Browsing by Subject "Amblyomma"
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Item Genetic variation in the 16s mitochondrial rDNA gene from Texas and Oklahoma populations of Amblyomma maculatum(2009-05-15) Lostak, Tracy KaronSingle-strand conformation polymorphism was used to detect different haplotypes of the 16S mitochondrial rDNA gene within samples of Gulf Coast ticks, Amblyomma maculatum Koch, collected from Payne County, Oklahoma and Brazos and Refugio Counties, Texas. Ticks were collected from dogs, horses, and cattle. The haplotype frequencies from the cattle collections were compared to a similar study, conducted in 1999, to detect if any changes in frequencies had occurred. There were significant differences (p<0.05) between the haplotype frequencies from 1999 and 2007. The haplotype designated as D was highly prevalent in all sampled populations, however was not detected in Oklahoma and Texas eight years earlier. Possible explanations for this occurrence include ticks with this haplotype having a higher fecundity, resistance to drought, or resistance to acaricides. Comparisons of the haplotypes of ticks collected from cattle solely in 2007 showed that the haplotype frequencies of Brazos County and Payne County are more similar than to Refugio County. The haplotype frequencies found on various hosts were also compared and no significant differences were found (p>0.05).Item The occurrence and movement of Fancisella tularensis McCoy and Chapin across landscapes(2009-05-15) Blount, Keith WayneTularemia is a one of the most complex zoonotic diseases. Francisella tularensis McCoy and Chapin, the causative agent of tularemia is considered endemic in Texas, but outbreaks are rare and there are few human cases each year. Tularemia is listed as a Category A biological weapon and air samples are taken daily in select major metropolitan areas, including Houston, to monitor for its presence. I determined the potential risk for tularemia introduction and spread in southeast Texas through field surveillance for the pathogen and its major arthropod vector in the region, Amblyomma americanum (L.); completion of a habitat capability map for A. americanum, based on landscape analysis of the study area; and potential movement and long-term establishment of tularemia through development of a spatially explicit, agent-based, simulation model. Field and laboratory investigations resulted in the identification of two samples positive for F. tularensis. A feral cat tested positive for Type B tularemia using a new aptamer-based assay, and one sample returned positive in Amblyomma maculatum by polymerase chain reaction. This work sheds light on a complex host-pathogen-vector interaction in the rural to urban interface and establishes a framework for future tularemia field work and pathogen modeling in the rural to urban interface.Item Ticks and Tick-Borne Pathogens Associated with Feral Swine in Edwards Plateau and Gulf Prairies and Marshes Ecoregions of Texas(2012-07-16) Sanders, David M.Feral swine (Sus scrofa domesticus) are spreading across North America at an alarming rate. Four Canadian provinces and 39 states within the continental United States now report standing populations of feral pigs. Estimates place the number of feral hogs in Texas >2M, accounting for more than half of the United States population. It is known that feral swine impact local ecology following establishment, with regard to shifts in local flora and fauna. The overall objective of this research was to investigate the role of feral swine in tick-borne pathogen transmission in Texas. The underpinning objectives were to establish host records for tick species parasitizing feral swine, determine the species assemblages associated with feral swine among different ecoregions of Texas, determine by immunoassay to which tick-borne bacteria feral pigs were being exposed, and detect the DNA of tick-borne bacteria by polymerase chain reaction assay in the event of poor or early immune response by the host. Feral pigs (N=432) were harvested from June 2008 to June 2010 using box and corral traps and by aerial gunning. Seven species of ticks, Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor albipictus, D. halli, and D. variabilis; and Ixodes scapularis, were collected. Immature stages of A. cajennense and A. americanum were collected as well. All classes of feral pigs, gender by age, were infested with ticks. Serum was collected through a multi-organizational effort from 2006 to 2010 and tested by ELISA for previous exposure to tick-borne pathogens in the genera Rickettsia and Ehrlichia (N=888) and Borrelia (N=849). Prevalence percentages by immunoassay were 27.59 percent, 13.18 percent and 2.12 percent for Rickettsia, Ehrlichia, and Borrelia, respectively. Samples positive by ELISA for exposure to Borrelia were further screened by Western Blot for exposure to Borrelia turicatae. The results were equivocal in most cases. Blood samples (N=233) were collected from 2008 to 2010 and analyzed by polymerase chain reaction for the detection of the DNA of these same three genera of bacteria. Two of the samples were positive by PCR for the presence of Borrelia DNA. Texas feral swine are serving as hosts for at least seven species of ticks and are interacting with tick-borne pathogen transmissions cycles in Texas.