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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.

African swine fever (ASF), a disease notifiable to the World Organization of Animal Health (OIE), is characterized by severe, unspecific clinical signs and high mortality rates. Hosts for ASF virus (ASFV) are only members of the family Suidae and soft ticks of the genus Ornithodoros. Currently, no vaccine is available and therefore, the control is primarily based on strict sanitary measures. The most important part is the early detection of the disease within affected animal holdings and the fast and reliable confirmation by laboratory diagnosis. Infections of domestic pigs and European wild boar with recent Armenian, Sardinian, Lithuanian or Kenyan ASFV isolates lead to severe, acute disease courses with the predominant symptom of high fever (> 41 degrees C) accompanied by further unspecific clinical signs such as lethargy, loss of appetite, diarrhoea, respiratory symptoms, and an increased bleeding tendency. In experimental infection studies the mortality rate reached 100%. The most prominent pathomorphological findings included ebony-colored gastrohepatic lymph nodes, lung oedema, petechiae in the renal cortex, and oedema of the gallbladder wall. In the light of the current epidemiological situation with endemic ASFV infections on Sardinia, outbreaks in Russia and several Eastern EU Member States there is a risk for an introduction in further, previously unaffected EU countries including Germany. Hence, appropriate sample materials (serum, blood, spleen) of domestic pigs with unspecific clinical symptoms or pathomorphological findings should be examined for both ASFV and classical swine fever virus.

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., (Copyright © 2014 Elsevier B.V. All rights reserved.)