Host behavioral responses to perceived risk shape spatial disease dynamics

Abstract

There is growing recognition that host behavioral responses to disease risk are critical factors driving disease dynamics, but understanding how behavioral responses influence dynamics remains a major challenge. Coupled behavioral and epidemiological models commonly assume that hosts use population prevalence as an indicator of disease risk. However, real-world estimates of prevalence come from data aggregated over coarse spatial scales, while transmission occurs through fine-scale contacts. Fine-scale changes in movement behavior represent an important type of risk response because individuals must use proxies for infection risk, such as host density or environmental factors, whose relationship with actual transmission risk may vary across contexts. In this study, we examine the consequences of using diierent risk proxies to inform fine-scale movement and determine when and if relying on imperfect proxies can cause risk-averse behaviors to increase, rather than decrease, disease transmission relative to no behavioral change. We examine the effect of three risk proxies - local prevalence, local host density, and local transmission coefficient (i.e., "place") - in the context of "simple trips", where individuals may respond to disease risk by altering rates of travel from home to "away" locations and back. In one case, individuals stay home more frequently (an absolute risk response) and in the other case, individuals shift their travel to less risky, away locations (a relative risk response). Absolute responses were far more effective in reducing prevalence than relative responses, which were detrimental in some parameter regimes. Detrimental responses occurred when information used to perceive risk was mismatched with the mode of transmission (either density-dependent or frequency-dependent), such that individuals either failed to use pertinent information or used irrelevant information. Imperfect information thus plays a critical role in determining whether behavioral response reduces or elevates disease risk.