Dengue Virus - Serology and PCR

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.

Background
This page provides information on the testing available for Dengue virus (DENV) at Public Health Ontario (PHO).

The DENV is a mosquito-borne, single-stranded RNA virus that is a member of the Flaviviridae family and can cause a febrile illness known as Dengue fever.
This virus is transmitted through the bite of infected mosquitos in disease-endemic areas, including Central and South America, the Caribbean, Africa, South-East Asia. Some cases have been recently acquired in Europe and the US^1,2.

Testing for DENV infection can be performed at PHO by serology or PCR depending on the specific clinical scenario.

Updates
Effective July 2, 2025, submission of the new Vector-borne and Zoonotic Virus Testing Intake Form is mandatory, along with the General Test Requisition when requesting specific vector-borne or zoonotic virus tests. The new intake form replaces both the Arbovirus (Non-Zika) Testing Intake Form and the Mandatory Intake Form for Zika Virus Testing.

*Uncontrolled print copy. Valid only on day of print: 03 July 2025.

Testing Indications

Testing for DENV infection is indicated for individuals with^1,3:

clinically compatible signs/symptoms of infection AND
a relevant exposure history (e.g. returned from travel to or residence in a DENV-endemic area, noted mosquito bites, among others)

Individuals exposed to DENV can be asymptomatically infected or develop an acute febrile illness within 3 to 14 days of exposure^1,3. Initial infections can cause mild symptoms, including (but not limited) to: headache, myalgia/arthralgia, nausea and vomiting or a rash. In some cases, secondary or subsequent DENV infections at a later date, may progress to severe disease with hemorrhagic manifestations. These severe cases can culminate with shock and organ failure.

Laboratory diagnosis can be accomplished by detecting DENV nucleic acid or virus specific antibodies. Testing by PCR is preferred during the acute phase of infection which is typically within the first 7 days after symptom onset⁴. Serology testing (IgM and IgG) is preferred at least 7 days after symptom onset⁵. Testing of asymptomatic individuals is not recommended.

Acceptance/Rejection Criteria

Specimens received without the appropriate forms (See: Submission and Collection Notes) are subject to cancellation.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
Dengue Virus Serology	General Test Requisition	Serum	5 ml blood or 1 ml serum	Red top tube or Serum separator tubes (SST)
Dengue Virus PCR	General Test Requisition Vector-borne and Zoonotic Virus Testing Intake Form	Serum	5 ml blood or 1 ml serum	Red top tube or Serum separator tubes (SST)
Dengue Virus PCR	General Test Requisition Vector-borne and Zoonotic Virus Testing Intake Form	Plasma	5 ml blood or 1 ml serum	EDTA, heparin or citrated plasma

Submission and Collection Notes

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.

Each specimen submitted for testing must be accompanied by a separate PHO General Test Requisition, with all fields completed.

For Dengue virus PCR testing, it is MANDATORY to provide the clinical information, relevant travel(s), and relevant exposures for Vector-borne viruses requested on the Vector-borne and Zoonotic Virus Testing Intake Form. Test requests that are submitted without the appropriate mandatory information are subject to cancellation.

PCR testing is not validated for specimen types not listed in the table above (e.g. urine, CSF). These requests must be approved by a PHO Microbiologist. Submission of the mandatory Vector-borne and Zoonotic Virus Testing Intake Form will initiate the review process at PHO provided the form contains all necessary information. Requests received without the form, forms submitted with insufficient information or insufficient justification for testing are subject to cancellation.

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):
Specimens submitted for molecular testing (PCR) should be collected as soon as possible after symptom onset, but no later than 14 days following onset of illness. For other non-validated specimen types, consult with a PHO Microbiologist.

Limitations

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

Storage and Transport

All clinical specimens must be shipped in accordance with the Transportation of Dangerous Goods Act/Regulations.

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.

All specimens submitted for molecular testing should be stored at 2-8°C following collection and shipped to PHO on ice packs. If a delay in transport to PHO is anticipated (more than 72 hours), specimens should be frozen (at -80°C if possible) and shipped on dry ice.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Serology:
DENV serology testing is performed once per week at PHO.
TAT is up to 8 days from receipt at PHO.

Molecular (Real-Time PCR):
DENV PCR is performed twice per week at PHO.
TAT is up to 5 days from receipt at PHO.

Test Methods

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

Molecular (Real-Time PCR):
PHO uses a laboratory-developed multiplex real-time polymerase chain reaction (RT-PCR) assay to detect Chikungunya, Dengue and Zika virus nucleic acids in parallel6. All three viruses will be tested and reported if a PCR request is received for any of these viral targets. 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 pathogens should be considered, where applicable.

