Three pigs in Minnesota may have tested positive for the H1N1 virus, the first potential U.S. cases in swine, but infectious disease experts cautioned that the pigs pose no risk to human health.
Researchers collected the samples from pigs at the Minnesota State Fair between Aug. 26 and Sept. 1, as part of a study conducted by the University of Minnesota, University of Iowa, and the Centers for Disease Control and Prevention.
The USDA will conduct further tests to confirm the pigs had been infected with H1N1. The results are expected within the next several weeks.
The three infected pigs came from different owners, but researchers are unable to locate the animals, due to confidentiality agreements signed by swine owners prior to the study.
Infectious disease experts and state officials reiterated today that the virus cannot be transmitted from a pig to a human via food. Transmission of the virus from pigs to humans is also rare.
"We want to make sure that the public knows that this is not a situation that they need to be concerned about in terms of transmission to people," said Michael Osterholm, the director of the University of Minnesota's Center for Infectious Disease Research and Policy. "This is really a situation where we're trying to keep people from transmitting the virus to pigs."
State officials plan to send a letter to all State Fair swine exhibitors, advising swine owners to contact a veterinarian if they notice influenza-like symptoms in their herds.
Officials said the pigs did not exhibit signs of sickness and may have been exposed to a group of 4-H students who had contracted the flu virus.
Osterholm said that officials have not yet determined how the pigs contracted the virus, but he said it's possible that a group of 4-H students with influenza who were sent home from the fair may have spread the illness to the pigs.
The H1N1 virus has already been found in swine from Canada, Argentina, Ireland, the United Kingdom, and Norway.