Pigs in the Canadian province of Alberta have been infected with the new swine flu virus and are under quarantine, officials said Saturday. It is the first known case of pigs having the virus. But officials quickly urged caution. Swine flu regularly causes outbreaks in pigs, and the pigs do not pose a food safety risk, Dr. Brian Evans, executive vice president with the Canadian Food Inspection Agency, told a news conference. The officials said the pigs were thought to be infected by a Canadian farm worker who recently visited Mexico and got sick after returning to Canada. The traveler has recovered, and the estimated 200 sickened pigs are recovering as well, officials said. No pigs have died, and officials said they don't think the flu has spread beyond the farm.