Laboratory TestsFor Domestic Pig (DP)
1. PCR/DNA Amplification Tests :
2. Antigen Detection :
3. Antibody Tests
NB: Further information on ASF field tests can be found at:
For Wild Boar (WB):The same tests used in domestic pigs are valid for ASFV detection in wild boar.
Identification of the agent
ASFV genotyping: i) sequencing of the C- terminal end of VP72 gene,which differentiates up to 22 distinct genotypes; ii) full genome sequence of the p54-gene and iii) analysis of the central variable region (CVR) to distinguish between closely related isolates and identify virus subgroups within the 22 p72 genotypes. Described in the OIE Manual of ASF diagnosis (OIE, 2012) and by the EURL (http://asf-referencelab.info/asf/en/).
- Update of the EU and OIE Manual of diagnosis for ASF.
Refer to the current version of the ASF Chapter (3.9.1) in the WOAH Terrestrial Manual for recommendations on validated diagnostic tests, vaccines and for guidance on the purpose of their use.
Diagnostic tests validated at the EU level are described by the EURL (https://asf-referencelab.info/asf/en/procedures-diagnosis/sops).
Further information can be found at:
1. Virus Isolation.
2. Antigen detection
3. PCR Tests
4. Genotyping Tests
5. Serological tests
There are now many examples of commercial tests available for ASF laboratory and field diagnostics, as detailed above. These test kits have focused on PCR and ELISA for laboratory testing, and antigen/antibody or molecular testing for field tests. The number of commercially available tests has increased markedly in recent years. While many are available globally, others are restricted to regional distribution. There is only one commercially available antigen ELISA kit. With the continuing spread of ASF globally, it is expected that there will continue to be a high level of commercial potential for diagnostic kits. The future development and use of licensed/approved vaccines with DIVA capability will require complementary diagnostics, which will expand commercial opportunities.
Easy to use and interpret kits with worldwide distribution offered at competitive prices are in demand.
Specific diagnostic rapid tools for detection of ASFV genome using Dry-Sponges (3 M pre-hydrated with a surfactant liquid (Kosowska et al 2021). This method can be assessed without common test biosafety requirements due to the inactivation properties of the surfactant liquid.
NAVETCO (navet-ASF-vac) vaccine in Vietnam in DP. No information about potential DIVA test for this vaccine.
NAVETCO vaccine (navet-ASF-vac) under field evaluation in Vietnam in Domestic pig.
Due to the current global ASF situation and the absence of global authorized vaccines or treatment, the commercial potential for a safe and effective DIVA vaccine against ASFV will be huge to control and prevent the disease in both domestic pigs and wild boar.
Continuous engagement with the private sector and regulatory authorities.
New approaches are now available e.g. Z-MAC cell system for mass production of virus that avoids primary PBMC culture systems.
None.Some antivirals have shown the potential to inhibit replication in cell culture.At least one antiviral has shown a potential effect on disease development in pigs (Goulding et al., 2022).
Some studies are ongoing. Preliminary results obtained by “in-vitro” experiments using antiviral substances that antivirals might be used as an additional tool in ASF control.
Require regulatory approval.
Development of a cell line of immortalized porcine kidney macrophages (IPKM) for ASFV infection. Valuable tool for the isolation, replication, and genetic manipulation of ASFV in both basic and applied ASF research. IPKM cells can facilitate high levels (> 107 TCID50/mL) of viral replication of ASFV, and hemadsorption reactions and cytopathic effects can be observed as with porcine alveolar macrophages with virulent field isolates: Armenia07, Kenya05/Tk-1, and España75 (Masujin et al 2021).
- Developed MA-104 cells (ATCC #CRL-2378.1), a commercially available cell line isolated from African green monkey (Cercopithecus aethiops). MA-104 cells could be used as a substitute for primary swine macrophages to save significant lead time by avoiding the production of primary swine macrophages, but not for all isolates (Rai et al 2021).
- Z-MAC continuous cell line has potential to be used for diagnosis and research (Portugal et al 2020); however, requires macrophage growth factor for culture.
The lack of a safe and effective vaccine and the reliance on herd culling to prevent the spread of the disease has resulted in significant economic losses worldwide. Therefore, improved early detection remains a significant priority. Despite the availability of sensitive, specific and robust diagnostic assays for both ASFV genome and antibody detection there are still some gaps to fill.
Point of care tests:
DIVA tests will be required to complement any vaccine candidate. Primarily, DIVA test will be directed for differential Ab detection as an essential tool in the control strategies under a future vaccination scenario. Additionally, DIVA molecular assays are also necessary.
The time to develop new diagnostic tests depends on the nature of the test and its intended use. Generally, the development and validation of a completely new assay can take around 3 years, while the amendment of an established method to improve its performance could be done in several months. Development of diagnostic tests for an urgent use could be accomplished within some months in proficient and equipped reference laboratories.Further time will elapse before the tests are commercially available.
Cost depends on the nature of the test. Strong cooperation between all parties involved from design to commercial availability is needed.
Medium at Laboratory.
Field studies would also be relevant.
Following up on the molecular and biological characterization of the circulating ASFV strains is key to assure the competence of the diagnostic tests and to developing new tests or improving the existing techniques in the different scenarios.
PCR and serological tests (ELISA, IPT, IFAT), see details in the WOAH Manual of diagnostic tests and vaccines, chapter 3.9.1 African swine fever (https://www.oie.int/fileadmin/Home/eng/Health_standards/tahm/3.09.01_ASF.pdf), 2021 edition.
Identifying unique host biomarkers for infection and vaccination (immune system).
A safe, effective, and DIVA vaccine development has proved to be one of the top priorities in ASF research. In the shorter to medium term, live attenuated vaccines (LAVs) are the most promising and best-positioned candidates. The solid protection so far demonstrated by several LAVs (up to 100%), the increased safety achieved by making multiple gene deletions together with their potential to confer solid cross-protection, support optimism about their potential for field implementation in the medium term. These favorable candidates are based on the targeted gene deletion from virulent or naturally attenuated field strains. NGS technologies together with genetic manipulation tools are greatly favoring the design of safer and more efficient vaccine candidates.DIVA vaccines are critically demanded to control and prevent ASF in both domestic pigs and wild boar.
Improved safety and efficacy of modified live vaccines. Inclusion of DIVA diagnostic assays to distinguish infected from vaccinated animals.
