Suspected cases must be reported immediately by phone to the Thunder Bay District Health Unit at 625-8318 or toll-free 1-888-294-6630, ext. 8318 (Monday-Friday, 8:30am to 4:30pm). After hours and on weekends/holidays call Thunder Bay Answering Service at (807) 624-1280.


2024 NEWS

Ontario’s CMOH has released a new memo (English and French) with an update to the measles situation in Ontario (March 27, 2024)

Additional resources are available:



See Public Health Ontario's (PHO) Measles webpage for current provincial epidemiology

Aetiologic Agent:

The measles virus is a member of the genus Morbillivirus of the family Paramyxoviridae.

Clinical Presentation:

Symptoms of measles begin 7 to 21 days after exposure to a case of measles and include fever, runny nose, cough, drowsiness, irritability and red eyes (conjunctivitis). Small white spots (known as "Koplik’s spots") appear on the inside of the mouth and throat. Then, 3 to 7 days after the start of the symptoms a red, blotchy (maculopapular) rash appears on the face and then progresses down the body. Complications include diarrhea, respiratory problems, pneumonia, otitis media and encephalitis.

Modes of transmission:

The virus is highly contagious and is spread by airborne droplet nuclei, close personal contact or direct contact with the respiratory secretions of a case.. Transmission can occur as a result of the persistence of the virus in the air or on environmental surfaces.  Measles virus can remain active and contagious in the air or on infected surfaces for at least two hours. Measles is one of the most highly communicable infectious diseases.

Incubation Period:

The incubation period from exposure to prodrome averages 10-12 days. The time from exposure to rash onset averages 14 days (range is 7-21 days).

Period of Communicability:

One day before the start of prodromal period, which is usually about 4 days before rash onset, to 4 days after the onset of rash.

Risk Factors/Susceptibility

  • Contact with case
  • Travel
  • Not immunized or partially immunized
  • Immunocompromised/pregnant

After infection, immunity is generally lifelong. The following individuals should be considered susceptible:  lack of documented evidence of vaccination with measles-containing vaccine (age dependent) or lack of laboratory evidence of prior measles infection or immunity.

Diagnosis & Laboratory Testing

Testing Information & Requisition

In preparation for the potential increase in measles cases under investigation across the province, Public Health Ontario’s (PHO) laboratory has taken measures to expand testing capacity to ensure efficient and timely reporting of results. To prioritize measles requests, follow the guidelines below when submitting measles specimens for urgent or emergency circumstance (STAT) testing at PHO’s laboratory:

1. During regular hours, please notify PHO’s Laboratory Customer Service Centre and during after-hours, the Duty Officer at 416-605-3113, prior to submitting STAT measles specimen(s) to our laboratory. Submitters must indicate the types and numbers of specimen(s) being sent.

2. STAT Measles specimens must be shipped separate from routine specimens.

3. Clearly mark the outside of the package indicating:

  • 'STAT' (preferably in a large bold bright colour)
  • Outbreak//Investigation number (if applicable)

4. Specimens must be handled in accordance with the Canadian Biosafety Standards and shipped in accordance with the Transportation of Dangerous Goods Regulations.

5. Submitters should ship the package directly to PHO’s laboratory, preferably the Toronto site, in order to expedite testing.

6. Measles PCR testing is currently routinely available Monday to Friday at PHO’s Toronto laboratory site. Samples must be received before 11:00 AM EST to ensure results are reported to the submitter on the same day.

  • To support the increase in Measles PCR testing requests, in the interim, PHO’s laboratory will offer weekend testing upon a microbiologist’s approval. For weekend testing, the sample(s) must be received before 1:00 PM EST for same day testing, otherwise samples will be not be tested until the next business day (e.g., Monday). Please contact our Laboratory Customer Service Centre or Duty Officer at 416-605-3113 for discussion of these requests.

7.    Measles serology testing is currently routinely available Monday to Saturday at PHO’s Toronto laboratory site. Samples must be received before 4:00 PM EST on weekdays and 11:00 AM EST on Saturdays for same day testing.

Treatment & Case Management

There is no specific treatment for persons with measles infection; however severe complications can be avoided through supportive care that ensures good nutrition and adequate fluid intake. Individuals diagnosed with measles should be advised to stay home for 4 days after the appearance of the rash.. Self-isolation will help to prevent further transmission of the virus..

A measles contact is any susceptible person who shared the same air space for any length of time during the period of communicability, including two hours after the case left the air space (e.g. home, school, day care, school bus, doctor’s office, emergency room, etc.). .

The timely administration of MMR vaccine or immune globulin (Ig) can be used to reduce the risk of infection in susceptible individuals exposed to measles. Post-exposure prophylaxis (PEP) is not 100% effective and contacts who receive PEP should be counseled on the signs and symptoms of measles and to avoid contact with high risk individuals.

Immunization with MMR vaccine of immunocompetent susceptible contacts over 6 months of age within 72 hours after exposure may prevent measles infection. Susceptible individuals with a medical contraindication to MMR vaccine (infants under 6 months of age, pregnant women, and immunocompromised individuals) who are within 6 days of exposure should be offered Ig at the recommended dose.  Certain immunocompromised individuals should also be considered to receive Ig for PEP regardless of their past vaccination status.

Refer to the GamaSTAN®S/D product monograph for dosing recommendations. 

TBDHU staff will be involved with contact identification, assessing susceptibility, PEP information, and exclusion decisions.


Patient Information

Patient Fact Sheet



1. Ministry of Health, Infectious Diseases Protocol - Appendix 1- Measles.


Additional Resources

Public Health Ontario. "Measles." (includes links to provincial epidemiology, resources and testing information)

Ministry of Health. "Publicly Funded Immunization Schedules for Ontario", January 2021

PHAC. "Measles – Vaccine Preventable Diseases"


Last Updated: