A Review of Risk Factors of African Swine Fever Incursion in Pig Farming within the European Union Scenario

Abstract

African swine fever (ASF) is a notifiable viral disease of pigs and wild boars that could lead to serious economic losses for the entire European pork industry. As no effective treatment or vaccination is available, disease prevention and control rely on strictly enforced biosecurity measures tailored to the specific risk factors of ASF introduction within domestic pig populations. Here, we present a review addressing the risk factors associated with different European pig farming systems in the context of the actual epidemiological scenario. A list of keywords was combined into a Boolean query, “African swine fever” AND (“Risk factors” OR “Transmission” OR “Spread” OR “Pig farming” OR “Pigs” OR “Wild boars”); was run on 4 databases; and resulted in 52 documents of interest being reviewed. Based on our review, each farming system has its own peculiar risk factors: commercial farms, where best practices are already in place, may suffer from unintentional breaches in biosecurity, while backyard and outdoor farms may suffer from poor ASF awareness, sociocultural factors, and contact with wild boars. In the literature selected for our review, human-related activities and behaviours are presented as the main risks, but we also stress the need to implement biosecurity measures also tailored to risks factors that are specific for the different pig farming practices in the European Union (EU).

The Context of Application of Biosecurity for Control of African Swine Fever in Smallholder Pig Systems: Current Gaps and Recommendations

“…Feeding strategies change depending on availability of feed resources, which also follow a seasonal pattern ( 9 , 34 , 75 ). It is worth noting that ASF can be perpetuated among permanently confined pigs through swill feeding ( 76 ). The virus can survive in chilled meat or carcasses for up to 6 months, and at 4°C for two years.…”

African Swine Fever Outbreak Investigation on Large Commercial Pig Farm in Serbia

“…There is a disinfection barrier on the farm entrance for all transportation vehicles and automatic sprayer with nozzles. According to the research of Bellini et al [18] and De Lorenzi [19], high levels of farm biosecurity including paying special attention to the disinfection process is considered as the most important tool for preventing ASF virus entering pig farms.…”

“…However, indirect (mechanical) ASF transmission of virus is realistic and possible to happen by people (there is a chance that clean and potentially dirty routes that people use can intersect) [11]. Another potential way to transmit the virus is through frequent feed unloading, where vehicles can contract the ASF virus when passing through the infected area near the farm [18].…”

African Swine Fever in Smallholder Sardinian Farms: Last 10 Years of Network Transmission Reconstruction and Analysis

“…In this document, pig farms are classified as non-commercial, commercial, and outdoor farms. As underlined by Bellini et al (28), this classification takes into account the commercial attitude of the holdings rather than the size of the farm or the type of establishment, thus making the application of most established biosecurity measures difficult (28)(29)(30). Furthermore, the last EFSA opinion on ASF and outdoor farming system underlines the lack of specific and harmonized system to categorize different types of pig farms (31).…”