School
School of Public Health
Document Type
Dissertation
Department (new version)
Public Health
Date of Award
1999
Degree Name by School
Doctor of Public Health (DrPH) School of Public Health
Abstract
A retrospective cohort study was conducted, to assess the relationship between onsite sewage treatment and disposal system (OSTDS) failures and giardiasis and shigellosis. Cases in close proximity to OSTDS were analyzed to ascertain any association with failed systems. It was predicted that the risk of acquiring giardiasis or shigellosis was greater than one when comparing exposure to failed versus functional OSTDS. Records of failed systems, functional systems, and disease cases were mapped using a geographical information system (GIS). Cases and households with cases around failed systems were considered exposed cases, and cases and households with cases around functional systems were considered unexposed cases. The GIS was used to determine spatial and temporal associations between OSTDS and cases of illness. Boundary areas were drawn around each failed and functional system. Although a common design for assembling, organizing, and analyzing the data to detect spatial and temporal associations was used, five different analytical methods were employed to test the null hypothesis. The original analytical method (analyzing cases in relation to total population and total households in the study areas) revealed serious limitations. The relative risk and confidence intervals indicated a statistically significant protective effect from living in close proximity to a failed system, which may be allowing raw sewage to enter the drinking water or accumulate on the ground. Because sewage is a known source of disease transmission, the analytical design was reevaluated and four other analytical approaches based on person time at risk and matched analyses were employed. The point estimates and confidence intervals of these four methods were similar and indicated a positive, although not statistically significant association between cases of illness and failed OSTDS. Point estimates and 95% confidence intervals were the following: Individuals RR = 1.50 (CI, 0.65–3.44), Households RR = 1.78 (CI, 0.69–4.60); Individuals IrR = 1.36 (CI, 0.67–2.77), Households IrR = 1.58 (CI, 0.70–3.54); Individuals IrR = 1.29 (CI, 0.61–2.71), Households IrR = 1.43 (CI, 0.62–3.29); Individuals RR = 1.60 (CI, 0.58–4.43), Households RR = 2.00 (CI, 0.69–5.83). This study suggests an increased in risk of acquiring giardiasis or shigellosis when living in close proximity to a failed OSTDS.
ProQuest Publication Number
ProQuest ID
9952582
ISBN
978-0-599-54957-9
Recommended Citation
Heber, Sharon, "The relationship between septic systems and incidence of giardiasis and shigellosis in Florida" (1999). All ETDs from UAB. 7203.
https://digitalcommons.library.uab.edu/etd-collection/7203
Comments
DrPH