Babesia microti Infection Presenting as Acute Splenic Laceration Joshua C. Leinwand, 1 Juan Pablo Arroyo, 2 Daniel Solomon, 2 and Lewis J. Kaplan 2,3 Abstract Background: Blunt abdominal trauma leading to splenic injury can cause substantial morbidity, particularly in patients with established splenic pathology. In such cases, the extant pathology may increase a patient’s sus- ceptibility to blunt injury, most notably by inducing hypersplenism; Babesia microti may create such a condition. Methods: Case report and English language-based literature review. Results: Obtaining an appropriate travel history and understanding endemic infectious conditions will better enable the clinician to establish readily treatable concomitant diagnoses in the setting of injury. Conclusions: Failure to treat such infections may delay solid organ healing, leading to the patient being released to unrestricted and therefore risky activity with persistently abnormal splenic architecture. T he spleen is the abdominal organ injured most fre- quently in blunt trauma. Among injured patients with blunt splenic injury, 36.5% have other intra-abdominal in- juries, and approximately 80% have concurrent extra- abdominal injuries [1]. Conditions such as babesiosis that increase the size of the spleen elevate the risk of parenchymal disruption, either spontaneously or secondary to blunt impact injury. We present a case of Babesia microti infection followed by splenic laceration secondary to blunt abdominal trauma. The unexpectedly large size of the spleen coupled with recent travel to a tick-infested region led to the prompt diagnosis of B. microti infection. Appropriate antimicrobial therapy was a unique component of successful non-operative management of this patient. Case Report A 48-year-old male presented one week after being struck in the left upper quadrant of the abdomen with a wooden board. He complained of general malaise, weak- ness, and headache as well as left upper quadrant abdom- inal pain. Admission vital signs were temperature 37.1°C, pulse 79 beats/min, blood pressure 116/51 mm Hg, venti- latory rate 17 breaths/min, and oxygen saturation 98% on room air. There was no abdominal distention or external sign of injury. The left upper quadrant was full and tender. The remainder of the physical examination was unre- markable. Abnormal laboratory values included a hemoglobin con- centration of 10.5 g/dL and a platelet count of 137,000 mcL. A focused assessment by sonography for trauma (FAST) was positive for pelvic fluid, and a computed tomographic (CT) scan identified a 14.6 cm · 9.5-cm spleen (normal up to 11 · 7 cm) with wedge-shaped defects consistent with a Grade III splenic laceration, accompanied by pelvic hemoperitoneum (Fig. 1). The enlarged spleen prompted a peripheral smear that identified intra-erythrocytic parasites. A detailed travel history revealed a camping trip one month earlier to a heavily tick- infested area, suggesting the diagnosis of babesiosis; no tick bites could be recalled. The diagnosis of babesiosis was sup- ported by the finding of 10% parasitemia on a peripheral blood smear (Fig. 2) and validated by polymerase chain reaction (PCR) testing. Tests for immunoglobulin (Ig) M and Ig G an- tibodies for the other likely infecting tick-borne organism, Borrelia burgdorferi, were negative. Treatment with azithromycin and atovaquone (antipara- sitic) was initiated. Within 96 h, the parasitic load had de- creased to 1%, along with a general improvement in the patient’s constitutional symptoms and abdominal pain. Discussion There are seven reports of spontaneous splenic rupture secondary to babesiosis [2–7]; four cases were managed non- operatively [3,5,6]. One report describes the diagnosis of babesiosis after splenectomy for trauma [8]. Our patient 1 Yale School of Medicine and 2 Department of Surgery, 3 Section of Trauma, Surgical Critical Care, and Surgical Emergencies, New Haven, Connecticut. SURGICAL INFECTIONS Volume 14, Number 4, 2013 ª Mary Ann Liebert, Inc. DOI: 10.1089/sur.2012.137 1