Date of Award

January 2020

Document Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Peter Krause

Abstract

Introduction: Diseases vectored by the tick species Ixodes scapularis have increased in incidence over the past 50 years and have been expanding to previously non-endemic areas. Unlike Borrelia burgdorferi (the causative agent of Lyme disease) the more recently described spirochetal pathogen, Borrelia miyamotoi, has been less well studied. We have limited knowledge of the frequency and geographic distribution of this pathogen. The purpose of this study is to compare the range of human exposure to B. miyamotoi and B. burgdorferi in New England, the pattern of their spatial expansion, and risk factors that affect their frequency.

Methods: Serum samples were collected from 11 study sites across New England. Age, gender, race, and residential zip code or county were recorded for each study participant and aggregate data analyzed by study sites, study site zones and residential county for spatial analysis. Each serum sample was tested for B. miyamotoi antibody using a multiplex Luminex assay and B. burgdorferi antibody using a new FDA approved Zeus ELISA kit to determine seroprevalence at each study site. Fischer exact tests and map visualizations in ArcGIS Pro 2.4.2 (Copyright ©2019 Esri Inc.) were used to determine spatial distribution of human B. miyamotoi and B. burgdorferi infection in New England. A logistic regression model was used to determine any association in seropositivity with tick-borne infection risk factors.

Results: A subset of study subjects were seropositive for B. miyamotoi and B. burgdorferi at all study sites. B. burgdorferi seroprevalence was greater than that of B. miyamotoi at all but one study site. The average B. burgdorferi seroprevalence at all study sites combined was not quite double that of B. miyamotoi (mean 2.3% [0.6-6.2%] and mean 4.1% [2.2-7.5%], respectively). No longitudinal or latitudinal gradient was observed for B. miyamotoi or B. burgdorferi seroprevalence by study site zone or county analysis. Men were found to be twice as likely as women to be seropositive for B. miyamotoi and B. burgdorferi.

Conclusion: Human exposure to B. miyamotoi and B. burgdorferi is highly dispersed throughout New England. B. miyamotoi seroprevalence is about half that of B. burgdorferi in New England. Additional studies are needed to explain the disparity between B. burgdorferi and B. miyamotoi infection and disease.

Comments

This thesis is restricted to Yale network users only. This thesis is permanently embargoed from public release.

Download

Share

COinS