West Nile encephalitis mimicking herpes encephalitis.

A male with a febrile illness, altered consciousness, and seizures was diagnosed with meningoencephalitis. The suspected etiology was herpes simplex virus on the basis of a focal seizure at presentation, and he was treated with acyclovir until this pathogen was excluded. The patient made a complete recovery. Because of a West Nile fever epidemic in Israel at the time, serology tests for West Nile virus were performed; results were positive. This case highlights the diagnostic problems in West Nile fever. The literature is discussed in brief.