More than a week after the swine flu outbreak rattled the world, with cases of infected people popping up from Mexico to South Korea, the new virus strain has shown up in a herd of swine.
The catch, Canadian officials say, is that the animals may have caught the flu from a human.
Canadian officials are quarantining pigs that tested positive for the virus -- scientifically known as 2009 H1N1 -- at an Alberta farm in what could be the first identified case of pigs infected during the recent outbreak.
They said the pigs may have been infected by a Canadian farmer who recently returned from a trip to Mexico, the epicenter of the outbreak that has sickened more than 680 people.
The farmer "may have exposed swine on the farm to an influenza virus," said Dr. Brian Evans of the Canadian Food Inspection Agency.
"We have determined that the virus H1N1, found in these pigs, is the virus which is being tracked in the human population," he added.
Evans and other officials said it is not uncommon for flu viruses to jump from humans to animals, and that it does not pose a risk for consuming pork. The number of pigs infected was not disclosed.
The infected farmer had flu-like symptoms and is recovering, Evans said.
Meanwhile, as the number of confirmed swine flu cases reached 787 worldwide, the World Health Organization said Sunday it had started distributing 2.4 million doses of a common anti-viral drug to 72 nations. So far, 17 countries have confirmed cases of swine flu, the WHO said.
The World Health Organization cautioned that the swine flu outbreak could gain momentum in the months ahead, despite claims by the health secretary of Mexico -- the epicenter of the outbreak -- that the virus "is in its declining phase."
The outbreak is only about 10 days old, and even if the illness is declining, it could return, said Gregory Hartl, the WHO spokesman for epidemic and pandemic diseases, at a briefing Sunday.
"I ... would like to remind people that in 1918 the Spanish flu showed a surge in the spring, and then disappeared in the summer months, only to return in the autumn of 1918 with a vengeance," Hartl said. "And we know that that eventually killed 40 million to 50 million people."
Mexican authorities believe the virus's most active period in Mexico was between April 23 and April 28, and Mexican Health Secretary Jose Cordova described the outbreak as being in decline in his country.
As of Sunday, WHO confirmed 898 cases of swine flu -- known to scientists as influenza A (H1N1) -- reported in 18 countries.
Mexico has 506 confirmed cases, including 19 deaths, WHO reported.