Key facts about African swine fever (ASF)

African swine fever (ASF) is a highly contagious and deadly disease that affects domestic and wild pigs regardless of age and sex. ASF cannot be spread to humans and other non-swine animals and livestock and is not a threat to human health. However, humans can carry the virus on their clothing, shoes and equipment and can spread the disease unknowingly.

Historically endemic to African countries, ASF has been spreading rapidly throughout Asia and parts of Europe through 2018 and 2019. What are the symptoms of ASF, what can we do to prevent the disease, and are there any treatment options?

Signs and symptoms of ASF

• High fever (40.5–42oC)
• Sudden loss of appetite
• Hemorrhages on skin and internal organs, particularly lymph nodes
• Diarrhea, vomiting (sometimes with bloody discharge)
• Abortion
• Depression
• Coughing
• Difficulty breathing
• Sudden death
• High death loss

While these symptoms are similar to classical swine fever (CSF), ASF is caused by a unique virus that is distinct from CSF. Unusually high mortality rates among pigs of all ages can be a strong indicator of ASF. However, the only way to know for sure which virus pigs might be infected with is through laboratory testing. If you notice any of the symptoms mentioned above in your herd, contact a vet as soon as you can to ensure that the correct quarantine and treatment are completed. This could help limit the damage on your farm.

Tips to prevent ASF from entering your farm

It is possible to keep ASF out of the farm, even in countries where ASF is endemic. Here are nine prevention measures you can take to avoid ASF.

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1. Implementation of strict importation measures for animal products:

Ensure that neither infected live pigs nor pork products are introduced into areas free of ASF. ASF-positive countries can have their animal exportations restricted or prohibited as a result of the detection of infected meat. Check infected regions before importing products that could potentially be contaminated.

2. Proper disposal of all food waste from aircrafts or ships coming from infected countries.

Furthermore, no human food waste should be fed to pigs.

3. Efficient sterilization and disposal of garbage: Avoid swill feeding (i.e., garbage feeding).

Feeding of catering waste is a high-risk practice; if the food waste is contaminated with ASF, it can infect a healthy herd. Do not expose food waste that wild swine species could access. Carcasses, discarded parts from slaughtered pigs and food waste should be disposed of appropriately. 

4. Rapid slaughtering of all pigs, infected or not (stamping out):

Recovered or surviving animals are virus carriers for life. Therefore, to avoid spreading the disease to other pigs and to prevent relapse, it is safer to slaughter both infected and potentially infected pigs. Stamping out tends to be a short-term method to eradicate the disease. Nevertheless, it is generally the most cost-effective method that allows farms to be free from ASF in the shortest time.

5. Strict on-farm biosecurity:

Keep viruses and bacteria out by complying with biosecurity rules, including proper disinfection of clothing and boots, as well as not bringing pork products that have not been properly heat-treated onto a farm. Farms should maintain dedicated footwear and clothing that stay on the farm.

6. Controlled animal and human movements:

Pigs should be sourced from trusted and certified suppliers. Vehicles, equipment and people are also fomites of ASF. Ensure that anyone who enters the farm has not been in contact with any other pigs over the past 48 hours. Farm visitors who have been in countries that are ASF-positive need at least five days of downtime before entering the farm. Vehicles and equipment should be properly cleaned and disinfected before entering the premises. As secretions and excretions from sick or dead animals are a source of ASF, carcass-hauling trucks are high-risk and should not enter the farm.

7. Disease surveillance and monitoring:

This is especially important when transporting live pigs and pork products. In addition, pig farms should maintain a strict health monitoring program. All sick or dead pigs should be inspected and examined for ASF. To detect ASF early, pigs slaughtered for own-home consumption should be inspected by an official veterinarian. Regarding staff training, holding regular prevention lectures and strengthening quality assessments as well as the daily records of feed ingredients is advised.

8. Efficient and early detection of the virus through laboratory tests:

Notify a vet immediately upon spotting signs of ASF, and get the pigs tested.

9. Strict quarantine protocol:

Strict quarantine measures should be applied in both ASF-free zones and infected zones to prevent the entry of the disease and/or to keep ASF from spreading further.

Treatments for ASF

• Currently, there are no treatments or vaccinations available for this animal disease.
• Preventative and cautionary measures can be taken to protect animal health.
• Contact between sick and healthy animals can transmit ASF. Therefore, infected animals must be isolated and culled immediately upon confirmation of ASF.

Did you know?

• North America and the Oceania region remain the only areas that have never had reported cases of ASF.
• ASF poses no risk to human health. Humans cannot get infected by ASF.
• ASF infects domestic and wild pigs, as well as a variety of soft-bodied ticks.
• Wild boars and warthogs can be carriers of ASF. Make sure they don’t come in contact with domestic pigs.
• Frozen meat from infected pigs can harbor the virus for up to six months.
• The ASF virus has been estimated to survive for up to 15 days in feces and five days in urine at 21°C.
• It takes 30 minutes of cooking at 70oC to deactivate ASF in meat products and 30 minutes at 60°C for serum and body fluids.
• Curing or smoking pork products does not destroy the virus.
• ASF can be transferred via feed (Niederwerder, et al., 2019). It is important to work with trusted suppliers and vendors to verify ingredient sources and determine what their biosecurity and quality programs entail.

The importance of feed safety and a favorable health status

Studies have shown that feed can be a carrier of certain harmful pathogens (Dee, et al., 2018). As an added layer of protection, put safeguards in place and utilize feed intervention technologies, such as acidifiers, to support the integrity and quality of your feed.

Acidifiers are known to have beneficial properties that “control bacterial growth in feed, […] inhibiting growth of pathogenic microbes” (Jacela, et al., 2009).

Products such as Guardicate™* have been shown to be effective for promoting feed safety and can be used as an important component of your farm’s greater biosecurity program. Over almost four years of research, Guardicate has shown its effectiveness as an acidifier, as it addresses feed quality concerns by helping maintain a favorable feed environment.

Together with other solutions, like Sel-Plex®, Bioplex® and Actigen®, Alltech’s nutritional technologies provide peace of mind that you are safe from the risks that could negatively impact your production while promoting a positive health status for your animals.

Improper mineral supply can have major consequences for the health and productivity of your herd. Improved mineral status has been shown to have a positive effect on immune function. The Alltech Mineral Management program focuses on feeding organic minerals such as Sel-Plex and Bioplex, which are better absorbed and utilized by the animal and, thus, can meet their nutrient needs for optimal health.

Gut health and the microbiome also play a key role in maintaining the overall health status of the pig. Actigen is able to support immune function, gut microbial health and gut function and development, promoting overall animal health and performance.

*Guardicate is only available in select countries.

References:

Dee, S. A., Bauermann, F. V., Niederwerder, M. C., Singrey, A., Clement, T., de Lima, M., & Petrovan, V. (2018). Survival of viral pathogens in animal feed ingredients under transboundary shipping models. PloS one, 13(3), e0194509. https://doi.org/10.1371/journal.pone.0194509

Jacela, J.Y., DeRouchey, J.M., Tokach, M.D., et al. Feed additives for swine: Fact sheets – acidifiers and antibiotics. J Swine Health Prod. 2009;17(5):270–275. https://www.aasv.org/shap/issues/v17n5/v17n5p270.pdf

Niederwerder, M. C., Stoian, A., Rowland, R., Dritz, S. S., Petrovan, V., Constance, L. A....Hefley, T. J. (2019). Infectious Dose of African Swine Fever Virus When Consumed Naturally in Liquid or Feed. Emerging Infectious Diseases, 25(5), 891-897. https://dx.doi.org/10.3201/eid2505.181495

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