A Case of West Nile Virus Neuroinvasive Disease Presenting With Isolated Diplopia.

West Nile virus (WNV) is a single-stranded RNA virus causing a wide spectrum of diseases. Neuroinvasive conditions such as meningitis and encephalitis are feared complications of WNV infection. Here, we describe the case of a 78-year-old male whose only initial presenting symptoms were fever and transient diplopia, whose initial MRI imaging with and without contrast did not reveal any abnormalities. He was discharged, only to return to care the next day; lumbar puncture was performed suggesting bacterial meningitis, and he was admitted and given antibiotics. Repeat MRI was negative, and he developed an altered mental status requiring intubation. WNV neuroinvasive disease was subsequently found after serology was performed. Supportive care was given, and he made a full recovery with no residual deficits. This case highlights an unusual presentation of WNV encephalitis and highlights the difficulty that can be present in diagnosing this disease.