West Nile Virus – Ontario 2002

Ian K. Barker

Canadian Cooperative Wildlife Health Centre

Ontario Veterinary College

University of Guelph

West Nile Virus Transmission Cycle

Avian reservoirs

VIRUS VIRUS

Dead - - end hosts

Mosquito vectors Culex species mainly

Spill-overvia bridging vectors

VIRUS

Amplification

WNV Surveillance Method v.s. Virus Amplification in Nature

To detect and report the presence of WNVin the ecosystem

in timeto mitigate the risk of infectionin people and domestic animals

PremiseDead birds with WNVare detected/diagnosed

before people and domestic animalsbecome infected

Objective of Wild Bird Surveillance

Enhanced Passive Surveillancefor WNV in Wild Birds

Canada 2001-2002

Health Unit Level

CCWHC Regional Lab

Health Canada Zoonoses/Special Pathogens

LaboratoryWinnipeg

CCWHC Dead Bird Processing• carcasses, sightings• accession, dissection, specimen collection

& shipment• database: tracking, reporting, mapping,

accounting

WNV Positive Wild Birds - Ontario 2001

Health Unit 1st + Bird Species Total WNV +

Winsdsor-Essex 8 August Crow 20Halton 13 August Blue Jay 7Peel 14 August Crow & Jay 17 Toronto 15 August Crow 41Ham-Wentworth 23 August Crow 4Chatham-Kent 24 August Blue Jay 3York 25 August Blue Jay 25Durham 29 August Crow 5Lond-Middlesex 29 August Crow 3Lambton 30 August Crow 1Niagara 11 September Blue Jay 1Waterloo 24 September Blue Jay 1

TOTAL 128

Last WNV positive birds found 29 October

Dead Birds Detected Early in Outbreak

WNV Dissemination by Migratory Birds 2000 - 2001?

To Central and South America

Aug 1, 2002

Aug 23, 2002Sept. 7, 2002

WNV Explosion - 2002

Nov 1, 2002

Index case – WNV in a dead crow – May 19, 2002