Animal health authorities, veterinarians and pork industry officials are investigating the novel H1N1 influenza virus, which sickened thousands of people worldwide, to determine what impact it may have on animals.

The virus strain, initially labeled by federal health authorities as "swine influenza", had not infected any swine in the United States by early May.

"A lot of diagnostic samples have gone to the veterinary diagnostic labs throughout the influenza season, and there are labs that are going back and looking at those viruses and sequencing them to see if this novel H1N1 sequence is there," said Harry Snelson, communications director for the American Association of Swine Veterinarians,

The H1N1 virus was found in pigs on an Alberta, Canada farm, and the pigs were likely exposed to the virus by a worker with flulike symptoms who had recently returned from Mexico.

Snelson said the Department of Agriculture's National Veterinary Services Laboratories and National Animal Disease Center were considering development of a test to differentiate between the novel H1N1 and typical influenza viruses that circulate in swineherds. He also said officials with those agencies would perform challenge studies to determine the pathogenesis and transmissibility of the virus and the effectiveness of vaccines.

Federal authorities and veterinary organizations urged pork producers to take precautions to ensure their animals do not become infected.

David Warner, communications director for the National Pork Producers Council, said his organization encourages producers to vaccinate pigs and workers against influenza viruses.

Read more about the H1N1 virus from the American Association of Swine Veterinarians.