Correlates for protection.
Determination of cross-protective potential against ASFV strains circulating in domestic pigs in different regions.
Subunit vaccines: identification and rationalisation of protective antigens. Testing novel delivery systems, for example mRNA vaccines.
Conventional strategies for a vaccine have not been useful to date. New strategies should be attempted.
Some live attenuated vaccine candidates have shown already favourable results in the in vivo studies performed so far.Several years (1-5 years) could still be needed for the registration and approval of a DIVA vaccine against ASFV, a period variable depending on each country's regulations.
Longer for subunit vaccines.
High cost of several million € for development and clinical trials needed to assess the safety and efficacy of the vaccine candidates and accompanying DIVA tests.
Develop a better understanding of the immune response to infection and the humoral and cellular basis for lifelong immunity post-infection. Identification of target proteins or genes.
Understanding of the host-pathogen interactions, and also, whether immunity is humoral or cell-mediated.
Assessment of whether antibodies alone can passively protect pigs against ASF virus has demonstrated not complete protection. There is no protection induced by passively acquired antibodies.
Further research on virulence factors and immunogenic targets for serological DIVA tests.
Correlates for cross-protection.
Identification of protective antigens. Testing novel delivery technologies.
No effective treatment is available for ASFV.
EU legislation does not allow antiviral treatment of infected pigs. Opportunities for antiviral drug development are more stimulating outside Europe. Antiviral substances may offer new additional tools for ASF control.
Requirements for antiviral treatments :
It will take a long time (more than 10 years).
In vitro and in vivo studies are needed to fully assess the safety and efficacy of the potential antiviral drugs.
Molecules have been reported to inhibit ASFV replication, either as direct-acting antivirals, host-targeting drugs, or through an unknown mechanism.
The mode of actions of the antiviral molecules is unknown.
ASFV is a complex icosahedral virus with a large double-stranded DNA (dsDNA). It is currently, the only member of the Asfaviridae family, genus Asfivirus, which corresponds with the only DNA arbovirus, a unique group of animal viruses that have arthropod vectors among their forms of transmission. The viral genome consists of a single molecule of linear, covalently linked dsDNA that contains terminal inverted repeats of 2.1 kbp units at both ends and complementary terminal loops present inverted flip-flop forms. The inverted repeat sequences are further characterized by numerous tandem repeat arrays. It ranges in length between 165 and 194 kbp and encodes between 151 and 167 open reading frames. The genome has terminal covalently closed loop structures adjacent to tandem repeat arrays. Replication occurs in perinuclear virus factories using enzymes coded for by the virus. The virus particle contains the transcription machinery required for early gene expression to initiate the replication cycle. The virus genome is therefore not infectious. About one third of the genes are not required for virus replication in cells but have important roles in evading and modulating host responses to infection. Many proteins including members of MGF 360 and 505 families, inhibit host innate immune responses including type I interferon the main host antiviral pathway. Deletion of some MGF360, 505 or 110 and other genes can reduce virus virulence. Target cells for replication of field isolates are of myeloid origin and predominantly monocytes and macrophages of intermediate to late stage of differentiation. Some isolates have been adapted to cell lines but this is often associated with genomic changes which may affect virulence.
The size differences in the ASFV genome are primarily due to variable copy numbers of several multigene families (MGFs), located in the left- and right-hand variable regions of the genome. Partial sequencing of the p72 (B646L) gene, which encodes the ASFV major capsid protein, has identified 24 different genotypes. In addition, sequencing of p54 (E183L gene) has also been successfully used for some ASFV genotypes (e.g., genotype I) as it discriminates between additional subgroups and provides better resolution of ASFV strains. Sequencing of both genetic regions p72 and p54 is often performed for ASFV initial classification to support epidemiological investigation in the event of an ASF introduction into new territories. Further discrimination between different ASFV strains can be achieved by sequencing other regions of the ASFV genome, known as genetic markers. A number of genetic markers such as the Central Variable Region (CVR) of the B602L gene, the intergenic region between I73R and I329L genes (characterized by the presence of tandem repeat sequences (TRS), and the CD2v lectin-like protein (EP402R gene) are also used.
ASFV infects wild suids in Africa without significant disease signs. A transmission cycle involving soft ticks of Ornithodoros species maintains a reservoir of infection in East and South-East Africa. Several species of Ornithodoros can be infected. Evidence suggests that the dissemination of the virus in different Ornithodoros species and the ability to transmit to pigs varies. Also, Ornithodoros ticks have a limited distribution depending on climate and vegetation. Although the role of ticks in ASFV transmission outside Africa, particularly in Asia, has not been investigated but is not thought to be a major transmission route. From the sylvatic cycle reservoirs, 24 genotypes have been described based on sequencing the 3’ end of the p72 major capsid protein gene B646L. These genotypes evolved during the long-term circulation of virus in the sylvatic cycle in Africa. The spillover of genotypes from wildlife to domestic pigs in Africa has been limited. ASFV can cause an acutely fatal haemorrhagic fever in domestic pigs and wild boar. Currently, genotype II is circulating in Europe, Asia and parts of the Caribbean. Genotype I is currently restricted to Sardinia in Europe. Recently in 2021 attenuated genotype I isolates were described in China. The virus is relatively antigenically stable within genotypes. However, different cross-protective serogroups have been described within some genotypes including genotype I. Attempts to determine mutation rates have provided variable results. Many genome changes result from gain or loss of genes including members of five different multi-gene families (MGFs). Some of these rearrangements result in a reduction in virulence in pigs. Frameshift mutations can lead to truncation of open reading frames. For example frameshift mutations in the EP402R gene results in the loss of the hemadsorption phenotype which is used for virus diagnosis. Rare examples of gene translocation from one genome end to the other have been described. Importantly severity of the disease is not related to the virus genotype and different isolates from any genotype may be virulent or attenuated. Highly virulent isolates cause peracute and acute disease whereas moderately virulent isolates cause reduced fatality but similar disease signs. Low virulence isolates can cause few disease signs or a chronic form of the disease which can persist over weeks or months.
Long-term stability in the environment depending on climatic conditions can be weeks or months.Pathogen is highly stable in the environment.
