DISSERTATION RESEARCH: Pathogen transmission in wild and domestic ungulates: Quantifying risk and identifying transmission routes among cattle and wildlife in central Kenya

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Wildlife diseases are a recognized conservation threat and public health concern, yet there is remarkably little information on how diseases spread through wildlife populations. In this study, microbial genetics and network analysis are integrated to assess routes of (I) intraspecific pathogen transmission in reticulated giraffe, and (II) interspecific transmission between wild and domestic herbivores (black rhinoceros, Grevy's zebra, giraffe, impala, buffalo, and cattle) in Kenya. Our understanding of the dynamics of pathogen transmission is limited because it is difficult to assess who transmitted to whom. This project uses Escherichia coli as a proxy for pathogen transmission. Transmission between two individuals can be inferred if they share genetically similar subtypes of E. coli. Inferred transmission will be used to construct a transmission network for wildlife and livestock in Kenya. The first component of this project investigates how the spatial and social organization of the giraffe population influences transmission dynamics. The second component quantifies the extent and directionality of interspecific transmission and identifies species that contribute disproportionately to pathogen spread, termed "super-spreaders." Two of the species included in this study, the Grevy?s zebra and black rhinoceros, are endangered and vulnerable to disease-related population declines, which gives this study immediate conservation relevance. Broader impacts. Although not usually pathogenic, E. coli transmission routes demonstrate where contact is sufficient for transmission to occur. Knowledge of these routes can be incorporated into disease control strategies. Targeted vaccination of super-spreaders is theoretically more effective at limiting disease than conventional vaccination strategies, but there are no existing methods to identify super-spreaders in wild populations. A major outcome of this project will be to develop new tools for identifying super-spreaders and tracing transmission routes in wildlife. This is a novel approach and will be broadly applicable in improving our ability to predict the impacts of disease.