TOPIC: Chest Infections TYPE: Medical Student/Resident Case Reports INTRODUCTION: Babesiosis is an emerging health risk and a nationally notifiable disease in the United States.1 It can present as shock and multi-organ dysfunction in immunocompromised host. As babesiosis prophylaxis in patients with splenectomy is not common, it should be considered in post-splenectomy sepsis syndrome.1 This case describes a post-splenectomy patient with severe babesiosis presenting with refractory Acute Respiratory Distress Syndrome (ARDS). CASE PRESENTATION: 59-year-old man presented to emergency department with 2 weeks of worsening generalized weakness, fever, and headaches, not getting better on oral antibiotics prescribed outpatient. His Computed Tomography (CT) head, lumbar puncture was normal. He developed severe respiratory distress and was emergently intubated. Chest imaging revealed bilateral pulmonary infiltrates. Arterial blood gas analysis confirmed severe ARDS with a PaO2/FiO2 (P/F) ratio <100. The patient was managed with lung protective ventilation and prone positioning. Peripheral smear revealed intraerythrocytic ring inclusions consistent with Babesia microti trophozoites (Figure1). Testing for other bacterial infections, viral pathogens, and tick-borne illnesses were negative. Labs were significant for hemoglobin (Hb) 10.8 g/dl, platelet count 170 K/uL, haptoglobin <10 mg/dl, lactate dehydrogenase 373 U/L, aspartate aminotransferase 68 U/L and alanine aminotransferase 71 U/L. He was treated with atovaquone and azithromycin. Doxycycline was initiated for possible co-infection with other tick-borne illnesses. The patient also had red cell exchange transfusion given his critical condition and history of splenectomy. He was evaluated for Veno-venous extracorporeal membrane oxygenation (ECMO), but cannulation was deferred due to initial improvement with prone positioning. Though there was initial improvement, his hemodynamic status continued to decline requiring initiation of vasopressor support and was transitioned to comfort care after prolonged intubation with goals of care discussions with family. DISCUSSION: Early recognition and diagnosis of babesia, especially in patients with asplenia, is imperative as babesiosis can progress to refractory ARDS, shock and multi-organ dysfunction. Clinicians should have a high index of suspicion for a patient living in an endemic area who presents with unexplained nonspecific symptoms and laboratory findings including thrombocytopenia, hemolytic anemia, and/or elevation of liver enzymes. If clinical suspicion is high, sever real-time PCR assays are useful to detect low-grade parasitemia and are more sensitive than blood smears.2 Prone positioning has been shown to improve outcomes with ARDS if used early and for longer sessions and may help patients avoid need for ECMO.3 CONCLUSIONS: Our case reveals the importance of early recognition of babesiosis in immunocompromised patients living in endemic areas for preventing refractory ARDS. REFERENCE #1: Rosner F, Zarrabi MH, Benach JL, Habicht GS. Babesiosis in splenectomized adults: review of 22 reported cases. The American journal of medicine. 1984 Apr 1;76(4):696-701. REFERENCE #2: Sanchez E, Vannier E, Wormser GP, Hu LT. Diagnosis, treatment, and prevention of Lyme disease, human granulocytic anaplasmosis, and babesiosis: a review. Jama. 2016 Apr 26;315(16):1767-77. REFERENCE #3: Guérin C, Reignier J, Richard JC, Beuret P, Gacouin A, Boulain T, Mercier E, Badet M, Mercat A, Baudin O, Clavel M. Prone positioning in severe acute respiratory distress syndrome. New England Journal of Medicine. 2013 Jun 6;368(23):2159-68. DISCLOSURES: No relevant relationships by Kinjal Banerjee, source=Web Response No relevant relationships by Taesung Kwon, source=Web Response No relevant relationships by Thomas Lettich, source=Web Response No relevant relationships by Sanjeev Shrestha, source=Web Response No relevant relationships by Cynthia Tsai, source=Web Response