Prognosis after West Nile virus infection

The long-term prognosis of patients infected with West Nile virus is not well understood.

To describe the patterns of physical and mental function after infection with West Nile virus and to determine factors associated with recovery.

Longitudinal cohort study.

Data were collected during home visits and from ambulatory clinics in 4 Canadian provinces.

156 persons with West Nile virus infection.

Scores on the Physical Component Summary and Mental Component Summary of the Short Form-36, Depression Anxiety Stress Scale, and Fatigue Severity Scale.

Physical and mental function, as well as mood and fatigue, seemed to return to normal within 1 year of symptom onset. Participants with neuroinvasive disease took slightly longer to recover. Maximum predicted recovery or rate of recovery in any domain did not differ between participants with meningoencephalitis and those with encephalitis. Lack of preexisting comorbid conditions was associated with faster recovery of physical function, whereas lack of comorbid conditions and male sex were associated with faster recovery of mental function.

The analysis excluded 7 patients who died shortly after diagnosis, so the study's estimates of prognosis may be overoptimistic. The authors did not formally assess neuropsychological difficulties. The estimates of recovery are relative to the U.S. population, not to participants' function levels before West Nile virus infection.

Physical and mental outcome measures seem to normalize within approximately 1 year in patients with West Nile virus. The presence of preexisting comorbid conditions is associated with longer recovery.