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A risk assessment was organized during the early EU ASF outbreaks of early 2014 (February-April) and performed in cooperation with 15 Belgian and European experts on ASFV and its epidemiology in pigs/wild boar. African swine fever ( ASF) is considered as one of the most dangerous infectious pig diseases, causing many outbreaks. Since the end of 2013 - early 2014, several outbreaks within the European Union (Lithuania, Poland, Estonia and Latvia) were reported to OIE, which prompted several risk assessments by (inter)national bodies and scientists. In this study, the open source, semiquantitative Pandora risk assessment tool was used for a quick overall screening of the risk posed by ASF to Belgium early 2014. A set of integrated risk scores was calculated within the Pandora framework. Experts scored the questions and uncertainty levels in the Pandora modules individually, after which the calculations were performed and averaged scores were used within pre-defined risk scales to define and visualize the ASF risk to Belgium. Emergence risk was considered low (Pandora score 0.29), while disease consequences were deemed high (0.93); the resulting multiplicative overall risk of ASFV for Belgium was low (0.27). The Belgian experts tended to give lower risk scores than the European experts, especially for entry risk and trade/public opinion consequences. These risk scores are further interpreted with a due consideration of the qualitative data in the expert remarks and of other ASF risk assessments. The results are similar to more extensive and elaborate risk assessment models/procedures which may require more time and resources. The Pandora tool allows sequential updates to monitor (rates of) increasing risk and provides information for risk managers to organize targeted control. [ABSTRACT FROM AUTHOR]

The outbreak of infectious diseases in swine, such as classical swine fever (CSF), has become a significant concern in the pig‐farming industry. In Japan, after the re‐emergence of CSF in 2018, farms are now exposed to the risk of transmission from infected wild boar and CSF‐contaminated farms. This study aimed to identify biosecurity measures that were effective for the prevention of CSF introduction into farms during the period from the beginning of the CSF epidemic to the implementation of a vaccination campaign for domestic pigs at risk. The probability of virus introduction was assumed to be increased by the elevated risk from CSF‐infected wild boar and infected farms around the farm. The risk from infected wild boar was represented by the prevalence of CSF in wild boar or the occupancy of 1‐km grid cells with infected wild boar within 10‐km radii from a pig farm and the occurrence of CSF outbreaks on neighboring farms. Conversely, the probability of virus introduction was assumed to decrease in response to on‐farm biosecurity measures being implemented on each farm. The implementation of biosecurity measures on the farms and farm attributes were obtained through a questionnaire survey. Analyses were performed on each farm under the weekly situations where infected wild boar were both absent and present in the vicinity using a binomial generalized linear model. On farms where infected wild boar were not present around farms, daily washing and disinfecting of work clothing in pig houses was identified as the main measure to reduce the risk of CSF introduction into farms. On farms with infected wild boar in the vicinity, the absence of public roads on the farm and preventing wildlife intrusion into the areas where pig carcasses were stored were demonstrated to be effective in preventing CSF introduction. Based on the assumption that strict and comprehensive biosecurity measures are required to prevent CSF introduction, the implementation of these potentially effective measures is worth being prioritized. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is one of the most severe diseases of pigs, with drastic impact on pig industry. Wild boar populations play the role of ASF virus epidemiological reservoir. No effective and safe ASF vaccine is available, yet, but a future vaccine will not be 100% effective and will provide protection for no more than a few months. We present an individual-based spatially explicit model of wild boar demography and ASF epidemiology, allowing to simulate a vaccination campaign. We tested how many animals should be vaccinated in relation to vaccine efficacy and to the duration of vaccine protection. We estimated how these parameters will affect ASF eradication probabilities. We also assessed how partial vaccination will interact with a series of ecological, epidemiological, and management-related factors linked to ASF persistence. In the case of a highly effective vaccine with short duration, eradication chances were generally low, and the virus disappeared only when simulating a high effort (2.5 vaccinated wild boars/km2). A vaccine with low efficacy and long duration was even less