Continued vigilance needed on African swine fever in Spain

“So far the outbreak has remained confined to wild boar, but it represents a significant epidemio-logical threat for the Spanish and European pig sectors Enhanced passive and active surveillance was immediately implemented. Control measures included systematic carcase searches, targeted population reductions, continued monitoring of wild boar populations and reinforcement of physical containment barriers (including fencing and control structures at identified risk points). Within the IZ, 57 domestic pig holdings (including backyard farms) were placed under reinforced official surveillance and biosecurity verifications. As of 5 March 2026, 216 ASF virus PCR-positive cases have been identified, mostly displaying acute forms of ASF. In parallel, 1708 wild boar cases tested PCR-negative, including 1176 animals sampled through active capture and 532 through passive surveillance.2 The epizootic spread continues within two confined zones of the IZ. Importantly, no clinical signs compatible with ASF or positive cases have been detected in domestic pigs to date. The European Union Reference Laboratory for ASF confirmed a genotype II strain, responsible for the ongoing Eurasian epidemic, and classified the isolate within a newly defined genetic group 29.3 The detection of a genetically distinct lineage without closely related isolates highlights the complexity of the global epidemiology of ASF virus and underscores the limited understanding of its evolutionary dynamics in many geographic regions. The re-emergence of ASF in Spain, distant from the nearest affected regions, reinforces the widely accepted view that human-mediated activities are a major driver of long-distance spread, potentially exacerbated by wild boars exploiting anthropogenic resources near human settlements.4 The experience in Spain illustrates both the persistent risk of longdistance introduction into previously ASF-free regions, and the critical role of early detection and coordinated control measures. Continued vigilance, strict biosecurity and prompt reporting of suspect cases are essential to prevent further spread within Spain and beyond.