Thesis (Ph. D.)--Ohio State University, 2006. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2009 Sep 19

Batrachochytrium dendrobatidis (Bd) has contributed to population declines and extinction of amphibians worldwide. Disease-caused extinction is rare, but may occur where reservoirs exist or where transmission is independent of host density. Because some species persist after Bd epizootic events, they may act as potential reservoirs of the infection. I studied seasonal and elevational patterns of prevalence and intensity of Bd infection in eight pond-breeding species that persisted after an epizootic event at three low- and three mid-elevation ponds in Central America. I visited each pond three times over the rainy season to sample for Bd and to quantify frog density. I recorded air and water temperature at each pond. I analyzed 1,288 samples and detected Bd in all six ponds and in six of the eight species. Elevation and time affected Bd prevalence (F2,7 = 8.90, p = 0.01) and Bd intensity (F2,8 = 9.09, p = 0.008). Frog density was not correlated with Bd prevalence (F1,7= 4.75, p= 0.06), and temperature did not affect prevalence or intensity of the infection. Bd is enzootic at all 6 sites and six pond-breeding species are reservoirs. The presence of abundant reservoirs at enzootic conditions explains the persistence of Bd in areas where other species declined without showing evidence of recovery. Low intensities of infection explain the survivorship of these reservoir species. I suggest that temperature might not be the principal factor molding Bd dynamics in the humid Neotropical forests, and present evidence that ponds are ecosystems where frogs might clean or reduce their infections

This thesis explores the impact that the Seasonal Agricultural Workers Program (SAWP) between Mexico and Canada has on the Mexican workers participating in it and in their communities in Mexico. The experience of the SAWP allows its participants to develop themselves and therefore contribute to the development of their communities and home towns. While some people will see this program as merely for poverty alleviation, this research shows that with the right incentives it has potential to become a development tool for many rural communities in different states of Mexico.

The components of the northern hemisphere cryosphere and their relationship to Atlantic tropical cyclone activity are investigated in this study. Multiple ordinary least-squares regression with a stepwise selection procedure is used to develop a new statistical forecasting scheme for 13 seasonal tropical cyclone parameters at four lead times for the period 1980-2010. Sea ice area and sea ice extent in 10 geographic regions, snow cover extent in three geographic regions and five indices reflecting major modes of climate variability were analyzed as possible predictors. Three model groups, based on predictors, were constructed and evaluated: 1) only climate mode predictors, 2) only cryosphere predictors, and 3) both cryosphere and climate mode predictors. Models using only climate mode predictors showed poor predictability of the tropical cyclone parameters across all four lead times while the models using only cryosphere predictors and those using both sets of predictors showed improved predictability. Baffin Bay and Hudson Bay sea ice area were found to be the most significant predictors, exhibiting an inverse relationship with overall tropical cyclone activity. The developed models were also compared to current operational statistical models of tropical cyclone activity. While the operational models were generally more skillful, June hindcasts of major hurricanes outperformed the operational models by as much as 20%.

3 pp. / Frequently asked questions and answers regarding the Arizona Seasonal Pass application. Any Arizona resident exhibiting cattle, goats, sheep, or swine at any Arizona show or fair is required to obtain a Seasonal Pass.

The overarching objective of this thesis was to investigate the phenomenon of vaccine hesitancy in Canada and examine relationships among vaccine beliefs, socio-demographic characteristics, and seasonal influenza immunization. Quantitative findings were derived from a national health risk perception survey administered to adults across Canada (N = 1,125). Respondents were asked to provide their level of agreement (1 = do not agree at all to 5 = agree completely) with 2 vaccine-related behaviour statements and 21 vaccine-related beliefs statements. A principal components analysis was performed to reduce the number of belief statements into meaningful components. Two components were retained and reflected negative beliefs about ‘vaccine safety’ and positive beliefs about ‘vaccine regulation and benefits’. Descriptive results presented in the first study indicated a heightened uncertainty about the long-term side effects of vaccination, particularly with respect to the purported link between the Measles-Mumps-Rubella vaccine and the development of autism, among survey respondents. Multivariate analyses identified differences in the endorsement of numerous vaccine beliefs according to age and educational attainment. Findings revealed that older respondents and respondents without a university education demonstrated more negative attitudes towards vaccination, whereas younger respondents and respondents with a university education demonstrated more positive vaccine attitudes, respectively. Finally, both components of vaccine beliefs were significant predictors of vaccine-related behaviours, including discussing information about vaccines with others and reported receipt of the seasonal influenza vaccine. The second study investigated interrelationships among components of vaccine beliefs, socio-demographic characteristics, and reported receipt of the seasonal influenza vaccine. A mediation analysis revealed that higher levels of agreement with the statement ‘I usually get the seasonal flu vaccine’ among older adults was associated with lower levels of agreement with negative beliefs about vaccine safety in conjunction with higher levels of agreement with positive beliefs about the regulation and benefits of vaccines, whereas the opposite was true for younger adults. Also, a significant moderation analysis revealed that among respondents with greater concern about vaccine safety, those with higher educational attainment reported lower levels of agreement with the statement ‘I usually get the seasonal flu vaccine’ compared to those with lower educational attainment. Recognizing the limitations of quantitative findings, a qualitative investigation was undertaken to provide more in-depth insight on the factors driving influenza immunization among healthy adults. A thematic analysis was performed on transcripts from 6 semi-structured focus group discussions with a total of 18 participants residing in Ottawa, Ontario. Findings identified 7 themes and 8 sub-themes related to contextual, vaccine specific, and individual determinants of vaccine hesitancy. Participants predominantly discussed themes related to individual determinants of vaccine hesitancy (perceived severity, susceptibility, and likelihood of contracting the influenza virus; personal interests; interactions with healthcare professionals). The perceived novelty, severity and effectiveness of the influenza vaccine, as well as a lack of information and discontent with communication by government health authorities and the media were also discussed. Overall, findings identified salient themes informing vaccine decision-making and behaviours among a sample of educated adults, which can inform subsequent studies investigating influenza immunization in a more representative sample of Canadian adults.

