You may have already noticed the signs in the windows of your local pharmacy or doctor's office declaring, "Flu Shots Today." Perhaps you already knew it was flu season because your children are sick after being back in school for just a few days, or your pigs have that barking cough after the first cool night.
If you didn't know flu season was fast approaching, let this serve as your reminder to Just Flu It! More specifically, just do flu vaccination for yourself, your family, and your farm staff and just do flu surveillance on your pigs. Why? It's because I care about you too much to argue.
Emerging Flu Changes
But seriously, the real reasons to Just Flu It are quite important. Flu in pigs is already changing. With the introduction of the 2009 pandemic H1N1 into the swine population, we have since seen several reassortant viruses emerge (Ducatez MF, Hause B, Stigger-Rosser E, Darnell D, Corzo C, Juleen K, et al. Multiple reassortment between pandemic 2009 H1N1 (2009pH1N1) and endemic influenza. Emerg Infect Dis [serial on the Internet]. 2011 Sept. [accessed 26 Aug 2011] www.cdc.gov/eid/content/17/.
What we are detecting through the United States flu surveillance efforts are viruses in pigs that contain a mixture of genes from endemic swine influenza viruses (e.g. flu strains that have been commonly circulating since 2003 in U.S. pigs) and the 2009 pH1N1. Additionally, interesting things are happening in human and animal populations that require our attention and investigation (Cox CM, Neises D, Garten RJ, Bryant B, Hesse RA, Anderson GA, et al. Swine influenza virus A (H3N2) infection in human, Kansas, USA, 2009 [letter]. Emerg Infect Dis [serial on the Internet]. 2011 Jun [accessed 26 Aug 2011]. www.cdc.gov/EID/content and Jun 6 2011 MMWR report www.cdc.gov/mmwr/.
At the University of Minnesota Veterinary Diagnostic Laboratory in 2011, we have routinely detected subtypes H1N1 (27% out of over 1,000 viruses successfully subtyped), H1N2 (57%), and H3N2 (16%) in swine nasal swabs, lung tissues and oral fluids. The H1 viruses are diverse, coming from three different genetic groups. All of the H3 viruses are similar, sharing more than 95% genetic similarity in the H3 gene. The animal biologics companies and swine veterinarians are aware of the diversity in influenza A viruses in U.S. pigs and have made the appropriate changes to their available influenza vaccines. The diagnostic labs have recognized the changes and have updated their tests. The researchers are looking at the changes to try to determine what impact they will have on pig and human health.
Even though we’ve subtyped over 1,000 viruses and sequenced over 300 so far in 2011, the majority of the viruses are coming from just two states – Minnesota and Illinois. Do we really know what is going on in other parts of the United States? Are pigs in North Carolina exposed to the same influenza viruses as pigs in Minnesota? We just don’t know and we won’t know how good are our surveillance efforts, how widespread are the changes are, how effective are our vaccines, nor how well we can protect our pigs, our families, and our consumers unless we all Just Flu It!
Marie Gramer, DVM
Associate Clinical Professor
University of Minnesota Veterinary Diagnostic Laboratory