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Abstract Background African swine fever (ASF) is one of the most complex viral diseases affecting both domestic and wild pigs. It is caused by ASF virus (ASFV), the only DNA virus which can be efficiently transmitted by an arthropod vector, soft ticks of the genus Ornithodoros . These ticks can be part of ASFV-transmission cycles, and in Europe, O. erraticus was shown to be responsible for long-term maintenance of ASFV in Spain and Portugal. In 2014, the disease has been reintroduced into the European Union, affecting domestic pigs and, importantly, also the Eurasian wild boar population. In a first attempt to assess the risk of a tick-wild boar transmission cycle in Central Europe that would further complicate eradication of the disease, over 700 pre-existing serum samples from wild boar hunted in four representative German Federal States were investigated for the presence of antibodies directed against salivary antigen of Ornithodoros erraticus ticks using an indirect ELISA format. Results Out of these samples, 16 reacted with moderate to high optical densities that could be indicative of tick bites in sampled wild boar. However, these samples did not show a spatial clustering (they were collected from distant geographical regions) and were of bad quality (hemolysis/impurities). Furthermore, all positive samples came from areas with suboptimal climate for soft ticks. For this reason, false positive reactions are likely. Conclusion In conclusion, the study did not provide stringent evidence for soft tick-wild boar contact in the investigated German Federal States and thus, a relevant involvement in the epidemiology of ASF in German wild boar is unlikely. This fact would facilitate the eradication of ASF in the area, although other complex relations (wild boar biology and interactions with domestic pigs) need to be considered.

BACKGROUND African swine fever (ASF) is one of the most complex viral diseases affecting both domestic and wild pigs. It is caused by ASF virus (ASFV), the only DNA virus which can be efficiently transmitted by an arthropod vector, soft ticks of the genus Ornithodoros. These ticks can be part of ASFV-transmission cycles, and in Europe, O. erraticus was shown to be responsible for long-term maintenance of ASFV in Spain and Portugal. In 2014, the disease has been reintroduced into the European Union, affecting domestic pigs and, importantly, also the Eurasian wild boar population. In a first attempt to assess the risk of a tick-wild boar transmission cycle in Central Europe that would further complicate eradication of the disease, over 700 pre-existing serum samples from wild boar hunted in four representative German Federal States were investigated for the presence of antibodies directed against salivary antigen of Ornithodoros erraticus ticks using an indirect ELISA format. RESULTS Out of these samples, 16 reacted with moderate to high optical densities that could be indicative of tick bites in sampled wild boar. However, these samples did not show a spatial clustering (they were collected from distant geographical regions) and were of bad quality (hemolysis/impurities). Furthermore, all positive samples came from areas with suboptimal climate for soft ticks. For this reason, false positive reactions are likely. CONCLUSION In conclusion, the study did not provide stringent evidence for soft tick-wild boar contact in the investigated German Federal States and thus, a relevant involvement in the epidemiology of ASF in German wild boar is unlikely. This fact would facilitate the eradication of ASF in the area, although other complex relations (wild boar biology and interactions with domestic pigs) need to be considered.

5 páginas, 1 tabla, 1 figura. ; African swine fever (ASF) is one of the most complex viral diseases affecting both domestic and wild pigs. It is caused by ASF virus (ASFV), the only DNA virus which can be efficiently transmitted by an arthropod vector, soft ticks of the genus Ornithodoros. These ticks can be part of ASFV-transmission cycles, and in Europe, O. erraticus was shown to be responsible for long-term maintenance of ASFV in Spain and Portugal. In 2014, the disease has been reintroduced into the European Union, affecting domestic pigs and, importantly, also the Eurasian wild boar population. In a first attempt to assess the risk of a tick-wild boar transmission cycle in Central Europe that would further complicate eradication of the disease, over 700 pre-existing serum samples from wild boar hunted in four representative German Federal States were investigated for the presence of antibodies directed against salivary antigen of Ornithodoros erraticus ticks using an indirect ELISA format. ; This work has been funded by the European Research Project ASFORCE ("Targeted research effort on African swine fever", grant agreement 311931). ; Peer reviewed

