title: Neuroinvasive West Nile virus disease in Canada. The Saskatchewan experience.
abstract: BACKGROUND
  West Nile virus (WNV) is a virus of the family Flaviviridae. The main route of human infection is through the bite of an infected mosquito. Approximately 90% of WNV infections in humans are asymptomatic, but neurologic manifestations can be severe.
  
  
  METHODS
  This study reviews the clinical profile of cases with neuroinvasive West Nile infection (NWNI) reported by the Surveillance program of the government of Saskatchewan in the Saskatoon Health Region (SHR). In 2007, 1456 cases of human West Nile cases were reported by the government of Saskatchewan in the whole province. One hundred and thirteen cases had severe symptoms of NWNI (8%), 1172 (80%) cases had mild symptoms of WNI and 171 (12%) had asymptomatic disease. Three hundred and fifty six cases were reported in the SHR, where 57 (16%) fulfilled criteria for NWNI.
  
  
  RESULTS
  From the 57 cases, 39 (68%) were females. Nine (16%) patients had a history of recent camping, two (4%) reported outdoor sports and four (8%) reported outdoor activities not otherwise specified. Twenty five patients had headache (43.9%), 25 confusion (42.1%), 23 meningitis (40.4%), 17 encephalitis (29.8%), 14 encephalopathy (24.6%), 11 meningoencephalitis (19.3%), 10 tremor (17.5%), acute flaccid paralysis 10 (17.5%), myoclonus 1 (1.8%), nystagmus 2 (3.5%), diplopia 2 (3.5%), dizziness 2 (3.5%). Three patients died related with comorbidities during admission.
  
  
  CONCLUSIONS
  During a year of high occurrence of WNI in Saskatchewan, 16% of cases developed NWNI. The recognition of neurological complications associated with WNI is important to improve their referral to tertiary centers.
authors.affiliation: Division of Neurology, Department of Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. jftellez@yahoo.com
authors.forename: José F
authors.initials: JF
authors.lastname: Téllez-Zenteno
authors.forename: Gary
authors.initials: G
authors.lastname: Hunter
authors.forename: Lizbeth
authors.initials: L
authors.lastname: Hernández-Ronquillo
authors.forename: Edrish
authors.initials: E
authors.lastname: Haghir
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012525:Saskatchewan / Q000453:epidemiology; D013997:Time Factors; D014901:West Nile Fever / Q000150:complications* / Q000453:epidemiology*; D055815:Young Adult