effective in eradicating the ASFV, as none of the simulated scenarios provided acceptable eradication rates. Our results indicate that, under realistic conditions, vaccination against the ASF genotype II virus cannot be seen as an effective stand-alone tool for eradication. Its use should be integrated into a more comprehensive strategy, making use of all the available management tools, such as density control through hunting and carcass removal. If the vaccine will exhibit 12 months or longer duration of its protection, splitting the vaccination effort into two or three bait distribution campaigns during the year will be a feasible option. If the vaccine will exhibit a duration of its immunization significantly shorter than 1 year, a single distribution at the end of winter will maximize the probability of eradication. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is one of the most severe suid diseases, impacting the pig industry and wild suid populations. Once an ASF vaccine is available, identifying a sufficient density of vaccination fields will be crucial to achieve eradication success. In 2020–2023, we live-trapped and monitored 27 wild boars in different areas of Lithuania, in which the wild boars were fed at artificial stations. We built a simulation study to estimate the probability of a successful ASF vaccination as a function of different eco-epidemiological factors. The average 32-day home range size across all individuals was 16.2 km2 (SD = 16.9). The wild boars made frequent visits of short durations to the feeding sites rather than long visits interposed by long periods of absence. A feeding site density of 0.5/km2 corresponded to an expected vaccination rate of only 20%. The vaccination probability increased to about 75% when the feeding site density was 1.0/km2. Our results suggest that at least one vaccination field/km2 should be used when planning an ASF vaccination campaign to ensure that everyone in the population has at least 5–10 vaccination sites available inside the home range. Similar studies should be conducted in the other ecological contexts in which ASF is present today or will be present in the future, with the objective being to estimate a context-specific relationship between wild boar movement patterns and an optimal vaccination strategy. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is one of the most important and serious contagious hemorrhagic viral diseases affecting domestic pigs and wild boar and is associated with high mortality rates while also having an extensive sanitary and socioeconomic impact on the international trade of animal and swine products. The early detection of the disease is often hampered by inadequate surveillance. Among the surveillance strategies used, passive surveillance of wild boars is considered the most effective method for controlling the African swine fever virus (ASFV). Otherwise, the design of a sufficiently sensitive ASF surveillance system requires a solid understanding of the epidemiology related to the local eco-social context, especially in the absence of virus detection. Even if the number of carcasses needed to demonstrate ASF eradication has been established, the scientific context lacks detail compared to protocols applied in the active search for wild boar carcasses. The aim of this study was to describe the protocol applied in the active search for carcasses, providing detailed information on the number of people and dogs as well as the amount of time and space used within the Mediterranean area. Using a specific tool developed to record, trace, and share field data (the GAIA observer app), a total of 33 active searches for wild boar carcasses were organized during 2021–2023. Most of these searches were planned to find carcasses that had previously been reported by hunters. A total of 24 carcasses were found, with only 2 carcasses not previously reported. The final protocol applied involved four people, with an average speed of 1.5 km/h. When a carcass had been previously reported, about 2 km of distance had to be covered in about 1.5 h to find the carcass, and even less time was spent when a dog (untrained) was present. In conclusion, it can be stated that, when searching for carcasses, solid collaboration with local hunters or other forest visitors is necessary to ensure carcasses are reported. The process involves small groups of experts actively searching for carcasses, possibly with the use of hunting dogs without special training. The data presented could be of valid support for those countries characterized by Mediterranean vegetation that are faced with the need to plan active carcass searches. [ABSTRACT FROM AUTHOR]

