Theses and Dissertations
Issuing Body
Mississippi State University
Advisor
Varela-Stokes, Andrea S.
Committee Member
Goddard, Jerome
Committee Member
Paddock, Christopher D.
Committee Member
Lawrence, Mark
Committee Member
Caprio, Michael
Date of Degree
8-11-2012
Document Type
Dissertation - Open Access
Major
Veterinary Medical Science
Degree Name
Doctor of Philosophy
College
College of Veterinary Medicine
Department
Veterinary Medical Science Program
Abstract
The public health and veterinary importance of Gulf Coast ticks, Amblyomma maculatum Koch (1844) have become more apparent during the last several decades. In addition, new records of this three-host ixodid tick presently show a geographic distribution throughout much of the southern United States. Rickettsia parkeri, a spotted fever group rickettsia (SFGR) that is commonly found infecting the Gulf Coast tick, was only recently recognized as a human pathogen. Over the last decade, more than 20 human cases of disease caused by R. parkeri have been recognized in the Americas, all of which were similar in presentation to mild Rocky Mountain spotted fever. In addition, a novel, poorly characterized SFGR, “Candidatus Rickettsia andeanae”, was recently identified in A. maculatum from Peru, United States, Chile and Argentina. As the recognition of R. parkeri as a pathogen and “Ca. R. andeanae” as an additional SFGR in A. maculatum only recently occurred, a general gap exists in our understanding of the biology of these SFGRs. The overall objective of this dissertation was to contribute to our knowledge of SFGR infecting A. maculatum. In Chapter 3, we present a prevalence study of R. parkeri, and “Ca. R. andeanae” in A. maculatum from Mississippi where we detected 15.2% R. parkeri-singly infected ticks and 3.1% total “Ca. R. andeanae” infected ticks of which 1.7% were co-infected with R. parkeri. In Chapter 4, we discuss finding four genetically different populations of A. maculatum from Mississippi infected with a homogenous population of R. parkeri, using Single Strand Conformation Polymorphism analysis. Those initial data relating to “Ca. R. andeanae” provided a foundation for studies described in Chapters 5 and 6. We report the first morphological study of “Ca. R. andeanae” using transmission electron microscopy in Chapter 5 and isolation of this SFGR in ,A. maculatum cell co-culture in Chapter 6. We anticipate that results presented in this dissertation will contribute to our understanding of the ecology of ,A. maculatum as a vector for the human pathogen, R. parkeri, and increase the current understanding of both R. parkeri and “Ca. R. andeanae” in A. maculatum.
URI
https://hdl.handle.net/11668/20140
Recommended Citation
Ferrari, Flavia Araujo Girao, "Spotted Fever Group Rickettsiae, Rickettsia Parkeri And "Candidatus Rickettsia Andeanae", Associated With The Gulf Coast Tick, Amblyomma Maculatum Koch" (2012). Theses and Dissertations. 4032.
https://scholarsjunction.msstate.edu/td/4032
Comments
Gulf Coast tick||Amblyomma maculatum||spotted fever group rickettsia||Rickettsia parkeri||America boutonneuse fever||“Candidatus Rickettsia andeanae”||prevalence||population heterogeneity||single strand conformation polymorphism||transmission electron microscopy||embryonic tick cell line