The timing of raccoon rabies outbreaks in the eastern USA is non-random and often exhibits a seasonal peak. While fluctuations in disease transmission can be driven by seasonal changes in animal population dynamics, behaviour and physiology, it is still unclear which causal factors lead to seasonal outbreaks of raccoon rabies. We used dynamic network modelling to test which of three seasonally changing factors are most likely responsible for raccoon rabies outbreaks: (i) birth pulses, (ii) changes in social network structure and (iii) changes in social contact duration. In contrast to previous predictions, we found that a change in social contact duration was the single most important driver of rabies seasonality. More specifically, co-denning for thermoregulation during the winter increases the amount of time individuals spend in close contact, which in turn should lead to peaks in rabies transmission during the winter. Increased time spent in close proximity during cold winter months has implications for seasonal disease patterns in raccoon populations across a latitudinal gradient, as well as potentially being important for pathogens transmitted by close contact in other wildlife hosts. Synthesis and applications. By incorporating detailed empirical data describing variation in raccoon contacts into a network modelling framework, it is possible to determine the likely causal mechanisms driving seasonal disease patterns. This can be crucial information for wildlife and public health officials implementing wildlife disease control programmes.
Bibliographical noteFunding Information:
Access to the field site and logistical support were provided by the Forest Preserve District of Cook County. Numerous technicians assisted with fieldwork and we are particularly grateful for the contributions of Stephanie Hauver and Suzanne Prange. We also extend thanks to Chris Anchor, Eva Enns, Dan Parmer (deceased), Tiffany Wolf, Kimberly VanderWaal and Donna Alexander for their support in various aspects of the project. This project was funded by grants from the Cook County Animal and Rabies Control office as administered through the Environmental Research Program; Max McGraw Wildlife Foundation; National Science Foundation (EF-0425203, DEB-1413925); University of Minnesota's Institute on the Environment and Office of the Vice President for Research; and the Cooperative State Research Service, U.S. Department of Agriculture, under Project Numbers MINV 62-044 and 62-051. Data available from the Dryad Digital Repository doi: 10.5061/dryad.gr40r (Reynolds et?al.).
- contact network
- epidemiological modelling
- host–pathogen interactions
- infectious disease management
- network modelling
- proximity collar
- transmission dynamics
- wildlife disease