Classical swine fever (CSF) is a highly contagious transboundary viral disease of domestic and wild pigs. Despite mass vaccination and continuous eradication programs, CSF remains endemic in Asia, some countries in Europe, the Caribbean and South America. Since June 2013, Northern Colombia has reported 137 CSF outbreaks, mostly in backyard production systems with low vaccination coverage. The purpose of this study was to characterize the virus responsible for the outbreak. Phylogenetic analysis based on the full-length E2 sequence shows that the virus is closely related to CSF virus (CSFV) genotype 2.6 strains circulating in Southeast Asia. The pathotyping experiment suggests that the virus responsible is a moderately virulent strain. The 190 nucleotide stretch of the E2 hypervariable region of these isolates also shows high similarity to the CSFV isolates from Colombia in 2005 and 2006, suggesting a common origin for the CSF outbreaks caused by genotype 2.6 strains. The emergence of genotype 2.6 in Colombia suggests a potential transboundary spread of CSFV from Asia to the Americas, complicating the ongoing CSF eradication efforts in the Americas, and emphasizes the need for continuous surveillance in the region. [ABSTRACT FROM AUTHOR]

Classical swine fever (CSF) remains one of the most economically significant viral diseases affecting domestic pigs and wild boars worldwide. To develop a safe and effective vaccine against CSF, we have constructed a triple gene-deleted pseudorabies virus (PRVtmv)-vectored bivalent subunit vaccine against porcine circovirus type 2b (PCV2b) and CSFV (PRVtmv+). In this study, we determined the protective efficacy of the PRVtmv+ against virulent CSFV challenge in pigs. The results revealed that the sham-vaccinated control group pigs developed severe CSFV-specific clinical signs characterized by pyrexia and diarrhea, and became moribund on or before the seventh day post challenge (dpc). However, the PRVtmv+-vaccinated pigs survived until the day of euthanasia at 21 dpc. A few vaccinated pigs showed transient diarrhea but recovered within a day or two. One pig had a low-grade fever for a day but recovered. The sham-vaccinated control group pigs had a high level of viremia, severe lymphocytopenia, and thrombocytopenia. In contrast, the vaccinated pigs had a low–moderate degree of lymphocytopenia and thrombocytopenia on four dpc, but recovered by seven dpc. Based on the gross pathology, none of the vaccinated pigs had any CSFV-specific lesions. Therefore, our results demonstrated that the PRVtmv+ vaccinated pigs are protected against virulent CSFV challenge. [ABSTRACT FROM AUTHOR]

The native Eurasian wild boar (Sus scrofa) is a relevant wildlife host for African swine fever (ASF) virus, contributing to infection maintenance and spread and representing a challenge for disease control. Combining published scientific evidence with expert opinion, we provide an updated global overview of ASF control in wild boar and feral pigs in different epidemiological scenarios. We synthesize current knowledge on key background aspects of wild boar ecology and management and on ASF epidemiology in wild boar and their relative, the feral pig. We propose that establishing a proper surveillance and monitoring scheme is a requisite for disease control in wildlife and that ASF and wild boar should be monitored in an integrated way, considering the changes in the host population as well as the spatial spread and temporal distribution of disease indicators, to make possible a critical assessment of the impact of interventions. The main body of the manuscript reviews the intervention options and ASF control attempts and their outcomes in different epidemiological situations from peacetime to endemicity. Current ASF control in wild boar relies on three essential tools: carcass destruction, wild boar culling, and fencing. The experience gained since the onset of the ongoing ASF pandemic shows that certain combinations of interventions can slow down ASF spread and eventually succeed in ASF eradication in wild boar, at least after point introductions. Several strengths and weaknesses of these strategies are identified. [ABSTRACT FROM AUTHOR]

Despite Brucella suis biovar 2's (BSB2) active circulation in wildlife, no canine infections have been reported. The present paper is the first to describe two cases of BSB2 infections in French dogs. The first case occurred in 2020 and concerned a 13-year-old male neutered Border Collie with clinical signs of prostatitis. The urine culture revealed the excretion of significant levels of Brucella in the sample. The second case concerned a German Shepherd with bilateral orchitis, in which it was possible to detect Brucella colonies following neutering. HRM-PCR and classical biotyping methods classified both isolated strains as BSB2, in contrast to expected B. canis, which is usually the etiological agent of canine brucellosis in Europe. The wgSNP and MLVA analyses highlighted the genetic proximity of two isolates to BSB2 strains originating from wildlife. No pig farms were present in the proximity of either dog's residence, ruling out potential spill over from infected pigs. Nevertheless, the dogs used to take walks in the surrounding forests, where contact with wildlife (i.e., wild boars or hares, or their excrements) was possible. These cases highlight the importance of adopting a One Health approach to control the presence of zoonotic bacteria in wild animals and avoid spillovers into domestic animals and, potentially, humans. [ABSTRACT FROM AUTHOR]

