Canadian officials said on Tuesday they had identified yet another new flu virus, this one a mixture of human and swine influenza viruses, in two farm workers in Western Canada.

The new virus did not make the two workers seriously ill and is not related to the current H1N1 pandemic influenza strain, the Public Health Agency of Canada said.

The two workers, both employees at a hog barn operation in the province of Saskatchewan, have fully recovered. A third case is under investigation.

“Preliminary results indicate the risk to public health is low and that Canadians who have been vaccinated against the regular, seasonal flu should have some immunity to this new flu strain,” Canada’s health minister, Leona Aglukkaq, said in a statement.

The new virus contains genes from a seasonal human H1N1 flu strain and a flu virus common in the swine population called triple reassortant H3N2, said Dr. Greg Douglas, Saskatchewan’s chief veterinary officer.

The virus is not connected to the new swine flu H1N1 strain that has killed 429 people worldwide. That strain, labeled a pandemic by the World Health Organization, is also a mixture of swine viruses with some genes from human and avian influenzas.

Since the new H1N1 broke out, officials in Canada, the United States and a few other countries have stepped up testing of both people and swine for flu viruses. People and pigs can swap flu viruses, although it has been documented only rarely.

In April, a herd in Alberta became infected with the new H1N1 virus and although health officials initially suspected a visiting worker infected the herd, that has since been ruled out and no one knows how the pigs became infected.

“Initial testing of some of the pigs on the farm suggests they were infected with swine influenza A virus, a common flu found in swine herds,” the Public Health Agency of Canada said in a statement.

HUMAN HEALTH ISSUE

But Douglas said the herd did not have an unusually high level of illness. Flu viruses are common among pigs and cause mild disease, usually. “This is a human health issue,” Douglas said. “Saskatchewan pork continues to be safe… This is not a food safety issue at all.”

The Saskatchewan farm is not under quarantine, but the owner has agreed not to move the pigs, said Dr. Frank Plummer, chief science adviser for the Public Health Agency of Canada.

The virus would likely not have been detected at all if not for heightened influenza testing as a result of the pandemic, Plummer said.

“Any time there’s a new influenza A strain, we have to be concerned about it, but these events occur and are almost always dead ends,” he said.

All workers on the hog farm are being vaccinated. Douglas said he expects the hogs will eventually go to slaughter as they normally would.

The workers have been in Saskatchewan for about one year and had not recently traveled, said Dr. Moira McKinnon, Saskatchewan’s chief medical officer.

Plummer said the new virus was likely transmitted from the pigs to the workers.

More than a dozen countries have banned Canadian hogs or pork since the quarantine.

Bob Harding, executive director of the Canadian Swine Health Board, said there is concern that markets could misinterpret the new virus’s connection to swine.

“This is a poorly understood science. It’s changing as we speak, but it’s not a pig thing,” Harding said.

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* New flu virus not connected to H1N1 outbreak

* Hogs may have transmitted virus to workers

By Rod Nickel

SASKATOON, Saskatchewan (Reuters)