Infection with WNV causes a spectrum of disease. Approximately 80% of those infected remain asymptomatic (including virtually all previously well children and young adults), and 20% have only fever and headache (West Nile fever [WNF]).5 Approximately 1 in 150 infected individuals develop inflammation of the brain and nervous system, manifested by a wide variety of neurologic symptoms, most commonly disorientation, cognitive impairment, stiff neck, muscle weakness, Parkinson-like movement disorders, and, possibly, coma, collectively referred to as West Nile neuroinvasive disease (WNND), which typically affects people older than 50 years. Rarely, patients can develop a polio-like condition with flaccid paralysis from damage to anterior horn cell neurons. Among patients with WNND, the case-fatality rate is 4% to 18% (8% this summer in Dallas County2), with deaths generally confined to older patients with underlying medical conditions. Although many patients with WNND recover fully, a considerable number are left with long-term or permanent impairments, including depression, fatigue, cognitive deficits, movement disorders, or paralysis.