Monitoring and characterization of swine influenza virus (swIAV) in Europe since 2015

Influenza A virus infections causing economic losses are widely spread among swine populations worldwide. Swine can be infected by avian as well as by human influenza viruses. In Europe, over the last decade, three stable lineages of reassortant viruses between avian and human viruses have formed. The human pandemic H1N1/2009 virus has become a fourth player in this field and is currently disturbing the balance of the previously established European porcine influenza virus lineages. The emergence of the most recent human pandemic influenza virus (H1N1/2009) from reassortant porcine influenza viruses underlines the importance of swine populations as carriers of influenza lineages with zoonotic and even pandemic potential. In view of the OneHealth concept a closer surveillance of these populations therefore seemed a logical consequence of the most recent human influenza pandemic. However, surprisingly few countries actually embarked on sustained, governmentally driven and publicly controlled monitoring programs. It is therefore conceivable that, after closure of the EU-financed ESNIP3 program, a passive surveillance program for swIAV in selected European countries has been initiated on basis of funding by a veterinary vaccine producer.

This project targets nasal swab samples collected from pig farms with clinically apparent respiratory problems in European countries. Samples are screened by real time RT-PCR (RT-qPCR) for presence of influenza A viruses. Positive samples are subjected to molecular subtyping, virus isolation, antigenic and phylogenetic characterization.

About a quarter of the pigs with clinically apparent respiratory problems was found to be infected with influenza A virus. Three porcine H1 and one H3 lineages as well as various reassortant between them were detected. Prevalences of the different lineages are geographically restricted.

A high incidence of influenza virus infections representing all four lineages and various reassortants between them was detected in a season-independent manner. Incursions of new lineages and/or reassortants were documented for several European countries. Surveillance will continue into 2017 and comprise up to 6.000 samples.

Disclosure of Interest: None Declared.