399: A CASE OF SEVERE BABESIOSIS REQUIRING EXCHANGE TRANSFUSION

Abstract

Introduction: Babesiosis is an infection caused by a protozoan that infects human erythrocytes. In the United States, Babesia microti is the most commonly isolated strain transmitted by tick vector (Ixodes scapularis). The severity of infection usually depends on host immune status and Babesia species, ranging from asymptomatic to life-threatening. We describe a case of severe babesiosis requiring exchange transfusion in an elderly but otherwise healthy individual. Description: A previously healthy 90-year-old man presented to the emergency department with a 1-week history of dyspnea and dark-colored urine. Patient reported a tick bite two months prior for which he was empirically treated with doxycycline. On admission, he was afebrile, blood pressure was 130/69 mmHg, heart rate was 84 bpm, and respiratory rate was 22 breaths/min. Physical exam was unremarkable. Labs were notable for serum creatinine 2.70mg/dl, total bilirubin 3.2mg/dl, direct bilirubin 1.6mg/dl, AST 125U/L, ALT 66U/L, hemoglobin 10.1g/dl, and platelets 44k/µL. Peripheral smear showed babesia species without Anaplasma and Ehrlichia, and Lyme serology was negative. Patient was started on intravenous azithromycin and atovaquone and admitted to medical ward. Later that day he became hypotensive with elevated lactate of 3.1mmol/dl. His blood pressure was minimally fluid-responsive. Further labs revealed a haptoglobin < 10, elevated lactate dehydrogenase, and parasitemia of 31.4%. Due to the hypotension with evidence of organ damage, intravascular hemolysis, and high-grade parasitemia, he was transferred to the medical intensive care unit (MICU) for exchange transfusion. In the ICU patient received two rounds of exchange red blood cell transfusion with which parasitemia decreased to 1.4% and hemolysis parameters improved. His blood smear was negative for babesia on hospital day 5 and he was discharged home to complete a 2-week course of azithromycin and atovaquone from the day of negative smear. Discussion: Babesiosis can be life-threatening, especially in elderly, asplenic, and immunocompromised patients. Our case outlines the importance of early institution of exchange transfusion in addition to appropriate antimicrobial therapy in patients with end-organ damage, intra-vascular hemolysis, and high-grade parasitemia for better outcomes.