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Summary African swine fever (ASF) is one of the most important swine diseases, mainly because of its significant sanitary and socioeconomic consequences. This review gives an update on the epidemiology of the disease and reviews key issues and strategies to improve control of the disease and promote its eradication. Several characteristics of ASF virus (ASFV) make its control and eradication difficult, including the absence of available vaccines, marked virus resistance in infected material and contaminated animal products, and a complex epidemiology and transmission involving tick reservoir virus interactions. The incidence of ASF has not only increased on the African continent over the last 15 years, so that it now affects West African countries, Mauritius and Madagascar, but it has also reached new areas, such as the Caucasus region in 2007. In fact, the rapid spread of the disease on the European continent and the uncontrolled situation in the Russian Federation places all countries at great risk as a result of intense global trade. The proximity of some affected areas to the European Union (EU) borders (<150 km) has increased concerns about the potential economic consequences of an ASF incursion into the EU pig sector. Establishing effective surveillance, control and eradication programmes that implicate all actors (veterinarians, farmers, and policy makers) is essential for controlling ASF. African swine fever ‐free countries should be aware of the potential risk of ASF incursion and implement risk reduction measures such as trade controls and other sanitary measures. This review will discuss lessons learnt so far about ASF control, current challenges to its control and future studies needed to support global efforts at prevention and control.

BackgroundAfrican 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.ResultsOut 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.ConclusionIn 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.

Despite the implementation of control efforts and funds to fight against the disease, African swine fever (ASF) has been present in Sardinia since 1978. It has caused serious problems for both the industrial pig sector and the regional authorities in Sardinia, as well as the economy of Italy and the European Union, which annually supports the costly eradication programme. During this time, ASF has persisted, especially in the central-east part of Sardinia where almost 75% of the total outbreaks are concentrated. The Sardinian pig sector is clearly divided into two categories based on the specialization and industrialization of production: industrial farms, which represents only 1.8% of the farms in the island and non-professional holdings, which are comprised of small producers (90% of pig holdings have <15 pigs) and apply little to no biosecurity measures. Additionally, illegally raised pigs are still bred in free-ranging systems in certain isolated parts of the island, despite strict regulations. The illegal raising of pigs, along with other high-risk management practices (e.g., use of communal areas) are likely the primary reasons for endemic persistence of the virus in this area. The compensation provided to the farmers, and other aspects of the eradication programme have also negatively influenced eradication efforts, indicating that socio-cultural and economic factors play an important role in the epidemiology of ASF on the island. The aim of this study was to comprehensively review the evolution of the 35-year presence of ASF in Sardinia, including control measures, and the environmental and socio-economic factors that may have contributed to disease endemicity on the island. The present review highlights the need for a coordinated programme that considers these socio-economic and environmental factors and includes an assessment of new cost-effective control strategies and diagnostic tools for effectively controlling ASF in Sardinia.

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