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Colorized transmission electron micrograph of Avian influenza A H5N1 viruses (seen in gold) grown in MDCK cells (seen in green) are shown in this 1997 image.Cynthia Goldsmith/THE CANADIAN PRESS

Ontario has found a case of an infection with a new swine flu virus, in a man who had close contact with pigs.

The infection was caused by an H1N1-variant virus, which is not the swine flu virus that has been jumping from pigs to people in the United States this summer.

That virus was an H3N2-variant, and has caused 305 infections this year in the U.S. but has not been spotted in Canada to date. Most infections with the H3N2-variant flu have been in people who visited pig barns at state and county fairs.

The Ontario case was announced by the province's chief medical officer of health, Dr. Arlene King on Tuesday morning.

Ms. King said the man is being treated in hospital in southwestern Ontario. She did not indicate whether that is as a precaution or because he is seriously ill.

Health Minister Deb Matthews said the fact that the case was detected in Ontario demonstrates that the province has a strong surveillance system for infectious diseases.

"It's one case, the first we've seen in Ontario, but not really unexpected because there have been cases in the States," Ms. Matthews told reporters on Tuesday.

Ms. Matthews said health care providers in Ontario learned a lot about infectious diseases from the earlier outbreaks of SARS and H1N1.

"Our hospitals know exactly what to do when they get a case," she said.

Ms. King said this new virus is one that rarely spreads from animals to people, and human-to-human spread is also rare.

She stressed the discovery of the infection does not trigger food safety concerns. "Proper cooking of meats, including pork, kills all bacteria and viruses."

She also urged people to remember that hand washing and getting a flu shot are the best way to protect against contracting the flu.

The term variant is added to flu virus names when viruses that normally circulate in animals cause infections in humans. In written form it is often shortened to a "v" at the end of the virus's name.

This H1N1v virus would be a distant cousin of the H1N1 viruses that have been circulating in people for most of the last century. That family includes the virus that cause the 2009 pandemic.

But viruses within a large family group such as H1N1 can be sufficiently different from one another that antibodies to one won't fully protect a person from becoming infected with another.

U.S. authorities have also seen one case of infection with an H1N1v virus there this summer, in Missouri. Ms. King did not say whether the genetic blueprints of the Ontario and Missouri viruses were closely related.

With a report from Karen Howlett.

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