‘Keeping the kids at home’ can limit the persistence of contagious pathogens in social animals

Marescot, L.; Franz, M.; Benhaiem, S.; Hofer, H.; East, M.L.; Kramer-Schadt, S.

In social species where offspring are reared together in communal burrows or similar structures, young animals typically do not engage in between-group contact during their development – a behavioural trait we call ‘offspring with restricted between-group contact’ (ORC). The impact of this trait on the persistence of contagious pathogens that generate lifelong immunity in their hosts is currently unclear. We hypothesize that in populations with ORC, the formation, in groups, of a ‘protective barrier’ of only recovered adults, prevents the transmission of this type of pathogens to the new susceptible hosts (i.e. young animals), thereby increasing the probability of epidemic fade-out. We implement a spatially implicit individual-based Susceptible-Infected-Recovered (SIR) model for a large range of host and pathogen traits and show that the epidemic fade-out probability is consistently higher in populations with ORC, especially when disease spread is fast (high basic reproduction number R0). We also show that ORC can counteract the cost of group-living in terms of disease risk to a greater extent than variation in other traits. We discuss our findings in relation to herd immunity and outline how they could be used to implement efficient management measures such as vaccinations.