Temperature: Highly resistant to low temperatures. Heat inactivated by 56 °C/70 minutes; 60 °C/20 minutes.pH: Inactivated by pH <3.9 or >11.5 in serum-free medium. Serum increases the resistance of the virus, e.g. at pH 13.4 – resistance lasts up to 21 hours without serum, and 7 days with serum.Chemicals/disinfectants: Susceptible to ether and chloroform. Inactivated by 8/1000 sodium hydroxide (30 minutes), hypochlorite between 0.03% and 0.5% chlorine (30 minutes), 3/1000 formalin (30 minutes), 3% ortho-phenylphenol (30 minutes) and iodine compounds. Disinfectant activity may vary depending on the pH, time of storage and organic content.Survival: Remains viable for long periods in blood and tissues. Undercooked, insufficiently smoked, dried, and salted pork, as well as blood, carcasses, and carcass meal can be infective if fed to pigs or discarded in communal waste sites where pigs or wild boar may feed. It can remain infectious in slurry for up to 112 days at 4°C and up to 84 days at 17°C.Survival in soil; Soil pH, structure, and ambient temperature all played a role in the stability of infectious ASFV. Infectious ASFV was demonstrated in specimens from sterile sand for at least three weeks, from beach sand for up to two weeks, from garden soil for one week, and from bog soil for three days.Can multiply in vectors (Ornithodoros sp.).
The role of feed, water, and bedding for ASFV transmission needs further research.
Swine are the only animal species naturally infected by ASFV. All members of the pig family (Suidae) are susceptible to infection, but clinical disease is only seen in domestic and feral pigs, as well as in the closely related European wild boar. The disease occurs through complex transmission cycles involving domestic pigs, wild boars, warthogs, and bush pigs (African wild pigs). Domestic pigs, wild boars and feral/American pigs are susceptible to ASFV infection showing a range of clinical signs and mortality rates. ASFV usually induces an asymptomatic infection in wild African pigs. African wild pigs such as warthogs (Phacochoerus aethiopicus), bush pigs (Potamochoerus porcus) and giant forest hogs (Hylochoerus meinertzhageni) are tolerant or resistant to the disease and show few or no clinical signs, since viral replication in this kind of suids is limited, achieving titers under 102 copies/mL- However, in the presence of ticks, viral loads can increase at levels of 107 – 108 copies/ml.
None reported /Not applicable.
Soft ticks of the genus Ornithodoros spp, the, including O. moubata, O. porcinus and O. erraticus act as reservoirs and competent arthropod vectors for virus transmission[LM1] , but this can depend on the ASFV strain (Pereira de Oliveira et al., 2019). Virus is transmitted sexually and transtadially in ticks and can be isolated from all developmental stages. Transovarial transmission of the virus has also been shown in ticks from the O. moubata complex. The sylvatic cycle that occurs only in parts of Africa involves warthogs and ticks of the Ornithodoros moubata complex. The tick-pig cycle involves pigs and Ornithodoros spp. ticks, which have been described as infesting parts of Africa and the Iberian Peninsula. Transmission from the sylvatic cycle (African wild suids) to the domestic cycle (farmed pigs) occurs via indirect transmission by ticks. This can happen where pigs and warthogs share common grounds, particularly when warthogs establish burrows on farms, or when ticks are brought back to villages through the carcasses of warthogs killed for food. But also in natural areas of Africa, ASFV is thought to cycle between newborn warthogs and the soft ticks (Ornithodoros moubata) that live in their burrows. Individual ticks can remain infected over years, and infected soft tick colonies in warthog burrows can maintain this virus for years. All the Ornithodoros spp experimentally infected until now were susceptible to ASFV infection. However, it is not known if the virus is disseminated in tick tissues and can be transmitted by all species.Virus transmitted through a cycle involving soft tick and domestic/wild pigs.
[LM1]Depends on the ASFV strain? See : Pereira de Oliveira R, Hutet E, Paboeuf F, Duhayon M, Boinas F, Perez de Leon A, Filatov S, Vial L, Le Potier MF. Comparative vector competence of the Afrotropical soft tick Ornithodoros moubata and Palearctic species, O. erraticus and O. verrucosus, for African swine fever virus strains circulating in Eurasia. PLoS One. 2019 Nov 27;14(11):e0225657. doi: 10.1371/journal.pone.0225657. PMID: 31774871; PMCID: PMC6881060.
Wild African suids are asymptomatic carriers of ASF and act as the reservoir of the virus in parts of Africa. Soft ticks of the Ornithodoros genus, have been shown to be both reservoirs and transmission vectors of ASFV. The virus is present in tick salivary glands and passed to new hosts (domestic or wild suids) when feeding.
Wild boar or feral pigs in Europe and Asia. Wild suids including warthogs and bushpigs in E. Africa. Soft ticks of Ornithodoros spp. if present, for example in warthog burrows in some regions of Africa. Infected wild boar carcasses can play a role in transmission. But also the contaminated environment.
Direct and indirect contact between infected and susceptible pigs/wild boar and wild African pigs. See Route of Transmission.
Highly transmissible between domestic pigs and wild boars.
Peracute, Acute, Subacute, and Chronic forms of the disease are described.
Better understanding of pathogenesis including the chronic disease form.
ASF displays different clinical forms from peracute through acute, subacute, and chronic to unapparent. Concordantly, ASFV isolates can be classified as highly virulent, virulent, moderately virulent, and attenuated strains.
Mild form of the disease in endemic areas of Africa show transient fever, light peticheation on the skin followed by recovery. Severe forms of the disease mainly characterised by high fever (upto 42C). High morbidity in all pig species.
Evolution of circulating viruses in endemic regions: identification of low virulence ASFVs and the description of the “chronic type” of ASF in endemic areas.
The ASF has an incubation period, defined as the time point of likely infection to onset of clinical symptoms, of 2-19 days during natural infection.
Depends on the ASFV virulence and the clinical form induced:
Factors determining the mortality rate in host populations, particularly wild boar versus domestic pigs.
