Pigs provide a vital source of high-quality protein, and production is expected to increase in the future to meet global demand. However, pork supply is threatened by infectious diseases, notably African Swine Fever (ASF), which continues to spread beyond Africa into Europe, Russia, China, and recently the Americas. Its reemergence after decades of eradication has heightened awareness of the devastating threat this disease poses to the global swine industry.
Infection with the African Swine Fever Virus (ASFV) in pigs and wild boars can cause significant economic losses due to the high mortality rates observed in pig populations. The absence of a vaccine makes controlling the disease difficult, which is why biosecurity—at regional, national, and farm levels—plays a crucial role in prevention. But what is biosecurity? It is defined as: “The implementation of management measures that reduce the risk of introduction and spread of pathogenic agents; it requires adopting a set of attitudes and behaviors by people (producers, workers, professionals) to minimize risk in all activities involving domestic, captive/exotic, and wild animals and their products” (FAO / OIE / World Bank, 2008). All measures must be applied to protect a farm both from the entry of new pathogens and from internal transfer between different areas of the facility. Therefore, biosecurity consists of two components: **bio-exclusion (external biosecurity)**, which includes all activities to prevent disease introduction into the farm; and **bio-containment (internal biosecurity)**, which refers to efforts to prevent disease spread within the herd and to other farms (FAO, 2010).
Considering the history of how the virus has entered other countries, we can expect that ASF may enter our country through waste from airplanes and ships that are not properly inactivated in treatment plants, or that are disposed of in landfills accessible to pigs, or used to feed backyard pigs. However, the most likely route of ASF entry into Argentina may be through passengers arriving by air, sea, or land from countries where the disease is endemic, such as China, Russia, Poland, and the Dominican Republic, among others. These passengers might carry pork meat and by-products (cold cuts, sausages) contaminated with ASF, which could go undetected at border inspections and come into contact with domestic backyard pigs in dumps where household and restaurant waste is discarded. Wild boars and feral pigs may also feed on this waste in tourist areas. History shows that backyard and small-scale informal pig farming may be the first to become infected once the ASF virus enters, and in areas with a high population of wild boars or feral pigs, it is very likely that the wild population will also be affected, further complicating disease control.
Considering that biosecurity is currently the most important tool for controlling ASF, we must understand which preventive management measures (Biosecurity) should be implemented or improved to reduce the risk of the virus entering our farm (External Biosecurity). To date, available epidemiological data indicate that this virus can reach pig farms through several routes:
proximity to other farms: number and density of backyard farms within a 10 km radius of my farm
introduction of live animals, contact with trucks or other vehicles contaminated with feces or blood
staff or visitors and their belongings — they may engage in hunting of feral pigs or wild boars, or have direct contact with pigs from neighboring farms through friendship or shared tools
feeding or allowing pigs to feed on restaurant leftovers or other waste that may contain raw pork or uncooked sausages
direct or indirect contact with wild boars or feral pigs
ingredients and finished feed.
But to fully understand why these routes represent a real risk, we must be aware that the difficulty in controlling ASF lies in its high survival rate in the environment, carcasses, and pork products; the large amount of virus excreted by infected and carrier animals; and the very low infectious dose required for pigs. These factors contribute to its continued spread. If we know where the ASF virus is found, we can better prevent its arrival at our farm. This virus is excreted in feces for 5 to 15 days, persists in contaminated pens for up to 30 days, survives in blood for an astonishing 15 weeks, and remains active in raw pork and cured or smoked pork products for 100 to 1000 days.
Therefore, based on this information, we will describe some important biosecurity measures that can help mitigate risks.
– Purchase breeding pigs or others only from reliable suppliers with a sanitary status equal to or higher than that of your own facility and that maintain high biosecurity standards.
– Upon arrival at the farm, pigs should be segregated in an isolated area located 500–1000 meters away from the main herd, where they must remain under quarantine and observation for 40 days, since infected animals may not show clinical signs for 4 to 19 days or may be asymptomatic carriers capable of transmitting the disease.
– Quarantine facilities should have independent drainage systems, equipment, and tools.
– Both the farm and the quarantine area must have a complete perimeter fence with no openings such as unlocked gates, gaps under loading ramps, or structural breaks, in order to prevent contact with wild boars or feral pigs, which are highly prevalent in certain regions of our country. For the fence to be truly effective as a barrier, it should include a concrete base buried 30–50 cm underground and extending 10 cm above the surface, with a single access point and a minimum height of 1.5 to 2 meters, as wild boars tend to dig or jump in search of food or sows in heat. In areas with high wild boar prevalence, a double perimeter fence separated by 7 meters is recommended.
