Theses and Dissertations

Issuing Body

Mississippi State University


Varela-Stokes, Andrea S.

Committee Member

Goddard, Jerome

Committee Member

Belant, Jerrold L.

Committee Member

Paddock, Christopher D.

Committee Member

Huston, Carla L.

Date of Degree


Document Type

Dissertation - Open Access


Veterinary Medical Science

Degree Name

Doctor of Philosophy (Ph.D)


College of Veterinary Medicine


Veterinary Medical Science Program


Rickettsia parkeri is a tick-borne microorganism, only recently recognized to cause disease in humans. The ecology of this disease is largely unknown, and was addressed through a series of laboratory and field investigations. Feeding behavior of immature stages of the primary vector, Amblyomma maculatum, on mammalian, avian, and reptilian host models was investigated. It was determined that this tick does not feed on anoles, and nymphs do display longer periods of attachment to and are significantly heavier having fed on cotton rats as compared with quail. Field surveys indicate evidence of exposure to spotted fever group rickettsiae in small mammals and farm-raised quail in Mississippi, but not in passerines. Results from experimental studies demonstrated that cotton rats become acutely infected with R. parkeri, but that quail do not show evidence of infection. Additionally, nymphal ticks were not able to acquire the organism from inoculated animals. Finally, a reverse line-blot assay was developed to identify sources of bloodmeal in archived, field-collected A. maculatum samples. This dissertation contributes important findings to our understanding of the ecology of R. parkeri and has implications for future work on the subject.