High-resolution contact networks of free-ranging domestic dogs Canis familiaris and implications for transmission of infection.

Jared K Wilson-Aggarwal,Matthew J Silk,Tchonfienet Moundai,Michele Tizzoni,Robbie A Mcdonald,James A Zingeser,George J F Swan,Ciro Cattuto,Laura Ozella,Sergio Recuenco

doi:10.1371/journal.pntd.0007565

Abstract

Contact patterns strongly influence the dynamics of disease transmission in both human and non-human animal populations. Domestic dogs Canis familiaris are a social species and are a reservoir for several zoonotic infections, yet few studies have empirically determined contact patterns within dog populations. Using high-resolution proximity logging technology, we characterised the contact networks of free-ranging domestic dogs from two settlements (n = 108 dogs, covering >80% of the population in each settlement) in rural Chad. We used these data to simulate the transmission of an infection comparable to rabies and investigated the effects of including observed contact heterogeneities on epidemic outcomes. We found that dog contact networks displayed considerable heterogeneity, particularly in the duration of contacts and that the network had communities that were highly correlated with household membership. Simulations using observed contact networks had smaller epidemic sizes than those that assumed random mixing, demonstrating the unsuitability of homogenous mixing models in predicting epidemic outcomes. When contact heterogeneities were included in simulations, the network position of the individual initially infected had an important effect on epidemic outcomes. The risk of an epidemic occurring was best predicted by the initially infected individual’s ranked degree, while epidemic size was best predicted by the individual’s ranked eigenvector centrality. For dogs in one settlement, we found that ranked eigenvector centrality was correlated with range size. Our results demonstrate that observed heterogeneities in contacts are important for the prediction of epidemiological outcomes in free-ranging domestic dogs. We show that individuals presenting a higher risk for disease transmission can be identified by their network position and provide evidence that observable traits hold potential for informing targeted disease management strategies.

Highlights

Heterogeneity in contact rates is influential in the epidemiology of both human and nonhuman animal diseases
Free-ranging domestic dogs are susceptible to a number of zoonotic infections yet few studies have investigated their contact patterns
We describe high-resolution contact data for free-ranging dogs in rural Chad and simulate the transmission of an infection comparable to rabies

Summary

Introduction

Heterogeneity in contact rates is influential in the epidemiology of both human and nonhuman animal diseases. Relationships between host social behaviour and the distribution of infections have been demonstrated in several wild animal host-pathogen systems, from tuberculosis in badgers Meles meles [3] and meerkats Suricata suricatta [4] to nematodes in Japanese macaques Macaca fuscata [5] One driver of these relationships is the variation in contacts between individuals, which can influence the flow of infection through populations [6,7]. The number of infectious disease emergence events in humans has been increasing over time, and the majority of these are zoonotic in origin [9] This may, in part, be associated with the domestication of animals, as evidence suggests that the number of shared pathogens (between humans and non-human animals) increases with the time since a species was domesticated [10]. If domestic animals are free-ranging, they are more likely to interact with wild animals, further facilitating the transmission of disease between people and wildlife [12]

Methods

Results

Discussion

Conclusion