Babesiosis-Induced Hemophagocytic Lymphohistiocytosis Following Spontaneous Splenic Rupture in a Florida Resident: A Case Report

Babesiosis is a tick-borne protozoal infection caused by <i>Babesia</i> species, typically endemic to the northeastern United States. Cases in non-endemic regions, such as Florida, are exceptionally rare but can lead to severe complications if not promptly recognized. We report a case of hemophagocytic lymphohistiocytosis (HLH) secondary to babesiosis in a Florida resident who presented with spontaneous splenic rupture, a rare sequela of babesiosis. This patient, originally from New York, had a recent travel history to Maine, emphasizing the critical importance of a thorough epidemiological history in non-endemic areas. Diagnostic challenges were compounded by overlapping clinical features of HLH and sepsis. Key laboratory findings included anemia, thrombocytopenia, hyperferritinemia, and elevated inflammatory markers, with confirmatory diagnosis of babesiosis made via polymerase chain reaction (PCR) and peripheral blood smear. The patient responded well to atovaquone and azithromycin, with complete resolution of HLH symptoms and laboratory abnormalities. This case highlights the necessity for clinical vigilance, the integration of travel history into diagnostic evaluations, and the potential for fatal outcomes if babesiosis-induced HLH is not promptly diagnosed and treated. Increased awareness and training for clinicians in non-endemic regions, as well as public health measures, are essential to improving outcomes.