The Windsor-Essex County Health Unit (WECHU) would like to highlight that Ontario is currently experiencing a multi-jurisdictional measles outbreak that has included cases from New Brunswick and Manitoba1. In the past, measles has been rare in Ontario, with most cases associated with international travel. However, there has been an increase in measles world-wide and in Canada, with 98% of measles cases reported in 2025 resulting from exposures within Canada.2 As of February 12, 2025, 99 cases of measles (67 confirmed, 32 probable) have been reported in Ontario in association with this multi-jurisdictional outbreak1. All outbreak cases were in individuals born in or after 1970. Of those cases that were children and adolescents, 98.8% were unimmunized.1 Given the current prevalence of measles in Ontario, the WECHU encourages health care providers to take the following actions:
Consider Measles as a Differential Diagnosis: Clinicians are strongly encouraged to consider measles as part of the differential diagnosis when clients present with:
- febrile illness and rash
- history suggesting that they are not immune to measles
- history of travel to areas with measles outbreak or are known to have had an epidemiologic link to a measles case or outbreak.
Ensure appropriate testing for Measles: It is essential to complete ALL of the following tests to confirm diagnosis:
- Nasopharyngeal swab/aspirate or throat swab for PCR
- Blood specimen for serology
- Clean catch urine for PCR
Duty to Report: Timely reporting of communicable diseases is essential for their control.
- Clinicians are required to report all diseases of public health significance (DOPHS) as per the requirements in accordance with Ontario Reg 135/18 and amendments under the Health Protection and Promotion Act, R.S.O. 1990. Refer to the DOPHS List for all reporting requirements.
- Reporting forms are available on the WECHU website. Reporting forms should be filled out completely and faxed to 226-783-2132.
For questions or concerns, please call 519-258-2146 ext. 1420 during regular office hours, and 519-973-4510 during after-hours and weekends. You can also visit our website.
For more information, visit:
- Public Health Ontario, 2025: Enhanced Epidemiologic Summary. Measles in Ontario
- Government of Canada, 2025: Measles and Rubella Weekly Monitoring Report. Week 5 (January 26 to February 1, 2025)
- Measles: For Health Professionals
- Ministry of Health, 2024: Appendix 1: Case Definitions and Disease Specific Information: Measles
- Public Health Ontario, 2025: Measles Information for Clinicians
- Government of Canada, 2025, Measles vaccines: Canadian Immunization Guide
Infection Disease Prevention Department
Windsor-Essex County Health Unit
Ph. 519-258-2146 Ex. 1420
Fx. 226-783-2132