In a previous study, a semi-quantitative risk assessment was developed to rank pig holdings in terms of likelihood of introducing African swine fever virus (ASFV) by assessing their compliance with biosecurity and exposure to geographical risk factors. The method was initially developed for confined pig holdings, but given that ASF is endemic in wild boar of several countries, we modified the approach to make it suitable for free-range farms as well. In the current study, a total of 41 outdoor pig farms were assessed in an area where exposure to wild boar was generally high (density from 2.3 to 10.3 wild boar per Km2). As expected, non-compliance with biosecurity measures was frequent in outdoor farms, and the frequency of non-compliance indicated that the absence of adequate separation of pigs from the external environment was the major weakness in the farms assessed. In 46.3% of them, there was no fence or, if present, it was not adequate to avoid contact with wild boar. However, the approach adopted proved to be suitable for identifying intervention priorities to mitigate the risk of ASFV spread in free-range pig herds and for identifying the weaknesses of individual farms, as recommended by EFSA in 2021, which suggests implementing tools to improve biosecurity by favoring higher-risk farms. [ABSTRACT FROM AUTHOR]

Background. DNA of African swine fever virus (ASFV) has previously been detected in hematophagous insects on ASF outbreak farms. However, it remains unclear whether the viral DNA derived from blood meals that originated from pigs on the outbreak farm or was introduced from infected domestic pigs or wild boar sources located outside of the outbreak farm. Methods. We caught 644 hematophagous insects on the windows at two non-outbreak high-biosecurity pig farms (i.e., without ASFV-infected pigs) using plastic meshes coated with sticky glue, as well as 3576 hematophagous insects using H-traps on or around the farms. Using PCR analyses, we identified which insects were present, whether these hematophagous insects carried blood from an external (exogenous) source and if the blood contained ASFV DNA. Results. We found blood meals with ASFV DNA in one pool of five Haematopota spp. in the H-traps. From the window traps, we found 0–2.7% of Haematopota spp., Stomoxys calcitrans, and Aedes spp. carrying blood meals from exogenous sources into the farms. Some insects carried bovine blood; the closest registered source for this was 2500m from the pig farm. Conclusion. Hematophagous insects carrying ASFV-positive blood meals or blood meals from exogenous sources seem to be attracted to high-biosecurity pig farms and attempt to enter them through their windows. Despite the small percentage of insects carrying blood and the small amounts carried by each insect, the large numbers of insects result in a sufficient volume of exogenous blood, potentially containing ASFV, to constitute a non-negligible risk for ASFV-introduction into unprotected pig stables. This study is the first to provide quantitative data on the number of hematophagous insects trying to enter high-biosecurity pig farms. It is also the first to provide information about the origin of their blood meals, indicating that insect-borne introduction of blood containing ASFV into high-biosecurity pig farms is possible and, therefore, could potentially be responsible for some of the outbreaks observed during the summer peaks of infection. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a viral hemorrhagic disease affecting domestic and wild suids, with catastrophic socioeconomic impact worldwide. In the European scenario, wild boar (Sus scrofa) actively contributes to the maintenance and spread of the disease. In this study, we applied a multivariate clustering method to define ecoregions in the western Palearctic realm based on ecological and sanitary aspects of ASF in wild boar. Beforehand, we performed a principal components analysis for the eight selected variables. An analysis of the countries was carried out in terms of the extent of ecoregions and ASF notifications. After clustering, we identified nine eco-regions that showed important differences based on the used eco-sanitary variables. Several ecoregions stand out in the country and notification analysis for retaining the most ASF cases and being present in their surrounding locations. Here, we developed a cartographical tool to understand patterns in the distribution and spread of ASF in wild boar at the European level, as well as improve prevention, control, surveillance plans, and eradication strategies, especially future vaccination programs once a safe and effective vaccine is available. [ABSTRACT FROM AUTHOR]

