Browsing by Subject "epidemiology"
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Item Circulating Magnesium and Cardiovascular Disease(2019-05) Rooney, MaryLow circulating magnesium (Mg) or hypomagnesemia is thought to be common, and is traditionally measured by circulating total Mg. Proton pump inhibitor (PPI) medication use is also common and has been linked with low circulating Mg. Both low circulating Mg and PPI use have been associated with elevated cardiovascular disease (CVD) risk. This dissertation further characterizes the complex relationship between circulating Mg and CVD among older adults. Using data from a double-blind pilot Mg supplementation randomized controlled trial, the first manuscript characterizes the interrelationship of different circulating Mg status biomarkers (ionized and total Mg) at baseline and in response to Mg supplementation. Baseline ionized and total Mg were modestly and positively associated. Mg supplementation versus placebo over 10 weeks resulted in increased concentrations of ionized and total Mg. In the second manuscript, we test cross-sectional associations of circulating total Mg with burden of atrial and ventricular arrhythmias as measured over 2 weeks on an ambulatory electrocardiographic monitoring patch in the Atherosclerosis Risk in Communities (ARIC) study. In this now elderly population, serum Mg was inversely associated with premature ventricular contraction burden. While effect estimates were in the hypothesized direction, we found little evidence of an association between circulating Mg and atrial arrhythmias. These findings were similar even among those without a history of CVD. The third manuscript explores cross-sectional associations of PPI use with circulating total Mg and prospective associations of PPI use, hypomagnesemia and CVD risk in the ARIC study. One in four participants had used a PPI within the last 2 weeks, and PPI users had a greater prevalence of hypomagnesemia than non-users. Additionally, PPI users had modestly elevated risk of CVD; however, presence of hypomagnesemia did not explain this elevated risk of CVD. Collectively, this dissertation helps refine our understanding of Mg homeostasis in relation to CVD.Item Ecology Of Influenza A Virus In Avian Species In Minnesota(2018-02) Guo, XiThe fall introductions of Influenza A virus (IAV) to turkey flocks in Minnesota (MN) have occurred annually since 1982 with very few exceptions. These cases were associated with outdoor production of turkeys and their exposure to wild birds during migration. Since 2007, there has been an emerging trend of Spring introductions (SIs) of IAV in MN. The subtypes associated with SIs includes H3, H4, H7, H9, and highly pathogenic avian influenza (HPAI) H5N2 which were all avian-origin strains. Outdoor production practices were stopped in 1998 eliminating direct links between wild birds and domesticated turkeys. The factors that drive the Spring seasonality of IAV introductions has never been studied. The goal of this study is to identify these factors. We hypothesized that SIs of IAVs are driven by two synergistic factors, i.e. the presence of sufficient quantities of IAVs that can infect domesticated turkeys, and farm practices that link the flocks with a virus source. The approaches include to characterize the climate conditions, to investigate the epidemiological factors and to evaluate the virological basis. The findings demonstrate that these two factors work synergistically and were not deterministic to the occurrence of SIs. By detecting the viral persistence under SI related temperatures and by measuring the infectious dose of IAVs in turkeys, we show that IAV has long-term persistence under the temperature of both SI-years and non-SI years. Sufficient quantity of IAVs are necessary to drive SIs. By investigating risks associated with farm practices during 2014 – 2016, we illustrate that on-site mortality disposal and the activities of farm workers are critical factors that drive SIs. Improving the current understanding of SIs requires effective surveillance on the natural hosts of SIs. To control and prevent SIs in the future, on farm practices need to be adjusted for Spring conditions and to address risk factors like on site mortality disposal.Item Epidemiological Model and Weighted Edgelists of Contacts Among Cattle Herds in the Dry and Wet Season in Central Kenya(2017-07-13) VanderWaal, Kimberly; Gilbertson, Marie; Okanga, Sharon; Allan, Brian F.; Craft, Meggan E.; kvw@umn.edu; VanderWaal, KimberlyThis data consists of weighted edgelists representing the frequency with which mobile herds of cattle came into contact with one another in central Kenya. In addition, code is included that