Two weeks after detecting an african swine fever outbreak in wild boars in Cerdanyola del Vallés, Barcelona—the first in Spain since 1994—questions about its origin remain unresolved. The hypothesis of a leak from a nearby laboratory experimenting with a modified virus for vaccine development is gaining traction. Authorities urge caution as 16 positives are confirmed in the affected area.
The african swine fever (ASF) outbreak was detected on November 28, 2025, in dead wild boars in Cerdanyola del Vallés, Barcelona province. This lethal viral disease for pigs poses no risk to humans but threatens the pork industry. It is the first focus in Spain since 1994, with 16 positive cases confirmed in wild boars to date, all within the perimetrated zone, without reaching livestock farms.
The investigation keeps several hypotheses open, but a possible leak from the Animal Health Research Center (IRTA-CReSA) in Bellaterra, near the discovery site, stands out. This high-biosecurity facility, attached to the Catalan government, planned experiments with pigs inoculated with a genetically modified version of the ASF virus, specifically the Georgia 2007 strain, to develop a vaccine. The protocol involved 15 animals in three groups over five weeks, from October to November 2025, with blood and saliva sampling to assess immune response.
Analyses from the EU reference laboratory and the CISA-INIA in Madrid revealed that the strain in the wild boars belongs to genetic group 29, similar to group 1 from Georgia 2007, distinct from circulating strains in the EU (groups 2-28). This strain is commonly used in labs for studies and vaccine trials. The Ministry of Agriculture, Fisheries and Food raised the possibility of an origin in a biological containment facility on December 5.
IRTA-CReSA has not clarified if experiments were underway on November 28. Its spokeswoman stated: «We are focused on continuing to work on surveillance, analysis, and detection tasks to contribute to containing the current outbreak.» The Ministry for the Ecological Transition confirmed the evaluation of two level 3 activities with modified viruses, one approved by the Interministerial Committee on GMOs.
Catalan Agriculture councillor Òscar Ordeig called for «prudence» and «not drawing hasty conclusions,» pledging transparency once the origin is scientifically confirmed. The Catalan government assures that containment measures are working well.
