West Nile Virus Research Findings: the Houston Cohort
The following is from the abstract presented at the 2008 International Conference on Emerging Infectious Diseases in Atlanta, Georgia. For other publications related to the Houston WNV cohort, please click here.
Click here to see the Rueters article on the cohort research findings.
West Nile virus (WNV) is an important emerging pathogen, with the long-term clinical outcomes continuing to be defined. Following the introduction of WNV to Houston in 2002, we began enrolling clinical cases identified through surveillance into a longitudinal prospective study. In this study, 108 patients were evaluated every 6-months for up to 5 years to determine the subjective and objective clinical outcomes and rates of recovery following WNV infection. Of the 108 patients, 54 (50%) presented with encephalitis, 32 (30%) with meningitis, and 22 (20%) with uncomplicated fever. Persistent symptoms from WNV were reported by 60.1%, 46.4%, 40.6%, 38.9%, and 41.9% at 1, 2, 3, 4, and 5 years post-onset, respectively. Most commonly reported symptoms include fatigue, weakness, depression, personality changes, difficulty walking, and memory deficits. Survival analysis showed a significant difference in rates of recovery between those presenting with encephalitis when compared to meningitis and fever cases. The majority of those who reported full recovery resolved their symptoms in the first year following infection. Objective measurements revealed significant differences in both the cognitive functioning and physical functioning between encephalitis patients and those who presented with meningitis or fever. At the one-year follow-up, new onset depression was reported by 31% of cases, with 75% having CES-D scores indicative of mild to severe depression. Among a subset of 50 patients with neurological exams, the diagnosis of WNV encephalitis was significantly associated with an abnormal neurological examination when compared to the diagnosis of WNV meningitis, even after adjusting for age. WNV encephalitis patients had numerous neurological abnormalities, particularly muscle weakness and gait impairment. In conclusion, WNV infection can result in significant long-term clinical sequelae and cognitive and functional impairment, particularly in those who present with encephalitis. This study provides us with a better understanding of the clinical aspects of a virus that is likely to continue to be an important global emerging pathogen.