Thus far, the new H1N1 virus has not been discovered in any U.S. pig, but that doesn’t mean hogs are safe from it. "That is the question, isn't it?" Dr. Gregory Stevenson, Iowa State University professor and researcher, said at the World Pork Expo last week.
"We have to ask at risk in what way," Stevenson said. "I think the industry’s at risk potentially in two ways. H1N1 is not considered by the swine industry to be one of the major diseases as compared to the PRRS virus and other diseases. In regard to the economic question, I think we all realize that if the virus gets in our herds, there are potentially a lot of repercussions."
At this point, however, there was a study conducted where Iowa State University Veterinary Diagnostic Laboratory (ISUVDL) scientists took 125 H1N1 viruses of the last six months that represented all the geographic regions of state. They took the M and NA genes, which are the unique genes in this new virus, and sequenced them in their entirety. The scientists compared them to the new virus as well as standard endemic viruses in swine and found that all of the viruses found and were isolated "were those that we’ve had for many years," Stevenson said. The unique virus, the H1N1 quad virus that has been in people recently is not "in any of our Iowa swine and this has been the case with laboratories that have done similar studies, so as far as we know to this date, it is not in our swine population."
The biggest risk to pigs of the H1N1 virus outbreak that emerged in Mexico on April 24 is people, Stevenson said. One of the biggest factors potentially increasing the risk to pigs is whether the new human form of H1N1 becomes well established in the human population this fall. If it does, the risk posed to pigs would be workers who come to work sick, he said.
Stevenson said that while an H1N1 virus was isolated from diseased people in Mexico and rapidly spread around the world, its source remains unknown. This H1N1 flu outbreak virus (H1N1FOV), as it is now know, is composed of six genes that are like those in the common endemic North American swine H1N1 virus. However, the remaining two genes are like those in endemic influenza viruses infecting European and Asian swine. These genes are the NA gene and the matrix (M) gene, Stevenson said. "Just this past week we got a test that we don’t believe will give false positives," Stevenson said. This test will detect and identify only H1N1FOV and will test negative for all know endemic North American swine influenza viruses.