Contact tracing for the control of infectious disease epidemics: Chronic Wasting Disease in deer farms
Chris Rorres,
Maria Romano,
Jennifer A. Miller,
Jana M. Mossey,
Tony H. Grubesic,
David E. Zellner,
Gary Smith
Affiliations
Chris Rorres
Section of Epidemiology and Public Health, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, 19348, United States; Corresponding author.
Maria Romano
Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Bellet Building, 6th Floor, 1505 Race Street, Philadelphia, PA, 19102, United States
Jennifer A. Miller
Department of Geography and the Environment, 1 University Station A3100, The University of Texas at Austin, Austin, TX, 78712, United States
Jana M. Mossey
Department of Epidemiology and Biostatistics, School of Public Health, Drexel University, Nesbitt Hall, 3215 Market Street, Philadelphia, PA, 19104, United States
Tony H. Grubesic
Center for Spatial Reasoning & Policy Analytics, College of Public Service and Community Solutions, Arizona State University, Phoenix, AZ, 85004, United States
David E. Zellner
Bureau of Animal Health and Diagnostic Services, Pennsylvania Department of Agriculture, 2301 North Cameron Street, Harrisburg, PA, 17110, United States
Gary Smith
Section of Epidemiology and Public Health, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, 19348, United States
Contact tracing is a crucial component of the control of many infectious diseases, but is an arduous and time consuming process. Procedures that increase the efficiency of contact tracing increase the chance that effective controls can be implemented sooner and thus reduce the magnitude of the epidemic. We illustrate a procedure using Graph Theory in the context of infectious disease epidemics of farmed animals in which the epidemics are driven mainly by the shipment of animals between farms. Specifically, we created a directed graph of the recorded shipments of deer between deer farms in Pennsylvania over a timeframe and asked how the properties of the graph could be exploited to make contact tracing more efficient should Chronic Wasting Disease (a prion disease of deer) be discovered in one of the farms. We show that the presence of a large strongly connected component in the graph has a significant impact on the number of contacts that can arise. Keywords: Chronic Wasting Disease, Contact tracing, Directed graphs, Strongly connected components
