Medicine and Health Sciences Commons^™

Determination Of The Presence Of Rickettsia Spp. And Borrelia Spp. Carried By Tortoise Ticks From Madagascar, Anna Phan

Biological Sciences Theses & Dissertations

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. …

Infection Potential Of Rickettsia Felis Via Ingestion, Matthew M. Schexnayder

LSU Master's Theses

Rickettsia felis is the etiologic agent of flea-borne spotted fever (FBSF) in humans and a poorly described cause of fever in animals. It is transmitted by its primary arthropod vector and reservoir host, the cat flea Ctenocephalides felis. Known routes of Rickettsia felis transmission between Rickettsia felis-infected cat fleas and vertebrate hosts include cutaneous bites and contamination of cutaneous wounds with infective flea feces. The bulk of FBSF infections occur in young children in Africa, though infections of people at all ages all over the world have been confirmed. As mammals and young children frequently come into contact …

Geospatial Analysis Of Rickettsial Species, Amy Frank

Entomology Undergraduate Honors Theses

Rickettsia species are obligate intracellular, arthropod-borne bacteria with a potential to cause multiple diseases including Rocky Mountain spotted fever (RMSF). Fleas, mites, and ticks serve as vectors for Rickettsia, but ticks are the primary vector of interest. RMSF and other rickettsial diseases have continued to gain importance in both human and veterinary medicine as RMSF is the most common tick-borne disease within the United States according to the Lyme and Tick-Borne Disease Research Center. A statewide citizen science project was utilized to determine the prevalence of Spotted Fever Group (SFG) Rickettsia in Arkansas. This project yielded results in 64 …

Geospatial Analysis Of Rickettsial Species In Arkansas, Amy D. Frank, Ashley P.G. Dowling

Discovery, The Student Journal of Dale Bumpers College of Agricultural, Food and Life Sciences

Rickettsia species are obligate intracellular, arthropod-borne bacteria with a potential to cause multiple diseases including Rocky Mountain spotted fever (RMSF). Fleas, mites, and ticks serve as vectors for Rickettsia, but ticks are the primary vector of interest. RMSF and other rickettsial diseases have continued to gain importance in both human and veterinary medicine as RMSF is the most common tick-borne disease within the United States according to the Lyme and Tick-Borne Disease Research Center. A statewide citizen science project was utilized to determine the prevalence of Spotted Fever Group (SFG) Rickettsia in Arkansas. This project yielded results in 64 …

Rickettsia Felis, Transmission Mechanisms Of An Emerging Flea-Borne Rickettsiosis, Lisa Diane Brown

LSU Doctoral Dissertations

Rickettsia felis is an emerging insect-borne rickettsial pathogen and the causative agent of flea-borne spotted fever. First described as a human pathogen from the United States in 1991, R. felis is now identified throughout the world and considered a common cause of fever in Africa. The cosmopolitan distribution of this pathogen is credited to the equally widespread occurrence of cat fleas (Ctenocephalides felis), the primary vector and reservoir of R. felis. Additionally, R. felis has been identified in other hematophagous arthropods (including numerous species of fleas, ticks, mosquitoes, and mites). Most transmission cycles of pathogenic Rickettsia include transovarial and transstadial …

Characterization Of Rickettsial Infection Dynamics Within Dermacentor Variabilis And Amblyomma Maculatum, Emma Kate Harris

LSU Doctoral Dissertations

Spotted fever group (SFG) Rickettsia are primarily associated with their reservoir host and vector, the tick. Rickettsial colonization and maintenance within the arthropod is a key component of vector competence and pathogen transmission to the mammalian host. Contemporary detection of novel tick hosts for rickettsial species, combined with an unprecedented rise in human cases of SFG rickettsiosis, necessitates a deeper understanding of tick/Rickettsia interactions. The hypothesis for this work is that if primary tick/Rickettsia pairings do not exist then rickettsial determinants account for primary vector/pathogen relationships. To this end, Dermacentor variabilis and Amblyomma maculatum ticks were exposed to R. rickettsii, …

