One little piggy

As African swine fever (ASF) inches closer to the U.S., many countries are already dealing with the devastating disease that can shut down both large and small pig producers.

For countries like the U.S. that are currently free of ASF, all it will take is a single pig, wild or domestic, to initiate the spread of this virus.

Key swine industry partners play a major role in stopping the spread of all diseases, including ASF. The National Pork Board, Swine Health Information Center (SHIC), National Pork Producers Council and various academic and local industry associations contribute to ASF awareness by providing producers with the latest information on biosecurity to prevent potential disease transmission.

Patricia Ortiz, Agricultural and Livestock Service in Chile, emphasizes biosecurity measures that help prevent disease. While installing double fencing around a pig farm might seem extreme, Ortiz said it’s an important measure for pig producers in countries threatened by ASF.

“The main gap in implementing biosecurity is awareness among producers, especially when they have a low level of biosecurity,” said Ortiz. “Training for all stakeholders is important. We need to stress the importance of implementing measures to producers so they can enhance biosecurity measures. We stress the importance of wildlife management and perimeter fencing. It’s also important to clean and disinfect trucks, which is one of the main ways of transmitting ASF.”

According to the SHIC at the University of Minnesota, ASF in domestic pigs in Europe declined toward the end of 2025. Most outbreaks involved small scale farms. However, there has been a significant rise in ASF cases in wild boar, including new cases in Spain where wild boar thrive in dense vegetation along with access to food waste.

Polymerase chain reaction (PCR) testing revealed the first detection of ASF in Spain since eradication of the disease there in 1994. What’s notable is that genetic sequencing showed a genetic change and identified a new subtype within the ASF genotype.

As of January 2026, new ASF cases in Spain were found within a 3.7-mile radius of the initial detection site. Authorities established a 12-mile infected zone and identified a core high risk area, and initiated intense, active surveillance.

There is currently no evidence of ASF in Spain’s domestic pigs, likely due to the country’s diligence in promoting biosecurity. However, as a major a major pork producer in the EU, Spain has already experienced the economic impacts of the disease. According to the SHIC, one processing plant has sidelined nearly 500 workers and the region faces $1.2 billion in export losses. ASF in this area has resulted in lower market confidence along with falling pig and piglet prices. Several countries, including Japan, Mexico and Taiwan, have halted imports of pork products from Spain.

Measures to ensure ASF doesn’t spread to domestic herds in Spain include surveillance of the wild boar population by field teams, canine units and drones. Spain has also initiated measures to prevent wild boar from coming close to domestic production areas with enhanced fencing, repellents (odor, light and sound), prohibiting public access in high-risk zones and trapping wild boar to create a buffer zone.

The SHIC reports that neighboring countries, including France and Portugal, have intensified wild boar surveillance near the Spanish border and have reinforced farm biosecurity checks. Other countries with increased surveillance due to the detection of ASF in Spain include Italy, Germany, Belgium and the Netherlands.

In some countries, including South Korea, ASF is endemic in the wild boar population. The SHIC stated that sporadic outbreaks there are often isolated farm events. This may be due to the country’s capacity to limit secondary transmission when a case is detected. When ASF is confirmed, the country initiates immediate measures such as movement restrictions, vehicle standstills and intensive disinfection measures, all of which likely reduce the risk of farm-to-farm spread.

The most likely spread of ASF in South Korea is by humans via contaminated vehicles, feed or equipment, all of which can transmit the virus from wildlife sources or contaminated environments to commercial farms. Less common is wild boar-to-farm contact. Control measures have been effective in preventing sustained farm-to-farm spread, which has limited the number of outbreaks and duration.

USDA-APHIS has been closely monitoring the ASF situation in Haiti and the Dominican Republic, both of which are close to the U.S. and have active ASF outbreaks. Surveillance measures include monitoring pigs raised outdoors due to their potential exposure to feral swine (wild boar) or pigs that are fed garbage and testing of feral swine collected by APHIS Wildlife Services.

Dr. Lisa Rochette, USDA-APHIS veterinarian, explained the types of swine operations in the U.S.: Some are large sow farms, primarily in the Mid-Atlantic. While some pigs are finished on farms close to the sow farm, others are moved to farms in the central U.S. for finishing and processing. However, there are many smaller, diverse swine farms throughout the country, some of which have biosecurity levels that differ greatly from commercial swine farms. Routine swine movement will complicate biosecurity if ASF is discovered in the U.S.

“We are trending toward fewer commercial farms,” said Rochette, “but each farm has a larger number of pigs, which can create opportunities and challenges. Those are things we consider when we structure biosecurity, regulatory and promotion programs.”

While ASF has never been found in the U.S., many veterinarians say it’s a matter of not if, but when. Producers of all sizes can contribute to keeping this disease out of the U.S. and their herds by monitoring other countries’ efforts to stem the spread and by employing sound biosecurity measures.

by Sally Colby