Rabies – Serology
Consistent with O. Reg. 671/92 of the French Language Services Act, laboratory testing information on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.
This page provides immune status serology testing information for rabies at Public Health Ontario (PHO).
Rabies is a preventable viral disease of mammals most often transmitted through the bite or saliva of a rabid animal such as dogs, cats, raccoons, skunks, foxes, coyotes and especially bats.
Contact the local public health unit for advice on treatment and to order vaccine or Human Rabies Immune Globulin (HRIG).
Testing Indications
PHO’s laboratory performs serology testing for immunity purposes only in those who have been previously vaccinated (for example: individuals at risk for rabies such as animal workers, laboratory workers, veterinarians, hunters and travelers to endemic areas who received Pre-Exposure Prophylaxis as a vaccine series to protect against rabies).
PHO does NOT perform diagnostic testing for rabies. Submitters should contact the National Microbiology Laboratory (NML) and the Canadian Food Inspection Agency (CFIA) for diagnostic rabies submission. Refer to the following resources for guidance on human specimens submission in Canada:
- For CSF and serum rabies testing, contact NML in Winnipeg: Rabies Serum Neutralization Assay - Guide to Services.
- For saliva, nuchal skin biopsy and post-mortem brain tissue rabies testing, contact CFIA in Ottawa: Rabies Testing at the CFIA: Human Specimens.
Acceptance/Rejection Criteria
PHO does not perform diagnostic testing for rabies. Human specimens submitted for diagnostic testing will be rejected.
Specimen Requirements
| Test Requested | Required Requisition(s) | Specimen Type | Minimum Volume | Collection Kit |
Rabies immunity, rabies pre/post vaccination, Rabies post exposure immune status, or RFFIT |
Whole blood or serum |
5.0 ml whole blood or 1.0 ml serum |
Serum separator tube (SST) |
Submission and Collection Notes
Complete all fields of the requisition form, including:
- Test(s) requested and indications for testing
- Patient setting
- Specimen type
- Full clinical history including past vaccinations (number of shots and dates), details of exposure/source of bite, RIG administered, travel, symptoms, etc.
Label the specimen container(s) with the patient’s first and last name, date of collection, and one other unique identifier such as the patient’s date of birth or Health Card Number. For additional information see: Criteria for Acceptance of Patient Specimens. Failure to provide this information may result in rejection or testing delay.
For priority testing of time-sensitive specimens for RIG administration decision or determination of post-exposure prophylaxis dosage:
- Contact PHO laboratory's Customer Service Centre at 416-235-6556/1-877-604-4567 prior to submitting a serum sample for testing to notify them of the priority request and to provide patient information.
- Clearly mark packaging with “Priority for WRA-Immuno Laboratory” for easier identification and retrieval.
- Ship priority specimens separately from routine specimens in accordance with the Transportation of Dangerous Goods Regulations
- Ship priority specimens directly to PHO’s laboratory Toronto site to the shipping and receiving dock at 661 University Ave., Toronto, Ontario. For delivery instructions please see Directions to 661 University Shipping Dock for Clinical Samples.
- Failure to follow the submission instructions above may result in testing delays.
Limitations
Haemolysed, icteric, lipemic or microbially contaminated sera or plasma are not recommended for testing.
Storage and Transport
Centrifuge if using SST. Place specimen in biohazard bag and seal. Specimens should be stored at fridge temperature (2-8 °C) following collection and shipped to PHO’s laboratory with ice packs. All clinical specimens must be shipped in accordance to the Transportation of Dangerous Good Act.
Test Frequency and Turnaround Time (TAT)
Rabies serology test is performed twice per week on Tuesdays and Thursdays. The test takes 2 days to complete and results are reported on Wednesday and Friday afternoons.
Turnaround time is up to 7 business days from receipt at PHO’s laboratory.
Specimens that are requested for priority testing must be received at PHO by 4 pm the day before the testing days, otherwise the specimens will be tested on the next available run.
STAT and Critical Samples Testing
For priority testing queries, please contact PHO’s laboratory Customer Service Centre at 416-235-6556 or 1-877-604-4567.
Rabies neutralizing antibody levels in humans is tested by Rapid Fluorescent Focus Inhibition Test (RFFIT) method at PHO’s laboratory. It is a serum neutralization (inhibition) test that measures the ability of rabies specific antibodies to neutralize rabies virus and prevent the virus from infecting cells.
Interpretation
Rabies RFFIT serology result interpretation table:
|
Result |
Interpretation |
Comments |
|---|---|---|
|
0.0 IU/mL |
No rabies antibody detected. |
If there is continued potential exposure, Rabies vaccination is recommended. |
|
>0.0 IU/ml - <0.5 IU/ml |
Inadequate response to vaccination; Antibody level below the minimum requirement. |
An adequate response after vaccination is ≥0.5 IU/mL as recommended by WHO. |
|
≥0.5 IU/ml to ≤1.0 IU/ml |
This is a low level antibody response. If there is continued potential exposure, a follow up in 6 months is recommended. |
An adequate response after vaccination is ≥0.5 IU/mL as recommended by WHO. |
|
>1.0 IU/ml to ≤6.0 IU/mL |
Positive antibody level and/or adequate response to vaccination. |
An adequate response after vaccination is ≥0.5 IU/mL as recommended by WHO. |
|
>6.0 IU/ml |
Positive antibody level and/or adequate response to vaccination. |
An adequate response after vaccination is ≥0.5 IU/mL as recommended by WHO. |
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