This study is based on ethnographic research that was conducted in the villages of Santa María de Rivas and San Gerardo de Rivas in the coffee farming region of Pérez Zeledón, Costa Rica. While these two villages are in close proximity to each other, the economy of San Gerardo is based more on tourism than the economy of Santa María, although both towns still engage in agricultural activities. Within each village, I conducted 15 preliminary interviews, followed by ten follow-up interviews with the main food preparers of the households. From in depth discussions, I found that food consumption patterns of people in both towns were being affected by seasonal variations in incomes due to the cyclical nature of employment in both tourism and agriculture. A number of households from these villages were experiencing periods of food worries throughout the year that were linked to the seasonality of tourism as well as agriculture, and in particular coffee production. Seasonal availability of particular food items also shaped consumption patterns; however, perceptions of food insecurity in this context appear to be primarily related to problems of access.

Background: International analyses suggest that routine maternal vaccination with seasonal trivalent influenza vaccine is cost-effective, but few studies have been done in middle- to low- income countries. Method: A decision-tree analysis was modelled for the South African public healthcare setting over one year from a payer's perspective. Direct medical costs and consequences were obtained from published literature. Incremental cost effectiveness ratios (ICERs) and univariate sensitivity analyses were then measured. Discounting was excluded due to the seasonality of influenza, limiting the time horizon to a one year period. Findings: The model predicted that to avert influenza-associated hospitalisations amongst pregnant women and their infants less than six months of age, vaccination of pregnant women was not cost-effective. This was irrespective of whether the universal vaccination or HIV-targeted approach was used. A base model simulating 100% vaccine uptake predicted that seasonal vaccination of 100,000 pregnant women results in an estimated net cost of R69,118,114.05 per neonatal influenza-associated hospitalisation averted. Similarly, the model suggested that vaccinating 100,000 pregnant women would cost R1,197,779.79 per maternal hospitalisation averted. Univariate sensitivity analyses reinforced that influenza vaccination of pregnant women was not cost-effective, except when lower incidence of maternal influenzaassociated hospitalisations associated with antenatal influenza vaccination were simulated where the targeted approach became dominant. The latter analysis predicted savings of R770,530.86 per maternal influenza-associated hospitalisation averted. Interpretation: The ICERs suggest that influenza vaccination amongst pregnant women is not cost-effective in the South African public healthcare sector compared to no vaccination, with respect to averting influenza-associated hospitalisations amongst pregnant women and their infants less than six months of age. However, these estimates should be re-evaluated, pending vaccine effectiveness studies of higher methodological quality for low- and middle- income countries and using cost inputs relevant to South African public healthcare setting. This analysis may provide preliminary information regarding the upscaling of influenza vaccination amongst pregnant women as a priority in the constraints of a limited healthcare budget and careful consideration is required regarding vaccine mobilisation amongst pregnant women. / Dissertation (MSc)--University of Pretoria, 2016. / School of Health Systems and Public Health (SHSPH) / MSc / Unrestricted

Seasonal influenza produces substantial disease within the United States every year. Despite the availability of safe and effective vaccines for influenza, millions of individuals go unvaccinated each flu season, with notable differences across racial/ethnic groups. Using the Behavioral Risk Factor Surveillance System (BRFSS), I examine vaccination rates among non-Hispanic whites and Hispanics during the 2000-2009 influenza seasons. After developing a new method that addresses shortcomings of BRFSS vaccination measures, I find that non-Hispanic whites exhibit higher vaccination rates than Hispanics. Through a series of logistic regression models I show that the disparities between non-Hispanic whites and Hispanics narrow after controlling for healthcare coverage and socioeconomic characteristics. This suggests that seasonal influenza vaccination may be improved among U.S. Hispanics by addressing structural barriers in receiving the vaccine, especially access to health care.

The study analyzes the effects of three maize market policies on strategic price volatility, oligopoly/oligopsony market power, distribution of market surplus and total welfare. Policies of interest are privatization, the Current Malawi government policy and a proposed policy. The study first develops a workable theory then tests the various government policies in laboratory market experiments. The laboratory results indicate that the proposed policy was the most effective in reducing strategic volatility, but resulted in high output and low input prices. In terms of welfare distribution, privatization had highest consumer surplus followed by the current policy. The same was the case with producers’ surplus. However, traders’ profits were substantially higher in the proposed policy treatment. Total welfare was highest in the proposed policy followed by the current policy. In all, there appears there can be significant policy tradeoffs between market volatility, market power, surplus distribution and total welfare.