(828) Fatal Tick-Borne Disease in a Very Young Infant: An Unusual Driver of HLH-Like Syndrome

Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening condition characterized by hyperinflammatory response due to immune dysregulation. HLH is categorized into primary HLH or secondary HLH. Primary HLH is thought to be due to genetic variants affecting the immune regulation; secondary HLH is caused by an initial insult i.e., malignancy, infection or rheumatologic disorders.
While Ehrlichia chaffeensis has been documented to trigger secondary HLH in immunocompromised patients; such instance has not been reported in infants. We present a 2-month-old diagnosed with HLH secondary to ehrlichiosis, severe enough to require VA ECMO for refractory septic shock.

Description: A 2-month-old previously healthy female presented with 6 days of persistent fevers, progressive decrease in feeding and activity.
On presentation, the patient was hemodynamically unstable and in respiratory distress. Initial septic workup showed markers of multiorgan failure. Broad spectrum antibiotics were given, and she required mechanical ventilation and vasoactive support. On the blood smear morula was seen, so doxycycline was added. Subsequent serum PCR confirmed Ehrlichia chaffeensis infection. Her elevated inflammatory markers prompted HLH work up which was consistent with secondary HLH. Her HLH genetic panel was negative. She was cannulated for VA ECMO due to hemodynamic instability and poor oxygenation. On Day 5, she had left sided focal electrographic seizures and her pupils became non-reactive. Head CT showed multiple foci of parenchymal hemorrhage throughout the left cerebral hemisphere and diffuse global cerebral edema with sulcal effacement. Due to the poor neurological exam, the family elected to withdraw life sustaining support.

Discussion: In regions where ehrlichiosis is prevalent, awareness of its potential to cause overwhelming sepsis with hyperinflammation is essential, even in individuals meeting criteria for HLH. Maintaining a high degree of suspicion is vital, and empiric treatment while testing for tick-borne illnesses is essential, even in young infants. Timely intervention can significantly improve these patients’ outcomes.