West Nile Virus Neuroinvasive Disease in Patients Treated With Anti-CD20 Therapies.

Background and Objectives: The literature on severe West Nile virus (WNV) neuroinvasive disease (WNND) in patients treated with anti-CD20 therapies is limited. We systematically characterize cases of WNND in the tertiary academic UCHealth system. Methods: A retrospective cohort (January 2016 to January 2024) of patients with a validated diagnosis of WNND and anti-CD20 medication use was identified with electronic medical record query followed by individual chart review. Results: We identified 25 patients; multiple sclerosis was the most common indication for anti-CD20 therapy in 13 patients (52%). Twenty-one patients (84%) presented with meningoencephalitis. CSF WNV IgM was positive in 5 of 21 patients (24%) who were tested while 13 of 14 tested patients (93%) had positive reverse-transcription PCR (RT-PCR) findings in the CSF. MRI demonstrated anomalies associated with WNND in 12 of 23 patients (52%) with available imaging. Intensive care unit admission was required in 8 patients (32%), and 12 patients (48%) were treated with intravenous immunoglobulin. Worsening of ≥1 point from pre-WNV baseline modified Rankin Scale (mRS) score to the 90-day postdischarge mRS score was seen in 18 patients (75%). Two patients (8%) died by 90 days. Discussion: WNND leads to disability accrual in patients on B cell-depleting anti-CD20 therapies. Utilization of RT-PCR is important in optimizing diagnosis in this patient population because of limited sensitivity of the WNV-IgM testing commonly used in the general population.