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- Creators: School of Life Sciences
- Creators: Collins, James P.
Description
Infectious diseases have emerged as a significant threat to wildlife. Environmental change is often implicated as an underlying factor driving this emergence. With this recent rise in disease emergence and the acceleration of environmental change, it is important to identify the environmental factors that alter host-pathogen dynamics and their underlying mechanisms. The emerging pathogen Batrachochytrium dendrobatidis (Bd) is a clear example of the negative effects infectious diseases can have on wildlife. Bd is linked to global declines in amphibian diversity and abundance. However, there is considerable variation in population-level responses to Bd, with some hosts experiencing marked declines while others persist. Environmental factors may play a role in this variation. This research used populations of pond-breeding chorus frogs (Pseudacris maculata) in Arizona to test if three rapidly changing environmental factors nitrogen (N), phosphorus (P), and temperature influence the presence, prevalence, and severity of Bd infections. I evaluated the reliability of a new technique for detecting Bd in water samples and combined this technique with animal sampling to monitor Bd in wild chorus frogs. Monitoring from 20 frog populations found high Bd presence and prevalence during breeding. A laboratory experiment found 85% adult mortality as a result of Bd infection; however, estimated chorus frog densities in wild populations increased significantly over two years of sampling despite high Bd prevalence. Presence, prevalence, and severity of Bd infections were not correlated with aqueous concentrations of N or P. There was, however, support for an annual temperature-induced reduction in Bd prevalence in newly metamorphosed larvae. A simple mathematical model suggests that this annual temperature-induced reduction of Bd infections in larvae in combination with rapid host maturation may help chorus frog populations persist despite high adult mortality. These results demonstrate that Bd can persist across a wide range of environmental conditions, providing little support for the influence of N and P on Bd dynamics, and show that water temperature may play an important role in altering Bd dynamics, enabling chorus frogs to persist with this pathogen. These findings demonstrate the importance of environmental context and host life history for the outcome of host-pathogen interactions.
ContributorsHyman, Oliver J. (Author) / Collins, James P. (Thesis advisor) / Davidson, Elizabeth W. (Committee member) / Anderies, John M. (Committee member) / Elser, James J. (Committee member) / Escalante, Ananias (Committee member) / Arizona State University (Publisher)
Created2012
Description
Memory CD8+ T-cells can persist in the absence of antigen, primed for immediate activation and proliferation if later exposed to the same antigen. These cytotoxic lymphocytes provide long-term immunity following an acute infection. Studies have observed that intermediate levels of general T cell transfer prior to infection may cause an inappropriate response resulting in increased pathology rather than prevention. Therefore, our study focused on a memory CD8 T-cell therapy using lymphocytic choriomeningitis virus (LCMV) specific splenocytes, which activate and proliferate at an accelerated pace compared to that of naive T-cells. LCMV is a natural murine pathogen which also poses a zoonotic infection threat to humans, and the effect of immune cell vaccination therapies for LCMV is not fully understood. We observed the effect of multiple memory CD8 T cell dosage levels on overall disease and memory CD8 T-cell response to the virus. Infection by exposure to a carrier was shown to have a reduced impact on mice receiving higher doses of memory T cells prior to infection compared to mice receiving less or no memory cells. Higher presence of activated memory cells were shown to correlate with less disease-related weight loss and accelerated recovery times. Survival rate after exposure to carriers was not shown to be affected by dosage level, warranting further research regarding the prevalence of the immunopathology observed in other studies in natural murine transmission models.
ContributorsMiller, Charles (Author) / Blattman, Joseph (Thesis director) / Holechek, Susan (Committee member) / Carmen, Joshua (Committee member) / W. P. Carey School of Business (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Tools that accurately assess physical activity and sedentary behaviors have broad implications relative to understanding the association of adverse health outcomes and these behaviors. Given the ease of distribution and inexpensive nature of self-report tools, they are the most widely used means to assess human behavior in large-scale populations. The purpose of this study was to validate the ACT24 online self-report recall for measures of sedentary and active behavior against criterion measure. Participants of a larger study were asked to complete the ACT24 recall on a random day in three different weeks during which they were wearing the criterion device. A total of 16 recalls were completed that were used to assess ACT24 measures of sedentary, active, and MVPA behavior. Four different comparisons afforded this analysis: criterion sitting time to ACT24 sedentary time, criterion standing time to ACT24 active behavior, criterion stepping time to ACT24 active behavior, and criterion stepping of 3.0+METs to ACT24 MVPA. Results for the comparisons made between ACT24 sedentary time versus criterion sitting time and ACT24 active time to criterion active time showed little systematic differences at the group level, but the limits of agreement were relatively wide. The comparisons made between ACT24 active time to criterion stepping time and ACT24 MVPA to criterion stepping time at 3.0+ METs both showed a positive systematic difference. Increased incidence of physical activity was correlated with more difference between the measures, likely due to an underestimation of criterion active time measurement. These results are important in the preliminary validity analysis of ACT24 measures of active and sedentary time. Future directions include implementing validation protocols in larger and more diverse samples.
