Integrating contact network structure into tuberculosis epidemiology in meerkats in South Africa: Implications for control.

Empirical studies that integrate information on host contact patterns with infectious disease transmission over time are rare. The aims of this study were to determine the relative importance of intra-group social interactions in the transmission of tuberculosis (TB; Mycobacterium bovis infection) in a population of wild meerkats (Suricata suricatta) in South Africa, and to use this information to propose an evidence-based intervention strategy to manage this disease. Detailed behavioural observations of all members of eight meerkat groups (n=134 individuals) were made over 24 months from January 2006 to December 2007. Social network analysis of three types of interaction (aggression, foraging competitions and grooming) revealed social structure to be very stable over time. Clustering of interactions was positively correlated with group size for both aggression (r=0.73) and grooming interactions (r=0.71), suggesting that infections may spread locally within clusters of interacting individuals but be limited from infecting all members of large groups by an apparent threshold in connections between different clusters. Repeated biological sampling every three months of all members of one social group (n=37 meerkats) was undertaken to quantify individual changes in M. bovis infection status. These empirical data were used to construct a dynamic network model of TB transmission within a meerkat group. The results indicated that grooming (both giving and receiving) was more likely than aggression to be correlated with M. bovis transmission and that groomers were at higher risk of infection than groomees. Intervention strategies for managing TB in meerkats that focus on those individuals engaging in the highest amount of grooming are therefore proposed.