Oropouche Virus

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 testing information for Oropouche virus at Public Health Ontario (PHO). The causative agent of Oropouche fever is the Oropouche virus, an RNA virus that is a member of the Peribunyaviridae family. This arthropod-borne virus (arbovirus) is transmitted primarily by the bite of an infected midge or mosquito¹. Recent evidence also suggests mother-to-fetus (vertical) transmission may be possible, but a clear relationship has not yet been established^2,3. The virus is believed to have a similar geographic distribution and clinical presentation as other more common arboviruses, including Dengue virus, Chikungunya virus and Zika virus. Cases of Oropouche fever have been detected predominantly in Central and South America and the Caribbean^1,2,4.

As of August 12, 2024, 5 countries in South America and the Caribbean (Bolivia, Brazil, Colombia, Cuba and Peru) are currently experiencing outbreaks of Oropouche fever.
Recommendations for laboratory testing have been described by the Pan American Health Organization (PAHO) and the Centers for Disease Control and Prevention (CDC)^5,6.

*Uncontrolled print copy. Valid only on day of print: 21 Nov 2024.

Testing Indications

Testing for Oropouche virus is performed only upon special request and should not be considered as a routine test. Specimens are referred out to the National Microbiology Laboratory (NML) for investigational purposes only. All test requests require discussion and pre-approval by a Microbiologist at PHO’s laboratory.

A clinical risk assessment should be performed prior to requesting Oropouche virus testing. This should include a review of the individual’s clinical status, travel and exposure history and a consideration of alternative diagnoses, including infections by Dengue virus, Chikungunya virus or Zika virus. Molecular testing by polymerase chain reaction (PCR) is the preferred test method. Testing of asymptomatic individuals is not recommended.

Individuals that may be considered for Oropouche virus testing include:

Returned travellers OR individuals who reside in areas of risk that meet the following criteria^4-6:

Compatible symptoms⁴
Symptoms of Oropouche fever include but are not limited to: fever, headache, chills, myalgia and/or arthralgia, nausea, vomiting, abdominal pain, photophobia or retro-orbital pain, and/or a maculopapular rash (starts on the trunk and spreads to extremities). Severe cases may display symptoms consistent with neuroinvasive disease.
Travel to an area with documented or suspected transmission of Oropouche virus⁴
Testing for other relevant arboviruses has been performed^4-6
- Dengue virus, Chikungunya virus, and Zika virus targets are not detected by PCR^5,6 when testing is performed on a specimen collected within 10 days of symptom onset.
  
  OR
  
  Dengue virus, Chikungunya virus or Zika virus serology (as appropriate) is non-reactive when testing is performed on a serum specimen that was collected more than 7 days from symptom onset.
  Due to the overlap in arbovirus disease distribution, other more common arboviral infections must be ruled out first. PHO’s laboratory offers PCR and serology testing for Dengue virus, Chikungunya virus and Zika virus. Refer to PHO’s test information index for specific information on the appropriate tests to order for those viruses.
Oropouche virus testing may impact patient management
Testing of individuals that are critically ill or at risk of severe disease or its complications and who have compatible symptoms and a relevant travel history may be considered.

Acceptance/Rejection Criteria

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

Requests for Oropouche virus testing received by PHO’s laboratory without discussion and pre-approval by a Microbiologist at PHO’s laboratory will be delayed.

Specimen Collection and Handling

Specimen Requirements

Test Requested	Required Requisition(s)	Specimen Type	Minimum Volume	Collection Kit
Oropouche virus PCR	General Test Requisition Arbovirus (Non-Zika) Testing Intake Form	Serum	1 mL	Serum separator tube (SST)
Oropouche virus PCR	General Test Requisition Arbovirus (Non-Zika) Testing Intake Form	Other specimen type (e.g. CSF, tissues or urine)	1 mL	Sterile container
Oropouche virus serology (PRNT)	General Test Requisition Arbovirus (Non-Zika) Testing Intake Form	Serum	1 mL	Serum separator tubes (SST)

Submission and Collection Notes

Complete all fields of the General Test Requisition, including:

Test(s) requests and indications for testing
Patient setting/specimen source
Full travel history including travel destinations, dates and relevant exposures
Symptoms and symptom onset date

For clinical specimens, 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.

Testing is not performed routinely, and must be pre-approved by a Microbiologist at PHO’s laboratory. Contact PHO’s laboratory Customer Service at 416-235-6556 or 1-877-604-4567 to request approval.

Testing for Dengue virus, Chikungunya virus and Zika virus should be ordered at the same time as any request for Oropouche virus. The appropriate testing method is dependent on the time between symptom onset and specimen collection. Refer to PHO’s test information index for specific information on the appropriate tests to order for those viruses.

Serology testing for Oropouche virus is not routinely recommended and requires both an acute and convalescent specimen to be submitted before testing will be performed. All Oropouche virus serology requests will not proceed until both specimens have been received. If only a single specimen is received, the laboratory will only perform PCR, if approved.

