(CNN) -- The H1N1 virus has been confirmed in a sample taken from a pig that was displayed at the Minnesota State Fair, the first time the virus has been found in a U.S. pig, the U.S. Department of Agriculture said Monday.
The Department of Agriculture quickly issued a statement saying the food supply is safe.
"We have fully engaged our trading partners to remind them that several international organizations, including the World Organization for Animal Health, have advised that there is no scientific basis to restrict trade in pork and pork products," Agriculture Secretary Tom Vilsack said in the statement. "People cannot get this flu from eating pork or pork products. Pork is safe to eat."
The announcement came three days after health officials announced that three pigs that were displayed during the fair had tested positive in a preliminary test for the H1N1 flu virus. Final results on the other two pigs have not been announced.
"This, of course, may be the first indication that it is present in some swine here in the United States," Gene Hugoson, commissioner of the Minnesota Department of Agriculture, told reporters in a conference call on Friday.
The U.S. Department of Agriculture National veterinary services laboratories conducted the confirmatory testing on the sample collected at the fair, held in Saint Paul, Minnesota, between August 26 and September 1. Further testing is ongoing.
The pigs sampled showed no signs of sickness and were apparently healthy, the officials said.
The samples collected were part of a joint University of Iowa and University of Minnesota research project funded by the Centers for Disease Control and Prevention to determine whether animals at such events had the infection.
"Like people, swine routinely get sick or contract influenza viruses," Vilsack said.
The misconception that the virus, sometimes called the swine flu, could be contracted through eating pork has hurt sales of the meat in the wake of the expanding pandemic.
This year's crowd of 1.79 million attendees was a record.
Though an outbreak of H1N1 was reported among a group of 4-H'ers who had attended the fair, officials said it was unlikely they contracted the virus from the animals, since few of them had contact with the pigs.
The report came as no surprise to experts, since herds in other countries, including Argentina, Canada, Ireland and Norway, have been infected with H1N1.
Pigs that do get sick with H1N1 typically recover from it, the officials said.
The officials said the display animals likely were sent to slaughter.
Even if they were slaughtered while still infected, that would not be an issue for anyone eating the meat, said Dr. Jeff Bender, co-director of the University of Minnesota Center for Animal Health and Food Safety. "This virus is not in muscle tissue, so if these animals were slaughtered or processed there would be no risk to the public."
A vaccine to protect swine from H1N1 is under development but is not yet commercially available, one official said.