Harmless or Just Neglected? Revisiting the Role of 'Minor' Pig Viral Infections in Italy.

Abstract

In 2023, the Italian National Livestock Registry estimated that the pig population in Italy exceeded 8.1 million animals, with approximately 26,000 pig farms nationwide. The pig farming sector is highly concentrated in the northern regions, which account for about 89% of the national swine stock (ISMEA,  2024). Pig farming worldwide can generally be divided into intensive, semi-intensive, and extensive systems, each characterized by different management practices and biosecurity levels (Racewicz et al., 2021). In Italy, intensive systems predominate in the north and parts of the centre, often with a high degree of specialization and integrated production chains. Conversely, in the remaining central and southern regions, pig farming tends to be less specialized, frequently family-run, and strongly influenced by local customs and traditions (Bellini et al., 2009). This coexistence of diverse farming systems results in significant differences in herd management, biosecurity standards, production inputs, and market demands, all of which can directly or indirectly influence the spread of infectious diseases. In recent years, several emerging and re-emerging viral pathogens have been identified in swine populations worldwide, some with considerable clinical and economic impact, while others remain largely understudied, with uncertain effects on pig health. Advances in diagnostic technologies, such as next-generation sequencing (NGS), have improved virus detection, revealing the presence of previously undetected agents. This review aims to provide an updated overview of emerging swine viruses reported in the Italian pig industry, with particular attention to those whose roles within current farming systems are still unclear.