Evaluation of prolonged fatigue post-West Nile virus infection and association of fatigue with elevated antiviral and proinflammatory cytokines.

This study aimed to characterize fatigue postinfection among study participants with a history of West Nile virus (WNV) infection and determine whether antiviral and pro-inflammatory cytokines were significantly elevated in those reporting prolonged fatigue. We found that 31% (44/140) of study participants experienced prolonged (more than 6 months) fatigue postinfection, with an average length of fatigue duration of 5 years. Females, those younger than 50 years of age, and those with symptomatic clinical WNV disease were significantly more likely to report fatigue. Pro-inflammatory and antiviral cytokines (granulocyte macrophage colony stimulating factor, interferon-γ, interferon-γ inducing protein 10, interleukin 2, interleukin 6, and interleukin 12p70) were significantly elevated in those reporting fatigue postinfection compared to those not reporting fatigue. Clinicians should consider history of WNV infection as a possible factor when evaluating causes of prolonged fatigue following a febrile viral illness in their patients.