Elisabeth Burnor

Project title: Development of Environmental Surveillance Methods for the Detection of Salmonella enterica serovar Typhi in Wastewater

Degree: MS | Program: Environmental Health (EH) | Project type: Thesis/Dissertation
Completed in: 2020 | Faculty advisor: John Meschke


Typhoid fever continues to be a leading cause of global morbidity and mortality, especially in developing countries with limited access to safe drinking water and adequate sanitation. Environmental surveillance – the process of examining samples contaminated with fecal matter for the presence of pathogens - is a useful tool for monitoring the circulation of Typhoid fever in populations. Many common methods for the detection of Salmonella enterica serovar Typhi (S. Typhi) in environmental samples benefit from an enrichment step. Selenite-based media - the enrichment media commonly recommended for S. Typhi - poses occupational and environmental health concerns. This study proposes an alternative enrichment media that does not contain hazardous material. Additionally, this new enrichment media outperforms Selenite F media for the enrichment of both pure cultures of S. Typhi and wastewater cultures seeded with S. Typhi. This study also reports the estimated limit of detection for the combination of a common wastewater sampling method – membrane filtration – with an enrichment step utilizing this new media. Finally, this study presents a dynamic computational model, designed to predict the concentration of S. Typhi bacteria and the probability of detection of S. Typhi at various sampling locations in a wastewater system. This model is utilized in conjunction with a quantitative microbial risk model to estimate the occupational risk of contracting Typhoid fever for environmental samplers handling contaminated wastewater in the field. URI