Date of Award

January 2014

Document Type

Open Access Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Meredith Stowe

Second Advisor

Peter Rabinowitz

Abstract

Introduction: Coxiella burnetii (C. burnetii) is an extremely infectious, environmentally persistent intracellular bacterium and the causative agent of the zoonosis Q fever. An unprecedented epidemic in the Netherlands between 2007 and 2010 revealed its public health importance. Recent investigations have focused on C. burnetii seroprevalence among livestock workers. The burden of disease in veterinary students, a group with arguably similar exposures, has been insufficiently characterized.

Methods: Students beginning veterinary study at Utrecht University's Veterinary Medical School in 2006 were invited to participate. Questionnaires and serum samples for the detection of IgM and IgG antibodies against C. burnetii were collected at baseline and during two follow-up periods. Data was analyzed by the less familiar Random Forest method in addition to classical logistic regression due to the underlying assumptions of generalized linear models that may not be appropriate in this case.

Results: During the four-year study period, 19.4% of veterinary students seroconverted. None reported experiencing symptoms. Regression results found students who recently lived on a farm were 5.9 times as likely to seroconvert, and those who completed both the "pain management" and "pre/postnatal care of sheep and lambs" elective courses were 9.3 times as likely to seroconvert. Random forest confirmed the regression model's findings and identified male gender as an additional risk factor.

Discussion: Students' seroconversion rates were comparable to studies in high-risk occupational groups. Assuming veterinary students are generally subject to chronic, low-intensity exposures, these findings supporting the existing hypothesis that inoculum size determines the severity of acute Q fever. As asymptomatic acute Q fever may progress to symptomatic chronic Q fever, targeted education, surveillance, and vaccination programs should be reconsidered.

Comments

This is an Open Access Thesis.

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