In 2007, African swine fever virus (ASFV) was introduced into the Transcaucasian countries and Russia. Since then, it has spread alarmingly and reached the European Union. ASFV strains are highly virulent and lead to almost 100 % mortality under experimental conditions. However, the possibility of dose-dependent disease courses has been discussed. For this reason, a study was undertaken to assess the risk of chronic disease and the establishment of carriers upon low-dose oronasal infection of domestic pigs and European wild boar. It was demonstrated that very low doses of ASFV are sufficient to infect especially weak or runted animals by the oronasal route. Some of these animals did not show clinical signs indicative of ASF, and they developed almost no fever. However, no changes were observed in individual animal regarding the onset, course and outcome of infection as assessed by diagnostic tests. After amplification of ASFV by these animals, pen- and stablemates became infected and developed acute lethal disease with similar characteristics in all animals. Thus, we found no indication of prolonged or chronic individual courses upon low-dose infection in either species. The scattered onset of clinical signs and pathogen detection within and among groups confirms moderate contagiosity that is strongly linked with blood contact. In conclusion, the prolonged course at the "herd level" together with the exceptionally low dose that proved to be sufficient to infect a runted wild boar could be important for disease dynamics in wild-boar populations and in backyard settings.

In view of the fact that African swine fever (ASF) was recently introduced into the wild boar population of the European Union and that classical swine fever (CSF) keeps reoccurring, targeted surveillance is of utmost importance for early detection. Introduction of both diseases is usually accompanied by an increased occurrence of animals found dead. Thus, fallen wild boar are the main target for passive surveillance. However, encouraging reporting by hunters and sampling of these animals is difficult. Partly, these problems could be solved by providing a pragmatic sampling approach. For this reason, we assessed the applicability of three different dry/semi-dry blood swabs, namely a cotton swab, a flocked swab, and a forensic livestock swab, for molecular swine fever diagnosis. After nucleic acid extraction using manual and automated systems, routine quantitative real-time polymerase chain reactions (qPCR) were carried out. Results obtained from swabs or their fragments were compared to results generated from EDTA blood. It was shown that reliable detection of both pathogens was possible by qPCR. Shifts in genome copy numbers were observed, but they did not change the qualitative results. In general, all swabs were suitable, but the forensic swab showed slight advantages, especially in terms of cutting and further storage. Robustness of the method was confirmed by the fact that different extraction methods and protocols as well as storage at room temperature did not have an influence on the final outcome. Taken together, swab samples could be recommended as a pragmatic approach to sample fallen wild boar.

Classical swine fever (CSF) is one of the most important diseases of pigs. Although prophylactic vaccination is banned within the European Union, emergency vaccination, allowing differentiation of vaccinated from infected animals, is an option for disease control. Up to now, these strategies are based on antibody detection. In this context, conventional modified live vaccines are not suitable. A promising perspective could be genetic differentiation of vaccinated from infected animals where field virus strains are differentiated from vaccine viruses by sequence differences. This concept could also be used with marker vaccines. To this end, a set of real-time reverse transcription-polymerase chain reaction (RT-PCR) assays was developed and validated. Specific primers and probes were designed for detection of the C-strain "Riems" vaccine virus or the chimeric marker vaccine candidate CP7_E2alf. A heterologous internal positive control was also included. The assays were then multiplexed to detect simultaneously either CSF field virus, C-strain "Riems", and the internal control or CSF field virus, CP7_E2alf, and the internal control. To validate both systems, samples from vaccination/challenge trials were tested. Only samples from vaccinated animals were found to be positive, while all samples from wild type virus-infected animals and a broad test panel of different pestiviruses were negative. Field application of the "C-strain Riems" specific assay was proven with wild boar samples from surveillance programs in Germany and France. In conclusion, ready-to-use RT-PCR sets are presented as reliable tools for genetic differentiation of vaccinated from infected animals for CSFV eradication strategies. (c) 2009 Elsevier B.V. All rights reserved

