West Nile Virus–associated Flaccid Paralysis

TLDR

Acute paralysis and respiratory failure in West Nile virus infection have unclear causes and incidence. A prospective, population‑based study was conducted in Colorado during 2003 to investigate developing WNV‑associated paralysis. Among 32 patients, 84 % had a poliomyelitis‑like syndrome, 13 % a Guillain‑Barré‑like syndrome, and 4 % isolated brachial plexus involvement; the poliomyelitis‑like form (incidence 3.7/100 000) was most common, caused respiratory failure in 38 %, and led to death in 3 patients and long‑term morbidity in most survivors.

Abstract

Abstract 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.