A-Z Index × Submit A-Z Index × Submit A-Z Index Search Dropdown × Submit Facebook Twitter LinkedIn Syndicate Emerging Infectious Disease journal ISSN: 1080-6059 Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.
African swine fever virus genotype II was detected in wild boar in Spain in 2025 after >30 years of absence. Whole-genome sequencing and molecular follow-up of 8 representative cases identified a stable 9.8-kb deletion affecting the multigene family in the left variable region, defining an ASFV genotype II variant.
Figure 1 . Spatial distribution of African swine fever virus (ASFV)–positive wild boar cases detected in northeastern Spain, 2025–2026. A) Geographic distribution of ASFV-positive wild boar cases detected during November 2025–May 2026 in...
African swine fever (ASF) is a highly contagious disease of domestic pigs and wild suids with major economic consequences. After the emergence of ASF virus (ASFV) genotype II in Georgia in 2007 ( 1 ), the virus spread across Europe and Asia and reached the Caribbean, demonstrating its capacity for transcontinental spread. In Europe, ASFV circulation is maintained in wild boar populations ( 2 ). On November 26, 2025, ASFV was confirmed in Spain ( 3 ). By May 29, 2026, a total of 326 ASFV-positive wild boar had been detected ( Figure 1 , panel A). Spain rapidly implemented control measures to limit wild boar movement, including carcass search and removal, reinforced passive surveillance, movement restrictions, and installation of fencing. This study describes the genomic characterization and molecular follow-up of 8 representative ASFV-positive wild boar cases detected during November 2025–February 2026, including the index cases ( Figure 1 , panel B).
Two freshly dead wild boar ( Sus scrofa ) were found on November 26, 2025, during passive wildlife surveillance near Barcelona, northeastern Spain ( 3 ). The animals were located ≈1 km apart in a periurban area with high human connectivity. We analyzed whole blood, serum, spleen, tonsil, and lymph node samples at Unitat Mixta d’Investigació Institut de Recerca i Tecnologia Agroalimentàries, Centre de Recerca en Sanitat Animal (IRTA-CReSA; Bellaterra, Spain), the Spanish National Reference Laboratory for ASF (Algete, Spain), and the European Union Reference Laboratory for ASF (EURL-ASF; Valdeolmos, Spain).
We confirmed that both animals tested ASFV-positive by World Organisation for Animal Health (WOAH) real-time PCR procedure 2; virus isolation in primary porcine alveolar macrophages showed the characteristic hemadsorption pattern. We detected ASFV-specific antibodies in both animals by WOAH indirect immunoperoxidase test; serum titers were 1:2,560.
Figure 2 . Geographic distribution of African swine fever (ASF) virus genotype II genetic groups in Europe, 2007–2025. We combined analysis of 6 genomic regions to define genetic groups. We assigned groups through...
Genotyping based on partial B646L (p72) sequencing assigned the virus to genotype II, which has circulated in Europe since 2007 ( 4 ). To determine whether the Spain ASFV corresponded to any of the 28 genotype II genetic groups the EURL-ASF identified in Europe ( Figure 2 ), we analyzed viruses from both index wild boar using a harmonized 6-locus framework ( 5 ). Comparison with 1,192 homologous genotype II sequences available in the EURL-ASF sequenc…