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Abstract
Giardiasis remains one of the most reported intestinal parasitic infections in the United States, with significant public health implications due to its burden, health and economic impacts. This dissertation investigates domestic epidemiological trends of giardiasis and utilizes modeling to evaluate their relationship with social vulnerability. Using national surveillance data from the National Notifiable Diseases Surveillance System (NNDSS) between 2017 and 2021, this study applies mixed effects quasi-Poisson models to assess county-level giardiasis rates across space. To examine the influence of community vulnerabilities, the Centers for Disease Control and Prevention’s (CDC) Social Vulnerability Index (SVI) was integrated as a modeling parameter, capturing Socioeconomic Status, Household Characteristics, Racial & Ethnic Minority Status, and Housing Type & Transportation. This analysis identified significant associations among all SVI themes. Specifically, increased rates of giardiasis at the county level were associated with the SVI themes of Household Characteristics (RR=1.17, 95% CI: 1.03-1.32) , and Housing Type & Transportation (RR=2.11, 95% CI: 1.87-2.38). Conversely, decreased rates of giardiasis were associated with the SVI themes of Socioeconomic Status (RR=0.62, 95% CI: 0.53-0.71), Racial & Ethnic Minority Status (RR=0.08, 95% CI: 0.07-0.09), and the Overall SVI theme (RR=0.46, 95% CI: 0.42-0.51).
While these findings highlight the potential of social vulnerability metrics to inform targeted public health interventions, results should be interpreted with caution. The composite nature of SVI themes may mask the effects of individual components. Future work should explore validation of our findings with additional years of surveillance data or individual-level data, disaggregation of SVI themes into their components for analysis, and evaluation of different combinations of SVI themes Supplementing national epidemiology data with SVI metrics, this research enhances the understanding of giardiasis community-level risk factors, high-risk populations, and transmission dynamics in the United States. This research is a novel approach to assessing the epidemiology of giardiasis. It provides a framework for future integration with national surveillance, enabling more robust equity-driven approaches to disease prevention and control.