Timing of Specimen Collection

Molecular Real-Time PCR:
Collect specimen as soon as possible after symptom onset, ideally within 10 days⁶. Other specimen types (e.g. CSF, urine, tissues) may be considered acceptable beyond 10 days due to a lack of available information on viral detection in these specimen types.

Serology - Plaque Reduction Neutralization Test (PRNT):
Both an acute specimen (collected at least 7 days after of the onset of symptoms) and a convalescent specimen (collected 2-3 weeks after the acute specimen) are required to complete laboratory investigations.

Limitations

Oropouche virus testing is performed for investigational purposes only.

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. Specimens can be shipped as Category B (UN3373).
Specimens submitted for molecular testing (PCR) should be stored at 2-8°C following collection and shipped to PHO’s laboratory on ice packs.

If a delay in transport to PHO’s laboratory is anticipated (more than 72 hours), specimens should be frozen (at -80°C if possible) and shipped on dry ice.

Special Instructions

Each specimen submitted for testing must be accompanied by a separate PHO General Test Requisition Form. All fields on each requisition must be completed.
It is MANDATORY to submit the Arbovirus (Non-Zika) Testing Intake Form with all fields completed. Specimens submitted without this mandatory information will not be tested until that information is provided. If testing for Dengue virus, Chikungunya virus and Zika virus was performed prior to submitting an Oropouche virus request and all fields were completed on either the PHO General Test Requisition Form or the appropriate intake form, an exception to re-submitting the intake form may be made on a case-by-case basis.
Testing for Dengue virus, Chikungunya virus and Zika virus is required. The appropriate testing method should be selected based on the time from symptom onset, as described above. Requests should be submitted at the same time as any request for Oropouche virus testing.

Requisitions and Kit Ordering

Test Frequency and Turnaround Time (TAT)

Oropouche PCR and serology tests are referred-out tests. Testing is not performed routinely and is available only by special request. The TAT will be determined at the time of submission, but may be up to 21 business days upon being referred out by PHO’s laboratory.

Consult the specific PHO laboratory test information sheets for Dengue virus, Chikungunya virus and Zika virus testing TAT.

Test Methods

Molecular detection of Oropouche virus is performed by PCR at the NML. This test is for investigational use only.

Serology testing for Oropouche virus is performed by plaque reduction neutralization testing (PRNT) at the Centers for Disease Control and Prevention (CDC) in the US.

Algorithm

Requests for Oropouche virus testing are reviewed by a Microbiologist at PHO’s laboratory.

If the individual meets the criteria defined above (Testing Indications), testing for Oropouche virus will be considered. It is a requirement that all specimens submitted for Oropouche virus testing must first be tested for Dengue virus, Chikungunya virus or Zika virus by the appropriate method based on the time between symptom onset and specimen collection.

Testing for Oropouche virus will not be performed if one or more assays for Dengue virus, Chikungunya virus or Zika virus are positive.

Interpretation

All results should be interpreted in the context of the specific clinical scenario as testing is performed for investigational purposes only. Given the overlap in the distribution of disease, testing for other potential co-pathogens should be considered.

Molecular (real-time RT-PCR)
A positive PCR result (Oropouche PCR Positive) is considered presumptive and indicates that Oropouche virus nucleic acids may be present in the specimen and an acute/recent infection. Additional confirmation may be required.

A negative PCR result (Oropouche PCR Negative) indicates that Oropouche virus nucleic acids were not detected in the specimen. This does not exclude Oropouche virus infection.

Serology (PRNT)
The presence of anti-Oropouche virus antibodies in serum may indicate a recent or prior infection. A ≥ 4-fold increase in neutralizing antibody titre between acute and convalescent sera collected 2 to 3 weeks apart is considered indicative of recent seroconversion⁶. Depending on the time elapsed between symptom onset and specimen collection, a non-reactive serology result may not exclude an acute Oropouche 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

WHO. 2024. Disease Outbreak News - Oropouche virus disease - Region of the Americas. Available online at: https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON530
PAHO. 2024. Epidemiological Alert Oropouche in the Region of the Americas: vertical transmission event under investigation in Brazil - 17 July 2024. Available online at: https://www.paho.org/en/documents/epidemiological-alert-oropouche-region-americas-vertical-transmission-event-under
Pan American Health Organization. 2024. Guidelines for Detection and Surveillance of Oropouche in possible cases of vertical infection, congenital malformation or fetal deaths.
Government of Canada. 2024. Travel health notice – Oropouche fever in the Americas. Available online at: https://travel.gc.ca/travelling/health-safety/travel-health-notices/534
Pan American Health Organization. 2023. Guidelines for the Detection and Surveillance of Emerging Arboviruses in the Context of the Circulation of Other Arboviruses.
CDC. 2024. Interim Guidance for Health Departments on Testing and Reporting for Oropouche Virus Disease. Available online at: https://www.cdc.gov/oropouche/php/reporting/index.html.
Naveca FG et al. 2017. Multiplexed reverse transcription real-time polymerase chain reaction for simultaneous detection of Mayaro, Oropouche, and Oropouche-like viruses. Mem. Inst. Oswaldo Cruz. 112:7. 510-513.