Date of Award

Spring 2021

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

Wayne Hynes

Committee Member

Holly Gaff

Committee Member

Andrea Currylow


Ticks were removed from three species of Malagasy tortoises, Astrochelys yniphora, A. radiata, and Pyxis arachnoides (comprising two subspecies P. a. arachnoides and P. a. oblonga), between 2012 and 2015. The ticks were presumed to be from the genus Amblyomma. Ticks were morphologically identified and then checked molecularly to confirm their classification or identify any ticks that could not be morphologically identified. Molecular identification was done via end-point PCR that amplified tick cytochrome oxidase (CO1) and tick 12S rRNA genes. Ticks were screened via a real-time polymerase chain reaction assay for the presence of Rickettsia spp. and Borrelia spp., amplifying the rickettsial 17 kDA and Borrelia 16S rRNA gene, respectively. Those positive for either pathogen were analyzed to determine the specific species via end-point PCR and sequencing. One hundred eighty-three ticks out of 239 tested ticks (77%) were positive for the presence of Rickettsia spp. and/or Borrelia spp.; Rickettsia aeschlimannii and Rickettsia africae were sequenced from Rickettsia-positive ticks and a Borrelia species related to Borrelia turcica was sequenced from the Borrelia-positive ticks. The aim of this study was to determine the presence of Rickettsia spp. and Borrelia spp. infecting the ticks, as well as identifying the ticks, in order to determine veterinary and public health risks. This will help further our understanding of these ticks and their pathogens and their relationship to these tortoises, as well as the impact they may have on both human and veterinary health.


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