Multi-host wildlife pathogens are an increasing concern for both wildlife conservation and livestock husbandry. Here, we combined social network theory with microbial genetics to assess patterns of interspecific pathogen transmission among ten species of wild and domestic ungulates in Kenya. If two individuals shared the same genetic subtype of a genetically diverse microbe, Escherichia coli, then we inferred that these individuals were part of the same transmission chain. Individuals in the same transmission chain were interlinked to create a transmission network. Given interspecific variation in physiology and behavior, some species may function as "super-spreaders" if individuals of that species are consistently central in the transmission network. Pathogen management strategies targeted at key super-spreader species are theoretically more effective at limiting pathogen spread than conventional strategies, and our approach provides a means to identify candidate super-spreaders in wild populations. We found that Grant's gazelle (Gazella granti) typically occupied central network positions and were connected to a large number of other individuals in the network. Zebra (Equus burchelli), in contrast, seemed to function as bridges between regions of the network that would otherwise be poorly connected, and interventions targeted at zebra significantly increased the level of fragmentation in the network. Although not usually pathogenic, E. coli transmission pathways provide insight into transmission dynamics by demonstrating where contact between species is sufficient for transmission to occur and identifying species that are potential super-spreaders.
Bibliographical noteFunding Information:
We are grateful to Sophie Preckler-Quisquater, Nicole Sharpe, Joseph Makao, and Caroline Batty for their assistance in the field, and to the Atwill laboratory and Elaine Wang, Navreen Pandher, and Young ha Suh for assistance in laboratory work. We thank Kiama Gitahi of the University of Nairobi, Nathan Gichohi, George Omondi-Paul, and the entire OPC staff, and the Office of the President of the Republic of Kenya for enabling various facets of the research. We also thank the Kenya Wildlife Service, especially Matthew Mutinda, for assistance in collecting specimens from endangered species. This research was approved by Kenya’s National Council for Science and Technology (Permit NCST/RRI/12/1/MAS/147) and the UC Davis Institutional Animal Care and Use Committee (protocol no. 15887). This project was supported by the National Science Foundation (NSF Graduate Research Fellowship to KVW and Doctoral Dissertation Improvement Grant IOS-1209338), Phoenix Zoo, Cleveland Metroparks Zoo, Cleveland Zoological Society, Oregon Zoo, Northeastern Wisconsin Zoo, University of California-Davis Wildlife Health Center, Sigma Xi, ARCS Foundation, Explorer’s Club, Animal Behavior Society, and American Society of Mammalogists, all to KVW, and a UC Davis Faculty Research Grant to LAI.
- Interspecific transmission
- Microbial genetics
- Pathogen transmission
- Social network analysis
- Wildlife disease
- Wildlife-livestock interface