Abstract Introduction Babesiosis is a nationally reportable tick-borne parasitic infection with rising incidence in the northeastern United States. While many infections are mild, high-parasitemia disease (10%) is associated with severe hemolysis, acute respiratory distress syndrome (ARDS), circulatory shock, and increased mortality. Diagnostic complexity is heightened in endemic regions where overlapping tick-borne infections may obscure early presentation. We report a case of babesiosis complicated by ARDS, vasopressor-dependent shock, immune mediated hemolytic anemia (IMHA), intracranial hemorrhage, and dialysis-requiring acute kidney injury (AKI). Case Presentation A 66-year-old woman with chronic obstructive pulmonary disease presented with fever, fatigue, diarrhea, and abdominal discomfort. She reported outdoor exposure but no known tick bites, rash, or animal exposure. Peripheral blood smear demonstrated intra-erythrocytic parasites; confirmatory testing revealed high-grade babesiosis (10% parasitemia) and positive Lyme serology. Polymerase chain reaction (PCR) testing for Anaplasma phagocytophilum and Ehrlichia species was negative. She was started on atovaquone, azithromycin, and doxycycline. On hospital day 2, she developed acute hypoxemic respiratory failure with evolving ARDS requiring endotracheal intubation and vasopressor support. Parasitemia decreased to 4% by day 3 and cleared by day 8. Her course was complicated by severe hemolytic anemia resulting from parasitic hemolysis and suspected IMHA. Hemolysis studies showed elevated lactate dehydrogenase, decreased haptoglobin, indirect hyperbilirubinemia, and a positive direct antiglobulin (Coombs) test. High-dose dexamethasone followed by a prolonged prednisone taper led to stabilization. She subsequently developed AKI progressing to uremia, requiring renal replacement therapy. Neurologically, she experienced a seizure attributed to a 1.7-cm left frontal intraparenchymal hemorrhage identified on CT of the head. This was believed secondary to uremic platelet dysfunction, as coagulation studies showed no evidence of coagulopathy. She received levetiracetam and was managed non-operatively. Her condition improved, leading to successful extubation, discontinuation of vasopressors, and transfer to the medical floors. Discussion Severe babesiosis poses substantial diagnostic challenges, particularly when early symptoms resemble other infectious or inflammatory syndromes. In endemic regions, coexisting or seropositive tick-borne infections—such as Lyme disease in this case—can obscure diagnosis. Coinfection or multiple tick exposures may potentiate immune dysregulation and worsen clinical severity. High-parasitemia babesiosis is associated with ARDS, shock, and renal failure, yet IMHA remains an emerging and underrecognized complication that may require corticosteroids alongside antiparasitic therapy. The concurrence of ARDS, IMHA, intracranial hemorrhage, and dialysis-dependent AKI is extraordinary and highlights the potential for rapid multisystem deterioration, emphasizing the need for early recognition and multidisciplinary critical care. This abstract is funded by: none
Vontela et al. (Fri,) studied this question.