The Versatility of Influenza A Surveillance and Monitoring in European Swine; results from an electronic survey

Surveillance of influenza A virus in swine populations is essential, from both a veterinary and public health perspective. Although some international organizations have published guidelines for swine influenza A virus (swIAV) surveillance, there is no standardized guidelines available and a clear overview of current existing surveillance activities is lacking at the European level. This study aimed to describe swIAV surveillance systems across Europe in 2022. An electronic survey was distributed to 41 member countries of the Cost Action “ESFLU”, resulting in 44 responses from 39 institutions representing 25 countries. The analysis identified 26 unique surveillance systems, operating at local, national, regional, and multi-national levels. The majority of the systems had the objective of surveilling emerging strains or monitoring for swine influenza viruses in herds. In 2022, approximately 3,500 farms were sampled, with piglets and weaners being the most sampled age groups. Most systems (n=23) used RT-PCR for detection and fourteen used sequencing for viral characterization/subtyping. The study also highlighted a strong reliance on passive surveillance. While data sharing with OFFLU and other public databases is advocated, nine systems consistently shared their data, while eleven others indicated that data sharing occurs conditionally, depending on specific circumstances. The study emphasized the need for harmonized guidelines for surveillance and the establishment of pipelines for the systematic collection and analysis of data in swIAV in pigs.