St. Louis Encephalitis Virus

Conformément au Règlement de l’Ontario 671/92 de la Loi sur les services en français, les renseignements d’analyses de laboratoire liés à la présente page ne sont offerts qu’en anglais parce qu’ils sont de nature scientifique ou technique et destinés uniquement à l’usage des fournisseurs de soins de santé qualifiés et non aux membres du public.

Specimen Collection and Handling

Specimen Requirements

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

St. Louis Encephalitis (SLE) serology

Blood or serum

1.0 ml blood or 400 µl of serum

Vacutainer tubes (SST)

St. Louis Encephalitis (SLE) PCR

Plasma (preferred)

1.0 ml

Plasma with non-heparin anticoagulant (or serum)

St. Louis Encephalitis (SLE) PCR


400 µl

Sterile container

Submission and Collection Notes


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.


Complete the following on the General Test Requisition Form:

  • relevant travel history
  • onset date 
  • symptoms

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

Storage and 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 a biohazard bag and seal. Serology 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)

Serology turnaround time is up to 8 days and Molecular testing (PCR) turnaround time is up to 28 days from receipt by PHO laboratory.

Test Methods

The St. Louis Encephalitis virus serology testing is performed using a Hemagglutination Inhibition Assay (HAI) for the detection of antibodies to St. Louis Encephalitis Virus. Samples that are reactive can be further analyzed for the presence of neutralizing antibodies by plaque reduction neutralization test (PRNT).

Molecular detection by RT-PCR is performed after approval by the PHO laboratory microbiologist. Amplicons generated are subjected to DNA sequencing. CSF will only be tested once it has been shown that anti-flavivirus antibodies are present in the patient’s serum (via HAI testing).

All St. Louis Encephalitis virus testing is performed at the National Microbiology Laboratory.


Results are reported to the ordering physician or health care provider as indicated on the requisition. Specimens that are positive for St. Louis Encephalitis are to be reported to the Medical Officer of Health as per Health Protection and Promotion Act.

Mis à jour le 20 juill. 2020