In the acute and subacute forms, before the appearance of clinical signs, the virus is usually excreted in oronasal and lacrimal secretions, urine, and feces for between 1 and 7 days, depending on the isolate and the route of infection. The highest viral titers are generally reported in oronasal fluid, while the lowest titers are detected in the conjunctival and genital fluid. Shedding from the oral cavity occurs before the systemic spread of the virus. Generally, the level of infectious ASFV excreted through these routes is lower than the level in the blood. The excretion of the virus through the feces occurs only in the acute phase of infection and two or even four days later than in the blood.Animals that survived acute and subacute infections were shed in oral secretions for up to 22 to 30 days and in blood for up to about 44 to 60 days, and an infected animal could play a role as a carrier of the virus during that period. Pigs infected with attenuated strains can shed infectious virus from the blood for up to 15 to 20 days, but with titers similar to those in the moderate virulence group. On the contrary, the risk of oral transmission, which is the natural route of infection, is much lower than in the case of infections with strains of high or moderate virulence, although this circumstance cannot be ruled out since the virus could be retained in the respiratory tract and could be easily transmitted through oral excretions.
ASF is characterized by severe leukopenia, mostly associated with lymphopenia, and a general state of immunodeficiency. The oronasal route is considered the most common route of infection, with the conjunctiva, genital tract, skin abrasions, and infected tick bites described as alternative routes of exposure. The incubation period varies widely (4-19 days), depending on the ASFV isolate and the route of exposure. Independently from the route of infection, the virus replicates primarily in mononuclear phagocytic cells of tonsils and submandibular, retropharyngeal, and other regional lymph nodes where it is detected as early as 16-24 hours after infection. After initial replication, the virus spreads through lymph and blood (free in plasma, adhered to erythrocytes or carried by infected monocytes). It is detectable in almost all tissues between 48-72 hours after infection, with high titres in tissues such as the spleen, lymph nodes and bone marrow, as well as in liver, lung or kidney. The high viral replication rates in these organs are usually associated with a later peak of viraemia, which coincides with the appearance of pyrexia and a febrile syndrome from day 3-4 after infection. Viremia usually begins 1-8 days post infection depending of ASFV virulence and persists for weeks or months.
More research is required to understand some of the pathogenic mechanisms, including how ASFV modulates the host immune responses and the role of the multiple proteins encoded by the virus.
None/ None reported.
ASF outbreaks have an impact both due to the severity of the disease and with the introduction of control measures, especially movement controls.Given that there is no available vaccines or therapeutics for ASF, the disease affects susceptible animals without control thus having impact on animal welfare and leading to mortalities that can wipe out elite breeding animals. It is expensive to control the disease.
Wild boar and feral pigs in Europe. In Asia endangered species of wild suids at risk. In Africa wild suids (warthogs, bushpigs, red river hogs) infected but without significant disease signs. Several endangered wild suid species and domestic species (especially 11 native species), mainly in Asiatic zones. Some important species are: bearded pig (Sus barbatus) in Sabah, Malaysia, the Philippines warty pig (Sus philippensis), wild suids populations in Indonesia and the most critically endangered wild suid, the pygmy hog (Porcula salvania) in the Himalayas and some part of India and possibly Bhutan; zones close to the already affected areas of ASF in India, Nepal and Bhutan.
Slaughter of infected and in-contact pigs.Approach available.
East and sub-Saharan African countries, southern Europe (mainly in Portugal, Spain, France, Italy, Ex-Soviet Union, Malta, Belgium, the Netherlands), Russia, East Europe and most of the European Union countries (Baltic States, Poland, Germany) and central and south America (Cuba, Brazil, Dominican Republic, Haiti, Baltic States and Czech Republic ).
African swine fever was first recorded in Kenya in 1921 and is present as endemic in most sub-Saharan African countries. It spread to southern Europe in 1957 (genotype I) affecting different countries in Europe (mainly in Portugal, Spain but also in France, Italy, Ex-Soviet Union. Malta, Belgium, the Netherlands) and central and south America (Cuba, Brazil, Dominican Republic, Haiti). ASF has traditionally been present on the African continent, where since 2005 the disease has been reported in 32 countries. In Europe, ASF has been present in Sardinia (Italy) since 1978 but is close to eradication. Since the introduction of ASF in Georgia in 2007 from East Africa (genotype II) the disease is affecting Russia, East Europe and most of the European Union countries. The epidemic has spread substantially in wild boar in Europe most recently in Italy with occasional spillover to domestic pigs in some countries (e.g. Baltic States, Poland, Germany). ASF was eradicated from wild boar in Belgium and Czech Republic. In some countries extensive spread has occurred in domestic pigs, particularly those countries with a high percentage of small holder farms practising lower biosecurity (eg Romania and Bulgaria). In 2018 ASF spread to China and disseminated rapidly to most provinces causing very high losses in pig herds. From there ASF has continued to spread to most Asian countries and to islands in Oceania. In 2021 ASF was reported from the Dominican Republic and Haiti increasing the risk of further spread in the Americas.Source of information: EU Animal disease notification system (ADNS).
Information is not always up to date. While in the EU reporting of disease outbreaks is obligatory, several other countries do not report to the WOAH or no testing is performed. The disease status of such countries remains unknown. The occurrence of ASF remains also underestimated in some Eastern European countries.
Endemic mainly in countries, with wildlife reservoirs (wild or feral pigs, African wild suids, Ornithodoros spp ticks in contact with suids) or a high proportion of backyard farms and reduced biosecurity.
In wild boar: Questions and gaps.
Can be fast as if transport of infected meat or animals is involved. On farm,transmission slower than some other virus infectious diseases if spreading from a single or limited source of infection.
Potential to become endemic mainly in developing countries, due to presence of complex transmission cycles which could involve a sylvatic cycle, a domestic cycle and a pig-tick cycle. This is greatly influenced by presence – and subsequent infection- of wild boar and vectors (wild African pigs and soft ticks acting as reservoirs).
In Africa, the disease spreads very fast within herds. Between herd transmission is associated with panic sale following rumours of outbreaks or during outbreaks.
ASF is a transboundary disease with transmission related to import and export of pigs and pig products, and cultural exchanges between countries.International trade of pigs, wild boar crossing borders, legal and illegal import of infected meat, waste management, rendering, safe disposal and illegal swill feeding maybe the reasons for introduction into a free country.Potentially high and wide spreading, mainly due to transport and movements of affected animals (infected pigs/wild boars/African wild pigs) and products, and illegal movements, as well as the pig density and farms biosecurity.
Introduction of infected pigs, pork products. ASFV can be transmitted by direct contact between infected and susceptible animals and by indirect contact with contaminated objects or food. Contaminated pork meat (waste feed) and also blood products used as a protein source may play an important role for virus transmission. For example, virus remains infectious in meat or the environment over prolonged periods. Infected animal or meat movement is the most common mechanism of transmission. Additionally, fomites such as clothing, trucks, and veterinary equipment (especially vaccine guns and similar objects) can act as a source of infection. In wild boar habitats contaminated meat products and, carcasses are crucial in maintaining infection cycles.
