African swine fever (ASF) has the potential to destroy the U. S. pork industry by killing millions of pigs if it enters the country. A study from Iowa State University projected that if ASF spread to the United States and was not controlled within two years, the pork industry would lose $50 billion over ten years. Even in the best case scenario of the disease being controlled within two years, the projected losses are $15 billion (Carriquiry et al., 2020). In 2019, one fourth of the world’s pigs—about 440 million of them—died because of ASF outbreaks (Mackenzie, 2019). ASF does not infect humans, but it is responsible for global trade bans and the culling of infected herds due to its severity, resistance to disinfectants and adaptability to live in the environment (Iowa State University, 2018).
Although ASF has never been found in the United States, researchers are looking into options for managing the disease if an outbreak does occur. Currently, there is no vaccine available for ASF, but hope may be on the horizon. Scientists from the Pirbright Institute tested a new vaccine that reportedly protected all the pigs from ASF in one study (Goatley et al., 2020). Until a vaccine is commercially available, biosecurity practices nationwide and on the farm are our best defense against ASF.
ASF Transmission Pathways
Two different tick vectors for the disease have been identified: one species in Spain and Portugal and another species in Africa (Costard et al., 2013). Besides these tick vectors, ASF is transmitted to previously uninfected pigs via the consumption of contaminated, under-cooked pork mixed in their feed. The virus can then be passed between pigs via direct contact and contact with body fluids such as blood and urine (USAHA, 2008). Because of the virus’s resilience in the environment, it can also be transmitted from infected herds to new herds via contaminated vehicles, clothing and other human articles (USDA, 2018).
Current Status of ASF
During 2020, ASF outbreaks were reported in India, Vietnam, South Africa, North Korea and China (Perez et al., 2020). Poland has experienced their third outbreak in 2020 (USDA, 2020). The following WAHIS Interface Disease Distribution Map shows where cases of ASF have been reported this year.
What are the Symptoms of ASF?
To be proactive, pork producers in the United States should be familiar with the symptoms of ASF, which include the following (Oura, 2013):
- Loss of appetite, lethargy
- Respiratory distress
- Bleeding from the nose/rectum
ASF can have varying clinical signs and virulence or severity. In chronic instances of ASF, symptoms persist for a longer period and are less severe. Acute cases are those where sudden death occurs without many clinical signs. However, even in acute outbreaks, symptoms may present themselves generically, resulting in the animals’ conditions worsening or deaths before the cause is identified (Iowa State University, 2019).
Preventing ASF in the U.S.
Currently, prevention is the best defense against ASF. One important biosecurity protocol for pork producers is the use of disinfectants. Due to the adaptability of ASF, not every disinfectant effectively kills the virus, so pork producers must be sure they are using appropriate disinfectants (Juszkiewicz et al., 2019). Producers should reference the list of EPA-Approved Pesticides for ones that are effective against ASF. Some disinfectants that have been proven to work against ASF are those containing 1% formaldehyde or sodium hypochlorite, among others (Juszkiewicz et al., 2019).
Other biosecurity measures include:
- Management of wild pig populations, as they can transmit ASF to domesticated populations.
- Appropriate waste disposal.
- Managing pork imports (OIE, 2018).
In northeast Europe, ASF exists in wild boar populations without tick or domestic pig vectors. This makes managing their populations important in preventing ASF from spreading to new locations and to domestic swine (FAO). This is relevant to the United States because at least 35 different states have feral pigs, with a population of about 6 million animals (USDA APHIS, 2020). Thus, preventing ASF in the United States involves monitoring feral swine populations and their exposure to foreign animal diseases (FADs). It is also important to reference the USDA’s Carcass Management Considerations when disposing of infected animal carcasses or suspect animals. Responsible carcass management is important because ASF can persist in the environment, and scavengers can spread the disease from infected carcasses to other swine (FAO).
When traveling to the United States, travelers should “declare all meats, animals, and animal products” to U.S. Customs & Border Patrol, as well as informing them if they have “been on a farm, or near livestock or wild pigs” (U.S. Customs & Border Protection).
Pork producers should sign up for the National Pork Board’s FAD Newsletter and browse their resources for FAD prevention. Also download the National Pork Board’s FAD Preparation Checklist to streamline producer responses if an outbreak were to occur. As outlined in Healthy Farm Healthy Agriculture website’s Detect section, emerging and foreign disease observation is key in order to recognize FADs to prevent outbreaks.
According to the USDA APHIS ASF Response Strategy, rapid detection and management of ASF if it spread to the United States would be vital in minimizing the number of infected pigs and for protecting the food supply. By quickly isolating and culling infected herds, a potential outbreak could be contained before it spread to other farms. The goal is to enable the United States to “regain ASF-free status without the response effort causing more disruption and damage than the outbreak itself,” in the event of an outbreak (FAD PReP, 2019).
