Ontario's acting chief medical officer is asking people who were at a youth gathering in Toronto to check their immunization status after an individual with a confirmed case of measles was found to have attended the event.

Dr. Robin Williams says the event — called Acquire the Fire — was held at the Queensway Cathedral in Toronto on Feb. 6 and 7 and was attended by more than 1,300 youth from all over Ontario. Many of those who attended spent a number of hours together a single large room.

Individuals born after 1970 who attended the event are being asked to review their immunization status to ensure they are protected against measles.

Anyone who has not been adequately immunized is being asked to stay at home and contact their local public health unit.

Individuals who attended the event and develop these symptoms over the next two weeks are being advised to contact their primary care provider by phone:

Fever.

Cough.

Runny nose.

Inflammation of the eyes.

Rash.

Williams' advisory comes after multiple new cases were confirmed in Ontario in recent days. Over the weekend, two adults were confirmed as the eighth and ninth measles cases in the Greater Toronto Area.

The number of measles cases in the Greater Toronto Area rose to nine on the weekend. Ontario's acting chief medical officer wants anyone who attended a youth gathering in Toronto to check immunization status after someone recently confirmed to have measles was at the event. (Alexander F. Yuan/Associated Press)

As of this morning, there were five lab-confirmed cases of measles in the Niagara Region, according to the website for Niagara Region Public Health. Officials had announced Saturday that a 14-year-old girl was the region's second case — meaning that between Saturday afternoon and this morning, three new cases have been confirmed.

No details about the patients or their conditions have been released.

Meanwhile. health officials in Quebec confirmed last Wednesday that 10 individuals in the Lanaudiere region northeast of Montreal had been infected with measles, with all cases linked to the outbreak at Disneyland in California.

On Tuesday, the Manitoba government reported the province's first case of measles of the year, a Winnipeg infant who had recently returned from India.

On mobile? Click here to read the province's warning