A woman wearing a mask to help ward off swine flu greets a boy after arriving at Pearson International Airport in Toronto on Monday from Mexico City. Ontario health officials said six of the seven swine flu cases in Ontario involve people who recently returned from trips to Mexico. (Nathan Denette/The Canadian Press)

Three more cases of swine flu have been confirmed in the province, all in the Toronto area, health officials in Ontario announced Wednesday.

Dr. David Williams, the chief medical health officer, announced that three women in their 20s have been diagnosed with mild cases of the respiratory illness.

Seven cases of swine flu have now been diagnosed in Ontario. In six of those cases, the people recently returned from Mexico.

"We're working, as always, with our national and international partners to respond to the situation in a consistent manner and we're continuing our enhanced surveillance and reporting activities across the province," said Williams said at a press conference.

Across Canada, there are 19 cases of swine flu that have been confirmed. In addition to the seven Ontario cases, there are four in Nova Scotia, six in British Columbia and two in Alberta.

"For the general public, our messaging is the same," said Williams.

He said health officials are still recommending that Ontario residents wash their hands frequently and thoroughly with soap and water, sneeze away from people and "use cough etiquette" by coughing into their sleeves.

"If you're unwell, stay home and do the right thing – anytime of the season," said Williams. "Whether it's Mexico-related or otherwise, we always tell people do that and to only go to the hospital if you have symptoms that are severe."

David Caplan, Ontario's health minister, said that at the moment, the province is taking full advantage of the experts it has in the area of infectious disease.

"We're continuing to support our front-line health care workers with frequently updated information," said Caplan. "I want to assure Ontarians that our heath care system is responsive, that our experts are doing all that they can and that they will keep everyone advised of developments as they occur."

Health officials said they are continuing to investigate the seventh Ontario case to see whether the person had recently visited Mexico. They also said they are investigating where in Mexico the other six people diagnosed with the flu had travelled.

The average age of the patients diagnosed in Ontario with the flu is 22.