Contact tracing for the control of infectious disease epidemics: Chronic Wasting Disease in deer farms

• Published in: Epidemics 2018-06, Vol.23, p.71-75
• Main Authors: Rorres, Chris, Romano, Maria, Miller, Jennifer A., Mossey, Jana M., Grubesic, Tony H., Zellner, David E., Smith, Gary
• Format: Article
• Language: English
• Subjects: Animals; Chronic Wasting Disease; Contact tracing; Contact Tracing - methods; Contact Tracing - statistics & numerical data; Deer; Directed graphs; Farms; Pennsylvania; Strongly connected components; Wasting Disease, Chronic - epidemiology; Wasting Disease, Chronic - prevention & control
• ISSN: 1755-4365; 1878-0067
• DOI: 10.1016/j.epidem.2017.12.006

•Graph theory is applied to contact tracing for infectious disease epidemics.•Chronic Wasting Disease among deer farms in Pennsylvania is used as an example.•The impact of Strongly Connected Components of the directed graph is illustrated. 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.