Identification And Characterization Of A Relish-Type Nf-Kb, Dvrelish In Dermacentor Variabilis, The American Dog Tick, Victoria Irene Verhoeve

LSU Doctoral Dissertations

Ticks are important worldwide as vectors of bacteria, viruses, and parasites. Pathogenic and non-pathogenic Spotted fever group (SFG) Rickettsia are maintained and transmitted by ticks with specific hard tick-Rickettsia pairings evident in nature. The pathogenic SFG Rickettsia rickettsii is transmitted by the hard tick Dermacentor variabilis. In response to infection, D. variabilis is known differentially respond to SFG Rickettsia infection. The mechanisms of differential immune induction are currently unknown, and are likely involved in the establishment of specific tick-SFG Rickettsia pairings. It was hypothesized that the level of response by D. variabilis to SFG Rickettsia occurs in a species-specific manner, …

Prevalence Of Tick-Borne Pathogens In Small Mammals And White-Tailed Deer In Southeast Nebraska, Tim Hotaling

School of Veterinary and Biomedical Sciences: Dissertations, Theses, and Student Research

The prevalence of tick-borne diseases has been increasing in the United States for the past couple decades. Studies have been conducted throughout the US identifying tick-borne disease pathogens as well as their hosts and prevalence. Research was conducted in Nebraska to determine the presence of some tick-borne disease pathogens, their vectors, and their hosts, with emphasis made on Borrelia spp., Rickettsia rickettsii, and Ehrlichia chaffeensis.

Small rodents in southeast Nebraska were trapped and sampled at eight study sites using live capture traps. Captured rodents were assessed for active parasitism by ticks which were collected and placed in alcohol. …

Signal Transduction And Rickettsial Infection Of Tick Cells, Natthida Petchampai

LSU Doctoral Dissertations

Spotted fever group (SFG) Rickettsia are obligate intracellular bacteria that are carried by ticks. One such tick, Dermacentor variabilis is a vector for the etiologic agent of Rocky Mountain spotted fever, R. rickettsii. These ticks also carry a non-pathogenic R. montanensis, the agent used in this study. Interestingly, field data collected from infected D. variabilis throughout the United States revealed that the majority of Rickettsia in ticks are non-pathogenic species such as R. montanensis. Although ticks serve as both vector and reservoir hosts for SFG Rickettsia, many questions regarding tick-Rickettsia interaction remain unresolved. Therefore, the overall goal of this research …

Influence Of Tick Transmission On The Host Response To Rickettsial Infection, Soma Chowdhury

LSU Master's Theses

Several members of the spotted fever group (SFG) of Rickettsia are transmitted to the host through infected ixodid (hard) ticks, which can serve as both vectors and reservoirs. Multiple studies have demonstrated that ticks secrete proteins into the bite site of the host that suppress innate and adaptive immune responses. While this suppression of immune responses is beneficial to the tick, it may also be beneficial to the transmitted Rickettsia. We hypothesize that Rickettsia utilize the tick’s ability to alter the host immune response at the tick feeding site to successfully establish infection. In the current study, we analyzed how …

Plasmid-Mediated Expression Of Foreign Genes In Ehrlichia Canis, Langston Dolphus Hull

LSU Doctoral Dissertations

Ehrlichia canis is the etiologic agent of “tropical canine pancytopenia”, or canine ehrlichiosis. The impetus for this research was to overcome the lack of any reliable means of elucidating the genetic profiles of these illusive and historically difficult to manipulate organisms. The use of a broad-host range plasmid greatly facilitated the determination of an electro-transformation protocol. The transforming plasmid possesses a chloramphenicol antibiotic resistance gene marker (chloramphenicol acetyltransferase [CAT] gene), and a visual reporter gene marker, the Green Fluorescent Protein (GFP) gene. With primer sets designed to specifically amplify these two plasmid encoded gene markers, thus verifying the presence of …