Pig and piglet.

2016-17 Rapid Ag: A Comprehensive Surveillance System to Control Influenza Virus in Pigs

November 1, 2015

Principal Leader

 Montse Torremorell


Department of Veterinary Population Medicine

Funding Awarded

  • 2016 Fiscal Year: $64,115
  • 2017 Fiscal Year: $71,115

The Problem

 It is an unprecedented time for influenza infections. In pigs, the 2009 H1N1 pandemic had devastating effects on the swine industry and changed the landscape of circulating viruses in the US herd, with both animal and public health consequences. Therefore the risk that influenza infections pose to animal agriculture and people can hardly be overstated.


Prior to 1998, IAV infections in pigs were considered of limited importance, and swine-origin infections to people were sporadic. However, in the last few years, we have seen an unprecedented number of IAV infections proving very difficult to control in pigs. In addition, infections from pigs to people have also been more common and in the summer of 2012 there were more than 300 documented cases of people becoming infected with an H3N2 variant associated with exposure to swine at agricultural fairs (Jhung et 2 al., 2013). Reports of infections transmitted from pigs to people, or the emergence of a new strain linked to swine, can be devastating to the industry as markets can collapse and the ability to sell pork is reduced.

Unfortunately the emergence of novel strains in pigs is not a rare event, but rather it is becoming the norm. This is due to the on-going introduction of human-like IAV strains, the increased number of endemic strains co-circulating in pigs and continuous genetic change and reassortment (Webby et al., 2004; Nelson et al.,2014). Thus the level of strains co-circulating in pigs has never been greater and there is an urgent need to provide strategies to decrease the burden of IAV infections in pigs.

Despite all the efforts on influenza research, we know little about what happens in pigs and what to do to control infections effectively. Our group has been at the forefront to understand influenza epidemiology, what happens within farms and what factors drive the maintenance and dissemination of influenza viruses. We have identified subpopulations of pigs that are at higher risk of sustaining and introducing influenza infections in breeding herds. We have documented the co-circulation of multiple viruses of different genetic lineages and have highlighted that influenza infections in populations can be prolonged despite the general knowledge that influenza infections are self-limited at the individual level. However, our results also indicate that influenza infections at the herd level vary in duration, magnitude and season, and herds have a combination of scenarios where new strains are continually introduced, some die-out whereas others persist over time, which makes the evaluation of control strategies difficult.


  1. To create a real time reporting system to estimate incidence and prevalence of IAV infections in breeding herds. 

  2. To identify epidemiological factors that will enhance veterinarians’ ability to control influenza infections.

  3. To identify herd level factors that are associated with IAV diversity.