ContributorsBrinkman, Joseph Connor (Author) / Buman, Matthew P. (Thesis director) / Hekler, Eric (Committee member) / Matthews, Charles E. (Committee member) / Barrett, The Honors College (Contributor) / W. P. Carey School of Business (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Background: While research has quantified the mortality burden of the 1957 H2N2 influenza pandemic in the United States, little is known about how the virus spread locally in Arizona, an area where the dry climate was promoted as reducing respiratory illness transmission yet tuberculosis prevalence was high.
Methods: Using archival death certificates from 1954 to 1961, this study quantified the age-specific seasonal patterns, excess-mortality rates, and transmissibility patterns of the 1957 pandemic in Maricopa County, Arizona. By applying cyclical Serfling linear regression models to weekly mortality rates, the excess-mortality rates due to respiratory and all-causes were estimated for each age group during the pandemic period. The reproduction number was quantified from weekly data using a simple growth rate method and generation intervals of 3 and 4 days. Local newspaper articles from The Arizona Republic were analyzed from 1957-1958.
Results: Excess-mortality rates varied between waves, age groups, and causes of death, but overall remained low. From October 1959-June 1960, the most severe wave of the pandemic, the absolute excess-mortality rate based on respiratory deaths per 10,000 population was 17.85 in the elderly (≥65 years). All other age groups had extremely low excess-mortality and the typical U-shaped age-pattern was absent. However, relative risk was greatest (3.61) among children and young adolescents (5-14 years) from October 1957-March 1958, based on incidence rates of respiratory deaths. Transmissibility was greatest during the same 1957-1958 period, when the mean reproduction number was 1.08-1.11, assuming 3 or 4 day generation intervals and exponential or fixed distributions.
Conclusions: Maricopa County largely avoided pandemic influenza from 1957-1961. Understanding this historical pandemic and the absence of high excess-mortality rates and transmissibility in Maricopa County may help public health officials prepare for and mitigate future outbreaks of influenza.
Methods: Using archival death certificates from 1954 to 1961, this study quantified the age-specific seasonal patterns, excess-mortality rates, and transmissibility patterns of the 1957 pandemic in Maricopa County, Arizona. By applying cyclical Serfling linear regression models to weekly mortality rates, the excess-mortality rates due to respiratory and all-causes were estimated for each age group during the pandemic period. The reproduction number was quantified from weekly data using a simple growth rate method and generation intervals of 3 and 4 days. Local newspaper articles from The Arizona Republic were analyzed from 1957-1958.
Results: Excess-mortality rates varied between waves, age groups, and causes of death, but overall remained low. From October 1959-June 1960, the most severe wave of the pandemic, the absolute excess-mortality rate based on respiratory deaths per 10,000 population was 17.85 in the elderly (≥65 years). All other age groups had extremely low excess-mortality and the typical U-shaped age-pattern was absent. However, relative risk was greatest (3.61) among children and young adolescents (5-14 years) from October 1957-March 1958, based on incidence rates of respiratory deaths. Transmissibility was greatest during the same 1957-1958 period, when the mean reproduction number was 1.08-1.11, assuming 3 or 4 day generation intervals and exponential or fixed distributions.
Conclusions: Maricopa County largely avoided pandemic influenza from 1957-1961. Understanding this historical pandemic and the absence of high excess-mortality rates and transmissibility in Maricopa County may help public health officials prepare for and mitigate future outbreaks of influenza.
