Browsing by Subject "Disease"
Now showing 1 - 8 of 8
Results Per Page
Sort Options
Item An economic exploration of prevention versus response in animal related bioterrorism decision making(Texas A&M University, 2006-04-12) Elbakidze, LevanAnimal disease outbreaks either through deliberate terroristic act or accidental introductions present a serious economic problem. This work concentrates on the economics of choosing strategies to mitigate possible agricultural terrorism and accidental introduction events largely in the animal disease management setting. General economic issues and the economic literature related to agricultural terrorism broadly and animal disease concerns specifically are reviewed. Basic economic aspects, such as the economic consequences of outbreaks, costs and benefits of various mitigation strategies, and stochastic characteristics of the problem are discussed. A conceptual economic model is formulated to depict the animal disease outbreak related decision making process. The key element of this framework is the choice between ex ante versus ex post mitigation strategies. The decision of investing in preventative and/or responsive strategies prior to the occurrence of an event versus relying on response and recovery actions after an outbreak event needs careful consideration. Comparative statics investigations reveal that factors that affect this decision are event probability, and severity, as well as costs, benefits, and effectiveness of various mitigation strategies. A relatively simplified empirical case study is done analyzing the economic tradeoffs between and optimum levels of ex ante detection, as a form of prevention, and ex post slaughter, as a form of response. The setting chosen involves Foot and Mouth Disease management. Empirical investigation is done on the conditions under which it is economically more advantageous to invest in ex ante detection as opposed to relying just on ex post response. Results show that investment in ex ante activities becomes more advantageous as the probability and severity of an agricultural terrorism event increases, response effectiveness decreases, and costs of surveillance decrease. Also spread rate is found to play a key role in determining optimal combination of ex ante and ex post strategies with more done ex ante the faster the disease spread. Finally, an economic framework is posed for future work given availability of a more detailed epidemiologic model. Access to such a model will allow for incorporation of wider spectrum of strategies including numerous possibilities for prevention, detection, response and market recovery facilitation. The framework allows more localized options, multiple possible events and incorporation of risk aversion among other features.Item Endohelminths from six rare species of turtles (Bataguridae) from Southeast Asia confiscated by international authorities in Hong Kong, China(Texas A&M University, 2004-09-30) Murray, Rebecca AnnSpecimens of 6 species of threatened, vulnerable, and endangered turtles (Cuora amboinensis, Cyclemys dentata, Heosemys grandis, Orlitia borneensis, Pyxidea mouhotii, and Siebenrockiella crassicollis) belonging to family Bataguridae, were confiscated in Hong Kong, China on 11 December 2001 by international authorities. Endohelminth studies on these turtle species are scarce, and this study provided a rare opportunity to examine a limited number of specimens for endohelminths. Ten different parasite species were collected and there were 16 new host records. This is the first record of a parasite from P. mouhotii. The parasite prevalences found in this study provide a basis for a better understanding of the phylogenetic relationships of the family Bataguridae to other families, especially Testudinidae. Based on known life cycles, parasites found provided an indication of food preferences of these 6 turtle species that support previous studies of the turtles' feeding habits. However, the results of the parasite survey from O. borneensis provided additional feeding habit information. The list of endohelminths herein is intended to provide a foundation for future parasite studies of the 6 species of Asian turtles.Item Evaluation of agricultural disinfectants and necrotic enteritis preventatives in broiler chickens(2009-05-15) Stringfellow, Kendre DuaronThe objective of this study was to determine the effect of time, temperature and organic matter on disinfectant efficacy. Staphylococcus aureus (SA) and Salmonella Typhimurium (ST) were used as organisms to represent Gram positive and Gram negative bacteria, respectively, commonly found in poultry housing. Three independent experiments evaluated the effect of temperature, time, and organic matter on the efficacy of working concentrations of disinfectants against representative organisms found in commercial poultry housing. Quaternary ammonium, chlorhexidine, phenolic and binary ammonium based solutions represented disinfectants commonly used within the poultry industry. Results from these experiments indicated that long term storage of disinfectants will reduce their efficacy against SA. However, a reduction (p ? 0.05) in efficacy was observed with the phenolic compound against ST at elevated temperatures. Following the inclusion of organic matter (OM), reduced (p ? 