Delayed Diagnosis of West Nile Meningoencephalitis in a Patient Receiving Rituximab for Rheumatoid Arthritis

Area of Science:

• Neurovirology
• Immunology

Background:

• West Nile virus (WNV) neuroinvasive disease presents significant morbidity and mortality.
• Diagnosis typically relies on cerebrospinal fluid (CSF) immunoglobulin M (IgM) detection via enzyme-linked immunoassay (ELISA).
• CSF polymerase chain reaction (PCR) is less common and not widely accessible for WNV confirmation.

Observation:

• A patient undergoing rituximab therapy for rheumatoid arthritis developed WNV infection during peak immunosuppression.
• Standard WNV IgM testing in CSF yielded a false-negative result.
• Clinical suspicion was high despite negative IgM results.

Findings:

• West Nile virus (WNV) polymerase chain reaction (PCR) successfully confirmed the diagnosis in the patient.
• This case demonstrates a potential for false-negative WNV IgM results in patients treated with rituximab.
• The findings underscore the importance of considering alternative diagnostic methods in immunosuppressed populations.

Implications:

• The increasing use of rituximab therapy necessitates awareness of its potential impact on WNV diagnostic accuracy.
• Delayed diagnosis in immunosuppressed patients can lead to extensive testing and increased healthcare costs.
• Consideration of WNV PCR is crucial for accurate and timely diagnosis in immunocompromised individuals receiving rituximab therapy.