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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Theileria orientalis Ikeda Genotype: Implications for Cattle Health in Virginia

Oakes, Vanessa Jacqueline 30 June 2022 (has links)
Of the four most economically important tickborne diseases of cattle in the world, two have been identified in Virginia, occasionally as co-infections: anaplasmosis and theileriosis. The latter is caused by the emerging infectious agent, the Theileria orientalis complex, in particular the Ikeda and Chitose genotypes. These organisms are carried by the ixodid tick, Haemaphysalis longicornis, recently identified in the United States. Our work has been focused on initially identifying the protozoal organisms, crafting assays to aid in the identification of these organisms in clinically affected animals, and briefly examining the rate of co-occurrence of theileriosis and anaplasmosis. This is important, as Anaplasma marginale - the most common etiologic agent of anaplasmosis in cattle in Virginia - is treatable with a safe, effective, FDA-approved compound, whereas there is no currently approved treatment for theileriosis. Finally, we seek to contextualize theilerosis as a cause of infectious bovine anemia (IBA) and its expected economic impact on the cattle industry in Virginia. / Doctor of Philosophy / Theileriosis is a disease that infects cattle, caused by the blood parasite, Theileria orientalis, specifically two distinct genotypes of T. orientalis, Ikeda and Chitose. Theileriosis is transmitted to cattle by the Asian longhorned tick, Haemaphysalis longicornis, which was recently identified in the United States. Globally, theileriosis is one of four major tickborne diseases of cattle with significant economic importance, so the discovery of this parasite in the state of Virginia is of special importance to the cattle industry in Virginia. My work has revolved around making the initial discovery of T. orientalis Ikeda in the United States, and developing tests for cattle producers and veterinarians to use to help diagnose theileriosis in sick animals. Another tickborne disease of cattle, anaplasmosis, is caused by a bacterium, A. marginale. These two organisms have different biology, are transmitted by different ticks, and are treated differently, but cause identical clinical disease in cattle. In addition to identifying T. orientalis, we have developed a single test that can determine if sick cattle have T. orientalis or A. marginale – this is important, because the antibiotic used to treat A. marginale does not work to treat T. orientalis. In fact, there is no treatment for T. orientalis available in the United States. In addition to developing diagnostic assays, I seek to put into pathobiological, ecological, and economic context the importance of theileriosis on the cattle industry in Virginia.
12

The occurrence of tick-borne pathogens, in dogs in welfare organisations and townships of Cape Town

Allan, Rosalind Elizabeth 02 1900 (has links)
In impoverished and resource limited communities such as townships, and welfare organizations, areas such as living and sleeping spaces are sometimes shared with animals, and occasionally humans. Dogs play an integral role in our lives and have become part of the family. Therefore, it is probable that ectoparasites, such as ticks, that feed on dogs also feed on other vertebrates, thereby, transmitting pathogens. The primary aim of this study was to screen for the presence of tick-borne pathogens in dogs from welfare organisations and townships in Cape Town, with special focus on Ehrlichia and Babesia spp. The reason for this choice of subject is due to the fact that very few tick-borne infection studies have focused on resource limited communities. Furthermore, welfare organisations have continuously attracted awareness due to the amount of unrestricted work performed by veterinarians in communities with limited resources. Consequently, the topic was borne. A total of 126 blood samples and 509 ticks (adults and nymphs) were collected directly from dogs from four welfare organisations and two townships in Cape Town. Samples were collected from April to July 2014. The four welfare organisations where samples were collected included the Animal Anti Cruelty League welfare organisations in Epping and Bellville, the Lucky Lucy Foundation in Joostenberg Vlakte and The Emma Animal Rescue Society (TEARS), located in the Sunnydale area. Samples were also collected from the Asanda village and Nomzamo, two townships located just outside the Cape Town suburb, the Strand. DNA was extracted from blood and ectoparasites and screened for the presence of Ehrlichia, Anaplasma, Theileria and Babesia species infections using touchdown PCR and RLB hybridization assays. Genus and species-specific probes were used during hybridization in order to identify specific parasite infections in the blood samples and the tick samples pooled according to geographical origin and species. Forty six (36.5%) of the blood samples tested positive for tick-borne pathogen DNA. Of the positive blood samples, 17 (13.5%) were infected with Ehrlichia canis; 16 (12.7%) with Babesia rossi and four (3.2%) samples were infected with Babesia vogeli. Incidental infections were also detected, these included Ehrlichia ruminantium (n=6, [4.7%]), Theileria taurotragi (n=2, [1.6%]) and Anaplasma sp. Omatjenne (n=1, [0.8%]) infections. DNA detected from 10 samples (7.94%) hybridized only to the Ehrlichia/Anaplasma genus-specific probes and four samples (3.17%) hybridized only to the Theileria/Babesia genus-specific probes. None of these 14 samples hybridized to any of the species-specific probes. Collected Rhipicephalus sanguineus (n=457) and Haemaphysalis elliptica (n=52) ticks were grouped into 15 pools, representing both tick species according to specific collection locations. Since only two H. elliptica from Asanda and one R. sanguineus from TEARS were collected, these ticks were mixed in pools of the dominant species as they were too few for DNA extraction. Ticks were collected from the Nomzamo Township (R. sanguineus n=400), Asanda village (H. elliptica n=2; R. sanguineus n=42), TEARS (H. elliptica n=21; R. sanguineus n=1), and the Animal Anti Cruelty League in both Epping (R. sanguineus n=14), and Bellville (H. elliptica n=29), in Cape Town. Analysis by the RLB assay showed that 11 (73.3%) of the 15 tick pools representing both tick species were positive for at least one parasite species. All positive samples hybridized with the Ehrlichia/Anaplasma genus-specific probe. Three (20%) tick pools containing both tick species tested positive for Ehrlichia canis infection, two (13.3%) tested positive for Babesia rossi and Babesia vogeli DNA was identified in one (6.6%) tick pool. The Theileria/Babesia genus-specific probe hybridised in three (20%) tick pools. These three pools were comprised of both R. sanguineus and H. elliptica tick species. These tick pools also tested positive for a specific Babesia tick-borne pathogen. Tick-borne pathogen DNA could not be detected in four (26.6%) tick pools. The fore-mentioned tick-borne pathogen DNA detected in the dog blood samples, and the ectoparasites collected from the same dogs during this study, suggests that dogs play a large role in the endemicity of these pathogens / Environmental Sciences / M. Sc. (Life Science)

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