Michael E. Rockman, MD, PhD; Zaynab Almothafer, MD; Rylee Doucette, MD, MPH; Daniel J. Robbins, MD; Michael Scolarici, MD; Manlu Liu, BA; Caitlin S. Pepperell, MD; Eduard Matkovic, MD; Jordan Kenik, MD, MPH
WMJ. 2025;123(1):e1-e4. Published early online March 10, 2025.
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ABSTRACT
Introduction: Tick-borne relapsing fever is a zoonotic infection caused by members of the Borrelia genus of spirochetes found predominantly in the southwestern United States.
Case Presentation: A 65-year-old woman presented to a Wisconsin emergency department with a 2-day history of fevers and altered mental status after returning from a 5-week stay in Colorado. Initial labs were notable for elevated transaminases, thrombocytopenia, mild hyponatremia, mild hypokalemia, and elevated procalcitonin.
Discussion: Rapid identification of patients with tick-borne relapsing fever is essential to minimize morbidity and mortality. Peripheral blood smear – especially during a febrile episode – can serve as a quick and accurate way to diagnose the illness with direct visualization of spirochetes.
Conclusions: Early analysis of a peripheral blood smear can lead to a swift diagnosis of tick-borne relapsing fever, particularly in nonendemic states such as Wisconsin.