Serology:
Consult the table below for general interpretations of DENV serologic testing.

Table 1. Interpretation of DENV Serology tests

IgM ELISA	IgG ELISA	Possible Interpretation and Recommendations
Non-reactive	Non-reactive	No serological evidence of infection. Advise a follow-up specimen in 2 to 3 weeks if clinically indicated, unless DENV nucleic acids were also detected by PCR.
Non-reactive	Indeterminate	DENV antibody status inconclusive. Previous DENV or other arboviral infection with waning immunity, or prior arboviral vaccination is possible. Advise a follow-up specimen in 2 to 3 weeks to assist with interpretation. Persistent indeterminate results for DENV IgG antibodies suggest a non-specific reaction.
Non-reactive	Reactive	Previous DENV or other arboviral infection or prior arboviral vaccination likely. Advise a follow-up specimen in 2 to 3 weeks to assist with interpretation. Consider investigating other possible etiologic agents if individual continues to have acute symptoms.
Indeterminate	Indeterminate	DENV antibody status inconclusive. Advise a follow-up specimen in 2 to 3 weeks to assist with interpretation if an acute or recent infection is suspected. Persistent indeterminate results for DENV IgM or IgG antibodies suggest a non-specific reaction.
Indeterminate	Reactive	DENV antibody status inconclusive. Previous DENV or other arboviral infection with waning immunity, or prior arboviral vaccination possible. Advise a follow-up specimen in 2 to 3 weeks if clinically indicated if an acute or recent infection is suspected. Persistent indeterminate results for CHIKV IgM suggests a non-specific reaction or waning IgM.
Indeterminate	Non-reactive	DENV antibody status inconclusive. Advise a follow-up specimen in 2 to 3 weeks to assist with interpretation. Persistent indeterminate results for DENV IgM (with nucleic acids not detected by PCR) suggests a non-specific reaction.
Reactive	Non-reactive or Indeterminate	Acute or recent DENV infection possible. Advise a follow-up specimen in 2 to 3 weeks to assist with interpretation if an acute or recent infection is suspected. If a non-reactive IgG result was obtained on the follow-up serum specimen, a non-specific IgM reaction may be possible. Other etiologic agents may be investigated.
Reactive	Reactive	Acute or recent DENV infection possible. Advise a follow-up specimen in 2 to 3 weeks to assist with interpretation, if clinically indicated.

Additional notes on DENV serology:

Serologic cross-reactions in IgM or IgG may occur due to a recent or past infection with related Flaviviruses (e.g. St. Louis Encephalitis, West Nile, Japanese B Encephalitis, Powassan and Yellow Fever viruses). Reactive serology results may also occur following vaccination against a relevant Flavivirus.
Seroconversion in the IgM or IgG antibodies alongside compatible symptoms may indicate an acute or recent infection. IgM antibodies may persist for several months following infection. Serologic reactivity in this setting may reflect a recent or resolved infection.

Molecular (Real-Time PCR):
A positive PCR result (Dengue virus detected by RT-PCR) indicates that DENV nucleic acids were detected in the specimen and an acute infection.

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

Additional notes on DENV PCR:

This DENV PCR test detects all DENV serotypes but does not differentiate among them.

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.

For reportable diseases: Positive IgM and RT-PCR specimens from patients with Viral hemorrhagic fever are reported to the Medical Officer of Health as per the Ontario Health Protection and Promotion Act.²

References

Committee to Advise on Tropical Medicine and Travel. 2011. Fever in the Returning International Traveller Initial Assessment Guidelines. Can Commun Dis Rep. 37. ACS-3.
World Health Organization. 2025. Global dengue surveillance. Available from: https://worldhealthorg.shinyapps.io/dengue_global/
Government of Canada. 2025. Dengue fever. Available from: https://www.canada.ca/en/public-health/services/infectious-diseases/viral-haemorrhagic-fevers/dengue-fever.html
Centers for Disease Prevention and Control. 2025. Molecular Tests for Dengue Virus. Available from: https://www.cdc.gov/dengue/hcp/diagnosis-testing/molecular-tests-for-dengue-virus.html
Centers for Disease Prevention and Control. 2025. Serologic Tests for Dengue Virus. Available from: https://www.cdc.gov/dengue/hcp/diagnosis-testing/serologic-tests-for-dengue-virus.html
Pabbaraju K, Wong S, Gill K, Fonseca K, Tipples GA, Tellier R.. 2016. Simultaneous detection of Zika, Chikungunya and Dengue viruses by a multiplex real-time RT-PCR assay. J. Clin. Virol. 83:66-71.