Vaccine rates sink as cases mount

Ontario’s response efforts hampered by lack of data: experts

- By Megan Ogilvie

Though measles was largely eliminated in Canada as of 1998, isolated cases have been known to pop up when the virus is introduced through travel.

The warnings that Ontario could soon face a measles outbreak have come in quick succession.

On Jan. 26, the Windsor-Essex County Health Unit issued an alert for a possible measles exposure linked to international travel, confirming the case — the province’s first for 2024 — four days later.

On Feb. 13, Peel Public Health reported a child, recently returned from international travel, went to a Mississauga hospital emergency department after developing symptoms of the highly contagious disease.

Three days later, Toronto Public Health reported a third case — an infant needing hospital care, the illness again linked to travel outside Canada.

Last week, a child — this time from Brantford, about 100 kilometers southwest of Toronto — was diagnosed with the virus and hospitalized after traveling to Europe.

Then, on Feb. 19, health officials in York Region announced a “unique” case. The man in his 30s had no travel history and had not knowingly been in contact with someone with the virus, suggesting he was infected by community transmission.

That the man doesn’t know how he got sick is the strongest signal yet that Ontario may be vulnerable to a measles outbreak, health experts say.

“It implies that there is a number of undetected or undiagnosed cases locally. It might represent a tip of the iceberg,” said Dr. Danny Chen, the lead in infection prevention and control at Mackenzie Health.

The network’s two large hospitals are in York Region.