What is African Swine Fever and How Can Exposure Risk Be Reduced?

What is African Swine Fever (ASF)?

ASF is a severe, hemorrhagic viral disease that affects both domestic and wild pigs. ASF is classified as a “transboundary animal disease,” a highly infectious disease that can spread across national borders. Although signs of ASF and Classical Swine Fever (CSF) may be similar, the ASF virus is not related to the CSF virus. Unlike CSF, there is no vaccine for ASF.

How is ASF spread?

The ASF virus is highly infectious. ASF has high “environmental survivability.” This means it can survive for extended periods of time on contacted surfaces like vehicles, feed, or equipment, and for even longer periods in manure, raw pork products, or frozen pork products. The virus can be spread by live or dead pigs, both domestic and wild. It can also be spread in contaminated feed. Humans can spread the virus as well, via contaminated objects such as shoes and clothes. Soft ticks of the genus Ornithodoros can transmit ASF. These ticks are long-lived and can remain infected with ASF for years.

Can humans get ASF?

No, ASF is not a zoonotic disease; it does not infect humans. There is no known risk to humans from ASF-infected meat.

Why is ASF such a major concern?

Current reports estimate that over half of the domestic hogs in China have been lost to the current ASF outbreak. While the disease has not yet been detected in the U.S., it poses a significant threat to an $8 billion industry and its associated jobs and farm operations. Scientists believe that the risk of an outbreak of ASF in the U.S. doubled in 2019. For individuals, the impact of ASF can mean increased costs or lack of access to pork products.  Hog production industries, such as processing, row crops, and feed ingredients, are likely to be economically impacted by an ASF outbreak in this country.

What countries are affected by ASF?

ASF outbreaks have been reported in Africa and parts of Europe, South America, and the Caribbean prior to 2007. Currently, the disease has been reported in 25 countries across Africa, Asia, and Europe including Belgium, Bulgaria, Estonia, Hungary, Latvia, Lithuania, Moldova, Poland, Romania, Russia, Serbia, Slovakia and Ukraine, China, Korea, Laos, Myanmar, Philippines, Russia, Timor-Leste, Vietnam, Cote D’Ivoire, Kenya, South Africa, and Zimbabwe. ASF was most recently reported in the Dominican Republic.

How does African Swine Fever affect pigs?

ASF has up to a 100 percent mortality rate. It can take either a peracute, acute, subacute, or chronic form, depending on the virulence of the ASF strain and the species or type of pig infected. Some data suggests that African wild pigs, such as warthogs, may be infected without displaying clinical signs, thus creating a reservoir for the disease. A disease reservoir is the population of organisms in which a virus naturally lives and reproduces. A lab test is required to confirm ASF infection because the symptoms are similar to those of other infections such as CSF. The World Organisation for Animal Health has a complete guide to signs of ASF.

Signs of acute forms of ASF:

• High fever
• Behavior changes such as depression, anorexia, and loss of appetite
• Redness of skin on ears, abdomen, and legs
• Abortion in pregnant sows
• Cyanosis
• Vomiting and diarrhea
• Death occurring within 6-13 days (or up to 20 days)
• Mortality rates up to 100 percent

Signs of subacute forms of ASF:

• Loss of weight
• Intermittent fever
• Abortion in pregnant sows
• Mortality rates ranging from 30-70 percent
• Death occurring within 15-45 days

Peracute forms of ASF can result in sudden death with few signs. Signs of chronic ASF, as can occur in some species of wild pigs, include loss of weight, irregular increases in temperature, respiratory signs, skin conditions, swellings over joints, and lung issues. A surviving animal with chronic ASF can become a carrier of the virus for life.

Can ASF be treated?

Currently, there is no validated vaccine or treatment for ASF. Enhanced biosecurity and preparedness is critical to prevent ASF. These are the primary mechanisms to mitigate the risk of infection.

How can African Swine Fever be prevented?

Emergency preparedness and biosecurity measures are required to prevent or mitigate an outbreak of ASF. The Secure Pork Supply program presents comprehensive guides and standards for preparedness and biosecurity to mitigate the risk of ASF infection and spread.

Emergency preparedness includes developing the plan, procedures, and policies required for detection, notification, and response to an outbreak. Preparedness must also include training and exercises to simulate an outbreak and practice the appropriate response measures, at both the producer level and state/federal levels.

Biosecurity is key to prevent ASF

Prevention at the producer level relies on strict biosecurity measures. These measures include:

• Cleaning and disinfection of farm facilities, equipment and transport vehicles.
• Controlling access.
• Controlling production inputs such as feed.
• Establishing a line-of-separation between the outside world and the healthy animals in a production operation.

Surveillance and monitoring of transport of live pigs and pork products needs to be increased. This requires coordination and communication among producers, processors, the industry as a whole, regulators, veterinarians, and others in the value chain including the transportation sector.

Who is responsible for responding to an outbreak?

Because ASF is a global problem, its containment should be a high priority for governments. However, prevention and mitigation require the full participation of both public and private sectors, including the entire value chain associated with the pork industry.

Preparedness and outbreak control are shared responsibilities of both public and private sector entities including:

• Federal, state, and local authorities
• Pig producers and industry
• Processors
• Veterinarians
• Value chain participants including transport and feed operators

How can my organization minimize risk from ASF?

The most important step you can take to protect your operation is to improve biosecurity practices and develop an emergency preparedness strategy. SES offers a suite of services from strategy development to leading full-scale functional exercises to prepare organizations for the threat of foreign animal disease outbreaks.