– In some geographic regions, it has been observed that simple electric fences with only two electrified wires—one at 20 cm and another at 50 cm above the ground—are as effective as three-wire designs. Placing the perimeter fence 12 to 15 meters away from the pig production barns further reduces the risk of indirect contact.
– Visitors must ensure they have not had contact with other pigs or livestock species within 48 hours prior to entering the farm.
– Workers must not own pigs at home and must be prohibited from engaging in hunting activities involving feral pigs and/or wild boars.
– All persons entering facilities to come into contact with pigs must shower and change into farm-specific clothing and boots. If showers are not available, they must wash their hands and face and apply antiseptic solutions to their hands.
– Any materials or equipment to be brought into the farm must be disinfected prior to entry.
– Another potential route for ASF virus introduction to the farm is through vehicles, especially those transporting animals to other farms or slaughterhouses. These vehicles often retain fecal residues due to poor cleaning, and the ASF virus can remain infectious for up to 15 days. Therefore, an external loading area should be built, separated from the main herd, or strict verification must ensure that trucks are fully washed, disinfected, and dried. They should be visually inspected upon arrival, and any that do not meet hygiene standards must be rejected and disinfected again. If no separate loading zone exists, pigs should be loaded using a ramp or dock that physically separates the barn from the vehicle. Drivers must not come into contact with the loading area or the pig housing facilities under any circumstances.
Currently, although not commonly practiced, it must be made absolutely clear that pigs should never be fed leftovers or waste from restaurants or any other sources that may contain pork or pork by-products, as these could serve as a source of infection for the herd. It is equally important to remember that undercooked pork can also transmit the virus. Therefore, no person entering the farm should bring pork meat or any of its derivatives under any circumstances.
Finally, under the current circumstances, it has become a high priority to establish both external and internal biosecurity measures with rigorous cleaning and disinfection programs to eliminate any trace of blood (the virus can survive up to 15 weeks in blood) and organic material that may serve as a source of infection on the farm. Biosecurity protocols must be established with simple yet precise procedures that can be sustained over time. These must be accompanied by continuous training for veterinarians, farm workers, drivers, and visitors, both internal and external to the farm.
Finally, each producer and veterinarian should define their surveillance plan — that is, the actions to be taken at specific intervals to quickly detect the presence of the ASF virus if it were to enter their facility. An important on-farm tool for developing this plan is syndromic surveillance, which prioritizes the detection of easily recognizable clinical signs. This enables early outbreak identification and reporting (ALERT), as well as timely implementation of preventive and control measures (RESPONSE) to minimize morbidity and mortality. In the case of ASF, different viral strains affect domestic and feral pigs as well as wild boars. The strain currently present in China is particularly virulent, causing nearly 100% mortality. However, moderately virulent (low pathogenicity) strains, such as those detected in the Dominican Republic, have been reported in other countries, where outbreaks on commercial farms have indicated that some strains may be of low or moderate pathogenicity. Therefore, constant vigilance is required, since the disease may not always manifest as a sudden increase in deaths. It may appear as a respiratory or digestive outbreak easily confused with other diseases. Consequently, it is essential that veterinarians and producers lose their fear of issuing an ALERT and promptly send samples to official laboratories of the National Food Quality and Health Service (SENASA) to rule out the disease whenever clinical signs of a systemic illness appear. The most frequent clinical signs and lesions include: high fever, abortions, respiratory distress, splenomegaly, skin erythema, bluish discoloration of ears and ventral areas, hemorrhages and ecchymoses in various organs, lymph node enlargement, and fluid accumulation in the thoracic and/or pericardial cavity.
After establishing a surveillance plan, each farm should prepare a contingency plan aimed at limiting virus spread, reducing economic losses, and attempting eradication whenever feasible.
In conclusion, countries free of ASF enjoy a major competitive advantage — both in production costs and access to export markets. Maintaining Argentina’s ASF-free status must therefore be an absolute priority for the swine sector. For instance, the economic cost of controlling African Swine Fever in 1978 reached 140 million USD. A more recent example is the outbreak that hit China in 2018, where industry estimates suggest that between 150 and 200 million pigs (around 30% of China’s herd) were infected by mid-2019. Some reports indicate that, accounting for underreporting, this number could reach 50–70%. It is estimated that this represented a 9–34% reduction in global pork production (equivalent to 120 million tons in 2018). Therefore, efforts aimed at preventing the entry of the ASF virus are highly cost-effective. If, unfortunately, the disease were to enter the country, rapid recognition would be critical to confine it to as few farms as possible, which could make eventual eradication achievable.
Source: infopork.com