The Risk of Infection by African Swine Fever Virus in European Swine Through Boar Movement and Legal Trade of Pigs and Pig Meat

Abstract

African swine fever (ASF) is currently spreading westwards throughout Europe and eastwards into China, with cases occurring in both wild boar and domestic pigs. A generic risk assessment framework is used to determine the probability of first infection with ASF virus (ASFV) at a fine spatial scale across European Union Member States. The framework aims to assist risk managers across Europe with their ASF surveillance and intervention activities. Performing the risk assessment at a fine spatial scale allows for hot-spot surveillance, which can aid risk managers by directing surveillance or intervention resources at those areas or pathways deemed most at risk, and hence enables prioritization of limited resources. We use 2018 cases of ASF to estimate prevalence of the disease in both wild boar and pig populations and compute the risk of initial infection for 2019 at a 100 km 2 cell resolution via three potential pathways: legal trade in live pigs, natural movement of wild boar, and legal trade in pig meat products. We consider the number of pigs, boar and amount of pig meat entering our area of interest, the prevalence of the disease in the origin country, the probability of exposure of susceptible pigs or boar in the area of interest to introduced infected pigs, boar, or meat from an infected pig, and the probability of transmission to susceptible animals. We provide maps across Europe indicating regions at highest risk of initial infection. Results indicate that the risk of ASF in 2019 was predominantly focused on those regions which already had numerous cases in 2018 (Poland, Lithuania, Hungary, Romania, and Latvia). The riskiest pathway for ASFV transmission to pigs was the movement of wild boar for Eastern European countries and legal trade of pigs for Western European countries. New infections are more likely to occur in wild boar rather than pigs, for both the pig meat and wild boar movement pathways. Our results provide an opportunity to focus surveillance activities and thus increase our ability to detect ASF introductions earlier, a necessary requirement if we are to successfully control the spread of this devastating disease for the pig industry.

Stability of African Swine Fever Virus in Carcasses of Domestic Pigs and Wild Boar Experimentally Infected with the ASFV “Estonia 2014” Isolate

“…Therefore, a series of studies have addressed the persistence of ASFV in pork products [ 5 ] including ham [ 6 , 7 , 8 , 9 ]. Given the high stability of ASFV in the environment, the concern about a further spread of ASF and its introduction into disease-free regions through contaminated pork products has risen [ 10 , 11 ].…”

Major swine viral diseases: an Asian perspective after the African swine fever introduction

“…Moreover, the back-yard and industrial farms are frequently found in close proximity to each other. This could be the major factor facilitating the faster spread of ASFV in Asian countries when compared with the European countries where wild boars play a major role in disease spread [2,3].…”

Genetic Analysis of African Swine Fever Virus From the 2018 Outbreak in South-Eastern Burundi

“…FIGURE 4 | Distribution of ASFV p72 genotype X isolates in the East African Community (EAC) between 1954 and 2018. 1 Rutana 2018 [domestic pig (Dp)]; 2 Muyinga 1990 (Dp); 3 Gitega 1984 (Dp); 4 Ngara 2016 (Dp); 5 Kigoma 2004 and 2015 (Dp); 6 Mwanza 2015 (Dp); 7 Longido 2009 (Dp); 8 Rombo 2013 (Dp); 9 Moshi 2013 (Dp); 10 Machame 2013 (Dp); 11 Arusha 2013 (Dp); 12 Babati 2016 (Dp); 13 Manyoni 2015 (Dp); 14 Kirawira 1968 [warthog (Wh)] and 1989 [Wh and tick (Tk)]; 15 Nyanza 2008 (Continued) FIGURE 4 | (Dp and Wh); 16 Nandi 2005 (Dp); 17 Nanyuki 1954 (Dp), 1959 (Dp and Wh), and 1961 (Dp); 18 Kiambu 2005 (Dp); 19 Kiganjo and Mweiga 1957 and 1959 (Wh); 20 Rift valley 1959 (Wh); 21 Machakos 2005 and 2009 (Tk); 22 SSembabule 1995 (Dp); 23 Lake Mburu national park 2010 (Tk). The isolates from Kenya in 1950 (Kenya 1950) and Uganda in 1964 (Ug64) are not indicated on the map, because their locations are not mentioned in the available literature.…”

“…ASF has neither a cure nor a vaccine, and its effective control relies on quarantine, stamping out, and strict biosecurity measures (9,10). ASF is endemic in many African countries south of the Sahara and in Sardinia (Italy), and in recent years, it has spread beyond its traditional geographical boundaries to the Caucasus region, the European Union, and Asia (11)(12)(13)(14). The recent spread to China, which is the major pork-producing country, is threatening global food security (15,16).…”