simulates the spread of a pathogen through the cattle network. This data can be used to better understand patterns of contact among cattle herds and its implication for the spread of pathogens.Item Epidemiology of chronic low back pain in US adults: The National Health and Nutrition Examination Survey 2009-2010(2016-05) Shmagel, AnnaAbstract Objective: To describe epidemiologic characteristics and associations with increased healthcare utilization in US adults with chronic low back pain (cLBP). Methods: NHANES back pain survey 2009-2010, administered to adults aged 20- 69 (N = 5103). cLBP was defined as pain in the area between the lower posterior margin of the rib cage and the horizontal gluteal fold, with a history of pain lasting almost every day for at least 3 months. Demographic and behavioral characteristics were compared between those with cLBP and without. Factors, associated with ≥10 healthcare visits/year were evaluated in the cLBP subgroup (N=700). Results: cLBP associations with adjusted odds ratios (aORs) ≥2 included age 50-69, education less than high school, annual household income <$20 000, income from disability, depression, sleep disturbances, and medical comorbidities. Subjects with cLBP were more likely to be covered by government-sponsored insurance plans: aOR 3.23 ([95% CI] 2.19-4.75) for Medicaid, aOR 2.25 (1.57-3.22) for Medicare (p < 0.0001), and visited healthcare providers more frequently: aOR 3.35 (2.40-4.67) for ≥10 healthcare visits in the past year (p < 0.0001). In the cLBP subgroup aORs ≥2 were found for associations between ≥10 visits per year and unemployment, income from disability, depression, and sleep disturbances. Conclusion: US adults with cLBP are socio-economically disadvantaged, make frequent healthcare visits and are often covered by government-sponsored health insurance. The clustering of behavioral, psychosocial, and medical issues should be considered in the care of Americans with cLBP.Item The Epidemiology of Civil War(2022-07) Stundal, LoganThis dissertation explores the causal connection between violence occurring in armed conflicts and the emergence of infectious disease within or in close proximity to active conflict zones. While we have known for quite some time that war leads to disease, our understanding of what types of violence contribute to higher (or lower) incidence of specific types of infectious disease remains limited. Establishing the connection between disease and patterns of violence in armed conflict is important since that knowledge can help to inform where humanitarian aid should go and, crucially, what form that aid should take to best support the health needs of civilians suffering the effects of violence. I propose a new theory explaining the disease-conflict connection through a mechanism of civilian population movements in response to changing patterns of observable violence occurring across varying conflict contexts. Variation in conflict intensity as well as the spatial location of that violence – conflict geography – helps to explain downstream variation in the spread of infectious disease. This theory relies upon a mechanism of rational civilians making decisions to maximize their safety in response to violence. As security conditions deteriorate, civilians attempt to improve their situation by pursuing a strategy to remove themselves from areas which present the greatest risk to their personal integrity. In order to decide how to respond to the violence they observe, civilians jointly examine the intensity and geographic location of violence and decide whether to shelter in place, shuffle into nearby areas to find safety, or flee longer distances into neighboring regions or countries. My dissertation demonstrates that conflict context shapes how civilians respond to changing levels of violence. The varied strategies civilians pursue in response to this violence influences the spread of infectious disease by shaping which disease-causing pathogens civilians are more or less likely to encounter. Some patterns of violence facilitate contagious disease transmission while others create ideal conditions for noncontagious disease infections. By explaining the connection between conflict and war through civilian displacement mechanisms, the theory presented and tested in this dissertation allows us to better understand why disease emerges in some conflicts but not others, but also where and what types of disease will emerge across different conflict contexts.Item Extracranial Systemic Embolic Events in a Nationally Representative Discharge Database(2020-12) Adam, TerrenceIntroduction: Systemic emboli affect the brain and extracranial sites resulting in ischemic events with high