CHRONIC PROGRESSIVE MENINGOENCEPHALITIS AFTER WEST NILE INFECTION: DIAGNOSTIC CHALLENGES IN PROLONGED IMMUNOSUPPRESSION FROM RITUXIMAB (P3.303)

Objective: To report a case of progressive meningoencephalitis after West Nile virus infection in a patient with hypogammaglobulinemia and absent CD19, CD20 from remote use of rituximab. Background: West Nile virus is an arthropod-borne virus that causes meningoencephalitis. A few cases with chronic symptoms were found to have persistent infection in the urine. Rituximab is a monoclonal antibody against B-cell and CD20. However, prolonged suppression for several years is rare and can interfere with serologic testing of encephalitis. Design/Methods: Case analysis and literature review Results: We report a 26-year-old woman with history of juvenile rheumatoid arthritis and immune thrombocytopenic purpura who received rituximab 6 years previously and presented with clinical encephalitis and positive West Nile PCR in plasma. Her symptoms initially improved significantly but two years later she developed progressive fatigue, diplopia, gait disturbance, pseudobulbar affect, and parkinsonism. MRI brain showed worsening atrophy and white matter hyperintensities in temporal and bilateral frontal lobes. Extensive investigations for encephalitis including blood and CSF tests for infection, autoimmune, paraneoplastic, genetic tests for dementia and leukodystrophy failed to identify a cause. She has persistently low IgG and IgM levels, absent CD19, CD20 and mature B-cell. No other causes were identified except for prior rituximab use. West Nile virus serologic tests and PCR in blood, CSF and urine became negative. Brain biopsy demonstrated active meningoencephalitis. Muscle biopsy showed denervation atrophy. Electrophysiologic tests suggested disorder of anterior horn cells. Her condition did not improve with 5-day-course of methylprednisolone and IVIG. The longer courses of treatment with IVIG are being considered. Conclusions: Prolonged suppression of CD20 and B-cell can occur for several years after treatment with rituximab. The persistent hypogammaglobulinemia may interfere with serologic tests of meningoencephalitis. Diagnosis of chronic progressive meningoencephalitis can be challenging and requires systematic approaches, especially in immunocompromised individuals. Disclosure: Dr. Ruthirago has nothing to disclose. Dr. Julayanont has nothing to disclose. Dr. Alderazi has nothing to disclose.