Date of Award

Fall 2023

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

David T. Gauthier

Committee Member

Wayne Hynes

Committee Member

Chris Paddock


Rickettsia parkeri is a pathogen of interest to public health as the causative agent of R. parkeri rickettsiosis. Amblyomma maculatum, a vector of R. parkeri, is currently undergoing a range expansion out of its historic range along the Gulf Coast of the United States, including northwards into Southeastern Virginia. Within this expansion front, the prevalence of R. parkeri within A. maculatum differs from the historic range; the historic range has a prevalence of 7.9- 38.6% while the expansion front in SE VA has a prevalence of 41.8-55.7%. While the reason for this disparity has not been established, one potential explanation could be that R. parkeri strains present in the Gulf Coast region differs from those in southeastern Virginia. This study establishes a novel genotyping tool for R. parkeri targeting three variable intergenic spacer regions as well as a variable region within a gene. In addition to establishing these regions as targets for the genotyping set, this work differs from previous attempts to genotype Rickettsia species by utilizing field-caught ticks positive for R. parkeri as a source of DNA over isolates of R. parkeri. This work also differs in its sizing methodology; previous attempts to genotype R. parkeri utilized sequencing, while this work uses fragment analysis. These changes to methodology were incorporated due to the laborious, time-consuming, and expensive nature of the previous methodologies. The genotyping set was deployed upon R. parkeri positive ticks collected from the Southeastern Virginia area in order to characterize the present populations and explore population diversity.


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