West Nile virus neuroinvasive disease and cardiac involvement in critically ill patients in central Italy: a case series

Introduction West Nile virus (WNV) infection represents an emerging health concern in Southern Europe. Although most infections are asymptomatic, a small proportion progress to WNV neuroinvasive disease (WNND), occasionally complicated by cardiac involvement. Data describing critically ill patients with WNND and cardiac involvement requiring intensive care (ICU) are limited. Methods We conducted a two-month observational case-series of consecutive adult patients with confirmed WNND admitted to the ICUs of two tertiary hospitals in Lazio region, Italy from July 1 to September 1, 2025. Clinical, laboratory, imaging, and outcome data were collected, with particular focus on neurological and cardiac manifestations. Results Among 197 patients with confirmed WNV infection, 64 (32%) had WNND, of whom 12 (6.1%) required ICU admission. These 12 patients were subsequently enrolled in the study. The median age was 76.5 years (IQR 70–83), and 75% were male. The most common symptoms were fever, myalgia, and gastrointestinal complaints, followed by confusion, limb weakness, and psychomotor slowing. Cerebrospinal fluid analysis showed lymphocytic pleocytosis (median 135 cells/mm 3 ), elevated protein (median 126 mg/dL), and normal glucose. Brain MRI revealed T2/FLAIR hyperintensities in the thalami and brainstem in most cases, 2 patients had normal imaging. Four patients had cardiac involvement; two fulfilled criteria for suspected myocarditis and one was diagnosed with Takotsubo syndrome, based on new left ventricular dysfunction, elevated troponin, and diffuse hypokinesis not confined to a coronary territory. Five patients (41.7%) died within 30 days of admission. Non-survivors were older (median 83 years) and had more comorbidities. Survivors showed higher inflammatory markers. Conclusion WNND remains a life-threatening condition requiring multi-disciplinary critical care. Cardiac involvement, including suspected myocarditis, was observed in a substantial proportion of critically ill WNND patients and occurred more frequently among non-survivors in this cohort. Although descriptive, these findings highlight the importance of early neuro-cardiac assessment and comprehensive supportive management to optimize outcomes in severe WNND.