Die Afrikanische Schweinepest (ASP) ist aufgrund ihrer schweren sozioökonomischen Konsequenzen, der unvorhersehbaren internationalen Verbreitung sowie fehlender Möglichkeiten zur therapeutischen oder impfprophylaktischen Bekämpfung eine der wichtigsten Tierseuchen des Schweines. Im Jahr 2014 erreichte die ASP die Ostgrenze der EU. Im Januar 2014 meldete Litauen die ersten ASP-positiven Wildschweine, es folgten im Februar Meldungen aus Polen, im Juni aus Lettland und im September 2014 aus Estland. Die Ausbrüche in den Hausschweinbeständen konnten schnell und problemlos getilgt werden. Im Gegensatz dazu erweist sich das Geschehen in der Wildschweinpopulation als sehr komplex und schwer kontrollierbar. Feldbeobachtungen und experimentelle Studien deuten auf eine hohe Letalität und geringe Kontagiosität in der Anfangsphase der ASP hin. Die geringe Kontagiosität erfordert ein Umdenken und ein dementsprechend angepasstes Vorgehen bei der Bekämpfung im Wildschweinbereich. Bei der Bekämpfung der Tierseuche beim Hausschwein erweist sich die geringe Kontagiosität als ein Vorteil (genügend Zeit, um die Maßnahmen durchzuführen), beim Wildschwein hingegen ist sie ein Nachteil, wenn andere Faktoren wie hohe Wildschweindichten und lange Überlebenszeiten des Virus in der Natur die Bekämpfung erschweren. Nach bisherigen Erkenntnissen verhält sich die ASP in einer Wildschweinpopulation eher wie eine langjährige (eher stationäre), an das Habitat gebundene Seuche ohne Tendenz zur schnellen Ausbreitung. Dabei könnten vornehmlich infektiöse Kadaver in Verbindung mit der hohen Tenazität des ASP-Virus und der niedrigen Kontagiosität die Tierseuche in einer Region "binden". Dieses Phänomen könnte erklären, warum sich die ASP zwar langsam ausbreitet, das Infektionsgeschehen jedoch nicht von selbst erlischt. ; African swine fever (ASF) is considered internationally as one of the most dangerous animal diseases of pigs. The dis ease is affecting trade and having serious socio-economic impact on people's livelihood. No drugs or vaccines are available to fight ASF. ASF has reached the eastern borders of the European Union in January 2014. The very first cases of infected wild boar have been reported by Lithuania. Poland reported first cases in February, followed by Latvia in June and Estonia later in September of that same year. The outbreaks occurring in domestic pigs have been controlled timely and without major problems. Within the wild boar population however, the occurrence of ASF has shown to be very complex and difficult to control. Field data as well as experimental studies on ASF indicate an overall high case-fatality rate and a rather low contagiosity during the initial phase of infection. Within that context, a revision of the current understanding and approaches towards ASF control and eradication is needed. In domestic swine populations the low contagiosity is rather an advantageous feature reducing the urgency in the implementation of control measures. For wild boar however, in combination with the environmental stability of the virus and high animal densities, the low contagiosity represents a disadvantage for effective control. Current findings indicate that in wild boar populations ASF shows a pattern of habitat bound persistence lacking a tendency of dynamic spatial spread. Therefore ASF in wild boar can be considered a habitat-borne disease where infected carcasses in combination with the tenacity of the virus and the low contagiosity play a key role in capturing the disease within affected areas. Such circumstances are likely to contribute substantially to months or even years of pathogen persistence explaining the current picture of ASF spreading rather slowly and with continuing circulation in affected areas.

Nach den jüngsten Ausbrüchen der Afrikanischen Schweinepest in Russland, droht diese anzeigepflichtige Tierseuche in die Europäische Union eingeschleppt zu werden. Hier erfahren Sie u.a. das Wichtigste über die klinischen und pathologisch-anatomischen Symptome, um diese in Deutschland bisher nicht auftretende Erkrankung leichter erkennen zu können.

Question: Domestic pigs and Eurasian wild boar (Sus scrofa) share several important viral and bacterial pathogens. Therefore, direct and indirect contacts between domestic pigs and wild boar present a risk of pathogen spill-over and can lead to long-term perpetuation of infection. Biological indicators could be a powerful tool to understand and characterize contacts between wild boar and domestic pigs. Here, faecal E. coli were explored as potential biological indicator under experimental conditions. Methods: Within an animal trial domestic pigs (group 2, n=8) were brought into contact with faecal material of wild boar (group 1, n=8). Before and three to five weeks after transmission of faeces fecal samples of both groups were collected, coliforme bacteria isolated, and the bacteria tested by CHEF-PFGE for clonal relatedness. The study was meant as test and calibration phase for potential field studies. Results: Eighty-eight individual E. coli clones were detected by XbaI restriction and PFGE analysis. Selecting only one isolates representing a distinct clone from an individual faecal sample, 123 E. coli isolates were further analysed. Overall, 17 different clones were found in several animals of a group (1 or 2) or both samples from one animal. Additionally, five clones were detected in group 1 as well as in contact group 2. Conclusions: The data gained in our pilot study suggest that faecal E. coli can be used as biological indicator of contact between wild boar and domestic pig. Based on these promising results, future field studies will especially target the practicability of E. coli microbiome molecular typing as surrogate of contacts at the wildlife-livestock interface. This study is funded by the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 311931 (ASFORCE).

