDF