Prognosis after West Nile Virus Infection

Prognosis after West Nile Virus Infection

From McMaster University, Hamilton, Ontario; University of Manitoba and the Public Health Agency of Canada, Winnipeg, Manitoba; and Ontario Provincial Laboratory, Toronto, Ontario, Canada.

Abstract

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

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

Design: Longitudinal cohort study.

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

Participants: 156 persons with West Nile virus infection.

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

Results: 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.

Limitations: 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.

Conclusion: 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.

Article and Author Information

Grant Support: Funded by the Canadian Institutes of Health Research (grant no. 69010).
Potential Financial Conflicts of Interest: None disclosed.
Reproducible Research Statement: Study protocol and data set: Not available. Statistical code: The code for the nonlinear mixed-effects modeling is available from Dr. Hanna (e-mail, hannas{at}mcmaster.ca).
Requests for Single Reprints: Mark Loeb, MD, MSc, McMaster University, MDCL 3200, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada; e-mail, loebm{at}mcmaster.ca.
Current Author Addresses: Dr. Loeb and Mr. Neupane: McMaster University, MDCL 3200, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada.
Dr. Hanna: McMaster University, 1400 Main Street West, CE&B, IAHS Building, Room 408, Hamilton, Ontario L8S 1C7, Canada.
Dr. Nicolle: University of Manitoba, GG443-820 Sherbrook Street, Winnipeg, Manitoba R3N 0A3, Canada.
Dr. Eyles: McMaster University, 1280 Main Street West, General Sciences Building, Room 217, Hamilton, Ontario L8S 4K1, Canada.
Dr. Elliott: McMaster University, 1280 Main Street West, General Science Building, Room 229, Hamilton, Ontario L8S 4M4, Canada.
Dr. Rathbone: McMaster University/Henderson Hospital, 711 Concession Street, 70 Wing, Ground Floor, Room 23, Hamilton, Ontario L8V 1C3, Canada.
Dr. Drebot: National Microbiology Laboratory, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada.
Dr. Fearon: Canadian Blood Services, 87 College Street, Toronto, Ontario M5G 2M1, Canada.
Dr. Mahony: St. Joseph's Healthcare, 50 Charlton Avenue East, Luke Wing, Room 424, Hamilton, Ontario L8N 4A6, Canada.
Author Contributions: Conception and design: M. Loeb, S. Hanna, S. Elliott, J. Mahony, M. Rathbone.
Analysis and interpretation of the data: M. Loeb, S. Hanna, B. Neupane, M. Rathbone, M. Drebot.
Drafting of the article: M. Loeb, S. Hanna, M. Drebot.
Critical revision of the article for important intellectual content: M. Loeb, S. Hanna, J. Eyles, S. Elliott, J. Mahony, M. Rathbone, M. Drebot.
Final approval of the article: M. Loeb, S. Hanna, L. Nicolle, J. Eyles, J. Mahony, M. Rathbone, M. Drebot.
Provision of study materials or patients: M. Loeb, L. Nicolle, M. Drebot.
Statistical expertise: M. Loeb, S. Hanna, B. Neupane.
Obtaining of funding: M. Loeb, S. Hanna, J. Mahony.
Administrative, technical, or logistic support: M. Loeb, M. Fearon, J. Mahony.
Collection and assembly of data: M. Loeb, L. Nicolle.