ContributorsCobos, April J (Author) / Jehn, Megan (Thesis director) / Chowell-Puente, Gerardo (Committee member) / Barrett, The Honors College (Contributor) / School of Human Evolution and Social Change (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
The purpose of this study is to discover the exposure and network patterns during the 2013-2015 Ebola Virus Disease epidemic. The author accomplished this by taking an opportunistic sample of news and academic articles, some of which may also capture cases untreated and therefore unrecorded by hospitals and treatment units. Most of the 315 cases came from the Washington Post, New York Times, and World Health Organization, and they consistently captured between 1-2% of WHO case numbers. The results show that of cases with known exposures, 53.6% became infected through contact with sick family members. Hospital and funeral transmission accounted for the second and third most frequent exposure scenarios at 24.6% and 12.9% respectively. The exposures over time imply that hospital and funeral transmission prevention efforts have been successful, but family transmission has remained common throughout the outbreak. Prevention initiatives should focus on families earlier in epidemics to help control EVD's spread.
ContributorsCleaton, Julie Marie (Author) / Chowell, Gerardo (Thesis director) / Hurtado, Ana Magdalena (Committee member) / Barrett, The Honors College (Contributor) / School of Human Evolution and Social Change (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Among wild rodent populations, vertical transmission is believed to constitute the primary route of infection for Lymphocytic Choriomeningitis Virus (LCMV), a non-lytic arenavirus with both acute and chronic forms. When carrier mice infected at birth with the acute Armstrong strain reproduce, they generate congenital carrier offspring containing a quasispecies of LCMV that includes Armstrong as well as its chronic Clone-13 variant. This study examined the genetic trends in the vertical transmission of LCMV from mothers infected perinatally with Clone-13. Viral isolates obtained from the serum of congenital carrier offspring were partially sequenced to reveal residue 260 in the glycoprotein-encoding region of their S segment, the site of a major amino acid change differentiating the chronic and acute strains. It was found that the phenylalanine-to-leucine mutation associated with Clone-13 was present in 100% of the isolates, strongly indicating that the offspring of Clone-13 carriers contain exclusively the chronic variant. This research has broad implications for the epidemiology of the virus, and, given the predominance of Armstrong in the wild, suggests that there must be a biological cost associated with Clone-13 infection in non-carriers.
ContributorsFrear, Cody Christian (Author) / Blattman, Joseph (Thesis director) / Hogue, Brenda (Committee member) / Holechek, Susan (Committee member) / Barrett, The Honors College (Contributor) / School of Human Evolution and Social Change (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
Amphibians have been experiencing a worldwide decline that is in part caused by an infectious disease, chytridiomycosis, specific to frogs and salamanders. Globally many species have declined or gone extinct because of the pathogenic fungus Batrachochytrium dendrobatidis, also known as the amphibian chytrid or Bd. By the time Bd was discovered it was too late to stop the spread and it has now been found on almost every continent. The trade of captive amphibians, used as pets, bait, and educational animals provides an opportunity to spread Bd. Because some amphibians can carry Bd without experiencing symptoms, it is possible for even healthy looking amphibians to spread the amphibian chytrid if they are moved from one location to another. Recently, a new species Batrachochytrium salamandrivorans (Bsal) was found on salamanders. Bsal was identified before it reached the United States, prompting concern regarding its spread and a call for regulation regarding the trade of captive amphibians. There are some regulations in place controlling the trade of amphibians, but they are insufficient to stop the spread of amphibian chytrid in captive populations. A 2016 law prohibits the importation of 201 salamander species. However, there is no central organization to sample or certify if amphibians are free from Bd or Bsal. Although some stores say they test for these pathogens the tests are unregulated and not reported to any central body. If the captive amphibian trade is to go disease free, there would need to be a significant push to coordinate testing efforts. To estimate Bd's prevalence in Arizona captive amphibian populations, I contacted pet stores, bait stores, and sanctuary or educational organizations to ask if I could sample their amphibian collections. My research built on the 2008 work of Angela Picco, who sampled for the amphibian chytrid in Arizona bait shops. I found that amphibian owners were often hesitant and unwilling to participate in this research opportunity. There are multiple reasons for this hesitancy including a fear of increased regulation, the potential for reporting to a government agency (USDA), or the eventual cessation of amphibian trade. The lack of willing participants suggests there may be difficulties in coordinating future sampling efforts for Bd and Bsal.