Bite from infected soft tick because of spill overs from wildlife reservoirs. Consumption of infected pork from wild pigs by healthy susceptible pigs but also consumption of infected pork by wild boar in waste.Direct transmission: contact between sick (domestic and wild boar) and healthy animals; contact with asymptomatic infected African wild reservoirs (carriers) and soft ticks.Indirect transmission: feeding with garbage containing infected meat fomites: premises, vehicles, implements, clothes, …
Ornithodoros spp ticks in contact with suids are restricted in distribution can act as transmission vector of the ASF virus. Aerosol only over short distances.
Unawareness of disease. Poor biosecurity.High Pig density.Uncontrolled movement of infected pigs and pig products.Hunting of wildlife followed by domestic consumption and feeding of swill to pigs.Complex social networks and complex trade networks.Late diagnosis and reporting, non-appropriate control and eradication measures. Close contact between domestic pigs and wild boars.
Pigs often die before the development of a humoral response when infected with a virulent strain. Pigs which do not die will mount an antibody response and have significant levels of ASF specific cytotoxic T lymphocytes. CD8+ cells are required for protection induced by live attenuated strains. Cellular subsets correlating with protection are poorly understood. Neutralising antibodies are inconsistently detected and not fully effective. Passive transfer of antibodies from recovered to naïve animals can reduce or delay clinical signs. Pigs can demonstrate a solid immunity to challenge from homologous strains. Cross-protection between strains has been observed and 8 serogroups proposed. Sequences of proteins CD2v and EP153R can be correlated with cross-protective groups. See sections above for vaccine development.
However, there is an absence of neutralizing antibodies against ASFV.
Early following infection virus genome can be detected but virulent isolates may die before a detectable antibody response. For those pigs which survive long enough and or recover from infection, antibody responses are detected and these responses can be long lived.The early appearance and subsequent persistence of antibodies is the reason they are so useful in studying subacute and chronic forms of the disease. For the same reason, they play an important role in testing strategies implemented as part of eradication programmes.Detection of antibodies and evidence of the virus genome or virus antigen. ASFV infection produces a long-term viremia from early stages of infection. Specific IgG antibodies are detectable in blood from the first week and for a long period of time, months even year in the surviving pigs. The early appearance and subsequent persistence of antibodies is the reason they are so useful in studying subacute and chronic forms of the disease. For the same reason, they play an important role in testing strategies implemented as part of eradication programmes.
Not fully exploited.
Control of live animals and swine product imports, control of waste food. Movement controls can all be successful. Quarantine. Once established in an area application of strict sanitary measures on infected farms, stamping out of animals, cleansing, disinfection, sentinels, serological control of sentinels after a month. Serological surveillance to detect potentially infected carrier animals. Once established in an area, tick control becomes important using acaricides.
Surveillance by detection of virus or virus genome in animals or the environment. Detection of antibodies in sera.
In case of an ASF suspicion, the PCR is by far the most sensitive method for the detection of the agent and the method of choice for first‐line laboratory diagnosis. A variety of PCR tests, including both conventional and real time (rtPCR), as well as commercial kits have been developed and validated to detect a wide range of ASF isolates (see section 1). A primary outbreak (or wild boar case) of ASF should be confirmed by virus isolation and/or genetic typing. If virus isolation is not possible, at least two distinct virus or antibody detection tests on the same-suspected pig should be done. In the case of wild boar samples, a primary case of ASF must be confirmed by at least two virus or antibody detection tests have given a positive result.
Whenever the suspicion is raised that ASFV is circulating in a swine population, a negative PCR result cannot exclude the presence of ASF. Since animals usually develop antibodies within the second week after infection, they can test positive for both ASF virus (ASFV) and antibodies simultaneously for at least two months. Samples from animals surviving this period are usually positive for ASFV-specific antibodies, but negative for ASFV and its genome. Therefore, if the PCR gave a negative result but there is a suspicion that ASFV is circulating; serological assays should also be used for the diagnosis. The ELISA test is the choice technique in serum sample. IPT or IFAT can be easily used for analysing all type of porcine samples, including exudates from tissue, whole blood, fluids and even bone marrow. The antibody detection in exudates tissue samples is a common successful method when wild boar are analysed.
Available diagnostic methods are described in section “Diagnostic availability”.
NAVETCO (navet-asf-vac) Vietnam.
No effective treatment at present.
Avoid contact between pigs, wild boar, and soft tick vectors, including warthogs in Africa - i.e. prevent pigs from wandering. - Performing good tracing of sources of infection and sources of spreading.
Rapid slaughtering of all pigs and proper disposal of cadavers and litter is essential. Thorough cleaning and disinfection. Movement controls.
Evaluation of swill feeding ban enforcement.
Careful import policy for animals and animal products. Proper disposal of waste food from aircraft or ships coming from infected countries.
Through regular clinical monitoring of animals (wild and domestics), in parallel with appropriate sampling collection and laboratory diagnosis. Pigs recovered from acute and subacute or chronic infections usually exhibit a viremia for several weeks making the PCR test a very useful tool for the detection of ASFV in pigs infected with low or moderately virulent strains. In addition, Antibody detection techniques are very useful in detecting surviving infected animals.Surveillance tools available including outbreak investigation protocols, diagnostic kits, disease reporting systems.
Mainly for wild boar:
Past eradication from Europe (Spain, Portugal, and other European countries), the Caribbean, and Brazil.Recent eradication from wild boar in the Czech Republic and Belgium.Three countries (Mali, Mauritius, São Tomé e Principe) have suffered single incursions that were rapidly eradicated.Recovered ASFV carrier pigs and persistently infected wild pigs constitute the biggest problems in controlling the disease. Eradication was successful in the Iberian Peninsula and in the Caribbean.Some common failures have been identified:
- Late detection.
- Low/insufficient resources or political instability.
- Scavenging pig husbandry or free-roaming pigs.
- Uncooked swill feed.
- Presence of wild pigs and ticks as reservoirs.
- Co-circulation of several isolates and or genotypes with different characteristics
- Failure to identify risk factors. Invert in prevention is the best measure to avoid the significant socio-economic consequences of this disease.
