30 cases of measles in Guelph and area as virus spreads at elementary schools, medical officer says

There are now 30 cases of measles in the area covered by Wellington-Dufferin-Guelph Public Health and officials say there is now evidence the virus is spreading in schools.

"Initially when measles was circulating, and we had cases in our area, they were in communities that didn't have a lot of interaction. But now we have some children who are attending public schools who've come down with measles and now we have a lot more exposures and a lot more individuals that we're following up on," said Dr. Nicola Mercer, the CEO and medical officer of health for Wellington-Dufferin-Guelph Public Health.

"I do anticipate that we will see more cases."

Region of Waterloo Public Health says they currently have 31 cases of measles but there is "no evidence of transmission in local schools throughout the region."

On April 17, the province reported 109 new cases of measles, bringing the total to 925 in Ontario since the outbreak began in October 2024. New provincial numbers are expected to be released later this week.

'Measles is not a mild disease,' Dr. Nicola Mercer says

Mercer says while the "vast majority of parents" vaccinate their children, there may be some children who only have one dose of the measles vaccine, as the second dose isn't given until after a child's fourth birthday. 

She says parents can lose track of when to get the vaccine's second dose, and it's usually caught by the time they're seven years old because public health will issue reminders through the school system. She encouraged parents who aren't sure if their child has the second dose to check with their doctor.

"For those parents who haven't had any doses, I just want to say that measles is not a mild disease. It's actually quite a serious disease," Mercer said.

"We've had many children hospitalized in Ontario because of measles. We've had even more visit emergency departments with serious symptoms. We've had a number of children end up in ICU with critical issues."

At least two unvaccinated children in Texas and one unvaccinated adult in New Mexico have died from complications related to measles.

In Quebec, the health ministry says there have been no new cases of measles for 32 days, which means the outbreak in that province has ended.

Mercer says the Ontario outbreak is far from over.

"This is probably one of the more infectious diseases that we know of in humans. So if your child's not immunized, that virus is going to be looking for them," Mercer said. "When will this stop? Well, it actually won't stop until the virus can't find another person to pass from person-to-person."