The West Nile virus: a lesson in emerging infections.

Since its identification in New York City in 1999, the West Nile virus has spread to 45 states and caused human infections in at least 44 states. West Nile virus is difficult to correctly diagnose without a high level of clinical suspicion and can cause severe debilitation or death in those with the most severe symptoms. This paper reviews the epidemiology, surveillance, prevention, clinical features, diagnosis, and treatment of this important emerging infection. Lessons learned from West Nile virus are discussed at the conclusion of the paper.