It persistently infects its natural hosts, warthogs, bushpigs, and soft ticks of the genus Ornithodoros, which likely act as a vector, with no disease signs.

[5] ASFV is a large (175–215 nm),[citation needed] icosahedral, double-stranded DNA virus with a linear genome of 189 kilobases containing more than 180 genes.

The virus encodes proteins that inhibit signalling pathways in infected macrophages and thus modulate transcriptional activation of immune response genes.

[1] Based on sequence variation in the C-terminal region of the B646L gene encoding the major capsid protein p72, 22 ASFV genotypes (I–XXIII) have been identified.

[12] At the end of the 19th century, the extensive pig industry in the native region of ASFV (Kenya) started after massive losses of cattle due to a rinderpest outbreak.

[16] In milder infections, affected pigs lose weight, become thin, and develop signs of pneumonia, skin ulcers, and swollen joints.

[17] The clinical symptoms of ASFV infection are very similar to classical swine fever, and the two diseases normally have to be distinguished by laboratory diagnosis.

This diagnosis is usually performed by an ELISA, real time PCR, or isolation of the virus from either the blood, lymph nodes, spleen, or serum of an infected pig.

Laboratory tests have been conducted to assess the efficacy of chemical products and commercial disinfectants against African swine fever.

Subsequent to these initial introductions, the disease became established in the Iberian peninsula, and sporadic outbreaks occurred in France, Belgium, and other European countries during the 1980s.

[25] ASFV crossed the Atlantic Ocean, and outbreaks were reported in some Caribbean islands, including Hispaniola (Dominican Republic and Haiti).

[26] Resultantly, US Customs and Border Protection is on high alert to prevent any spread to the US, which would inflict billions of dollars of damage to the pork industry in the country.

[26] Major outbreaks of ASF in Africa are regularly reported to the World Organisation for Animal Health (previously called L'office international des épizooties).

[citation needed] Six years after the event, the newspaper Newsday, citing untraceable sources,[28][29] claimed that anti-Castro saboteurs, with at least the tacit backing of U.S. Central Intelligence Agency officials, allegedly introduced African swine fever virus into Cuba six weeks before the outbreak in 1971, to destabilize the Cuban economy and encourage domestic opposition to Fidel Castro.

The virus was allegedly delivered to the operatives from an army base in the Panama Canal Zone by an unnamed U.S. intelligence source.

[25][33][34] African swine fever had become endemic in the Russian Federation since spreading into the North Caucasus in November 2007, most likely through movements of infected wild boar from Georgia to Chechnya, said a 2013 report by the Food and Agriculture Organization, a United Nations agency.

Among the vectors for the spread in Russia of African swine fever virus was the 'distribution' of 'infected pig products' outside affected (quarantined and trade restricted) areas, travelling large distances (thousands of kilometers) within the country.

[36] The report warned that "countries immediately bordering the Russian Federation, particularly Ukraine, Moldova, Kazakhstan, and Latvia, are most vulnerable to [African swine fever] introduction and endemic establishment, largely because the biosecurity of their pig sector is predominantly low.

To stop the virus's spread, "the current scenario in the Russian Federation suggests that [prevention] should be particularly stressed at the often informal backyard level and should involve not just pig keepers, but all actors along the whole value chain—butchers, middlemen, slaughterhouses, etc.

[44] In January 2014, authorities announced the presence of African swine fever in Lithuania and Poland,[45] in June 2014 in Latvia, and in July 2015 in Estonia.

[46] Estonia in July 2015 recorded its first case of African swine fever in farmed pigs in Valgamaa on the country's border with Latvia.

[citation needed] In 2018, Romania experienced a nationwide African swine fever pandemic, which prompted the slaughter of most farm pigs.

[61] In September 2020, the German agriculture minister confirmed on a press conference that the African swine fever virus reached Germany.

[73] On April 25, 2019, the virus was reported to have spread to every region of China, as well as parts of Southeast Asia, including Cambodia, Laos, Thailand, and Vietnam.

[74] The Chinese pig population was reported to have declined by almost 100 million compared with the previous year, driving European pork prices to reach a six-year high.

[75] Ze Chen, Shan Gao and co-workers from Nankai University detected ASFV in Dermacentor (hard ticks) from sheep and bovines using small RNA sequencing.

[79] In Taiwan, between December 2018 and June 2019, ten pig carcasses infected with ASF washed up on the shore in Kinmen (Quemoy) County.

[81][82] In April 2020, a twelfth pig carcass confirmed to be carrying African swine fever virus washed up on the shore of Lieyu (Lesser Kinmen).

[81][83] On May 29, China's Ministry of Agriculture and Rural Affairs said it had found a new outbreak of ASF near the city of Lanzhou in northwestern Gansu Province.

[85] The Philippines' Department of Agriculture started a probe in August 2019 regarding incidents of hog deaths in towns in Rizal and Bulacan for suspected ASF cases.