morbidity and mortality. Extracranial systemic embolic events (ESEEs) frequently affect aortic, iliac, mesenteric, kidney, upper and lower extremity sites. The understanding of factors associated with ESEEs is limited, but atrial fibrillation is likely a major ESEE risk factor. Methods: A retrospective cross-sectional study was completed using the largest publicly available all-payer inpatient care database, the National Inpatient Sample (NIS). All adult NIS discharges were included and atrial fibrillation and ESEE subgroups identified for analysis. Descriptive statistics, multivariable logistic and linear regression were used to assess the association between ESEEs and atrial fibrillation. Other outcomes included inpatient mortality, length of stay and total hospital charges. Results: Hospital discharges with ESEEs had higher inpatient mortality (10.3% vs 2.2%), longer length of stay (6 days vs 3 days) and higher total charges ($86,888 vs $30,737) than non-ESEE discharges. The discharges with concurrent atrial fibrillation were more likely to experience ESEEs, with the majority of events involving lower limbs, mesentery and kidneys. After adjustment for demographic, geographic and institutional factors, ESEEs remained associated with increased mortality, higher total hospital charges and longer length of stay. Discussion: ESEEs with concurrent atrial fibrillation were associated with high inpatient mortality, total hospital charges and longer length of stay. Overall, among all NIS discharges, the most frequent ESEE sites were the lower extremity, mesentery and iliac regions.Item Genetic risk factors of pediatric germ cell tumors and the late effects of their treatment(2021-09) Hubbard, AubreyPediatric germ cell tumors (GCTs) are a heterogeneous group of tumors and their etiology is poorly understood. There are distinct differences between GCTs that arise in early childhood and those in adolescents and young adults, but recent studies of GCTs implicate genetics in the etiology of disease across all age groups. In Manuscript 1, we interrogated the genetically regulated expression of genes within the cell cycle control or apoptosis cellular pathways for their role in pediatric GCT risk. Our results suggest a previously identified association with an intronic variant near BAK1, a pro-apoptotic gene, may be acting through the reduced expression of BAK1. Hispanic children have the highest risk of pediatric GCTs overall, although incidence rates by race/ethnicity do vary by tumor location, sex, and age at diagnosis. No risk factors have been identified to date to explain the excess risk in Hispanic children and in countries in Central America. In Manuscript 2, we employed admixture mapping methods to interrogate genomic regions specific to Hispanic admixture to explore genetic loci contributing to the excess risk in GCTs among Hispanic children. We did not find any genetic loci that reached our threshold for statistical significance, but Amerindian ancestry regions on chromosome 7 were overrepresented among our top results and may warrant further exploration in a sample greater powered for subgroup analyses. Pediatric GCT survival has approached 90% due to the success of platinum-based therapies, but there are substantial late effects of treatment. Little is known about the burden of late effects in pediatric GCT survivors, as they were excluded from the Childhood Cancer Survivor Study. However, pediatric GCT survivors comprise the third largest group of pediatric cancer survivors in the United States. Platinum-based chemotherapy is a risk factor for chemotherapy-induced peripheral neuropathy (CIPN), which is a progressive, debilitating condition with significant effects on a survivor’s quality of life. In Manuscript 3, we characterized the prevalence of CIPN in pediatric GCT survivors and explored the genetic susceptibility to CIPN in survivors that received platinum-based chemotherapy. We found that 24% of our pediatric GCT survivors had at least two symptoms of CIPN after an average of 9 years following their diagnosis. Our genetic studies did not identify genetic risk factors although power was limited to detect variants that reached genome-wide significance. Overall, our first project provided information related to the functional significance of a previously identified variant, our second manuscript is the first genetic study in any age group to include cases of non-European ancestry and our final manuscript is the first study of CIPN in the pediatric age group.Item New Rules for Simulation and Analysis in Ecology, Epidemiology, and Elsewhere(2012-06-13) Lehman, Clarence; Keen, AdrienneAn invisible "phase change" has recently re-shaped computation, in