Swine influenza is a very common disease amongst swine populations and it can occur throughout the whole year.
Influenza viruses are considered ubiquitous in swine populations worldwide. Currently are H1N1, H1N2 and H3N2 the main influenza virus subtypes which are circulating in Europe.
H3N1 influenza viruses have also been isolated from pigs in the USA, Germany, Italy and Republic of Korea. H2N3 influenza viruses were detected in pigs in the USA. Both strains have not apparently become established in pig populations.
Swine are considered a “mixing vessel” for influenza viruses and were the source of the pandemic H1N1(2009) virus. The pandemic H1N1(2009) virus subtype which has been described the first time in 2009, is frequently detected in Europe, particularly in United Kingdom, Denmark, Poland, Germany and Eastern European Countries.
The Friedrich-Loeffler-Institute (Federal Research Institute for Animal Diseases in Germany) has been working on a passive surveillance study of Influenza A virus in pigs in Europe.
This study began in April 2015 and was completed in December 2017. By September 2017 this study had analysed 15.669 samples from 2.068 farms. Of these, 2.022 samples were positive for Influenza A and 11 different subtypes have been identified. H1avN1av (avian derived) is the most prevalent followed closely by H1pdmN1pdm (human pandemic A/H1N1, 2009).
See European countries in the graphic below. (Henritzi et al., personal communication, 2017).
Animated graphic "Epidemiological situation of swine influenza (SIV) in selected European countries" (Henritzi et al., personal communication).
Samples have been taken from April 2015 to September 2017.