How do infections impact social relationships?

Infectious disease dynamics are both a cause and a consequence of variation in sociality. Social interaction rates can shape parasite transmission, and conversely, parasite infection can alter social interaction rates. At the core of this feedback is a trade-off: although many social interactions yield fitness benefits, parasites impose fitness costs on infected hosts and risks to uninfected partners. Both the benefits of social interaction and the costs of infection are context-dependent, dynamic and often asymmetric within dyads. We therefore hypothesize that variation in this cost-benefit trade-off explains how and why behavioural responses to parasitism differ between individuals across stages of relationship development and across different types of social relationships (parent-offspring, pair-bond, affiliative, dominance relationships). We use these hypothetical cost-benefit trade-offs to generate testable predictions about how parasites will impact the behaviour of infected and uninfected hosts across different social relationships. We also explore the potential for acute infections to have long-term social consequences by influencing the development of social relationships.