Complex dynamics induced by delayed adaptive behavior during epidemics

Ronan F. Arthur; James H. Jones; Matthew H. Bonds; Marcus W. Feldman

Behavior should be considered endogenous to an infectious disease system because it is, in part, a consequence of the prevalence and severity of the disease, which also respond to changes in behavior [9] . Individuals have greater incentive to change behavior as prevalence increases; conversely they have reduced incentive as prevalence decreases [10, 11] . Endogenous behavioral response may then theoretically produce a non-zero endemic equilibrium of infection. This happens because, at low levels of prevalence, the cost of avoidance of a disease may be higher than the private benefit to the individual, even though the collective, public benefit in the long-term may be far greater. However, in epidemic response we typically think of behavior change as an exogenously-induced intervention. While guiding positive change is an important intervention, neglecting to recognize the endogeneity of behavior can lead to the reversal of those changes when they no longer appear necessary from an individual perspective. This can frustrate efforts to eradicate a disease.