Objectives: to analyse the trade flow of pigs to Lombardy (Northern Italy) to single out the farms more involved in animal movements to identify the holdings and areas most exposed to the risk of introducing pathogens into the region and to plan proper mitigation measures. Indeed, the movement of live animals and of the means of transport is one of the main risk factors in the spread of diseases and this is particularly relevant in areas with high stocking density.
Design: statistical analysis on movements of pigs entering Lombardy was carried out. Data on pigs' movements and farm characteristics were collected from the National and Regional databases. Social Network Analysis (SNA) was used to analyse the flows of pigs to Lombardy, to identify the holdings and geographical areas that are central in the trading network and that could have a role in the introduction of swine pathogens into the region.
Setting and participants: data on pigs' movements introduced into Lombardy in 2016 were analysed. Lombardy is a region of Northern Italy with intensive livestock husbandry. The pig sector is of particular economic relevance also in view of the processing industry, suited to the production of high quality pork products. Annually about 1.8 million pigs are introduced into the region also to satisfy the request of the processing industry for the production of pork products.
Main outcome measures: in this study, the farms that buy pigs from outside the region were identified as well as the territories where the largest number of pigs are introduced. The analysis was carried out also considering certain factors related to the movement of animals, which can be relevant for the transmission of pathogens, such as number of commercial partners, number of exchanged animals, and number of shipments.
Results: in 2016, 1,782,568 pigs were introduced into Lombardy; by using SNA, it was possible to highlight a complex trade network of pigs, mainly involving the Northern regions. Indeed, the pigs were mostly purchased from Emilia Romagna (33.4%), followed by Veneto and Piedmont. These regions have been the most closely analysed in this study. SNA was also used to identify Lombardy territories (provinces and municipalities) which, based on the number of introduced pigs, are potentially most exposed to the introduction of pathogens from outside the region. Mantua and Brescia provinces resulted the most exposed area.
Conclusions: Italy is one of most important European producers of pigs and about 50% of national pig assets is present in Lombardy; furthermore, about 1.8 million pigs are introduced yearly into the region. Currently, the region is free from the main diseases of pigs and the introduction of an epidemic disease into the pig population could adversely affect the entire productive sector. For this reason, an analysis of the movements of pigs entering the region was carried out to identify the areas (provinces, municipalities) and holdings most exposed to the risk of introduction of pathogens. This information is relevant for the veterinary authorities to plan appropriate control activities (official controls, surveillance, biosecurity, and vaccination, where possible) in order to enhance disease prevention and promote early detection.
Keywords: pig movements; social network analysis; pathogen transmission.