African swine fever (ASF) was introduced into the Eastern European Union in 2014 and led to considerable mortality among wild boar. In contrast, unexpected high antibody prevalence was reported in hunted wild boar in north-eastern Estonia. One of the causative virus strains was recently characterized. While it still showed rather high virulence in the majority of experimentally infected animals, one animal survived and recovered completely. Here, we report on the follow-up characterization of the isolate obtained from the survivor in the acute phase of infection. As a first step, three in vivo experiments were performed with different types of pigs: twelve minipigs (trial A), five domestic pigs (trial B), and five wild boar (trial C) were inoculated. 75% of the minipigs and all domestic pigs recovered after an acute course of disease. However, all wild boar succumbed to infection within 17 days. Representative samples were sequenced using NGS-technologies, and whole-genomes were compared to ASFV "Georgia 2007/1". The alignments indicated a deletion of 14560 base pairs at the 5' end, and genome reorganization by duplication. The characteristic deletion was confirmed in all trial samples and local field samples. In conclusion, an ASFV variant was found in Estonia that showed reduced virulence.

African swine fever (ASF) was introduced into the Eastern European Union in 2014 and led to considerable mortality among wild boar. In contrast, unexpected high antibody prevalence was reported in hunted wild boar in north-eastern Estonia. One of the causative virus strains was recently characterized. While it still showed rather high virulence in the majority of experimentally infected animals, one animal survived and recovered completely. Here, we report on the follow-up characterization of the isolate obtained from the survivor in the acute phase of infection. As a first step, three in vivo experiments were performed with different types of pigs: twelve minipigs (trial A), five domestic pigs (trial B), and five wild boar (trial C) were inoculated. 75% of the minipigs and all domestic pigs recovered after an acute course of disease. However, all wild boar succumbed to infection within 17 days. Representative samples were sequenced using NGS-technologies, and whole-genomes were compared to ASFV "Georgia 2007/1". The alignments indicated a deletion of 14560 base pairs at the 5' end, and genome reorganization by duplication. The characteristic deletion was confirmed in all trial samples and local field samples. In conclusion, an ASFV variant was found in Estonia that showed reduced virulence.

Das Auftreten und die seit dem Jahr 2007 stattfindende rasche Ausbreitung der Afrikanischen Scheinepest (ASP) in transkaukasischen Ländern, Teilen der Kaukasusregion der Russischen Föderation sowie Ausbrüche in anderen Gebieten des Europäischen Teils von Russland geben Anlass, die Bedrohungslage für die Bundesrepublik zu analysieren. Vor dem Hintergrund eines gestiegenen Einschleppungsrisikos in das Gebiet der Europäischen Union und damit auch nach Deutschland erscheint Aufklärungsarbeit zu dieser Tierseuche, die in Deutschland noch nie festgestellt wurde, geboten. Die Afrikanische Schweinepest wird durch ein DNA-Virus aus der Familie der Asfarviridae (ASPV) verursacht. Neben Haus- und Wildschweinen sind zumindest in Afrika auch Lederzecken der Gattung Ornithodorus in den Infektionszyklus involviert. Wie die Klassische Schweinepest, von der die ASP klinisch nicht zu unterscheiden ist, kann auch die ASP mit sehr variablen Krankheitsbildern einhergehen. Die in den transkaukasischen Ländern (Georgien, Armenien und Aserbaidschan) und der Russischen Föderation vorherrschenden Virusstämme sind für Schweine aller Altersstufen hoch virulent und verursachen eine Mortalität von nahezu 100 Prozent. Da die Einfuhr lebender Schweine und frischen Schweinefleisches aus der Russischen Föderation und den anderen betroffenen Ländern in die Europäische Union gegenwärtig nicht gestattet ist, geht ein vorherrschendes Einschleppungsrisiko des Erregers insbesondere von im Personen- und Güterreiseverkehr mitgeführten ASPV-kontaminierten Lebensmitteln bzw. Speiseabfällen aus. Weiterhin können kontaminierte und unzureichend desinfizierte Transportfahrzeuge, die aus betroffenen Gebieten zurückkehren, ein erhöhtes Einschleppungsrisiko darstellen. ; The occurrence and almost unhindered spread of African swine fever (ASF) in Trans-caucasian countries and the Russian Federation gives reason to analyze the level of threat for the German pig population. In view of a possible risk of introduction into the European Union, disease awareness campaigns and disease recognition training is urgently required, especially since ASF has never been reported in Germany. ASF is caused by a large, complex DNA virus of the Asfarviridae family. Beside domestic pigs and wild boar, soft ticks of the genus Ornithodorus are involved in the infection cycle, especially in Africa. Like classical swine fever (CSF), ASF can be associated with a wide range of clinical syndromes. Based on clinical signs only, discrimination of ASF and CSF is impossible. The virus strains prevailing in the Trans-caucasian countries and the Russian Federation are currently highly virulent indiscriminately both for domestic pigs and wild boar. Mortality may reach up to 100 % in pigs of all ages. As legal animal movements and the transport of pig products from Russia into the EU are not possible, the introduction risk rests with food waste and passenger traffic. Moreover, insufficiently disinfected transport vehicles returning from the Russian Federation and other affected countries pose an additional risk to the German pig population.

