Beyond Hemolysis: Babesiosis-Associated Atraumatic Splenic Infarction in an Immunocompetent Patient

Babesiosis is a protozoan infection transmitted by the tick, Ixodes scapularis. The disease presentation varies from asymptomatic to fatal illness. Usually, severe illness occurs in asplenic and immunocompromised patients. In rare cases, the complication of splenic injury, including infarcts and rupture, has been observed in young individuals. We present the case of a middle-aged woman who presented with abdominal pain and fatigue. She was found to be febrile and hypotensive with thrombocytopenia, hemolytic anemia, and elevated transaminases. Imaging of the abdomen demonstrated multiple splenic infarcts. The patient denied a history of abdominal trauma and tick exposure. Autoimmune and infective endocarditis workup was negative. Subsequently, she tested positive for Babesia microti by polymerase chain reaction (PCR) test, and peripheral smear was remarkable for intracellular and extracellular ring forms consistent with Babesia with a parasitemia index of 1%. She tested negative for Lyme disease and anaplasmosis by enzyme-linked immunosorbent assay (ELISA) and PCR, respectively. She was started on atovaquone and azithromycin. On day 8 of hospitalization, she was transfused with one unit of packed red blood cells due to a hemoglobin level of 6.8 g/dL. Repeat parasitemia index on discharge was 0.01%. She was later discharged without further need for blood transfusions or surgical interventions. This case highlights the importance of considering babesiosis as a cause of acute splenic infarcts in endemic regions, even without reported exposure.