In prevention tools:
Variable depending on the strains involved. With 100% mortality can have a very high cost. This disease produces huge economic and social loses in many African countries and impairs the development of the porcine industry.
Comprehensive studies limited due to the complex nature of disease outcomes, range of production systems and breed characteristics and lack of good data on social impact variables.
When disease outbreaks had occurred in Europe, South America, and the Caribbean in the 1959-90’s, the costs of eradication have been significant. During outbreaks in Malta and the Dominican Republic, the swine herds of these countries were completely depopulated. In Spain and Portugal, ASFV became endemic in the 1960s and complete eradication took more than 30 years. In Africa, studies are limited.
Very high. Loss of trade, security of food supply and impacts on animal breeding and welfare. In Africa, studies are limited.
National and international trade prohibited from infected and surveillance zones.
Controls on the movement, of pigs and products from infected countries. Likely ban on imports from affected countries. Quarantine measures.
In Africa, studies are limited.
Trade outside surveillance zones prohibited in the EU.Movement controls on live pigs and their products from infected areas.In Africa, studies are limited.
International trade prohibited.
In Africa, studies are limited.
- Lack of vaccines, carrier recovered pigs, reservoirs in ticks and wild pigs in Africa.
- Improvement of sanitary infrastructures at animal holdings and Biosecurity in some countries. .
- Individual identification of every animal.
- Census update, in some countries.
o improvement of sanitary infrastructures at animal holdings and Biosecurity in some countries. .
o Individual identification of every animal. Census up date in some countries.
o epidemiological surveys.
o promoting associations
- Ability to identify carriers, control of ticks.
- Improvement of sanitary infrastructures at animal holdings and Biosecurity in some countries. .
- Individual identification of every animal.
- Census up date, in some countries.GAP:- appropriate vaccines
Not known to be linked.
Temporal analysis of climatic/seasonal variability and host or vector ecology.
Tick vector Ornithodoros spread limited by climate, habitat.
Ornithodoros spp ticks range is influenced by temperature and vegetation therefore their range may expand due to global warming. None, the disease vector (soft tick) can survive extreme weather and can survive for long while maintaining infection without a blood meal.
Availability of effective vaccine or therapeutics.
Mainly for wild boar:
Government departments of veterinary services, private veterinary service providers, industry, smallholder farmers.
In affected areas:
Disease control leads to increased productivity meaning lowered demography of animals used to produce same amount of food and thus the animal’s impact less in altering ecosystem structure.Biosecurity approaches for control of ASF including housing impacts positively to prevent land use changes that can help mitigate negative impacts of climate change.Socio-cultural and behavioural changes due to climate change including alternative use of food sources that can lead to zoonotic infections can be prevented with improved pig productivity as a results of disease control.
Need for agroecological system studies as relates to pig systems and impact of disease control on the systems.
Effective control and or eradication frees resources for use in other progressive farming production options.
Disease control would result in requirement of less animal resources needed to produce same amount of pork demanded and thus reducing impact on emissions.
Swine have the lowest emissions factor as a class of livestock because they are non-ruminant.
Despite the measures to prevent ASF from entering a country, ASF still spreads across countries. Any country should be prepared to respond in a timely and effective way to a potential entry of ASF so that economic, welfare, and societal consequences can be limited. Planning, investment, and implementation of priority actions are essential.
Adequate diagnostic platforms available.
Mathematical modelling capabilities available.
Risk assessment of the main entry pathways, i.e., more attention should be directed at entry through ports and airports, and to returning livestock trucks (Ito et al., 2020).Cost-effectiveness estimation of preventive measures, i.e. quantification of the contribution of risk factors to the probability of ASF occurrence and the measures to limit their occurrence.Identification of the spatio-temporal variability in ASF probability of occurrence and consequence, through spatial risk mapping, network analysis, applied statistics, and models, etc.Economic analyses derived from a potential incursion of ASF.
Intervention’s platforms are limited to Biosecurity and movement control.
Coordination/funding/political will between health responses across different political and economic areas, i.e. EU and Eastern Europe; Latin and North America; South and East Asia, etc.
Communication strategies are available.
Training all stakeholders/citizens: vets, food handlers, and food establishments including community places where food with pork is served (for safe disposal of waste), hunters, livestock owners, livestock truck drivers, laboratory services, and agricultural and environmental agencies….
ASF remains to be the major problem for the animal health worldwide, currently affecting 4 continents where most of the swine production takes place. Consequently, ASF is at the same time a global challenge for food safety. Although a great effort has been done from the scientific community, industrial companies, and veterinary authorities since many years, still there are main gaps to contain and eradicate the disease. A safe and effective DIVA vaccine remains the most relevant gap for disease control, but further advances must also be made on diagnostics, epidemiology, biological and molecular characterization, immunology and immune response.
July 1, 2022
Aguero, M., Fernández, J., Romero, L., Sánchez Mascaraque, C., Arias, M., & Sánchez-Vizcaíno, J. M. (2003). Highly sensitive PCR assay for routine diagnosis of African swine fever virus in clinical samples. Journal of clinical microbiology, 41(9), 4431-4434.
Agüero, M., Fernández, J., Romero, L. J., Zamora, M. J., Sánchez, C., Belák, S.,... & Sánchez-Vizcaíno, J. M. (2004). A highly sensitive and specific gel-based multiplex RT-PCR assay for the simultaneous and differential diagnosis of African swine fever and Classical swine fever in clinical samples. Veterinary research, 35(5), 551-563.
Arabyan E, Kotsynyan A, Hakobyan A, Zakaryan H. Antiviral agents against African swine fever virus. Virus Res. 2019 Sep;270:197669. doi: 10.1016/j.virusres.2019.197669. Epub 2019 Jul 17. PMID: 31325472.
Arias, M., Sánchez-Vizcaíno, J. M., Morilla, A., Yoon, K. J., & Zimmerman, J. J. (2002). African swine fever. Trends in emerging viral infections of swine, 119-124.
Arias, M., De la Torre, A., Dixon, L., Gallardo, C., Jori, F., Laddomada, A.,... & Sanchez-Vizcaino, J. M. (2017). Approaches and perspectives for development of African swine fever virus vaccines. Vaccines, 5(4), 35.
