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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.
1

The detection and distrubution [i.e. distribution] of a Rocky Mountain spotted fever group Rickettsia sp. and Babesia microti from Ixodes scapularis in Indiana counties / Detection and distrubution of a Rocky Mountain spotted fever group Rickettsia sp. and Babesia microti from Ixodes scapularis in Indiana counties / Detection and distribution of a Rocky Mountain spotted fever group Rickettsia sp. and Babesia microti from Ixodes scapularis in Indiana counties

Abley, Melanie J. January 2004 (has links)
In Indiana, Ixodes scapularis is an important tick in public health because it feeds on a variety of hosts including humans, and transmits Borrelia burgdorferi (Lyme disease), Anaplasma phagocytophilum (human granulocytic ehrlichiosis), and Babesia microti (babesiosis). Symbiotic, non-pathogenic Rickettsia found in Ixodes scapularis may play a role in excluding pathogenic species of Rickettsia from being transovarially transmitted. In order to investigate this idea further in Indiana, a total of 378 adult I. scapularis from 4 different counties (Jasper, Pulaski, Newton and Starke) were tested by polymerase chain reaction analysis (PCR) for the presence of Rickettsia sp. Four positive samples from the PCR (using Rocky Mountain spotted fever group specific primers to target the rOmpA gene; Rr190.70p and RH 90.602n) reactions were sequenced to verify identity. These four samples matched closest to the reference number AB002268 from GenBank which describes, I. scapularis endosymbiont DNA for rOmpA. A total of 62 engorged females were tested; 53 (85.5%) harbored the rickettsial symbiont. A total of 41 questing females were tested; 33 (80.5%) were positive. Of the 249 males tested, 14 (5.6%) were positive. A restriction digestion on some of the positive samples revealed that the 1 scapularis symbiont was different from R. montana and R. rickettsii. The second goal of this study was to identify the presence of B. microti. In I. scapularis ticks, this would be the first time this pathogen was identified in Indiana. To accomplish this goal 106, ticks were tested using the primers Babl and Bab4, which target the 18S rRNA gene specific for B. microti. Three tick samples were found to harbor B. microti as determined by sequencing. However, sequencing of amplification band in the negative control also yielded B. microti. Thus, the presence of B. microti in Indiana ticks could not be confirmed. A negative control was also sequenced and was identified as Babesia microti indicating that there was a contamination so it is not possible to conclude that B. microti was found in Indiana ticks. / Department of Physiology and Health Science
2

Detection and quantification of Borrelia lonestari and a rickettsial endosymbiont in Amblyomma americanum ticks from southern Indiana using real-time PCR

Sullivan, Bridget E. January 2005 (has links)
Amblyomma americanum, the lone star tick, is an indigenous tick species in southern Indiana that harbors a diverse group of pathogenic and nonpathogenic microorganisms, including Borrelia lonestari, the putative agent for the southern tick associated rash illness (START) and a spotted fever group rickettsial endosymbiont. The purpose of this study was to implement the real-time polymerase chain reaction (real-time PCR) as a molecular technique to examine the microbial diversity in A. americanum ticks by estimating abundances of different microorgansisms. A SYBR Green real-time PCR assay was designed to detect and quantify B. lonestari in A. americanum ticks, and a previously published TaqMan real-time PCR assay, designed to detect (not quantify) Rickettsia species in ticks, was validated for the detection and quantification of the spotted fever group rickettsial endosymbiont in A. americanum ticks. Many pitfalls associated with real-time PCR were experienced in this study, such as difficulties in assay design and problems with contamination, and appropriate modifications are recommended to laboratories routinely performing real-time PCR. / Department of Biology
3

Genetic variants of Ehrlichia chaffeensis in southern Indiana

Seddighzadeh, Ali January 2003 (has links)
Human monocytotropic ehrlichiosis (HME) is a tick-borne infectious disease caused by the bacterium Ehrlichia chaffeensis and transmitted by the lone star tick, Amblyomma americanum. The disease was recognized in Indiana for the first time in 1994. Since 1999, 11 cases have been confirmed in Indiana and two additional cases are under investigation. In the past five years, the cases have been reported from Crawford, Harrison, Warrick, Martin, Perry, Spencer, and Madison counties.A total of 2765 adult Amblyomma americanum ticks were collected from eight counties in southern Indiana during two field trips in May 2000. Ticks were pooled and examined for the presence of Ehrlichia chaffeensis using nested PCR with primers HE1 and HE3, specific for the 16S rRNA gene of the pathogen. Ninety-six pools of A. americanum specimens tested positive for E. chaffeensis DNA. This represented a minimum infection rate (MIR) of 3.5%.To identify different genetic forms (strains) of E. chaffeensis, the positive tick pools were probed for the Variable Length PCR Target (VLPT) gene of E. chaffeensis. The data were used to develop a geographic map of the distribution of the different strains of the pathogen. Overall, nine different genetic variants (91HE17, Arkansas, Jax, Liberty, Osceola, Sapulpa, St. Vincent, Wakulla, West Paces) of E. chaffeensis were identified from pools of ticks collected in four counties (Harrison, Perry, Pike, Warrick). All samples positive for the 16S rRNA were also positive for the VLPT gene.E. chaffeensis isolates are polymorphic in the number of repetitive sequences within the genes encoding the VLPT, and the isolates obtained illustrate this phenomenon. The high concordance rate between the 16S rRNA and the VLPT gene reveals that the VLPT gene is a very sensitive tool for detecting E. chaffeensis in the lone star ticks. We found no clear correlation between geographic distribution of different genetic variants of E. chaffeensis and the genetic polymorphism of the VLPT gene. Further study with a relatively larger sample size from a wider geographical area might be able to detect such a pattern. / Department of Physiology and Health Science

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