African swine fever (ASF), a highly contagious viral disease of pigs, currently represents the biggest threat to the global swine industry. The disease has severe health and economic consequences, including complete depopulation, export bans and area movement restrictions. Historically, the virus was most commonly found in Africa; however, outbreaks have occurred since 2007 in Georgia and the Caucasus region, South America, the Caribbean and now China. The map below (Picture 1) indicates countries currently affected.

ASF affects only members of the pig family. Humans are not sus-ceptible to the ASF virus (ASFV).

The virus is often introduced into a herd by the feeding of un-cooked or undercooked garbage containing contaminated pork. Once infected, the virus is easily spread between pigs by direct contact or indirectly via contact with contaminated objects. Some species of ticks can transmit the virus, as well as blood sucking insects.

ASFV is highly resistant in the environment. Survivability of ASFV in different conditions is presented in Table 1 and Table 2.

Table 1: Survival of ASFV in different conditions (Source: Adkin et al 2004)

Conditions ASFv survival time Source

Temperature of 50º C 3 hours USDA, 1997

Temperature of 56º C 70 minutes Mebus et al. 1998 in Foreign Animal Diseases

Temperature of 60º C 20 minutes Mebus et al. 1998 in Foreign Animal Diseases

ph<3.9 or ph>11.5 (serum-free media)

Minutes Mebus et al. 1998 in Foreign Animal Diseases

ph 13.4 in serum free media

21 hours http://www.oie.int/esp/maladies/fiches/e_A120.htm

ph 13.4 with 24% serum 7 days http://www.oie.int/esp/maladies/fiches/e_A120.htm

Blood stored at 4º C 18 months Technical disease cards of Iowa State University, 2006

Blood on wooden boars 70 days USDA, 1997

Putrefied blood 15 weeks USDA, 1997

Faeces held at room temperature

11 days Technical disease cards of Iowa State University, 2006

Contaminated pig pens 1 month Technical disease cards of Iowa State University, 2006

Slurry at 65º C 1 minute C. Turner and S.M. Williams, 1997

TECH REPORT | SwineVolume S4 | Issue 4 | Sept. 24, 2018

African Swine FeverAuthor: Attila Farkas, DVM

Picture 1: Countries affected by ASF (Source: www.oie.int/wahis_2/public/wahid.php/Diseaseinformation/Diseaseout-breakmaps)

Table 2: Survival of ASFV in meat and meat products (Source: Adkin et al 2004)

Product ASFv survival time (days)

De-boned meat 105Meat bone-in 105Ground meat 105Salted de-boned meat 182Salted meat bone-in 182Cook meat *(At least 30 min at 70º C) 0Canned meat 0Dried meat 300Smoked de-boned meat 30Frozen meat 1000Chilled meat 110Dried fat 300Offals 105Skin/fat 300

Signs of ASF often include high fever, decreased appetite, weakness, diarrhea, vomiting, coughing and difficulty breathing. The skin may be reddened, blotchy, or have blackened lesions. The gross necropsy finding typical of acute ASF is a very enlarged and hemorrhagic spleen, which is almost black (Pictures 2 and 3). Abortions are frequently seen in pregnant sows. The expected mortality rate is 100%, with death occurring 7-10 days after symptoms surface. Animals that recover from the illness can be carriers of the virus for several months.

There are no vaccines or cures for ASF. Disease control is mainly based on early detection and rapid laboratory diagnosis along with the implementation of strict sanitary and biosecurity measures. If you suspect a case of ASF, State Animal Health Officials should be notified immediately.

ASF has never occurred in the US, but was eradicated from the Western Hemisphere (Cuba, Haiti, and the Dominican Republic) two years after the introduction of the disease following depopulation measures. For the US, the risk of contamination has increased with the outbreak in China. As an industry, we procure vitamins, amino acids, antibiotics and protein such as soybeans from China and/or other endemic ASF countries. In a study looking at the survival of viral pathogens in animal feed ingredients under transboundary shipping models, scientists were able to recover viable virus 30 days post-contamination from conventional soy bean meal, organic soy bean meal, soy oil cake, choline, moist cat food, moist dog food, dry dog food, pork sausage casings, complete feed and stock virus control (Dee et al., 2018). The constraints of supply chain logistics, inventory, lairage, storage, etc. may limit the time. The outcomes of the survival of viral pathogens in animal feed ingredients under

Table 3: Survival of viral pathogens in animal feed ingredients under transboundary shipping models. (Source: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0194509)

Picture 2: Clinical signs in affected pig (Source: https://www.evira.fi/globalassets/ti-etoa-evirasta/julkaisut/julkaisusarjat/elaimet/possible-routes-of-entry-into-the-country-for-african-swine-fe-ver---risk-profile.pdf)

Picture 3: Gross necropsy findings

transboundary shipping models study are illustrated in Table 3.Producers can reduce ASF risks by avoiding importing materials from countries where ASF and other foreign animal diseases are prevalent. Other mitigation steps include storing ingredients and supplies at room temperature for an extended period of time and adding feed mitigation products to the feed. A total of 50 days storage time (30 days shipping and 20 days storage) is effective in decreasing the survivability of the virus.

If the disease was discovered in the U.S., the consequences would be catastrophic. Export markets would disappear, and swine move-ment would come to a halt. Per Dee et al., the estimated impact of the introduction of ASFV to the US would cost $16.5 billion during the first year of the outbreak.

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About the Author - Attila Farkas, DVM

Attila Farkas is a veterinarian with Carthage Veterinary Service, Ltd. (CVS). Attila joined the practice in 2016. Prior to joining the practice, from 2008 until 2016, Attila was em-ployed by Texas Farm, LLC a farrow to finish swine operation in Perryton, TX.

Attila graduated in 2006 with a Doctor of Veterinary Med-icine degree from the University of Agricultural Sciences and Veterinary Medicine in Cluj-Napoca, Romania. In 2013, Attila completed 33 weeks of Clinical Rotations in the Clinical Program in the Department of Veterinary Clinical Sciences at Oklahoma State University. In 2014, Attila has complied with the requirements of the Educational Commission for Foreign Veterinary Graduates. In 2015, he fulfilled the requirements of the Texas State Board of Veterinary Medical Examiners and was authorized to practice Veterinary Medicine and Surgery in the State of Texas. In 2016, he complied with the provisions of the Illinois Statutes and/or rules and regulations and be-came a licensed veterinarian in the State of Illinois. In 2017, he complied with the provisions of the Missouri and Iowa Statutes and/or rules and regulations and became a licensed veterinarian in the States of Missouri and Iowa. He holds professional Veterinary Licenses in Romania, Texas, Illinois, Missouri and Iowa.

Attila is certified through the National Pork Board’s Pork Qual-ity Assurance Plus Program and is a member of the American Association of Swine Veterinarians, American Veterinary Medical Association, Texas Veterinary Medical Association, Illinois Veterinary Medical Association and Romanian College of Veterinarians.