West nile virus meningoencephalitis and acute flaccid paralysis after infliximab treatment.

West Nile virus (WNV) can cause severe central nervous system (CNS) illnesses including meningoencephalitis (MNE) and acute flaccid paralysis (AFP). Risk factors include advanced age, immunosuppression, cancer, and diabetes. In vitro studies show that tumor necrosis factor (TNF) has anti-WNV activity and is protective against WNV infection. Anti-TNF-a monoclonal antibodies may increase susceptibility to WNV by inhibiting an adequate TNF-a response, leading to prolonged viremia, viral penetration into the CNS, and fulminant WNV-CNS disease. We describe a fatal case of WNV with MNE and AFP after infliximab therapy. During WNV outbreaks, clinicians should encourage patients receiving anti-TNF-a drugs to take appropriate preventive measures because of the risk of severe WNV-CNS disease.