Undergraduate Honors Theses

Thesis Defended

Spring 2018

Document Type


Type of Thesis

Departmental Honors


Ecology and Evolutionary Biology

First Advisor

Dr. Pieter Johnson

Second Advisor

Dr. Stefanie Johnson

Third Advisor

Dr. Barbara Demmig-Adams


Worldwide parasite prevalence presents a considerable burden to human health and prosperity. As such, human parasitology is a pertinent research area to promote global public health. Toxoplasma gondii, a human parasite of public health concern, is present in many populations in most countries, including the United States. During the winter of 2017, we collected salivary samples and survey data from 400 undergraduate student volunteers at the University of Colorado Boulder to investigate: 1) if human saliva examination could be used as a valid method for determining T. gondii antibody presence; 2) the prevalence of T. gondii infection within the tested population; and 3) if any behavioral factors such as dietary preferences, water source and hygiene (environmental factors), or cat affinity (as reported by surveys) could be used to predict T. gondii infection exposure. The association between behavioral variables and T. gondii antibody presence was determined by chi-squared analysis and the creation of three generalized linear models (GLMs) that outlined the major known infection routes. Our results indicated that salivary examination for T. gondii antibodies using an enzyme-linked immunosorbent assay test was an accurate and non-invasive method of detecting T. gondii exposure (sensitivity = 94.2%, specificity = 100%). We saw an antibody prevalence of 27% in our sample population, which is considerably higher than the national average of 11% as reported by the Centers for Disease Control and Prevention. Chi-squared analysis showed a significant association between field of study and T. gondii antibody presence (P = 0.0482). Among the GLMs, we found that dietary choice best predicted T. gondii antibody presence. These results support salivary examination as a valid method of testing T. gondii seroprevalence, field of study is significantly related to antibody presence, and suggest that variation in diet is likely an important exposure pathway, despite the traditional focus on cat-related variables.

Available for download on Saturday, April 13, 2019