0.05) efficacy of all disinfectants was observed in a dose dependent manner against both organisms, with the exception of the phenolic compound against SA. Fresh disinfectant performed better (p ? 0.05) in the presence of OM than 30 wk old disinfectant. These results emphasize the need to use fresh disinfectants and that OM should be removed prior to disinfection. We also evaluated the effect of bismuth citrate, lactose and citric acids on the development of necrotic enteritis in broilers. Clostridium perfringens? associated necrotic enteritis in poultry causes significant loss and increased morbidity in the industry. Due to the reduced usage of antibiotic growth promoters, the incidence of necrotic enteritis has increased. These experiments evaluated different levels of bismuth citrate and bismuth citrate with lactose or citric acid added, on lesion development, bacterial intestinal colonization of C. perfringens and pH levels in the gut of broilers orally challenged with C.perfringens. Results from this investigation indicate that bismuth citrate at 100 ppm and 200 ppm caused a reduction (p ? 0.05) in C. perfringens colonization and intestinal lesion development. The addition of dietary lactose to bismuth citrate enhanced the effect of bismuth citrate on intestinal lesion development. These data suggest that bismuth citrate alone or in combination with dietary lactose will reduce intestinal lesion development in broilers with necrotic enteritis.Item Greenhouse techniques to screen for resistance to peanut diseases(2008-05) Wilson, Jeffrey N.; Wheeler, Terry A.; Burow, Mark D.; Black, Mark; Peffley, Ellen B.Soil-borne diseases have become a significant concern in West Texas peanut production. Cylindrocladium parasiticum is an important peanut (Arachis hypogaea L.) pathogen in the southeastern U.S. and was first confirmed in Texas in 2004. Two experiments were conducted to refine a screening technique for C. parasiticum using peanut germplasm with known resistance levels. Peanuts were screened using two container sizes (66 and 164 cm3), two inoculum densities (15 and 25 microsclerotia (ms)/g soil), and were sampled at three different times (4, 5, and 6 weeks after planting). Fresh root and shoot weights, root rot, and percentage visible taproot and secondary root necrosis were estimated at the three sampling intervals. Root weight and shoot weights complemented visual root ratings and were the only combinable measurements due to changes in C. parasiticum inoculum that occurred between trials. Percent taproot and secondary root necrosis on highly resistant genotype NC 3033 were significantly lower than on susceptible cultivar NC 7 in 66 cm3 containers at both inoculum densities. Percent taproot and secondary necrosis were simple, quick assessments of disease severity that unlike root rot ratings were continuous and less subjective. Neither taproot necrosis nor secondary root necrosis interacted with the effect of week of sampling which indicated that genotypes differences were apparent at 4 weeks after planting. In the growth chamber screening test, selected spanish genotypes had lower percentage taproot necrosis than selected runner genotypes (P < 0.0001). The majority of Texas Tech University, Jeffrey Wilson, May 2008 the spanish lines tested in this experiment had mean percent taproot necrosis values equivalent to highly resistant NC 3033. Six runner genotypes also had mean percent taproot necrosis values equivalent to highly resistant NC 3033. Sclerotinia minor is a serious disease of peanuts (Arachis hypogaea L.) in the southeastern U.S. that has become a problem in numerous West Texas peanut fields since 1996. Growers need peanut cultivars adapted to West Texas growing conditions with resistance to S. minor. Methods used to evaluate resistance to S. minor in peanut included field evaluations, detached leaflet assays, and stem assays. In 2006, selected runner, higholeic spanish, and bunch-type genotypes were field tested in Stephenville, TX. Endemic inoculum was supplemented with an aggressive isolate of the most predominate Texas peanut S. minor genotype, TX1. Field disease severities were correlated with results from detached stem and leaflet assays. Detached leaflets were inoculated with an aggressive and moderately aggressive isolate of genotype TX1 along with an aggressive isolate of TX2, another prevalent S. minor genotype. Detached stems were inoculated with the aggressive S. minor isolate TX2. For runner genotypes, a significant correlation between field ratings and detached leaflet assays occurred using the aggressive (R2 = 0.96) and moderately aggressive (R2 = 0.93) TX1 isolates when two leaflet trials (eight total replications) were combined. No correlation between field ratings and detached leaflet assays or detached stem assays occurred for spanish and bunch-types. Field ratings and detached stem assays were significantly correlated with runner genotypes only in trial I (six replications) and when trials were combined.Item The hedgehog pathway in retinal development and disease(2011-08) Bibliowicz, Jonathan; Gross, Jeffrey Martin; FISCHER, JANICE A.; MORGAN, JENNIFER; THOMPSON, WESLEY; VOKES, STEVEN A.The Hedgehog receptor Patched (Ptch) is a well-studied tumor suppressor. Mutations in Ptch have been linked to mis-regulation of stem cell proliferation and tumorigenesis in