Space-time differentiation of drivers of and barriers to H5N1 avian influenza evolution in Vietnam

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  • March 21, 2019
Creator
  • Carrel, Margaret A.
    • Affiliation: College of Arts and Sciences, Department of Geography
Abstract
  • The emergence and re-emergence of human pathogens resistant to traditional medical treatment will present a challenge to the international public health community in the coming decades. Geography is uniquely positioned to examine the progressive evolution of pathogens across space and through time, and to link molecular change to interactions between population and environmental drivers. The widespread outbreak of H5N1 avian influenza across Asia in 2003, and its continued circulation within both poultry and human populations, presents an opportunity for the integration of traditional disease ecology with the emergent field of landscape genetics. Combining spatial statistical methods with genetic analytic techniques, geographic space is used to explore genetic evolution of H5N1 highly pathogenic avian influenza viruses (HPAIV) at the sub-national scale in Vietnam. This dissertation investigates the following topics: differences in genetic characteristics by species of isolation, location and timing of barriers to gene flow, and population-environment characteristics associated with increased viral evolution in Vietnam from 2003 to 2007. A variety of methods are used, including cluster analysis, multidimensional scaling, analysis of variance, and linear regression. Results indicate that genetic differentiation of these viruses varies significantly according to both their host species and the isolation time, but has a complex relationship with the geographic location of virus isolation. The effect of geographic space, and underlying landscape differentiation, does not appear to create boundaries to gene exchange across Vietnam. Taking these indicators of the influence of species, temporal characteristics and geographic space into account, the drivers of molecular evolution of H5N1 HPAIV in Vietnam are as predicted by a disease ecology framework, a combination of both population and environmental characteristics. These findings indicate that there are significant spatial and temporal effects on the evolution of H5N1 HPAIVs, and that local-level conditions can affect viral genetic evolution. Given that areas of rapid genetic evolution are more likely to produce a highly pathogenic virus capable of sustained human-to-human transmission, further exploration of spatial variation in molecular change is needed.
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  • In Copyright
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  • "... in partial fulfillment of the requirements of the degree of Doctor of Philosophy in the Department of Geography."
Advisor
  • Emch, Michael
Degree granting institution
  • University of North Carolina at Chapel Hill
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Place of publication
  • Chapel Hill, NC
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  • Open access
Date uploaded
  • March 18, 2013

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