Courtesy Center for Emerging Infectious Diseases/ Gregory Gray Researchers from the University of Iowa tested pigs and humans for influenza viruses at the Minnesota and South Dakota state fairs.

The National Veterinary Services Laboratory confirmed five more pigs from the Minnesota and South Dakota with the H1N1 virus.

The infected pigs were tested as part of a study, “Swine Influenza at State and County Fairs,” proposed by Greg Gray, director of the Center for Emerging Infectious Diseases at the University of Iowa, to better understand the spread of influenza in places where pigs and animals converge.

“The fair setting was investigated because during 2005 to 2008, the Center for Disease Control and state and local health partners had identified a number of sporadic cases of swine influenza infection where the infected person had most likely been exposed at a fair or other public setting,” said Jeff Bender, director of the International Cooperative Zoonotic Influenza Research Center (ICZIRC) at the University of Minnesota, which is funding the study.

The study began before the H1N1 pandemic arose, Bender said, and the particular strain of the virus was not a focus of the study. Researchers tested 50 pigs at the Minnesota State Fair in 2008, and 102 pigs at the Minnesota and South Dakota state fairs in 2009. In addition to the six total cases of H1N1, one pig was found to have H1N2, a strain of flu rarely found in humans.

Although Gray said that the research team has not decided whether to continue the study in 2010, the results could help pig farmers have a better understanding of how to keep themselves and their herds healthy.

“It’s important to know that these viruses move from man to pigs and back again,” Gray said. “They can mix with other viruses in man or pigs and out can come new viruses that cause much more problems.”

Right now, the research team is looking for evidence where the influenza viruses cross over between species so they can make recommendations for how to reduce flu transmission. This involves documenting virus transmissions, determining risk factors and testing methods of intervention. In the meantime, they are advocating for pig farmers and veterinarians to be short-listed for the H1N1 vaccine.

“Swine veterinarians are important in reducing this problem and we have to protect them like we protect workers in hospitals,” Gray said.

Gray also recommends people working with swine receive the seasonal flu vaccine and educate themselves in biosecurity measures. Limiting human contact with pigs, especially in cases of sick humans, and using protective equipment can reduce disease transmission.

The pigs were not tracked after testing and the researchers could not comment on what happened to the infected pigs.
The H1N1 virus continues to threaten humans more than pigs, Gray said.

The University of Minnesota’s ICZIRC houses six other studies investigating influenza viruses and their effects on human health. The center was established because of increasing interactions among humans, livestock, poultry and wildlife that have resulted in the emergence of zoonotic diseases.