Chikungunya Virus- Serology and PCR

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Background
This page provides information on the testing available for Chikungunya virus at the Public Health Ontario’s (PHO). The Chikungunya virus is a single-stranded, enveloped RNA virus that is a member of the Togaviridae family. The primary route of transmission for this virus is through the bite of an infected mosquito in an endemic region.¹ The Chikungunya virus is endemic to Africa, tropical and subtropical regions of the Americas, Southeast Asia, as well as the Indian subcontinent and Pacific regions.¹ Testing for Chikungunya virus infection involves PCR and/or serology depending on the specific clinical scenario.

* Copie d'impression non contrôlée. Valide uniquement le jour de l'impression : 30 juin 2024.

Testing Indications

Testing for Chikungunya virus infection is indicated in patients with an acute onset of fever, rash and/or polyarthralgia, especially in travelers who recently returned from areas with known virus transmission. These symptoms may begin up to 12 days after infection. Other acute symptoms may include malaise, headache, photophobia, nausea, vomiting, and/or sore throat.

Laboratory diagnosis is accomplished by testing serum or plasma to detect viral nucleic acid or virus-specific antibodies.² Molecular testing by PCR is preferred if the specimen is collected within 14 days of symptom onset.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
Chikungunya Virus serology	General Test Requisition	Plasma or Serum	5 ml whole blood or 1 ml serum/plasma	Serum separator tube (SST), EDTA or heparin tubes
Chikungunya Virus PCR	General Test Requisition Arbovirus (Non-Zika) Testing Intake Form	Plasma or Serum	5 ml whole blood or 1 ml serum/plasma	Serum separator tube(SST), EDTA or heparin tubes

Submission and Collection Notes

Pregnancy status, travel history to endemic areas (including dates of departure and return) AND date of collection of samples within 14 days of symptom onset date should be clearly indicated on the requisition.

Testing is not validated for specimen types not included in the table above (e.g. CSF) and must be pre-approved by a PHO Microbiologist. Please contact PHO Laboratory Customer Service Centre at 416-235-6556 or 1-877-604-4567 before submission.

If Chikungunya PCR is requested, the Arbovirus (Non-Zika) Testing Intake Form is a mandatory requirement for testing. PHO utilizes the information on the requisition and the mandatory intake form to assess testing criteria, assign appropriate tests, and provide mandatory information required by the National Microbiology Laboratory.

Timing of Specimen Collection

Serology:
Acute and convalescent sera should be collected for serologic testing, where applicable. The convalescent serum specimen should be collected at least 2 to 3 weeks after the initial acute specimen.

Molecular Real-Time PCR:
Clotted blood, serum or plasma specimens for PCR testing should be collected as soon as possible after symptom onset, but no later than 14 days following onset of illness.

Limitations

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

Storage and Transport

For serum separator tubes: centrifuge sample prior to placing in biohazard bag.
Place each specimen type in an individual biohazard bag and seal. Insert the corresponding requisition in the pocket on the outside of each sealed biohazard bag.
Clotted blood/serum/plasma specimens should be stored at 2-8°C following collection and shipped to PHO on ice packs.
For any other specimens submitted for molecular testing, specimens may be stored at 2-8°C following collection and shipped to PHO on ice packs, but should be frozen (at -80°C if possible) and shipped on dry ice if delivery to PHO will take more than 72 hours.

Special Instructions

Each specimen submitted for testing must be accompanied by a separate PHO General Test Requisition. All fields on each requisition must be completed.

It is mandatory to submit the Arbovirus (Non-Zika) Testing Intake Form, if PCR requested, with all fields completed. However, if all of the requested information from the Arbovirus (Non-Zika) Intake Form has been provided on the PHO General Test Requisition, the additional Arbovirus (Non-Zika) Testing Intake Form is not required for tests that do not require PHO Microbiologist approval. Specimens submitted with this mandatory information missing will not be tested until it’s provided.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

The Chikungunya virus serology testing is performed once per week. The turnaround time (TAT) is up to 8 days from receipt at PHO.

The Chikungunya virus PCR is performed twice per week. The TAT is up to 5 days from receipt at PHO.

Test Methods

Serology:
Specimens submitted for Chikungunya serology are tested for IgM and IgG tests using a commercial ELISA (Enzyme Linked Immunosorbent Assay) test.

Molecular Real-Time PCR:
The PHO uses a laboratory-developed multiplex real-time polymerase chain reaction (RT-PCR) assay that simultaneously tests for targets in the Chikungunya, Dengue and Zika viruses, as there is overlap in the vectors transmitting these three diseases. PCR results reported by PHO are final results and results for all three targets will be released. Specimens submitted within 14 days of symptom onset will be tested by PCR.

Interpretation

All results should be interpreted in the context of the specific clinical scenario. Given the overlap in the distribution of disease vectors, testing for other potential co-pathogens may be considered, where applicable.

Serology
The presence of anti-Chikungunya virus antibodies in serum (IgM and/or IgG) may indicate a recent or prior infection. Depending on the time elapsed between symptom onset and specimen collection, a result of not detected by serologic testing may not exclude an acute Chikungunya virus infection.

A ≥ 4-fold increase in neutralizing antibody titre between acute and convalescent sera collected 2 to 3 weeks apart is considered indicative of seroconversion.

Molecular (real-time RT-PCR)
A positive PCR result (Chikungunya virus detected by RT-PCR) indicates that Chikungunya virus nucleic acids were detected in the specimen and an acute/recent infection.

A negative PCR result (Chikungunya virus not detected by RT-PCR) indicates that Chikungunya virus nucleic acids were not detected in the specimen. This does not exclude Chikungunya virus infection.

Reporting

Results are reported to the physician, authorized health care provider (General O. Reg 45/22, s.18) or submitter as indicated on the requisition.

References

Centers for Disease Control and Prevention. Chikungunya Virus [Internet]. Atlanta: Centers for Disease Control and Prevention; [cited 2024 Jan 22]. Available from: https://www.cdc.gov/chikungunya/index.html
Centers for Disease Control and Prevention. Chikungunya Virus - Healthcare Providers: Diagnostic Testing [Internet]. Atlanta: Centers for Disease Control and Prevention; [cited 2024 Jan 22]. Available from: https://www.cdc.gov/chikungunya/hc/diagnostic.html