African Swine Fever (ASF) is persistently spreading and hindering pork production in Europe. Slovenia is one of the last countries in Central Europe without a confirmed ASF case in domestic pigs or in wild boar. The aim of this study was to assess the current biosecurity implementation on different types of pig farms. Internal and external biosecurity status was determined in 17 commercial (CF), 15 non-commercial (NC), and 15 outdoor (O) farms. Data were collected using the Biocheck.UGent questionnaire and assessed in combination with the latest information on the wild boar population in Slovenia. Biosecurity was compared between farm types based on the assessment of 12 subcategories. Statistically significant differences (p < 0.05) were found in six subcategories: (i) purchase of pigs and semen, (ii) visitors and farmworkers, (iii) vermin and bird control, (iv) finishing unit, (v) measures between compartments and use of equipment, and (vi) cleaning and disinfection. The highest total biosecurity score (0–100%) was determined on CF with 64.59 ± 16.47%, followed by NC with 55.73 ± 10.67%, and O with 48.47 ± 8.20%. The density of the wild boar population was estimated from the number of wild boars per km2 per year, with 3 or more hunted wild boars per unit representing the highest density. Geolocation of farms on the wild boar population map showed that two O farms are at high risk and seven farms (1 O, 5 NC, and 1 CF) are at medium risk for disease transmission from wild to domestic pigs. Biosecurity measures must be tightened in some subcategories, especially in areas with a high density of wild boar. [ABSTRACT FROM AUTHOR]

In September 2018, classical swine fever (CSF) reemerged in Japan after more than a quarter of a century. After the first notification on a pig farm, wild boars positive for CSF were found continuously in the surrounding area. Gifu was the first prefecture in Japan to disseminate oral vaccines to wild boars in March 2019, with vaccines spread to approximately 14,000 sites between 2019 and 2020. While these diligent measures seemed to have shown some effectiveness, several vaccine spray sites remained without wild boar emergence. Based on the vaccine dissemination records from these periods, this study conducted a statistical analysis to propose more effective vaccine dissemination sites. First, a generalized linear mixed model was used to identify factors correlated with wild boar emergence. Then, two spatial interpolation methods, inverse distance weighted (IDW) and Kriging, were adopted to create a probability map of wild boar emergence for the entire Gifu Prefecture. The analysis showed a positive correlation between wild boar emergence and the appearance of raccoons, raccoon dogs, and crows as well as road density and wild boar distribution index. In particular, raccoon (OR: 1.83, 95%CI: 1.25–2.68, p < 0.001), raccoon dog (OR: 1.81, 95%CI: 1.25–2.66, p < 0.001), and medium level road density (OR: 1.56, 95%CI: 1.04–2.39, p = 0.04) were strongly correlated with wild boar emergence. The spatial interpolation approach resulted in better prediction accuracy for the Kriging method than for IDW by the root mean square error, but both approaches identified a high wild boar appearance probability area in southeastern Gifu and a low appearance probability area in central Gifu. Here we have demonstrated a tool to effectively disperse oral vaccine to wildlife. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a contagious viral disease of suids that induces high mortality in domestic pigs and wild boars. Given the current spread of ASF, the development of a vaccine is a priority. During an attempt to inactivate the Georgia 2007/1 strain via heat treatment, we fortuitously generated an attenuated strain called ASFV-989. Compared to Georgia, the ASFV-989 strain genome has a deletion of 7458 nucleotides located in the 5′-end encoding region of MGF 505/360, which allowed for developing a DIVA PCR system. In vitro, in porcine alveolar macrophages, the replication kinetics of the ASFV-989 and Georgia strains were identical. In vivo, specific-pathogen-free (SPF) pigs inoculated with the ASFV-989 strain, either intramuscularly or oronasally, exhibited transient hyperthermia and slightly decreased growth performance. Animals immunized with the ASFV-989 strain showed viremia 100 to 1000 times lower than those inoculated with the Georgia strain and developed a rapid antibody and cell-mediated response. In ASFV-989-immunized pigs challenged 2 or 4 weeks later with the Georgia strain, no symptoms were recorded and no viremia for the challenge strain was detected. These results show that the ASFV-989 strain is a promising non-GMO vaccine candidate that is usable either intramuscularly or oronasally. