Investigations into the cause of recent African swine fever (ASF) outbreaks in Spain’s wild boar suggest a research lab is a possible source of the virus.
After an absence of over 30 years, the ASF virus was detected in wild boar in Spain at the end of November. The infected animals were found dead less than 2 kilometers apart in Barcelona province in the northeastern region of Catalonia.
Latest update on the outbreak situation puts the number of animals testing positive for the virus at 13. This is according to the latest notification to the World Organisation for Animal Health (WOAH) from the Spanish veterinary authority.
All 13 ASF cases identified to date were found dead with a 6-kilometer radius, reported Spain’s agriculture ministry on December 5. Of 37 other wild boar tested, none was found to be infected. Furthermore, testing carried out on domestic pigs at 39 pig farms within 20 kilometers of the outbreak epicenter were also found to be free of the ASF virus.
First cases in the country after a long hiatus prompted investigations into the source of the infection as the outbreak occurred so far from the nearest known ASF cases.
Genome sequencing reveals that the virus involved in the Spanish outbreak belongs to Group 29, according to the ministry. This contrasts with the Groups 2-28 viruses that are circulating elsewhere in the European Union.
The virus isolated in the Barcelona area is similar to a Group 1 virus that was found in the European state of Georgia in 2007. This is a “reference virus” held in some research laboratories to carry out studies on the virus, or on vaccine efficacy.
So, while it is known that the genome of a virus undergoes changes during natural infection, the evidence so far points to a biological containment facility as the source of the virus found recently in Spain’s wild boar.
3 European countries confirm new cases in pigs
In the week starting November 27, further ASF outbreaks in domestic swine were reported to the European Commission (EC) by Romania and Serbia — affecting eight and three additional herds, respectively.
This is according to the most recent update of the Animal Disease Information System of the EC, which monitors outbreaks of listed animal diseases in European Union member states and selected adjacent countries.
To date in 2025, Romania has reached the highest outbreak total in this category at 459, and followed by Serbia with 229 (as of December 3).
Reporting to WOAH by the national veterinary agencies provide some additional detail on recent outbreaks.
In Romania, 20 herds of domestic pigs tested positive for the ASF virus in the period October 14 to December 1, according to this source. Outbreaks occurred in 12 different counties, and included two commercial farms, and 17 backyard herds. One of the farms held more than 4,100 animals. The other outbreak involved an infected pig carcass found in a public area.
Meanwhile, the authorities in Bosnia-Herzegovina have notified WOAH of eight new outbreaks involving domestic pigs.
Starting between November 12 and December 2, these all affected backyard herds, each comprising between two and 26 swine. All were located in one of two districts in the Republic of Srpska region.
As of December 3, 13 countries in the region had logged a total of 903 ASF outbreaks involving farmed pigs with the EC’s system in 2025.
For comparison, 764 herds were hit by the disease in 16 of the region’s states during the whole of last year, according to the database.
European wild boar outbreak total approaches 10,000
To date in 2025, 9,945 ASF outbreaks in this population have been registered with the EC’s system by 19 countries in the region (as of December 3).
In 2024, the database recorded an outbreak total of 7,892 outbreaks in 21 states.
For the period November 27 to December 3, Spain became the latest state to have logged its cases with the database this year.
Recording the week’s highest number of new outbreaks was Poland — adding 50 to its total — followed by Latvia (40) and Hungary (22).
Poland’s total is the highest at 3,084 for the year to date, followed by Germany (1,950), Latvia (1,171), Hungary (767), Bulgaria (667), Lithuania (657) and Italy (598).
In Italy, first ASF-positive cases have been identified recently in Reggio Emilia, according to the national ASF epidemiological bulletin.
Located in the northern region of Emilia-Romagna, this province is adjacent to that of Parma, where ASF outbreaks have previously been confirmed.
2 more outbreaks reported by South Africa
Recent WOAH notifications from the national authorities retrospectively cover two outbreaks involving the country’s domestic pigs.
First of these started in early August, and involved a farm with almost 500 animals in Gauteng. A further 100 swine were affected when ASF hit a village herd in Eastern Cape at the end of September.
South Africa’s two current ASF outbreak series covering different areas of the country began in 2019 and 2020. Since then, 282 herds of domestic pigs have been confirmed with the disease, according to WOAH notifications.
Taiwan to ban feeding food waste to pigs
From now until the end of 2026, feeding food waste to pigs will be phased out across the territory, reports Focus Taiwan.
A complete ban will come into effect at the start of 2027 to prevent ASF, the Cabinet decided last week.
Next year will serve as a transition period, during which strict conditions will apply to the practice. Incentives will be offered to farmers to switch to feeding commercial diets to their animals.
Pig farmers in Taiwan who switch immediately from food waste to commercial feeds for their animals stand to receive TWD3,600 (US$116) per head, as well as further cash incentives and access to low-interest loans.
Lesser incentives will be available to those who make the transition later during 2026. In the meantime, their waste processing will require official authorization and monitoring.
Specialized feed formulations will be developed for Taiwan’s native black pigs, which are widely fed on waste foods.
Taiwan’s first ASF outbreak was confirmed at the end of October. Investigations into the cause of the outbreak revealed poorly processed kitchen waste to be the likely source of the virus, and a lack of official oversight over its processing on farms.
Ongoing outbreaks in northeast Indian state
In the Jorhat district of Assam, new cases of ASF continue to be detected, despite a monthlong ban on the sale and movement of pigs.
Already in this period, 20 outbreaks have been confirmed in the region, and more than 520 swine have been culled, reported Assam Tribune on December 5.
As suspending movements and markets has not been completely successful so far, the local authority is urging owners to increase the level of biosecurity to protect their animals from infection.
View our continuing coverage of the global African swine fever situation.