only a few years. Vast memories allow new modeling methods–still being invented and deployed. We apply such methods to epidemiology and ecology, outlined here.Item Respiratory Diseases And Exposures To Taconite Dust Components(2018-04) Shao, YuanThe primary research question addressed in this work is whether long-term on-site exposure to non-asbestiform EMP contributes to the development of mesothelioma and lung cancer observed in the taconite mines. If so, which EMP exposure metric (what size range of the study EMP) is most associated with the mesothelioma cases among taconite worker population. The dissertation has a total of six main chapters. The first chapter includes a brief history of Minnesota iron mining industry, mining related health concerns, and the resulting Minnesota Taconite Worker Health Study (TWHS) conducted from 2008 to 2013. It summarizes the main findings of this previous study and the new research directions after this study. The primary research hypotheses and four associated specific aims are described. Chapter 2 describes the exposure reconstruction process for historical respirable silica (RS) and respirable dust (RD) exposures of workers in Minnesota taconite industry from 1955-2010 in specific aim 1. This chapter also discusses how the historical dust exposure changed over time in each mine-department combination. Chapter 3 addresses specific aim 2, and describes how the historical EMP exposure levels are predicted using EMP data and the time-trends obtained from specific aim 1. Chapter 4 describes the mathematical modeling approach for deriving numerical conversion factors (CFs) between EMP of different size ranges. This chapter also discusses how these CFs are important in the development of alternative dimension-specific EMP JEMs starting from the existing NIOSH-EMP based JEM developed in specific aim 2. This work addresses specific aim 3. Chapter 5 describes a mesothelioma case-control study conducted using an updated study cohort and new dimension-specific EMP JEMs developed in specific aim 3. The chapter addresses specific aim 4 and provides answers to the primary research question of this dissertation. In the last chapter, I summarize the overall conclusion and propose some future research directions.Item Using quantitative and qualitative epidemiological tools for holistic, effective African Swine Fever prevention, early detection, and control(2023-03) Schambow, RachelAfrican Swine Fever (ASF) is a viral, hemorrhagic disease of swine that is notifiable to the World Organization for Animal Health. ASF can cause nearly 100% mortality in affected swine herds, and no treatment or vaccine is available. Animal health officials rely on biosecurity, surveillance, and other control measures to manage ASF outbreaks. The United States is free of ASF, but widespread outbreaks in Europe, Asia, and the Dominican Republic have increased concern in the US swine industry. Studies have estimated that an ASF introduction could cost the US over $50 billion USD in losses and control efforts. The objective of this work was to use complementary quantitative and qualitative epidemiological and analytical tools to support the development of holistic ASF prevention and control strategies for the US and globally. Chapter 1 describes the background and important characteristics of ASF and reviews the use of some epidemiological techniques for ASF control. Chapter 2 describes how Strengths, Weaknesses, Opportunities, and Threats analysis was used to characterize stakeholders’ perceptions of ASF control strategies in the Dominican Republic. Chapter 3 demonstrates how quantitative risk analysis was used to characterize the risk of ASF introduction into the US in imported non-animal feed ingredients. In Chapter 4, qualitative participatory methods were used to characterize stakeholder values and needs regarding enhanced passive surveillance for early detection of ASF in the US. Chapter 5 demonstrates the use of Bayesian latent class analysis to estimate the sensitivity and specificity of novel ASF ELISA and qPCR diagnostic tests using field data from Vietnam. The work described in these chapters has demonstrated how both qualitative and quantitative tools can provide important data and socioeconomic context for the development of ASF prevention and control strategies. Future efforts for the US should encompass this holistic strategy to ASF preparedness, from understanding stakeholder values and providing training and support to using analytical and data-driven techniques to enhance biosecurity, surveillance, and outbreak preparedness. Ultimately, global cooperation, collaboration, and transparency will support the international fight against ASF.