Arias, M., Jurado, C., Gallardo, C., Fernández‐Pinero, J., & Sánchez‐Vizcaíno, J. M. (2018). Gaps in African swine fever: Analysis and priorities. Transboundary and emerging diseases, 65, 235-247.
Barasona, J. A., Gallardo, C., Cadenas-Fernández, E., Jurado, C., Rivera, B., Rodríguez-Bertos, A., ... & Sánchez-Vizcaíno, J. M. (2019). First oral vaccination of Eurasian wild boar against African swine fever virus genotype II. Frontiers in veterinary science, 6, 137.
Borca, M. V., Ramirez-Medina, E., Silva, E., Vuono, E., Rai, A., Pruitt, S., ... & Gladue, D. P. (2020). Development of a highly effective African swine fever virus vaccine by deletion of the I177L gene results in sterile immunity against the current epidemic Eurasia strain. Journal of virology, 94(7), e02017-19.
Bosch, J., Iglesias, I., Muñoz, M. J., & De la Torre, A. (2017). A cartographic tool for managing African swine fever in Eurasia: mapping wild boar distribution based on the quality of available habitats. Transboundary and emerging diseases, 64(6), 1720-1733. https://doi.org/10.1111/tbed.12559
Bosch J., Rodríguez A., de la Torre A., Peris S., Iglesias I., Muñoz M.J., (2016). Structural and functional connectivity of wild boar along agro-forested areas: Relationship to crop damage. Doi: 10.13140/RG.2.2.25468.62085
Bosch, J., Rodríguez, A., Iglesias, I., Muñoz, M. J., Jurado, C., Sánchez‐Vizcaíno, J. M., & De la Torre, A. (2017). Update on the risk of introduction of African swine fever by wild boar into disease‐free European Union countries. Transboundary and emerging diseases, 64(5), 1424-1432.
Cadenas-Fernández, E., Ito, S., Aguilar-Vega, C., Sánchez-Vizcaíno, J. M., & Bosch, J. (2022). The Role of the Wild Boar Spreading African Swine Fever Virus in Asia: Another Underestimated Problem. Frontiers in veterinary science, 9.
Chen, Y., Wu, S., Wu, H., Cheng, P., Wang, X., Qian, S., ... & Wu, J. (2021). CRISPR/Cas12a-based versatile method for checking quantitative polymerase chain reaction samples with cycles of threshold values in the gray zone. ACS sensors, 6(5), 1963-1970.
Chenais, E., Boqvist, S., Emanuelson, U., Brömssen, C. von, Ouma, E., Aliro, T., Masembe, C., Ståhl, K. and Sternberg-Lewerin, S. 2017. Quantitative assessment of social and economic impact of African swine fever outbreaks in northern Uganda. Preventive Veterinary Medicine 144:134–148.
de la Torre, A., Bosch, J., Sánchez-Vizcaíno, J. M., Ito, S., Muñoz, C., Iglesias, I., & Martínez-Avilés, M. (2022). African Swine Fever Survey in a European Context. Pathogens, 11(2), 137.
Fernández‐Pinero, J., Gallardo, C., Elizalde, M., Robles, A., Gómez, C., Bishop, R.,... & Arias, M. (2013). Molecular diagnosis of African swine fever by a new real‐time PCR using universal probe library. Transboundary and emerging diseases, 60(1), 48-58. http://dx.doi.org/10.1016/j.virusres.2012.10.011
Gallardo, C., Fernández-Pinero, J., & Arias, M. J. V. R. (2019). African swine fever (ASF) diagnosis, an essential tool in the epidemiological investigation. Virus research, 271, 197676.
Gallardo, C., Nieto, R., Soler, A., Pelayo, V., Fernández-Pinero, J., Markowska-Daniel, I., ... & Arias, M. (2015). Assessment of African swine fever diagnostic techniques as a response to the epidemic outbreaks in eastern european union countries: How to improve surveillance and control programs. Journal of clinical microbiology, 53(8), 2555-2565.
Goulding, L.V., Kiss, E., Goatley, L., Vrancken, R., Goris, N.E.J., Dixon, L. (2022). In vitro and in vivo antiviral activity of nucleoside analogue cHPMPC against African swine fever virus replication. Antiviral Res, 208, 105433. doi: 10.1016/j.antiviral.2022.105433.
Haines, F. J., Hofmann, M. A., King, D. P., Drew, T. W., & Crooke, H. R. (2013). Development and validation of a multiplex, real-time RT PCR assay for the simultaneous detection of classical and African swine fever viruses. PloS one, 8(7), e71019.
Ito, S., Bosch, J., Jurado, C., Sánchez-Vizcaíno, J. M., & Isoda, N. (2020). Risk assessment of african swine fever virus exposure to Sus scrofa in Japan via pork products brought in air passengers’ luggage. Pathogens, 9(4), 302.
Jurado, C., Martinez-Aviles, M., De La Torre, A., Štukelj, M., de Carvalho Ferreira, H. C., Cerioli, M., ... & Bellini, S. (2018). Relevant measures to prevent the spread of African swine fever in the European Union domestic pig sector. Frontiers in veterinary science, 5, 77.
Jurado, C., Mur, L., Pérez Aguirreburualde, M. S., Cadenas-Fernández, E., Martínez-López, B., Sánchez-Vizcaíno, J. M., & Perez, A. (2019). Risk of African swine fever virus introduction into the United States through smuggling of pork in air passenger luggage. Scientific reports, 9(1), 1-7.
King, D. P., Reid, S. M., Hutchings, G. H., Grierson, S. S., Wilkinson, P. J., Dixon, L. K., ... & Drew, T. W. (2003). Development of a TaqMan® PCR assay with internal amplification control for the detection of African swine fever virus. Journal of virological methods, 107(1), 53-61.
Kosowska, A., Barasona, J. A., Barroso-Arévalo, S., Rivera, B., Domínguez, L., & Sánchez-Vizcaíno, J. M. (2021). A new method for sampling African swine fever virus genome and its inactivation in environmental samples. Scientific reports, 11(1), 1-7.
Lewis, J. S., Farnsworth, M. L., Burdett, C. L., Theobald, D. M., Gray, M., & Miller, R. S. (2017). Biotic and abiotic factors predicting the global distribution and population density of an invasive large mammal. Scientific Reports, 7(1), 1-12.
