Canadian scientists have completed the full genetic sequencing of the H1N1 swine flu virus, vital to understanding the outbreak and developing a vaccine, officials said Wednesday.
"It gives me great pleasure to be able to announce today that our knowledge of the H1N1 flu virus has taken a great step forward," Health Minister Leona Aglukkaq told a press conference.
Scientists at the Public Health Agency of Canada's microbiology lab in Winnipeg cracked the genetic makeup of samples from Mexico and two Canadian provinces, she said.
Preliminary analysis found the trio of samples "do not differ significantly at the genetic level," Aglukkaq added.
"This is the first complete sequencing of the H1N1 flu virus and it's vitally important to our understanding of this outbreak," she said. "This is a world first."
The respiratory illness causes symptoms such as fever, fatigue, muscle aches or pain, lack of appetite, coughing and sore throat. Some people have also reported vomiting and diarrhea.
Canada currently has the third highest number of cases of swine flu after the United States and Mexico, which has been at the epicenter of the outbreak.
Of its 10 provinces, only western prairie Saskatchewan and island Newfoundland in the North Atlantic Ocean have not been affected.
Frank Plummer, Scientific Director General of the National Microbiology Laboratory, said it took less than a week for scientists working around the clock to map or decode the virus.
The discovery would help health authorities pinpoint the origin of the virus, how its spreads and how it changes over time, "giving us the knowledge that we need to fight the H1N1 flu virus," he said.
However, the near-identical genetic makeup of the samples from Mexico, as well as Canada's Nova Scotia and Ontario provinces, raises another key question: why were cases in Mexico more severe than elsewhere.
Earlier, Mexico raised its swine flu death toll to 42, while two deaths were confirmed in the United States.
In Canada, 165 cases have been identified so far. All of the Canadian cases have been mild, except for a young girl hospitalized in Edmonton, Alberta with severe symptoms.
Officials said she was treated in the Edmonton hospital's intensive care unit and was improving.
The World Health Organisation meanwhile said the number of people confirmed to have been infected with the swine flu virus worldwide has reached 1,516.
The Canadian lab work "appears to suggest that there's nothing at the genetic level that differentiates this virus that we've got from Mexico and those from Nova Scotia and Ontario that explains apparent differences in disease severity between Mexico and Canada and the United States," said Plummer.
"That's one of the big questions that everybody's been asking," he said.
"So part of the answer is that it's likely not the virus itself that is explaining the differential and severity of disease between Mexico and the rest of North America."