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a lethal haemorrhagic disease of Suidae, present in Poland since 2014. The natural reservoir of ASF in Europe is the wild boar (Sus scrofa); however, human activity facilitates long-distance introductions of the disease. In ASF control it is important to identify areas at increased risk of infection. Such identification and estimation of the disease's progress and subsequent spread will help to identify the specific preventive action needs in given zones. Serving this purpose, this study is a spatial and statistical analysis of ASF spread through noted outbreak data. The spatial-temporal analysis was conducted on the basis of data including the time and location of all ASF outbreaks both in wild boars and domestic pigs in Poland in 2014–2021. The analysis indicates possible routes and directions for further ASF spread in Poland, estimates the annual increase of the affected area (approx. 25,000 km2 every year since 2017) and marks trends. The strong method-independent correlation between the year and the surface area affected by African swine fever indicated a near-linear generalised trend. Given the growth trend, we can expect ASF to expand further into new territories of the country; however, it is important to realise that there is still a significant area to protect, because 60% of Poland remains ASF-free. [ABSTRACT FROM AUTHOR]

Simple Summary: Classical swine fever is a highly contagious disease that infects both domestic pigs and wild boars. Classical swine fever virus (CSFV) has not been detected in domestic pigs in South Korea since 2016, but has been increasing in wild boars since 2017. Two cases of CSFV subgenotype 2.1d were detected in wild Korean boars in 2011, but then no cases were detected until 2016; however, 16 cases of CSFV were detected between 2017 and 2019. In this study, we report seven CSFV-positive samples obtained from wild boars in 2020. In addition, although 13 mtDNA haplotypes were detected in wild boars in South Korea, all 25 cases of CSFV that occurred in wild boars between 2011 and 2020 were detected in animals with haplotype 01. Classical swine fever virus (CSFV) is one of the major pathogens that causes severe economic damage to the swine industry. Circulation of CSFV in wild boars carries the potential risk of reintroducing the virus into CSFV-free pig farms. This study carried out a genetic analysis of CSFV isolates from wild boars and analyzed the mtDNA haplotypes of the wild boars. Blood samples (n = 2140) from wild Korean boars captured in 2020 were subjected to qRT-PCR to detect CSFV, which was classified as subgenotype 2.1d based on phylogenetic analysis. CSFV had been detected in wild boars only in northern regions (Gangwon and Gyeonggi) of South Korea between 2011 and 2019. However, CSFV was identified in wild boars in the more southern regions (Chungbuk and Gyeongbuk) in 2020. Based on mitochondrial DNA analysis, all wild boars with CSFV were haplotype 01 (H01). Thus, we presume that the H01 haplotype is more susceptible to CSFV. In the future, infection of wild boars by CSFV is expected to occur intermittently every year, and we predict that most wild boars infected with CSFV will be haplotype H01. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is an internationally-spreading viral pig disease that severely damages agricultural pork production and trade economy as well as social welfare in disease-affected regions. A comprehensive understanding of ASF risk factors is imperative for efficient disease control. As the absence of effective ASF vaccines limits disease management options, the identification and minimisation of ASF-associated risk factors is critical to preventing ASF outbreaks. Here, we compile currently known potential ASF risk factors identified through a systematic literature review. We found 154 observation-based and 1239 potential ASF risk factors, which we were able to group into the following defined risk categories: 'ASF-virus', 'Biosecurity', 'Disease control', 'Environment', 'Husbandry', 'Movement', 'Network', 'Pig', 'Society' and 'Surveillance'. Throughout the epidemiological history of ASF there have been similar risk categories, such as 'Environment'-related risk factors, predominantly reported in the literature irrespective of the ASF situation at the time. While ASF risk factor reporting has markedly increased since 2010, the majority of identified risk factors overall have referred to domestic pigs. The reporting of risk factors for ASF in wild boar mostly commenced from 2016 onwards. The compendium of ASF risk factors presented herein defines our current knowledge of ASF risk factors, and critically informs ASF-related problem solving. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a pandemic threat to the global pig industry and wild suids. A safe and efficacious vaccine could monumentally assist in disease eradication. In the past years, promising live attenuated vaccine candidates emerged in proof-of-concept experiments, among which was "ASFV-G-∆MGF". In our study, we tested the vaccine candidate in three animal experiments intramuscularly in domestic pigs and orally in wild boar. Further, a macrophage-grown vaccine virus and a virus grown on permanent cells could be employed. Irrespective of the production system of the vaccine virus, a two-dose intramuscular immunization could induce close-to-sterile immunity with full clinical protection against challenge infection. After oral immunization, 50% of the vaccinees seroconverted and all responders were completely protected against subsequent challenge. All nonresponders developed ASF upon challenge with two acute lethal infections and two mild and transient courses. The latter results show a lower efficiency after oral administration that would have to be taken into consideration when designing vaccination-based control measures. Overall, our findings confirm that "ASFV-G-∆MGF" is a most promising vaccine candidate that could find its way into well-organized and controlled immunization campaigns. Further research is needed to characterize safety aspects and define possible improvements of oral efficiency. [ABSTRACT FROM AUTHOR]

