Prevention, recovery and repopulation – an Asia-specific response to ASF – Part 1

Prevention, recovery and repopulation –
an Asia-specific response to ASF

Part 1 of 3

African swine fever (ASF) is decimating herds across Asia, and swine farmers on the frontline of the disease have questions and concerns that beg response. In this first of a 3-article series, HERMAN JANSSEN and SUPARLARK NUNTAWAN NA AYUDHYA* offer seven strategies to respond to the ASF threat in Asia.

Although reports have largely focused on China, ASF has been reported in nine countries in Asia, including those with significant pig industries like Vietnam, the Philippines, and South Korea. ASF’s virulence poses a risk for swine-producing nations throughout all of Asia.

Amid a sea of uncertainty, a few factors are remarkably clear. First, ASF recovery efforts in Asia will take considerable time. The Food and Agriculture Organization (FAO) has issued a statement recognizing ASF as a highly virulent disease that is up to 100% lethal.[i] An ASF outbreak on a farm requires complete culling of herds and a comprehensive disinfecting of the farm environment to eliminate the pathogen threat.

The disease may survive in frozen meat for up to 1000 days, in animal bones for more than a year, in meat for 3-6 six months and in manure for up to six months. Thus, a second concern regarding ASF in Asia is that recovery must start with prevention and an unrelenting focus on achieving 100% biosecurity on the farm and at the feedmill. Given the virulent nature of the ASF virus and its history of contagion, 99% biosecurity effectiveness is akin to zero effectiveness.

Seven strategies in ASF prevention

As Asian producers seek to avoid ASF infection and eventually repopulate their swine farms, internal and external prevention must be the starting point. Several external factors that may allow pathogens to enter the farm include conditions at the feed mill, vehicles and visitors entering the farm. Internal factors that can introduce ASF risk include production practices and behaviors, such as disposal of animal carcasses and lax biosecurity practices. To help mitigate these risks, Trouw Nutrition offers services and products. A few preventative tools are noted below:

Herman Janssen
Suparlark Nuntawan Na Ayudhya

Conduct a feedmill scan

Critical raw materials and feed hygiene conditions in the feedmill may introduce pathogen risk to the swine farm. At the mill, pathogens may be present in both raw materials and finished feed. Trouw Nutrition developed a Feedmill SCAN to safeguard against microbial pathogens and mycotoxin risks infiltrating raw materials and feed. The Feedmill SCAN includes technologies to define a microbial, mycotoxin and efficiency blueprint; this includes an analysis of raw materials to test for the presence of Salmonella, yeast, molds, and potential pathogens at critical control points during processing. Based on the Feedmill SCAN, the need for feed safety and quality measures will be identified. Part of the solution can be buffered and synergistic organic acid application and dosing equipment in combination with the right hydrothermal treatment. In Asia’s warm, humid climate, controlling for temperature and moisture levels during feed processing can be especially challenging, so this holistic approach combining ingredient analysis, hydrothermal treatment and buffered and synergistic organic acid interventions at the feedmill provides an important solution to fight pathogenic risks.

Acidify drinking water

High quality water is not only necessary for animal health and performance but may also help prevent the spread of ASF virus to pigs through water. Water quality may be compromised by microbiological and chemical risk factors, as well as practices on the farm. Using a water acidifier to reduce the pH of the drinking water below 4 and keep it stable may support biosecurity on the farm. The ASF virus is inactivated by a pH less than 3.9 or above 11.5 in a serum-free medium. Even when ASF is not present, high bacterial challenges from contaminated water could affect pigs’ health and performance. Researchers know that pathogens like E. coliSalmonella and Clostridium struggle at pH levels lower than 4.5. Thus, a drinking water acidifier may support defensive actions to guard against these pathogens.

Protect water quality

Farm practices such as burying pigs in the ground can contribute to pathogens being transmitted via rainwater run-off. Similarly, disposing of carcasses in rivers can also facilitate transmission. ASF contamination can infiltrate water and the dose of virus required to infect water is quite low, making sanitizing procedures a must. Combining chlorination with an organic acid to keep the pH low and maintaining water oxidation reduction potential (650 mV) can help protect water quality.

Conduct a farm score

Across Asia, Trouw Nutrition works with a team of farm advisors to conduct on-the-farm scoring, using the University of Ghent’s Biocheck scoring model. Biocheck is a risk-based system that evaluates the quality of on-farm biosecurity using a scientific and objective methodology.

Destroy and dispose of diseased animals

Diseased animals must be destroyed, and deceased animals must be properly disposed of to protect biosecurity. Unfortunately, the practice in many parts of Asia has been to move diseased hogs to market which actually speeds up spread of the ASF virus. The spread of ASF must usher in new methods for disposing of animals.

Protect against human transmission

People are often surprised to learn that humans are the highest risk for carrying this disease onto the farm. Although ASF is not transmittable from animals to humans, it can spread quickly from humans to animals. The disease may also spread via contaminated objects including equipment on the farm as well as through food. Because ASF can spread orally and live up to six months in meat, do not allow people to bring pork onto the farm. Swill feeding also facilitates the spread of the disease through food scraps and contact with wild boars who can perpetuate disease spread.

Guard against transport transmission

Contaminated vehicles and logistic systems are blamed for 90% of ASF virus spreading. Disinfecting becomes paramount to proper biosecurity. Disinfectant should always be changed daily and formulated with less organic matter and the proper ingredient concentrations. The proper amount of disinfectants should be applied for an extended time to deliver results.

Governments can lead change

While these preventive tools provide practical tactics, lessons can also be gleaned from regions that have successfully eradicated ASF following outbreaks. These examples show that governments’ support coupled with complete elimination of the virus on the farm is mandatory to eradicate it in a region. In 2017, parts of the Czech Republic and Romania were affected by ASF outbreaks. Today, the affected areas are disease-free and have restored ASF-free production environments, thanks largely to early support from governmental bodies mandating strict protocols and processes for animal health, animal movement and farm biosecurity.

EU initiatives to eradicate the ASF virus mandated the culling of thousands of pigs in affected regions. Once diseased pigs were removed, strong biosecurity practices helped with repopulation. Governments in many EU nations have mandated aggressive measures at the feed, farm and animal level to prevent ASF.  Additional measures regulating animal movement are credited with helping limit the spread of ASF.  In the next installment, we will look at some practical strategies based on the experiences of countries that successfully recovered from ASF outbreaks.


* Herman Janssen, Senior Swine Specialist, Trouw Nutrition, Innovation Swine; Suparlark Nuntawan Na Ayudhya , Regional Program Manager, Trouw Nutrition Asia Pacific.

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