West Nile virus-associated flaccid paralysis

Emerg Infect Dis. 2005 Jul;11(7):1021-7. doi: 10.3201/eid1107.040991.


The causes and frequency of acute paralysis and respiratory failure with West Nile virus (WNV) infection are incompletely understood. During the summer and fall of 2003, we conducted a prospective, population-based study among residents of a 3-county area in Colorado, United States, with developing WNV-associated paralysis. Thirty-two patients with developing paralysis and acute WNV infection were identified. Causes included a poliomyelitislike syndrome in 27 (84%) patients and a Guillain-Barré-like syndrome in 4 (13%); 1 had brachial plexus involvement alone. The incidence of poliomyelitislike syndrome was 3.7/100,000. Twelve patients (38%), including 1 with Guillain-Barré-like syndrome, had acute respiratory failure that required endotracheal intubation. At 4 months, 3 patients with respiratory failure died, 2 remained intubated, 25 showed various degrees of improvement, and 2 were lost to followup. A poliomyelitislike syndrome likely involving spinal anterior horn cells is the most common mechanism of WNV-associated paralysis and is associated with significant short- and long-term illness and death.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Female
  • Guillain-Barre Syndrome / virology
  • Humans
  • Incidence
  • Male
  • Middle Aged
  • Muscle Hypotonia / virology*
  • Odds Ratio
  • Paralysis / virology*
  • Respiratory Insufficiency / virology
  • West Nile Fever / cerebrospinal fluid
  • West Nile Fever / complications*