Study Shows High Levels of 3 Swine Flu Strains on Outbreak Pig Farms

January 20, 2016 — 

Three separate strains of influenza A virus (IAV) were detected in animal and environmental samples taken from 6 swine farms in southern Minnesota and northern Iowa with suspected flu outbreaks, according to a study in PLoS One. [Source: CIDRAP January 12, 2016]

US researchers took oral fluid, pen railing, and indoor air samples from farms that were identified by area veterinarians as likely hit by flu. Five of the outbreaks were confirmed to be caused by influenza A virus (IAV). Of those, 48 percent (47/98) of oral fluid, 38 percent (32/84) of pen railing, and 43 percent (35/82) of indoor air samples tested positive for influenza A by polymerase chain reaction.

Among the 5 outbreak farms, H1N1 was confirmed on 1, H3N2 on 1, both H1N1 and H1N2 on 2 farms, and both H1N1 and H3N2 on 1 farm.

The authors concluded, "We found that IAV could be isolated from indoor air of commercial swine production facilities, that airborne IAV levels were sustained for periods of 20 days and that there was a correlation between the number of positive samples of each type and the quantity of virus in the swine oral fluids and in the air.

"Our results provide a 1st estimation on levels of environmental IAV in swine commercial production facilities, and thus an assessment of potential sources of IAV exposure to swine workers or other pigs."