Persistent Infection with West Nile Virus Years after Initial Infection

(See the editorial commentary by Gould, on page 1.) West Nile virus (WNV) RNA was demonstrated in 5 (20%) of 25 urine samples collected from convalescent patients 573– 2452 days (1.6–6.7 years) after WNV infection. Four of the 5 amplicons sequenced showed 199 % homology to the WNV NY99 strain. These findings show that individuals with chronic symptoms after WNV infection may have persistent renal infection over several years. West Nile virus (WNV) is an important flavivirus in North America [1]. Since WNV was first detected in the United States in 1999 [2], ∼25,000 human clinically evident infections have been reported, with 11000 deaths [3, 4]. Less than 1 % of WNV-infected people develop acute neuroinvasive disease (including meningitis, encephalitis, and flaccid paralysis) or death [5]. Evidence of persistent WNV infection has been demonstrate