Host behavioral responses to perceived risk shape spatial disease dynamics

Abstract

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 to assess 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 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 examined the consequences of using different risk proxies to inform fine-scale movement and determined when imperfect proxies can cause risk-averse behaviors to increase, rather than decrease, disease transmission. We examined the effect of three risk proxies - local prevalence, local host density, and local transmission coefficient (i.e., ``place'') - in the context of ``simple trips'': Individuals respond to disease risk by altering travel rates from home to ``away'' locations and back, either leaving home less frequently (an absolute risk response) or shifting their travel to less risky away locations (a relative risk response). Absolute responses reduced prevalence more than relative responses, which were sometimes detrimental. Detrimental responses occurred when risk proxies were mismatched with the mode of disease transmission (either density- or frequency-dependent), causing individuals to either use irrelevant information or ignore pertinent information. Imperfect information thus plays a critical role in determining whether behavioral response reduces or elevates disease risk.