Who to test for measles
Health care providers should suspect measles in a patient with:
- Febrile illness and rash, and
- History suggesting they are not immune to measles – particularly if they
- Travelled, or
- Are known to have had contact with a measles case
- Other clinical manifestations which raise suspicion for measles include:
- Prodromal symptoms (i.e. cough, runny nose and conjunctivitis/watery eyes) followed by a rash
- Progression of the rash (i.e. macular or maculopapular to confluent red blotchy appearance)
- Koplik spots
Patients with suspected measles should be advised to isolate at home until after 4 days from the onset of rash (onset of rash is considered day 0).
How to test for measles
- Diagnostic laboratory testing is essential for all suspect measles cases and should include:
- Nasopharyngeal or throat swab, AND
- Urine, AND
- Serology
- To order measles laboratory testing, complete the General Test Requisition Form available on www.publichealthontario.ca/requisitions. Include all the following information: reason for testing, travel history, vaccination history, relevant signs/symptoms and onset dates, and clinical history. If this information is not provided on the requisition for serology, the Public Health Ontario Laboratory (PHOL) will not complete the Measles IgG and IgM testing for diagnosis.
- Ensure your facility has appropriate collection kits on hand that are not expired (see table 1 below). Specimens submitted in expired collection kits will be rejected.
Report all suspect measles cases to Hamilton Public Health Services by calling the Infectious Disease Program
- During regular business hours Monday to Friday 8:30 am to 4:30 pm, call 365-324-2467.
- After hours and weekends, call 905-546-2489 to speak with the on-call Public Health Nurse.
Table 1: Measles Testing
| Test | Specimen Type (Volume) | Collection Kit | Collection Timing | Turn Around Time |
|---|---|---|---|---|
| Measles virus detection (PCR)* | Nasopharyngeal swab | Virus respiratory kit order #390082 | Within 7 days of rash onset ** | Up to 3 business days from receipt at PHOL |
| Measles virus detection (PCR)* | Throat swab | Virus culture kit order #390081 | Within 7 days of rash onset ** | Up to 3 business days from receipt at PHOL |
| Measles virus detection (PCR)* | Urine (min. 50 mL) | Sterile container | Within 14 days of rash onset ** | Up to 3 business days from receipt at PHOL |
| Measles serology (diagnosis)*** | Whole blood (5.0 mL) or serum (1.0 mL) |
Blood, clotted- vacutainer tubes (SST) | Acute: Within 7 days of rash onset Convalescent: 7-10 days after the acute; preferably 10-30 days after acute |
Up to 5 business days from receipt at PHOL |
*Molecular assays for measles (PCR) is the preferred diagnostic test during acute stage of illness due to higher sensitivity compared to measles serology.
**For suspect cases with a high index of suspicion, it may be warranted to test beyond the above time periods after discussion with PHOL.
***IgM serology should not be the only diagnostic test relied upon for the diagnosis of measles. Diagnosis for a symptomatic patient requires additional samples (i.e. throat swab and urine) for testing by PCR.
(PHO, Measles Information for Health Care Providers, First Edition, March 2024)
Hamilton Public Health Services can provide guidance regarding specimen transportation and when to consider emergency (STAT) testing.
- STAT measles specimens must be packaged and shipped separate from routine specimens.
- Clearly mark the outside of the package indicating:
- ‘STAT’ (preferably in a large bold bright colour)
- Outbreak//Investigation number (if provided by Public Health)
- Specimens must be handled in accordance with the Canadian Biosafety Standards and shipped in accordance with the Transportation of Dangerous Goods Regulations.
Additional information about measles testing (including specimen types and collection) can be found on the PHO webpages Measles – Diagnostic – PCR and Measles – Serology, or by calling PHOL Customer Service Centre at 1-877-604-4567 (toll free) or 416-235-6556.
Infection Prevention and Control (IPAC) recommendations for suspect measles
- Routine practices and airborne precautions are recommended.
- Patients who request an assessment should be screened at time of booking for measles symptoms and risk factors.
- Consider appointments for symptomatic patients at the end of the day when no other patients are present.
- Not all patients with suspect measles require emergency medical attention. If the patient is not acutely unwell requiring emergency assessment, please collect testing specimens per above, and instruct to isolate at home.
- If the patient requires assessment at an emergency department, health care providers should call ahead and notify the hospital so appropriate IPAC measures can be put in place. Where possible, a caregiver not suspected of having measles should notify the emergency department when they have arrived so that where possible the patient can be brought directly into appropriate precautions.
- ONLY staff known to be immune to measles should provide care.
- Note: Hospital Occupational Health & Safety and health care provider offices should ensure all staff are up to date with either 2 documented doses of measles vaccination OR documented laboratory evidence of immunity, regardless of age, as per the Canadian Immunization Guide.
- Health care providers should wear a fit-tested, seal-checked N95 respirator upon entry to the room.
- If possible, have the patient enter and exit through a separate entrance directly to and from the exam room. Patients should not wait in the common waiting room.
- Ask the patient to wear a medical mask, if tolerated, upon entry to the building and to wear the mask until they leave the building. If client arrives without a medical mask, provide one to them.
- Immediately isolate the patient in an exam room with the door closed. DO NOT use the room for 2 hours after the patient leaves to allow for the appropriate number of air exchanges to remove the virus. Consider placing a sign on the door indicating the room cannot be used.
- Routine cleaning and disinfecting using a hospital-grade disinfectant for the room or equipment is sufficient, after examining a patient under airborne precautions.
- For patients requiring private lab testing, please call the lab ahead of time to arrange for appropriate IPAC measures. Instruct the patient to wear a mask while at the lab. Only lab staff known to be immune to measles should provide patient services.
How to prevent measles through vaccination
Everyone is recommended to stay up-to-date with measles-containing vaccines. According to the Publicly Funded Immunization Schedules for Ontario:
- Two doses of measles-containing vaccine are routinely given – the first dose at 12 months of age using measles, mumps, rubella (MMR) vaccine, and the second dose at 4-6 years of age using measles, mumps, rubella, varicella (MMRV) vaccine.
- Please ensure that children are up to date on routine vaccinations, including MMR and MMRV
- Adults born after 1970 who have only received one dose of MMR vaccine are eligible to receive a second dose if they meet any of the criteria below or based on the healthcare provider’s clinical judgement.
- Health care workers
- Post-secondary students
- Individuals planning to travel to areas outside of Canada
- If travelling, infants between 6 and 11 months of age can receive a single dose of MMR vaccine in advance. They will still be required to receive two doses after their first birthday to be considered to have completed the vaccination series.
- Adults born before 1970 should receive a single dose of MMR vaccine in advance of travel outside of Canada, unless there is lab evidence of immunity or history of lab-confirmed measles (vaccination is recommended over serological testing)
- Hamilton residents can report their vaccines
To speak with a Public Health Nurse, please contact the Infectious Disease Program 8:30 am to 4:30 pm Monday to Friday at 365-323-8170.