West Nile Virus

Specimen Collection and Handling

Specimen Requirements

Test Requested Required Requisition(s) Specimen Type Minimum Volume Collection Kit

West Nile Virus Serology

Blood or serum

5.0 ml blood or 1.0 ml serum

Vacutainer tubes (SST) 

West Nile Virus Serology

CSF

400 µl

Sterile container

West Nile Virus PCR

EDTA blood, plasma (or serum)2

5.0 ml blood or 1.0 ml plasma or serum

Non-heparin anticoagulant/Lavender top tube

Submission and Collection Notes

1

If submitting CSF, you must also submit a serum sample

2

CSF Serology is the preferred method of testing

3

Molecular testing must must be preapproved by the PHO laboratory microbiologist. Contact PHO laboratory Customer Service at 416-235-6556 or 1877-604-4567 to request approval.

4

Complete the following on the General Test Requisition Form:

  • relevant travel history
  • onset date 
  • symptoms
5

Instructions for using SST tubes are found in the document titled: LAB-SD-008, Blood Collection using Serum Separator Tubes

Limitations

Haemolysed, icteric, lipemic or microbially contaminated sera or plasma are not recommended for testing.

Preparation Prior to Transport

Label the specimen container with the patient’s full name, date of collection and one other unique identifier such as the patient’s date of birth or Health Card Number. Failure to provide this information may result in rejection or testing delay.

Special Instructions

Place specimen in biohazard bag and seal. Specimens should be stored at 2-8◦C following collection and shipped to the PHO laboratory on ice packs.

Specimens for molecular testing should be frozen and shipped on dry ice.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

West Nile virus IgG and IgM ELISA testing is performed daily Monday to Friday during peak season (summer months) and twice per week.at other times.

Turnaround time for ELISA IgG and IgM is up to 2 days during peak season and up to 5 days at other times from receipt by PHO laboratory.

Turnaround time for results on samples tested by PRNT is up to 10 days.

Reporting

Results are reported to the ordering physician or health care provider as indicated on the requisition.

Specimens that are positive for West Nile virus are reported to the Medical Officer of Health as per the Health Protection and Promotion Act.

Test Methods

Specimens for West Nile virus-(WNV) IgG and IgM serology are performed using enzyme–linked immunosorbent assay (ELISA).

Specimens may also undergo plaque reduction neutralization testing (PRNT).

West Nile avidity testing may be considered in order to differentiate recent (last few months) from remote infections. This should only be considered in patients with severe illness (e.g. hospitalized). Contact PHO laboratory Customer Service to speak to a microbiologist for approval.

Data and Analysis

contact lab

Contact Laboratory Customer Service

Laboratory Services

customerservicecentre@oahpp.ca

Updated 7 Jan 2019