Coupled contagion dynamics of fear and disease: mathematical and computational explorations.
BACKGROUND
In classical mathematical epidemiology, individuals do not adapt their contact behavior during epidemics. They do not endogenously engage, for example, in social distancing based on fear. Yet, adaptive behavior is well-documented in true epidemics. We explore the effect of including such behavior in models of epidemic dynamics.


RESULTS
Using both nonlinear dynamical systems and agent-based computation, we model two interacting contagion processes: one of disease and one of fear of the disease. Individuals can "contract" fear through contact with individuals who are infected with the disease (the sick), infected with fear only (the scared), and infected with both fear and disease (the sick and scared). Scared individuals--whether sick or not--may remove themselves from circulation with some probability, which affects the contact dynamic, and thus the disease epidemic proper. If we allow individuals to recover from fear and return to circulation, the coupled dynamics become quite rich, and can include multiple waves of infection. We also study flight as a behavioral response.


CONCLUSIONS
In a spatially extended setting, even relatively small levels of fear-inspired flight can have a dramatic impact on spatio-temporal epidemic dynamics. Self-isolation and spatial flight are only two of many possible actions that fear-infected individuals may take. Our main point is that behavioral adaptation of some sort must be considered.
Epstein
Joshua M
JM
Center on Social and Economic Dynamics, The Brookings Institution, Washington DC, United States of America. jepstein@brookings.edu
Parker
Jon
J
Cummings
Derek
D
Hammond
Ross A
RA
D001519:Behavior; D003141:Communicable Diseases / Q000635:transmission*; D003198:Computer Simulation; D004198:Disease Susceptibility; D004924:Escape Reaction; D005239:Fear; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000453:epidemiology / Q000635:transmission; D008954:Models, Biological