This opinion describes outdoor farming of pigs in the EU, assesses the risk of African swine fewer (ASF) introduction and spread associated with outdoor pig farms and proposes biosecurity and control measures for outdoor pig farms in ASF‐affected areas of the EU. Evidence was collected from Member States (MSs) veterinary authorities, farmers' associations, literature and legislative documents. An Expert knowledge elicitation (EKE) was carried out to group outdoor pig farms according to their risk of introduction and spread of ASF, to rank biosecurity measures regarding their effectiveness with regard to ASF and propose improvements of biosecurity for outdoor pig farming and accompanying control measures. Outdoor pig farming is common and various farm types are present throughout the EU. As there is no legislation at European level for categorising outdoor pig farms in the EU, information is limited, not harmonised and needs to be interpreted with care. The baseline risk of outdoor pig farms for ASFV introduction and its spread is high but with considerable uncertainty. The Panel is 66–90% certain that, if single solid or double fences were fully and properly implemented on all outdoor pig farms in areas of the EU where ASF is present in wild boar and in domestic pigs in indoor farms and outdoor farms (worst case scenario not considering different restriction zones or particular situations), without requiring any other outdoor‐specific biosecurity measures or control measures, this would reduce the number of new ASF outbreaks occurring in these farms within a year by more than 50% compared to the baseline risk. The Panel concludes that the regular implementation of independent and objective on‐farm biosecurity assessments using comprehensive standard protocols and approving outdoor pig farms on the basis of their biosecurity risk in an official system managed by competent authorities will further reduce the risk of ASF introduction and spread related to outdoor pig farms.

This opinion describes outdoor farming of pigs in the EU, assesses the risk of African swine fewer (ASF) introduction and spread associated with outdoor pig farms and proposes biosecurity and control measures for outdoor pig farms in ASF-affected areas of the EU. Evidence was collected from Member States (MSs) veterinary authorities, farmers' associations, literature and legislative documents. An Expert knowledge elicitation (EKE) was carried out to group outdoor pig farms according to their risk of introduction and spread of ASF, to rank biosecurity measures regarding their effectiveness with regard to ASF and propose improvements of biosecurity for outdoor pig farming and accompanying control measures. Outdoor pig farming is common and various farm types are present throughout the EU. As there is no legislation at European level for categorising outdoor pig farms in the EU, information is limited, not harmonised and needs to be interpreted with care. The baseline risk of outdoor pig farms for ASFV introduction and its spread is high but with considerable uncertainty. The Panel is 66-90% certain that, if single solid or double fences were fully and properly implemented on all outdoor pig farms in areas of the EU where ASF is present in wild boar and in domestic pigs in indoor farms and outdoor farms (worst case scenario not considering different restriction zones or particular situations), without requiring any other outdoor-specific biosecurity measures or control measures, this would reduce the number of new ASF outbreaks occurring in these farms within a year by more than 50% compared to the baseline risk. The Panel concludes that the regular implementation of independent and objective on-farm biosecurity assessments using comprehensive standard protocols and approving outdoor pig farms on the basis of their biosecurity risk in an official system managed by competent authorities will further reduce the risk of ASF introduction and spread related to outdoor pig farms. (C) 2021 European Food Safety Authority. EFSA Journal published by John Wiley and Sons Ltd on behalf of European Food Safety Authority.