SYMP 7-2 - Invasion of the BLTs: Can community ecology predict the establishment of the Lyme disease system?

Tuesday, August 9, 2016: 2:00 PM
Grand Floridian Blrm B, Ft Lauderdale Convention Center
Brian F. Allan, School of Integrative Biology, University of Illinois, Natalie Pawlikowski, University of Illinois Urbana-Champaign, Allison M. Gardner, School of Biology and Ecology, University of Maine, Orono, ME, Sarah H. Hamer, Depts. of Fisheries & Wildlife and Large Animal Clinical Sciences, Michigan State University, East Lansing, MI, Graham Hickling, Department of Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville, Knoxville, TN, James R. Miller, Natural Resources & Environmental Sciences, University of Illinois, Urbana, IL, Anna Schotthoefer, Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention (CDC), National Center for Emerging and Zoonotic Infectious Diseases, Fort Collins, CO and Jean I. Tsao, Department of Fisheries and Wildlife, Michigan State University, East Lansing, MI
Background/Question/Methods . Arthropod vectors of infectious diseases to humans are often embedded within wildlife food webs, the composition of which may influence the dispersal and invasion success of vectors to new geographic areas. The distribution of the black-legged tick (Ixodes scapularis), a vector of the Lyme disease pathogen, is expanding in the midwestern United States. We used scientific literature and public databases to reconstruct the invasion history of I. scapularis and human Lyme disease in this region and thereby inform future public health efforts. A literature search was conducted for studies on the distribution and/or range expansion of I. scapularis in the Midwest, specifically in Illinois, Indiana, Iowa, Michigan, Minnesota, Nebraska, North Dakota, Ohio, South Dakota, and Wisconsin. Human case data (1992-2011) were downloaded from the CDC. A literature search for published reports of Lyme disease cases was conducted to gather data for years prior to 1992. We tested the hypotheses that invasion of a county by I. scapularis is predicted by adjacency to a previously invaded county, forest cover, and adjacency to a river as the latter may serve as corridors for wildlife-mediated dispersal of tick or pathogen. 

Results/Conclusions . Forty-seven articles, published 1970-2014, were identified from the literature search. Forest cover, adjacency to a river, and adjacency to a previously tick-positive county were positively correlated to establishment of I. scapularis. Lyme disease incidence was significantly higher in counties after detection than before detection of I. scapularis, suggesting an increase in human exposure to the Lyme pathogen following tick invasion. We used these associations to develop a predictive model of counties likely to be invaded next by I. scapularis. Our findings suggest that host food webs may play a significant role in mediating the invasion of both I. scapularis and the Lyme pathogen. Further, understanding the history of the invasion of the Lyme system will facilitate efforts to forecast future Lyme disease risk and disseminate public health warnings.