Li, J. S., Hao, Y. Z., Hou, M. L., Zhang, X., Zhang, X. G., Cao, Y. X., ... & Zhou, Z. X. (2022). Development of a Recombinase-aided Amplification Combined With Lateral Flow Dipstick Assay for the Rapid Detection of the African Swine Fever Virus. Biomedical and Environmental Sciences, 35(2), 133-140.
Masujin, K., Kitamura, T., Kameyama, K. I., Okadera, K., Nishi, T., Takenouchi, T., ... & Kokuho, T. (2021). An immortalized porcine macrophage cell line competent for the isolation of African swine fever virus. Scientific Reports, 11(1), 1-11.
Miller, R. S., & Pepin, K. M. (2019). BOARD INVITED REVIEW: Prospects for improving management of animal disease introductions using disease-dynamic models. Journal of animal science, 97(6), 2291-2307.
Mur, L., Boadella, M., Martínez‐López, B., Gallardo, C., Gortazar, C., & Sánchez‐Vizcaíno, J. M. (2012). Monitoring of African swine fever in the wild boar population of the most recent endemic area of Spain. Transboundary and emerging diseases, 59(6), 526-531.
Mur, L., Gallardo, C., Soler, A., Zimmermman, J., Pelayo, V., Nieto, R.,... & Arias, M. (2013). Potential use of oral fluid samples for serological diagnosis of African swine fever. Veterinary microbiology, 165(1-2), 135-139.
Mur, L., Iscaro, C., Cocco, M., Jurado, C., Rolesu, S., De Mia, G. M.,... & Sánchez‐Vizcaíno, J. M. (2017). Serological surveillance and direct field searching reaffirm the absence of ornithodoros erraticus ticks role in african swine fever cycle in Sardinia. Transboundary and emerging diseases, 64(4), 1322-1328.
Mur, L., Martínez-López, B., & Sánchez-Vizcaíno, J. M. (2012). Risk of African swine fever introduction into the European Union through transport-associated routes: returning trucks and waste from international ships and planes. BMC veterinary research, 8(1), 1-12.
Oļševskis, E., Guberti, V., Seržants, M., Westergaard, J., Gallardo, C., Rodze, I., & Depner, K. (2016). African swine fever virus introduction into the EU in 2014: Experience of Latvia. Research in Veterinary Science, 105, 28-30.
Penrit Portugal, R., Goatley, L. C., Husmann, R., Zuckermann, F. A., & Dixon, L. K. (2020). A porcine macrophage cell line that supports high levels of replication of OURT88/3, an attenuated strain of African swine fever virus. Emerging Microbes & Infections, 9(1), 1245-1253.
Pereira de Oliveira, R., Hutet, E., Paboeuf, F., Duhayon, M., Boinas, F., Perez de Leon, A., et al. (2019). Comparative vector competence of the Afrotropical soft tick Ornithodoros moubata and Palearctic species, O. erraticus and O. verrucosus, for African swine fever virus strains circulating in Eurasia. PLoS ONE 14(11): e0225657. https://doi.org/10.1371/journal.pone.0225657
Probst, C., Gethmann, J., Amler, S., Globig, A., Knoll, B., & Conraths, F. J. (2019). The potential role of scavengers in spreading African swine fever among wild boar. Scientific reports, 9(1), 1-13.
Rai, A., Pruitt, S., Ramirez-Medina, E., Vuono, E. A., Silva, E., Velazquez-Salinas, L., ... & Gladue, D. P. (2020). Identification of a continuously stable and commercially available cell line for the identification of infectious African swine fever virus in clinical samples. Viruses, 12(8), 820.
Rai, A., Pruitt, S., Ramirez-Medina, E., Vuono, E. A., Silva, E., Velazquez-Salinas, L.,... & Gladue, D. P. (2021). Detection and quantification of African swine fever virus in MA-104 cells. Bio-protocol, 11(6), e3955-e3955.
Sánchez-Vizcaíno, J. M., Mur, L., & Martínez-López, B. (2013). African swine fever (ASF): five years around Europe. Veterinary microbiology, 165(1-2), 45-50.
Straw, B. E., Zimmerman, J. J., D'Allaire, S., & Taylor, D. J. (Eds.). (2013). Diseases of swine. John Wiley & Sons.
Tignon, M., Gallardo, C., Iscaro, C., Hutet, E., Van der Stede, Y., Kolbasov, D.,... & Koenen, F. (2011). Development and inter-laboratory validation study of an improved new real-time PCR assay with internal control for detection and laboratory diagnosis of African swine fever virus. Journal of virological methods, 178(1-2), 161-170.
Wang, Z., Yu, W., Xie, R., Yang, S., & Chen, A. (2021). A strip of lateral flow gene assay using gold nanoparticles for point-of-care diagnosis of African swine fever virus in limited environment. Analytical and Bioanalytical Chemistry, 413(18), 4665-4672.
Wei, N., Zheng, B., Niu, J., Chen, T., Ye, J., Si, Y., & Cao, S. (2022). Rapid Detection of Genotype II African Swine Fever Virus Using CRISPR Cas13a-Based Lateral Flow Strip. Viruses, 14(2), 179.
Wu, Y., Yang, Y., Ru, Y., Qin, X., Li, M., Zhang, Z. ... & Li, Y. (2022). The Development of a Real-Time Recombinase-Aid Amplification Assay for Rapid Detection of African Swine Fever Virus. Frontiers in Microbiology, 13.
Yang, A., Schlichting, P., Wight, B., Anderson, W. M., Chinn, S. M., Wilber, M. Q. ... & Pepin, K. M. (2021). Effects of social structure and management on risk of disease establishment in wild pigs. Journal of Animal Ecology, 90(4), 820-833.
Yue, H., Shu, B., Tian, T., Xiong, E., Huang, M., Zhu, D. ... & Zhou, X. (2021). Droplet Cas12a assay enables DNA quantification from unamplified samples at the single-molecule level. Nano Letters, 21(11), 4643-4653.
Zimmerman, J. J., Karriker, L. A., Ramirez, A., Stevenson, G. W., & Schwartz, K. J. (Eds.). (2012). Diseases of swine. John Wiley & Sons.
Zsak, L. A. S. Z. L. O., Borca, M. V., Risatti, G. R., Zsak, A., French, R. A., Lu, Z., ... & Rock, D. L. (2005). Preclinical diagnosis of African swine fever in contact-exposed swine by a real-time PCR assay. Journal of clinical microbiology, 43(1), 112-119.