C50-35 Beyond the Fever: A Case of Neuroinvasive West Nile Virus With Multisystem Involvement

Abstract Introduction With ongoing climate change comes shifts in temperature and vector ecology. One growing concern is the spread of West Nile Virus (WNV) through Culex mosquitoes. Although most infections are asymptomatic, WNV can occasionally progress to severe neuroinvasive disease and even death. We report a clinically challenging case of WNV meningoencephalitis in a 76-year old man from Ohio. Case report A 76-year-old Caucasian male with past medical history of hyperlipidemia, hypertension, and obstructive sleep apnea presented to the ED in late August 2025 with 5 days of severe nausea, vomiting, and diarrhea. Patient’s social history was pertinent for frequent outdoor activities including golfing and exposure to heavy mosquito presence around his home and place of work. The patient was diagnosed with high fevers, rhabdomyolysis and acute hypoxic respiratory failure on presentation. He was hospitalized and started on supplemental oxygen and empiric antibiotics. Patient’s hospital course was complicated by progressively worsening encephalopathy and hypoxia, leading to intubation and mechanical ventilation. He continued to have persistent fevers, worsening rhabdomyolysis, and developed an ileus, lymphopenia, and transaminitis. Initial laboratory and microbiology testing revealed positive ANA and dsDNA serologies. Empiric therapy with ceftriaxone, vancomycin, and acyclovir was initiated while infectious and autoimmune etiologies were pending. The Magnetic Resonance Imaging (MRI) study of the brain was unremarkable. A lumbar puncture was performed and confirmed WNV meningoencephalitis. Discussion This case of WNV meningoencephalitis is clinically significant for several reasons. WNV infections are relatively uncommon and progression to neuroinvasive disease occurs in less than 1% of cases. Our patient’s course was complicated by respiratory failure and rhabdomyolysis, which only has been described in isolated reports. Stated thus, WNV should be considered in older adults with unexplained encephalopathy and multi-organ involvement, even when autoimmune serologies suggest alternative diagnoses. This abstract is funded by: None