African Swine Fever

By: Joe C. Paschal, Livestock Specialist

Texas A&M AgriLife Extension

Corpus Christi, Texas

j-paschal@tamu.edu

African Swine Fever (ASF as it is commonly referred to) has been in the news recently as a result of an outbreak in China. It is a major health threat to swine production in many countries, but fortunately it is not in the US. ASF is a highly contagious viral disease that causes death in domestic and wild pigs of all ages. Symptoms include high fever; decreased appetite and weakness; red, blotchy skin or skin lesions; diarrhea and vomiting; and coughing and difficulty in breathing. Mortality rate is as high as 100% within 2-10 days. ASF is spread from hog to hog via body fluids and some ticks as well as feeding uncooked leftovers or by travelling from an infected farm to an uninfected one. ASF is not a threat to human health and cannot be transmitted from pigs to humans and it is not a food safety issue for people. Symptoms are similar to classical swine fever so accurate diagnosis is important.

ASF was first identified Africa in the 1920s. In 1957 it was found in Portugal after pigs were fed leftovers from airplanes from a nearby airport containing infected pork. Smaller outbreaks have occurred in other European and Caribbean countries since then. In 2007 it was reported in the Republic of Georgia and then China in 2018. In 2019 it has been reported in Mongolia, Vietnam and Japan (in March). Since there is no treatment or vaccine for ASF, the only option to reduce its spread is depopulation of sick or infected animals.

USDA’s Agricultural Research Service began to research it in the 1970s. In the 1990s, they began focusing on the genome of the virus (containing about 150 genes) to determine which genes might cause the sickness and keep them from activating the disease. Then they could then create a live attenuated vaccine, like the vaccines for measles, polio and smallpox in humans. That program was slowed by lack of funding in 2004 but has recently been revived with assistance from the Department of Homeland Security. In the meantime, since there is no vaccine, producers should practice good biosecurity management by restricting movement of hogs and people on and off their locations. In addition, Customs and Border Protection is on alert for passengers arriving from affected countries who might be carrying uncooked pork products. In March, over one million pounds of illegal products containing pork from China were confiscated in New York. China has culled over 1,000,000 pigs in an effort to control their ASF outbreak.

In addition to the research on vaccine development, there is also research on diagnostic methods. Being able to quickly and accurately determine presence of the contagious virus is critical to containment, since there are no vaccines currently. In one method, a rope is suspended in a pen for pigs to chew on and then the oral fluids can be collected and tested for the virus, a simple and effective method to test for a group of swine. Currently there are two vaccine candidates but no approved vaccine. This work is being conducted through USDA APHIS and the Department of Homeland Security Science and Technology.

The US pork industry is a powerhouse with its’ 2018 inventory of 73 million head producing 20 billion pounds of pork. But it is well behind No. 1 ranked China with 433 million and the No.2 European Union’s 150 million head of pigs. But Texas isn’t as well known for hog production. In 2018 it ranked 18th (out of 50 states) with an inventory of about one million head, the majority located in the Panhandle, well behind No. 1 ranked Iowa with an inventory of 23 million head. An ASF outbreak, however accidental or unintentional, would devastate the US swine herd and pork production. If you travel internationally, don’t bring pork products back unless you declare them!