Date of Award

Spring 2026

Document Type

Scholarly Project

Degree Name

Master of Physician Assistant Studies (MPAS)

Department

Physician Assistant Studies

First Advisor

Jay Metzger

Keywords

Lyme disease, tick bite, antibiotic prophylaxis, doxycycline, azithromycin, post-exposure prophylaxis, erythema migrans

Abstract

Lyme disease is the most common vector-borne illness in the United States and Europe, and timely prevention after tick exposure is critical to reduce the risk of early and late complications. This literature review examines the effectiveness and safety of antibiotic post-exposure prophylaxis in preventing Lyme disease. A systematic search was conducted in PubMed and Embase for primary research studies published from 2000 to 2025, focusing on oral and topical antibiotics administered after Ixodes tick bites. Eight studies met inclusion criteria, including randomized controlled trials, observational studies, and experimental animal studies. Evidence consistently demonstrates that a single 200 mg dose of oral doxycycline, administered within 72 hours of tick removal, significantly reduces the risk of developing early Lyme disease, particularly erythema migrans, with relative risk reductions ranging from 67% to 87%. Adverse effects were generally mild, most commonly nausea or gastrointestinal discomfort. Topical azithromycin showed efficacy in murine models but did not reduce infection risk in human trials. Observational data support these findings, indicating rare prophylaxis failures and generally favorable safety profiles. Collectively, the evidence supports oral doxycycline as a safe and effective prophylactic strategy for adult patients following high-risk tick exposures, while topical antibiotic approaches remain unproven in humans. Further research is warranted to evaluate prophylaxis in children, pregnant individuals, and diverse populations, as well as to assess long-term prevention of disseminated Lyme disease.

Comments

Note: this is a corrected draft of the student work, not the final version

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