numerous contexts. To study the role of Ptch function during retinal development and homeostasis, I analyzed retinal growth and patterning in the embryonic and post-embryonic (juvenile) zebrafish ptc2 mutant line. ptc2 deficiency in zebrafish results in an expansion of the stem/progenitor population of the ciliary marginal zone (CMZ), as well as ectopic proliferation within the neural retina at juvenile stages. ptc2-/- mutants also possess vitreo-retinal abnormalities that appear to be embryonic in origin. These phenotypes are similar to the ocular abnormalities previously reported in human patients suffering from Basal Cell Naevus Syndrome (BCNS), a disorder that has been linked to mutations in the human PTCH gene (the orthologue of the zebrafish ptc2), and point to the utility of the ptc2 mutant line as a model for the study of BCNS-related ocular pathologies. In addition, peripheral retinal dysplasias that include ectopic neuronal clusters and disrupted lamination were observed at later, juvenile stages. It has been previously proposed that retinal over-proliferation might contribute to retinal dysplasias observed in the post-natal Ptch1 /- mice (an established model for BCNS); however, this potential relationship has yet to be established experimentally. I demonstrated that a population of ectopically proliferating cells give rise to the ectopic neuronal clusters in the INL of ptc2-/- mutants and established ectopic proliferation as the likely cellular underpinning of retinal dysplasia in juvenile ptc2-/- mutants.Item Investigation into Possible Factors Affecting the Recruitment of Rocky Mountain Elk on the Valles Caldera National Preserve(2013-05) Bernal, Lance; Gipson, Philip S.; Wallace, Mark C.; Parmenter, Robert R.; Liley, StewartThe Valles Caldera National Preserve (VCNP) is a relatively new public land holding located in the Jemez Mountains in north-central New Mexico. For the past decade, low calf:cow ratios of elk (Cervus elaphus) have been recorded on the VCNP prompting concern by both the Valles Caldera Trust, the managing body for the VCNP, and the New Mexico Department of Game and Fish (NMDGF) managers who are responsible for ensuring a sustainable elk population. These studies were done to look at possible factors that may be contributing to the low recruitment of elk on the VCNP as well as simulate how the population may respond to different management actions. A serological survey was conducted on hunter-harvested elk from the VCNP during the 2010 and 2011 fall hunting seasons. We tested 119 (2010, n =74; 2011, n = 45) for brucellosis, bovine viral diarrhea virus (BVDV), infectious bovine rhinotracheitis (IBR), bluetongue (BT), epizootic hemorrhagic disease (EHD), parainfluenza-3 (PI-3) and 5 serovars of Leptospirosis. Exposure rates were highest for PI-3 (34.5%) and IBR (10.1%) for total samples. Exposure for BVDV was found in 2.5% of the total samples. Exposure to EHD and BT was in 1.7% and 0.8% of the total samples. Exposure to the Leptospirosis serovars hardjo (n=2) and canicola (n=1) were found in the samples tested. All samples tested negative for brucellosis. The low to medium positive exposure to all the diseases except brucellosis indicate these diseases are present within the VCNP elk population but are not likely causing the low recruitment rates. A secondary study was done to address the hypothesis that the observed low calf:cow ratios on the VCNP may be the result of low calf survival rates. To determine cause-specific mortality and estimate survival, we radio marked elk calves (n =140) born within the VCNP from 2009-2011. Two approaches were done to estimate 14 day survival, overall summer survival (t = 13 weeks), and annual survival. First, biological covariates were used to model survival for 14 day post capture and weekly summer survival for all calves. This was done in order to compare survival estimates to other studies experiencing low calf:cow ratios in the western United States. Then, the data were re-analyzed by censoring calves (n = 9) which died the day after tagging. This provided a more conservative survival estimate reduced possible biases due to handling calves and its potential effect on survival. Fourteen day survival was 0.57 (SE = 0.05, 95%CI: 0.48-0.66) when using uncensored data; survival was 0.64 (SE = 0.05, 95%CI 0.54-0.72) using censored data. Summer survival was estimated to be 0.37 (SE = 0.05, 95%CI 0.28-0.47) using uncensored data; summer survival was estimated 0.43 (SE = 0.05, 95%CI: 0.33-0.53) using censored data. Fall/winter survival (mid-August-April) ranged from 0.76-0.95 based on study year. Annual survival ranged from 0.32-0.55 with a mean of 0.42 using uncensored data; annual survival ranged from 0.32-0.59 with a mean of 0.46 using censored data. Predation accounted for 94.8% of the known deaths. Black bears (Ursus americanus) were the highest source of predation (47.3%, n = 26) and overall mortality (40.6%). Coyotes (Canis latrans) were the second highest source of predation (41.8%, n = 23) and overall mortality (35.9%). The results using both uncensored and censored data are comparable to other studies which were experiencing low calf:cow ratios. Therefore predation of elk calves is likely additive and causing suppressed recruitment rates in the elk population on the VCNP. However, it is highly