Six more cases of swine flu were confirmed in Canada Wednesday, bringing up the nationwide total to 19.

Three of the cases are in British Columbia, all in the Vancouver region. The other three were in Ontario, all in the Toronto area.

B.C. health officials say all the cases diagnosed there are considered mild.

Ontario public health officials say all three cases are women in their early 20s and all have mild versions of the flu. The trio are from the York, Durham and Peel regions outside of Toronto.

Of the seven confirmed cases in Ontario, at least six people had visited Mexico. Officials were unsure about the seventh case.

Of the 19 confirmed cases in Canada, seven are in Ontario, six in B.C., two in Alberta and four in Nova Scotia.

On Wednesday afternoon, the World Health Organization pushed the pandemic level for swine flu to five, just one level short of a full pandemic.

In addition, Canada announced that it is stepping up inspections of all pork products, both to protect the pork export market and to reassure a nervous public that the food supply is safe.

International Trade Minister Stockwell Day and Agriculture Minister Gerry Ritz stressed in a joint statement that human swine influenza cannot be contracted by eating pork.

Canadian pork exports were worth $2.7 billion in 2008.

Canada's biggest challenge

Canada's biggest challenge in dealing with the swine flu outbreak is to track down the thousands of Canadians who returned from Mexico in the last few months and may have contracted the disease, says one expert.

All cases are the same strain as the swine flu virus identified in Mexico and the U.S., and all the Canadian cases have been mild.

Dr. Donald Low, an infection disease specialist at Mt. Sinai Hospital in Toronto, said the challenge here is to locate and identify Canadian cases in order to get a handle on how widespread the disease is in this country.

"We're seeing so many of those individuals returning from Mexico who are sick," Low told CTV's Canada AM.

He said the goal is to track down those who are infected, give them the information and instruction they need to avoid infecting others, and to collect specimens to "get a sense of how much disease is out there."

He said it's too late to contain the disease, and efforts have turned to mitigating the damage and reducing the impact on people's health.

"If you can slow down the spread of this disease you can cope much better with it when it does happen," he said.

Swine flu is believed to have killed more than 150 people in Mexico. On Wednesday morning, the U.S. confirmed the death of a 23-month-old boy from swine flu -- the first swine flu death outside of Mexico.

However, the child was from Mexico, and it is believed he contacted the swine flu there.

Low said that's because the disease is much more widespread in Mexico than in other countries. However, he said the ratio of people in Mexico who have recovered from swine flu is much higher than the number of those who have died from it.

He said only the very sick are being identified in Mexico as having the disease, making the outbreak appear more severe than it really is.

In actual fact, Low said, the death-rate is very similar to that of seasonal influenza.

"When you infect one million, two million, three million people with seasonal influenza, some of those individuals are going to be at greater risk of having a bad outcome, and they die as a result of that," Low said.

Nova Scotia cases drop

There were four confirmed cases in Nova Scotia, all from the same private high school.

Many other students at King's-Edgehill School in Windsor had been put in quarantine. On Wednesday headmaster Joseph Seagram said 17 students had been cleared from quarantine and another eight nearly had the medical go-ahead.

The school became one of the first places in Canada to announce confirmed cases of swine flu on Sunday. Four students had tested positive after returning from a trip top Mexico.

Seagram says there are seven more students in quarantine but the virus had yet to spread past the original four cases.

"For me, no news is good news," he told The Canadian Press.

The cases at the school were all reported to much milder than the strain in Mexico.

Travel advisory

Canada has issued a travel advisory against all non-essential travel to Mexico.

"As of April 27, 2009, travellers from Canada are recommended to postpone elective or non-essential travel to Mexico until further notice," stated the advisory.

The U.S., France, Britain and Germany are also warning against unnecessary travel to Mexico.

Following the travel advisory, Canada's biggest travel companies cancelled trips to Mexico, including Transat AT, which will bring all employees and customers back to Canada.

The company said that flights to Mexico will be cancelled until at least June 1 and will impact people who booked trips with Air Transat, Transat Holidays, Nolitours, Vacances Transat and Look Voyages.

Air Canada and Air Canada Vacations also announced Tuesday they will suspend all operations to Cancun, Cozumel and Puerto Vallarta, Mexico, until June 1. The airline said, however, it will keep its flights to Mexico City going.