Rickettsial infection complicated by suspected hemophagocytic lymphohistiocytosis in a pediatric patient: a case report

Introduction: Rickettsial infections are vector-borne zoonoses that often present with nonspecific symptoms, making early diagnosis challenging, particularly in pediatric populations. Case report: A previously healthy six-year-old boy presented with a high-grade, persistent fever, generalized rash, abdominal pain, non-bloody diarrhea and lower limb myalgias. Initial laboratory tests revealed elevated liver enzymes and inflammatory markers. Despite empiric azithromycin therapy, he developed hepatosplenomegaly, cytopenias, hyperferritinemia, hypertriglyceridemia and polyserositis, raising suspicion for evolving hemophagocytic lymphohistiocytosis (HLH). Blood and stool cultures were negative, and a Rickettsia PCR assay later confirmed Rickettsia conorii infection, with serology showing positive IgM and negative IgG. The patient improved progressively with doxycycline and ceftriaxone, without the need for immunomodulatory therapy. Discussion: This case highlights the potential trigger of rickettsial infections for HLH-like hyperinflammatory syndromes and the importance of early empiric antibiotic therapy.