Epidemiological Characteristics of the African Swine Fever Genotype II Epidemic in Domestic Pigs in Lombardy (Northern Italy) in 2023 and 2024.

African swine fever (ASF) is a severe hemorrhagic disease of suids caused by the African swine fever virus (ASFV). In 2023, the introduction of genotype II ASFV into Lombardy was a cause for serious concern; the region is home to approximately 50% of the national pig population and is of economic importance to the processing industry of the entire country. Since then, two ASF epidemics have resulted in a total of 30 outbreaks in domestic pigs in the same areas of Lombardy, where the disease is endemic in wild boars. The results of the control activities conducted in the affected areas seem to indicate the establishment of self-sustaining infection cycles in the wild boar population with spillover and spillback events occurring between wild boars and domestic pigs. This manuscript describes some epidemiological features of the ASF epidemics in Lombardy with the aim of providing useful information to combat the disease.