West Nile Virus 2002

Laboratory PerspectivesLaboratories Branch MOHLTC

Pauline George

Overview

Test procedures

WNV Statistics

Laboratory Challenges

Principle of HI Test

Viral Antigen + Goose RBCs = Agglutination

Serum (Abs) + VAg + GRBCs = No Agglut/Reactive

Serum ( no Abs) + VAg + GRBCs = Agglut/Nonreactive

Test Procedures-Single Serum HI Test Process

• Day 1 Extraction

• Day 2 Absorption

• Day 2 Test Screen/Titrate

• Day 3 Add RBCs

• Day 3 Read

Confirmatory TestWinnipeg Federal Lab

• 2 week TAT

• Plaque Reduction Neutralization test Testing on paired serum against likely viruses

Presence/absence neutralizing antibody

• PCR

Tissue/CSF

WNV Tests 1999-2002WNV Tests 1999-2002

0

500

1000

1500

2000

Year

Te

sts

Series2 0 399 388 1876

1 2 3 4

WNV Tests May - Oct1999-2002

WNV HI

0

200

400

600

800

1000

1200

MAY AUGUST

Year

Te

sts

1999200020012002

Confirmed West Nile Human Cases - Ontario (to Nov 4, 2002)

Health Unit Cases

Toronto 19

Peel 7Halton 7

Windsor 6Mississauga 4Burlington 1Hamilton 1Bruce Grey Owen Sound 1Lambton 1

Niagara 1

York 1

TOTAL 49

Probable* West Nile Human Cases - Ontario (to Nov 4, 2002)Health Unit Cases

Toronto 34Halton 14Windsor 7Peel 6Niagara 6London 1Hamilton 1Lambton 1Brampton 1Oakville 1Haldimand 1Bruce Grey Owen Sound 1TOTAL 75

*seroconversion

WVN CasesSummary (to Nov 4, 2002)

• Confirmed * (PRNT) 49• Did not confirm *(PRNT) 9• Probable * (HI) 89• Suspect ^ 176

* seroconversion

^ seropositive

Laboratory Challenges 2002• Substantially increased test volumes• Staffing resources• Reagent Availability• Equipment• Antigenic Variation• Increased incoming/outgoing telephone calls• Other routine tests• Training• TDG• Space Allocation

Future Challenges 2002 and Beyond

• Funding

• Staffing

• In-house tests vs Commercial Tests Availability?

• Case criteria

• Data Analysis

• Training

• Confirmatory Test Availability

• Antigen consistency

• Antigen source/cost?

Future Challenges2002 and Beyond cont’d

• For confirmatory testing in Ontario

• Requires Level 3 Biosafety lab • PRNT confirmatory assay

• PCR

• Culture

Acknowledgements

OPHL

Arboviruses & Rickettsiae Laboratory Staff

Dr. M. Fearon, I Guglielmi, E Cheung,

Canadian Science Centre for Human & Animal Health , Winnipeg

Viral Zoonotic Staff

Dr. M. Drebot