Immune Modulatory Therapy for Severe Dengue Hemorrhagic Fever in a Patient With Mitochondrial Complex I Deficiency: A Case Report.

Dengue virus (DENV) poses a serious global health challenge, particularly in cases of dengue hemorrhagic fever (DHF). Patients with preexisting mitochondrial disorders may be at increased risk for complications due to the specific impact of DENV on mitochondrial-dependent cellular processes and immune function. We describe a 16-year-old male with known mitochondrial complex I deficiency caused by a homozygous likely pathogenic variant in NDUFV1 who subsequently developed DHF. His illness was marked by rapidly worsening weakness, respiratory distress, intracranial hemorrhage, and seizures. His clinical course was further complicated by encephalitis, arachnoiditis, and myelitis requiring extensive immunomodulation. He received corticosteroids, intravenous immunoglobulin (IVIG), and plasma exchange (PLEX), which led to improvement and partial recovery of functional status. This case highlights several rare complications of dengue fever, the impact of DENV on mitochondrial function, and underscores the complexity of managing infectious diseases in individuals with underlying mitochondrial disorders.