ContributorsFadlovich, Rachel Maurine (Author) / Collins, James (Thesis director) / Minteer, Ben (Committee member) / Brus, Evan (Committee member) / School of Life Sciences (Contributor) / Department of English (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Mortality of 1918 influenza virus was high, partly due to bacteria coinfections. We characterize pandemic mortality in Arizona, which had high prevalence of tuberculosis. We applied regressions to over 35,000 data points to estimate the basic reproduction number and excess mortality. Age-specific mortality curves show elevated mortality for all age groups, especially the young, and senior sparing effects. The low value for reproduction number indicates that transmissibility was moderately low.
ContributorsJenner, Melinda Eva (Author) / Chowell-Puente, Gerardo (Thesis director) / Kostelich, Eric (Committee member) / Barrett, The Honors College (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / School of Life Sciences (Contributor)
Created2015-05
Description
This paper will chronicle my personal experience in trying to design and initiate a retrospective patient data study to determine the prevalence of Primary Sclerosing Cholangitis (“PSC”) in certain races/ethnic groups in Arizona. This experience will also be the basis for my proposed roadmap for a more successful future study.
My nearly 10 month thesis project of trying to complete a study yielded considerable ‘learning opportunities’ in large part due to my inexperience. I made numerous errors in sequencing tasks, grossly under-scoping elapsed time and hours for other tasks, completely overlooking other critical tasks, and being insensitive to how irrelevant I and my project were to the many professionals whose help I needed to complete the study. Based upon the knowledge I gained through this process, I will describe the design of a future study of retrospective patient data that will assess whether PSC patients in Phoenix, Arizona follow racial/ethnic trends. I chose Phoenix as an ideal location to perform this proposed study because of the diverse racial/ethnic population in the greater Phoenix area. The goal will be to obtain and review 20 years of retrospective patient data from three large hospital groups in Phoenix, identify the races/ethnicities of PSC patients, and quantify the prevalence and incidence of PSC in such races/ethnicities. The lack of IRB uniformity among the subject hospitals/clinics will pose a challenge, but a detailed outline of how to approach the IRB approval process and obtain PSC patient data from each institution is provided.
My nearly 10 month thesis project of trying to complete a study yielded considerable ‘learning opportunities’ in large part due to my inexperience. I made numerous errors in sequencing tasks, grossly under-scoping elapsed time and hours for other tasks, completely overlooking other critical tasks, and being insensitive to how irrelevant I and my project were to the many professionals whose help I needed to complete the study. Based upon the knowledge I gained through this process, I will describe the design of a future study of retrospective patient data that will assess whether PSC patients in Phoenix, Arizona follow racial/ethnic trends. I chose Phoenix as an ideal location to perform this proposed study because of the diverse racial/ethnic population in the greater Phoenix area. The goal will be to obtain and review 20 years of retrospective patient data from three large hospital groups in Phoenix, identify the races/ethnicities of PSC patients, and quantify the prevalence and incidence of PSC in such races/ethnicities. The lack of IRB uniformity among the subject hospitals/clinics will pose a challenge, but a detailed outline of how to approach the IRB approval process and obtain PSC patient data from each institution is provided.
ContributorsBuness, James Gage (Author) / Lindor, Keith (Thesis director) / Ali, Ahmad (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Batrachochytrium dendrobatidis (Bd), the amphibian chytrid fungus causing chytridiomycosis, is the cause of massive amphibian die-offs. As with any host-pathogen relationship, it is paramount to understand the growth and reproduction of the pathogen that causes an infectious disease outbreak. The life-cycle of the pathogen, Bd, is strongly influenced by temperature; however, previous research has focused on Bd isolated from limited geographic ranges, and may not be representative of Bd on a global scale. My research examines the relationship between Bd and temperature on the global level to determine the actual thermal maximum of Bd. Six isolates of Bd, from three continents, were incubated at a temperature within the thermal range (21°C) and a temperature higher than the optimal thermal range (27°C). Temperature affected the growth and zoosporangium size of all six isolates of Bd. All six isolates had proliferative growth at 21°C, but at 27°C the amount and quality of growth varied per isolate. My results demonstrate that each Bd isolate has a different response to temperature, and the thermal maximum for growth varies with each isolate. Further understanding of the difference in isolate response to temperature can lead to a better understanding of Bd pathogen dynamics, as well as allow us the ability to identify susceptible hosts and environments before an outbreak.
ContributorsWoodland, Laura Elizabeth (Author) / Collins, James (Thesis director) / Davidson, Elizabeth (Committee member) / Roberson, Robert (Committee member) / School of Politics and Global Studies (Contributor) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12