African swine fever is endemic to Africa and there are 23 strains that have been identified. The disease typically spreads to wild boar through ticks (of the genus Ornithodoros) or via direct contact, causing an acute hemorrhagic fever. During 2018 and 2019 one strain of the virus has spread through Asia, affecting millions of pigs. Speaking with Popular Science, epidemiologist Andres Perez (University of Minnesota) remarks that the steady movement of the infection across Asia has surprised virologists: “Rather than spreading rapidly and then burning out, it does the opposite. It’s safe to say that somewhere along its journey from Africa to where it is now, the virus adapted to different environments. Because of that adaptation, it’s behaving differently than expected.”
What is African swine fever?
African swine fever is a highly contagious and deadly viral disease affecting both domestic and wild pigs. There is no evidence that the virus is zoonotic (that is it cannot jump between different animal species and there is no known threat to human health). The virus is a large complex DNA virus and is a member of the Asfarviridae family, genus Asfivirus.
High fever
Decreased appetite and weakness
Red, blotchy skin or skin lesions
Diarrhea and vomiting
Coughing and difficulty breathing
Since there is currently no treatment or vaccine available, biosecurity measures are essential to prevent an outbreak from spreading. This means killing infected pigs as indicated by a manifestation of the symptoms, pigs thought to be infected, and pigs that actual or suspected pigs have been in contact with.
One challenge with imposing biosecurity measures is that not all outbreaks are reported. One of the reasons for this, with some rural populations, is due to mistrust of the authorities or with governments offering what some farmers regard as inappropriate compensation schemes.
Financial impact
The impact of the virus is also financial. To date over one million pigs are estimated to have been culled in order to stop the spread of the virus, which will impact China’s $128 billion pork industry (China has the highest pork consumption per capita in the world). Financial analyst Juan R. Luciano, chief executive officer of Archer-Daniels-Midland Co., told Yahoo: “China will clearly need to import substantial amounts of pork and likely other meat and poultry to satisfy demand.”
African swine fever has also wiped out pork productions across Mongolia, Vietnam, and most recently, in Cambodia. The spread of the virus can be tracked via real-time updates from the Swine Disease Global Surveillance Project.
Vaccine research
Research is on-going to help find a vaccine. Scientists are attempting to delete these genes so that the modified virus can then be used as a vaccine, such as with a project run by Dr Linda Dixon led researchers at Pirbright and The Biodesign Institute at Arizona State University. To date the researchers have succeeded in modifying the virus. While the virus is still capable of replication, it displays a dramatically reduced ability to cause infection. In a different research strand, researches are screening the proteins of the virus in order to identify which protein would be best at creating a protective immune response.
