Send to

Choose Destination
Emerg Infect Dis. 2013 Jun;19(6):954-60. doi: 10.3201/eid1906.121637.

Active surveillance for influenza A virus among swine, midwestern United States, 2009-2011.

Author information

College of Veterinary Medicine, University of Minnesota, Saint Paul, Minnesota 55108, USA.


Veterinary diagnostic laboratories identify and characterize influenza A viruses primarily through passive surveillance. However, additional surveillance programs are needed. To meet this need, an active surveillance program was conducted at pig farms throughout the midwestern United States. From June 2009 through December 2011, nasal swab samples were collected monthly from among 540 groups of growing pigs and tested for influenza A virus by real-time reverse transcription PCR. Of 16,170 samples, 746 were positive for influenza A virus; of these, 18.0% were subtype H1N1, 16.0% H1N2, 7.6% H3N2, and 14.5% (H1N1)pdm09. An influenza (H3N2) and (H1N1)pdm09 virus were identified simultaneously in 8 groups. This active influenza A virus surveillance program provided quality data and increased the understanding of the current situation of circulating viruses in the midwestern US pig population.


Influenza; midwestern United States; monitoring; surveillance; swine; viruses

[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for CDC-NCEZID Icon for PubMed Central
Loading ...
Support Center