Stay Updated on ASF
Swine producers – the Pork Checkoff/National Pork Board website maintains current ASF and other foreign animal disease information on their website. Visit the site at https://www.pork.org/production/animal-disease/foreign-animal-disease-resources/.
Producers and veterinarians – the USDA NIFA website contains current information on ASF, including international and regulatory updates. Visit the site at https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/swine-disease-information/african-swine-fever
Carriquiry, M., Elobeid, A., Swenson, D. A., & Hayes, D. J. (2020, March). CARD @ Iowa State University. Retrieved from https://www.card.iastate.edu/products/publications/synopsis/?p=1300
Mackenzie, D. (2019, November 5). A quarter of all pgs have died this year due to African swine fever. Retrieved from https://www.newscientist.com/article/2222501-a-quarter-of-all-pigs-have-died-this-year-due-to-african-swine-fever/
Center for Food Security & Public Health Iowa State University (2018, November). African Swine Fever FastFacts [PDF]. Retrieved from http://www.cfsph.iastate.edu/FastFacts/pdfs/african_swine_fever_F.pdf
Goatley, L. C., Reis, A. L., Portugal, R., Goldswain, H., Shimmon, G. L., Hargreaves, Z., Ho, C.-S., et al. (2020). A Pool of Eight Virally Vectored African Swine Fever Antigens Protect Pigs against Fatal Disease. Vaccines, 8(2), 234. MDPI AG. Retrieved from http://dx.doi.org/10.3390/vaccines8020234
Costard, S., Jones, B., Martínez-López, B., Mur, L., Torre, A., Martínez, M., Wieland, B. (2013, April 15). Introduction of African Swine Fever into the European Union through Illegal Importation of Pork and Pork Products. Retrieved from https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0061104
Committee on Foreign and Emerging Diseases of the United States Animal Health Association (2008). Foreign Animal Diseases Seventh Edition [PDF]. Retrieved from https://www.aphis.usda.gov/emergency_response/downloads/nahems/fad.pdf
Perez, S., Brihn, A., & Perez, A. (2020, May/June). Swine Disease Global Surveillance Report [PDF]. University of Minnesota. Retrieved from https://www.swinehealth.org/wp-content/uploads/2020/06/SHIC-109-GSDMR-6-3-2020.pdf
U.S. Department of Agriculture (2020, June 9). Poland’s Third Commercial ASF Outbreak in 2020. Retrieved from https://www.fas.usda.gov/data/poland-polands-third-commercial-asf-outbreak-2020
Oura, C. (2013, November). Overview of African Swine Fever – Generalized Conditions. Retrieved from https://www.merckvetmanual.com/generalized-conditions/african-swine-fever/overview-of-african-swine-fever
Iowa State University (2019). African Swine Fever [PDF]. Retrieved from http://www.cfsph.iastate.edu/Factsheets/pdfs/african_swine_fever.pdf
Juszkiewicz M, Walczak M, Woźniakowski G. (2019). Characteristics of Selected Active Substances used in Disinfectants and their Virucidal Activity Against ASFV. J Vet Res., 63(1), 17-25. https://pubmed.ncbi.nlm.nih.gov/30989131/
U.S. Department of Agriculture, Animal and Plant Health Inspection Services (2018). Potential Pesticides to Use Against the Causative Agents of Selected Foreign Animal Diseases in Farm Settings [PDF]. Retrieved from https://www.aphis.usda.gov/animal_health/emergency_management/downloads/fad_epa_disinfectants.pdf
OIE – World Organisation for Animal Health (2018, October). African swine fever. Retrieved from https://www.oie.int/en/animal-health-in-the-world/animal-diseases/african-swine-fever/
U.S. Department of Agriculture, Animal and Plant Health Inspection Service (2020, June). History of Feral Swine in the Americas. Retrieved from https://www.aphis.usda.gov/aphis/resources/pests-diseases/feral-swine/sa-fs-history
U.S. Department of Agriculture (2019, November). ASF Response [PDF]. Retrieved from https://www.aphis.usda.gov/animal_health/carcass/docs/asf-3d-summary-guidance.pdf
U.S. Customs and Border Protection. African Swine Fever FAQs. Retrieved from https://www.cbp.gov/travel/international-visitors/agricultural-items/african-swine-fever-faqs
The Pork Checkoff. African Swine Fever & Foreign Animal Disease Resources. Retrieved from https://www.pork.org/production/animal-disease/foreign-animal-disease-resources/
U.S. Department of Agriculture, Animal and Plant Health Inspection Services (2019). The Foreign Animal Disease Preparedness and Response Plan (FAD PReP)—Disease Response Strategy: African Swine Fever [PDF]. Retrieved from https://www.aphis.usda.gov/animal_health/emergency_management/downloads/asf_strategies.pdf
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