The veterinary authorities of the Junta de Castilla y León notified today, Friday 19 September, an outbreak of Highly Pathogenic Avian Influenza (HPAI), subtype H5N1, on a laying hen farm with an approximate flock size of 760,000 birds, located in the municipality of Olmedo, in the comarca of Olmedo, province of Valladolid. See Map 1.
Map 1: Location of the HPAI outbreak in poultry in Olmedo, province of Valladolid.
The suspicion arose on 17 September following the detection and notification to the Official Veterinary Services (OVS) of the Junta de Castilla y León of a slight increase in mortality on the farm. The OVS visited the premises that same day and proceeded with the preventive standstill of the farm, conducting the epidemiological investigation and taking official samples, which were sent to the Central Veterinary Laboratory (LCV) in Algete, as Spain’s National Reference Laboratory for Avian Influenza, where the presence of HPAI subtype H5N1 has been confirmed.
Control measures implemented
The OVS of the Junta de Castilla y León have immediately implemented the following control measures in accordance with Commission Delegated Regulation (EU) 2020/687:
- Immediate standstill of the affected premises and those located within a 10 km radius from the moment of suspicion on 17 September 2025.
- Culling in progress of the birds on the affected premises and official disposal of carcasses, feed and other fomites that could carry the virus, in accordance with the regulations on Animal By-Products (ABP).
- Epidemiological investigation carried out in order to determine the possible source of the outbreak and identify potential risks through epidemiological links with the affected premises via movements of vehicles, products or workers.
- Establishment of a restricted zone around the outbreak: a 3 km protection zone and a 3–10 km surveillance zone. Within the 3 km radius there are five commercial holdings and within the 3 to 10 km radius a further twelve. All have been placed on standstill, biosecurity measures have been reinforced and they are being inspected by the OVS.
Epidemiological background
This is the sixth HPAI H5N1 outbreak reported in Spain on poultry farms in 2025, following outbreaks detected in Badajoz (1), Huelva (2), Toledo (1) and Guadalajara (1). No epidemiological link has been identified between the different outbreaks; the most likely route of virus introduction into the farm is considered to be through direct or indirect contact with wild birds, given that over recent weeks several HPAI H5N1 cases have been detected in wild birds in various parts of the Iberian Peninsula.
In addition, 38 outbreaks in wild birds have been detected in Andalusia, Extremadura, Galicia, the Basque Country, Asturias, Castilla-La Mancha, Castilla y León and Catalonia, and 2 outbreaks in captive birds in the Basque Country and Andalusia. See Map 2.
Map 2: Location of HPAI outbreaks in wild birds, captive birds and poultry reported in Spain in 2025. Updated 19 Sep. 2025.
Recommendations
A reminder is issued of the need to maintain and reinforce adequate biosecurity measures on poultry farms to prevent contact with wild birds, as well as to strengthen passive surveillance, both in wild birds and on poultry holdings, by notifying the OVS of any suspicion of disease — in particular, in the case of domestic poultry, through detection of drops in water and/or feed consumption, reduction in egg production, abnormally high mortality, or observation of other clinical signs compatible with the disease — in order to ensure the earliest possible detection of any new outbreak and enable the adoption of the necessary measures to prevent the spread of disease to other holdings.
The Junta de Castilla y León is working in a coordinated manner to minimise the impact of the declared outbreak.
Source: Ministry of Agriculture.
For more information on Avian Influenza:
-. News on Vaccination of poultry farmers and personnel in contact with production birds to prevent zoonosis risks.
-. News on Vaccination of production birds to prevent AI outbreaks
-. Triple avian influenza alert: Portugal, Spain and Germany confirm cases on poultry farms. (5 Sept 2025)
-. Avian Influenza on NeXusAvicultura
Tracking of Avian Influenza cases on poultry farms in Spain in 2025:
-. First case of 2025 (18 July, Extremadura): Alert over an Avian Influenza outbreak on a 7,000-turkey farm in Extremadura
-. Second case (28 July, Toledo): Second AI outbreak detected, this time in breeder flocks in Toledo
-. Third case (1 Sept., Huelva): The spectre of H5N1 returns to Andalusia: 8,500 turkeys culled due to avian influenza in Huelva.
-. Fourth case (8 Sept., Guadalajara): Spain records its fourth AI outbreak of 2025, this time on a breeder farm in Guadalajara
-. Fifth case (9 Sept., Huelva): H5N1 positive confirmed on the 8,400-bird poultry farm in Valverde del Camino, Huelva, Andalusia
-. Sixth case (19 Sept., Valladolid): H5N1 HPAI detected at a 760,000-hen layer farm in Valladolid
-. Furthermore, on 2 September 2025, Portugal confirmed an H5N1 outbreak on the largest commercial duck meat fattening farm on the Iberian Peninsula, specifically a poultry complex with 257,650 meat ducks in the locality of Samora Correia, near Lisbon, in the freguesia of Santo Estevão, concelho of Benavente, district of Santarém.