recommended to estimate the large predator population prior to any large predator management to ensure the population of large predators is not reduced to a level from which they cannot recover. For the third part of this study the overall objective was to incorporate data that were available into the population simulation program POP-II, to model current population trends based the current data and then run simulated population trends based on possible management decisions. Data that were used included: summer survey data which used distance sampling to estimate population size and herd ratios; fall harvest numbers for adult male and adult female elk; and estimated summer survival rates of elk calves born on the VCNP. Models were developed based on current preseason mortality of neonatal elk with a reduction in harvest of adult males and females by 10%, both separately and collectively. Current harvest numbers were maintained while preseason mortality of neonates was reduced by 25% and 50%. Comparisons of the model output were then made for both the reduction of preseason mortality along with a reduction in harvests. Models showed that decreasing preseason mortality while maintaining current harvest rates would either stabilize or begin a positive increase in the population trend. The models also showed that making a 10% sex-specific (males only or females only) harvest reduction while maintaining current preseason mortality would maintain the current population trend. Making a 10% harvest reduction of either sexes or both sexes along with a reduction in preseason mortality should lead to positive population trends. The results of this study might be used to help guide adaptive management decisions regarding population trends of the elk herd in the Valles Caldera National Preserve.Item Overlooked casualties : stories of families affected by vaccine-preventable diseases(2012-05) Haelle, Tara Susan; Darling, Dennis Carlyle; Minutaglio, BillThe invention of the vaccine has been one of the greatest public health triumphs of the modern world. Each new vaccine has saved thousands - even millions - of lives worldwide, but this success has been fraught with controversy over the safety and even the effectiveness of vaccines. Vaccines have not always had a spotless safety record, but today’s vaccines are incredibly safe and continue to protect millions of people against diseases that have significantly declined or nearly disappeared from the developing world. It is this very success that has led many people to forget, or never discover, what those diseases are and how destructive they can be. This report tells the story of several families whose lives were deeply affected by vaccine-preventable diseases, accompanied with images that help tell their story. Following these stories is a broader discussion of the issues related to vaccines, the misunderstandings and misinformation that often circulate about them, a brief mention of their safety and efficacy, and a general discussion of many of the diseases they can prevent.Item The Measure of Love Lost: Jeanette Winterson's "Written on the Body" and the Discourses of Love, Melancholy, and Disease(2010-10-12) Wheeler, Stephanie K.Jeanette Winterson?s novel Written on the Body asks what it means to express love not through language but through the body, where it is felt, challenging the boundaries placed between body and language. Using Winterson?s novel and Roland Barthes?s A Lover?s Discourse as points of inquiry, this thesis examines conceptions of love based on heteronormative and romanticized visions of present and healthy bodies. This thesis asks how a body that is diseased and dying can express an emotion that is predicated on these very notions of presence, absence, and health. The narrator of the novel sees love as a scripted story that, once adhered to, determines the (successful) experience of love. Louise?s cancer threatens these scripts of love, as it destroys the narrator?s conception of both love and Louise. Despite the fact that Louise is absent and dying, the narrator begins to write a new story that will allow him/her to have a perfect relationship with Louise, so that s/he can reconcile the contradictions of the scripts that the relationship exposed. Using Slavoj Zizek?s ?Melancholy and the Act? and Richard Stamelman?s Lost Beyond Telling as frameworks of mourning and melancholy, the narrator?s melancholy over a lost presence thus emerges as a way that allows him/her to create a perfect love story. To make Louise appear perfect in this perfect love story, the narrator manipulates the language of disease that reconstructs Louise's physical absence as a textual presence. The discourse surrounding Louise thus begins to operate out of the desire to compensate and supplement what is missing; in Louise's case, the narrator is supplementing her with a "normal," healthy body. Looking in the shadows of the narrator?s memories, Written on the Body emerges as not only an account of the narrator?s love story, but also an account of Louise?s story, a story of a body that refuses to be written on and demands to be heard. Winterson demonstrates how the body is always in the process of creating knowledge and meaning that can only be obtained by questioning what is normal, both for the body and for the scripts we all adhere to.