Ontario health officials say they are investigating whether one of the province's newest cases of COVID-19 is evidence of community spread.

The recent case is a man from Sudbury, Ont., who attended the Prospectors and Developers Association in Canada Convention on March 2 and 3 in Toronto. The conference attracts about 23,000 attendees from more than 130 countries, according to organizers.

The man in his 50s contracted the virus and is at home in self-isolation. Officials have not said if he had recently travelled internationally.

Based on their investigations, health officials have found that the man was not infectious while attending the conference in Toronto.

'Not a case of community transmission'

"To me, this is not a case of community transmission," said Dr. Barbara Yaffe, associate chief medical officer of health. She added that although it's unclear who the man contracted the virus from, it's likely he acquired it while at the conference where about 23,000 people were in attendance.

Yaffe defined community transmissions as cases where there is no travel history to affected regions, and no "epidemiological link" to other cases.

If the Sudbury man gives the virus to his wife for example, it would be an "epidemiological link" but not a case of community transmission, Yaffe added.

"Our working hypothesis at this time is that this individual was exposed to COVID-19 while at the conference," said Dr. Penny Sutcliffe, Sudbury & District Medical Officer of Health in a statement.

Sutcliffe advised those who attended to monitor themselves for symptoms for 14 days after leaving the conference.

Officials say organizers had consulted with Toronto Public Health about protective measures ahead of the conference. Organizers mentioned in a statement that they increased health and safety procedures during the conference, including frequent cleaning and increased availability of hand sanitizers.

In a statement, Toronto Public Health said that large gatherings with "transient interactions," including walking by or briefly being in the same room as a person who may be infected with COVID-19, are considered low risk.

Premier Ford and Prime Minister Trudeau attended

Canadian Prime Minister Justin Trudeau spoke at the Prospectors and Developers Association of Canada's annual convention in Toronto on Monday, March 2, 2020. (Nathan Denette/Canadian Press)

Premier Doug Ford and Prime Minister Justin Trudeau both attended the prominent mining conference on one of the same days as the new patient.

The Ontario government says Premier Doug Ford is in good health and not experiencing any COVID-19 symptoms after attending the conference.

A spokesperson for Ford said Sudbury health officials have not yet contacted the premier during their case tracking process.

"Premier Ford is in good health and has experienced none of the symptoms related to COVID-19," said spokesperson Ivana Yelich in an email.

42 cases in Ontario

Ontario also confirmed five other new cases of COVID-19 on Wednesday — including three in the Greater Toronto Area, one in Hamilton and one in Ottawa — bringing the provincial total to 42.

Wednesday's numbers include the first COVID-19 cases confirmed in Ottawa and Hamilton.

A radiation oncologist was the first in Hamilton confirmed to be infected, a hospital spokesperson confirmed to CBC News. The doctor, a 32-year-old Burlington woman, tested positive after returning from a personal trip to Hawaii. She had since been in contact with both cancer patients and staff members.

Ottawa's first case of COVID-19 was a man in his 40s who tested positive after travelling to Austria.

Among the Toronto-area cases, in York Region, a woman in her 30s tested positive after travel to Egypt. In Toronto, a man in his 30s tested positive after travel to the United States.

All the new patients are now self-isolating, according to the ministry's website.

Five of Ontario's 42 confirmed cases have been resolved, meaning the patients are no longer infectious.