Background: African swine fever (ASF) is a lethal hemorrhagic disease affecting domestic pigs resulting in up to 100% mortality rates caused by the ASF virus (ASFV). The locally-adapted pigs in South-western Kenya have been reported to be resilient to disease and harsh climatic conditions and tolerate ASF; however, the mechanisms by which this tolerance is sustained remain largely unknown. We evaluated the gene expression patterns in spleen tissues of these locally-adapted pigs in response to varying infective doses of ASFV to elucidate the virus-host interaction dynamics. Methods: Locally adapted pigs (n = 14) were experimentally infected with a high dose (1x106HAD50), medium dose (1x104HAD50), and low dose (1x102HAD50) of the highly virulent genotype IX ASFV Ken12/busia.1 (Ken-1033) isolate diluted in PBS and followed through the course of infection for 29 days. The in vivo pig host and ASFV pathogen gene expression in spleen tissues from 10 pigs (including three from each infective group and one uninfected control) were analyzed in a dual-RNASeq fashion. We compared gene expression between three varying doses in the host and pathogen by contrasting experiment groups against the naïve control. Results: A total of 4954 differentially expressed genes (DEGs) were detected after ASFV Ken12/1 infection, including 3055, 1771, and 128 DEGs in the high, medium, and low doses, respectively. Gene ontology and KEGG pathway analysis showed that the DEGs were enriched for genes involved in the innate immune response, inflammatory response, autophagy, and apoptosis in lethal dose groups. The surviving low dose group suppressed genes in pathways of physiopathological importance. We found a strong association between severe ASF pathogenesis in the high and medium dose groups with upregulation of proinflammatory cytokines and immunomodulation of cytokine expression possibly induced by overproduction of prostaglandin E synthase (4-fold; p < 0.05) or through downregulation of expression of M1-activating receptors, signal transductors, and transcription factors. The host-pathogen interaction resulted in induction of expression of immune-suppressive cytokines (IL-27), inactivation of autophagy and apoptosis through up-regulation of NUPR1 [5.7-fold (high dose) and 5.1-fold (medium dose) [p < 0.05] and IL7R expression. We detected repression of genes involved in MHC class II antigen processing and presentation, such as cathepsins, SLA-DQB1, SLA-DOB, SLA-DMB, SLA-DRA, and SLA-DQA in the medium and high dose groups. Additionally, the host-pathogen interaction activated the CD8+ cytotoxicity and neutrophil machinery by increasing the expression of neutrophils/CD8+ T effector cell-recruiting chemokines (CCL2, CXCL2, CXCL10, CCL23, CCL4, CXCL8, and CXCL13) in the lethal high and medium dose groups. The recovered pigs infected with ASFV at a low dose significantly repressed the expression of CXCL10, averting induction of T lymphocyte apoptosis and FUNDC1 that suppressed neutrophilia. Conclusions: We provide the first in vivo gene expression profile data from locally-adapted pigs from south-western Kenya following experimental infection with a highly virulent ASFV genotype IX isolate at varying doses that mimic acute and mild disease. Our study showed that the locally-adapted pigs induced the expression of genes associated with tolerance to infection and repression of genes involved in inflammation at varying levels depending upon the ASFV dose administered. [ABSTRACT FROM AUTHOR]

The aim of this study was to develop a multiplex bead assay using a Brucella rLPS antigen, a Brucella suis smooth antigen, and a Yersinia enterocolitica O:9 antigen that not only discriminates Brucella-infected from Brucella-uninfected pigs and wild boar, but also overcomes the cross reactivity with Y. enterocolitica O:9. Sera from 126 domestic pigs were tested: 29 pigs were Brucella infected, 80 were non-infected and 17 were confirmed to be false positive serological reactors (FPSR). Sera from 49 wild boar were tested: 18 were positive and 31 were negative. Using the rLPS antigen, 26/29 Brucella-infected domestic pigs and 15/18 seropositive wild boar were positive, while 75/80 non-Brucella infected domestic pigs, all FPSR, and all seronegative wild boar were negative. Using the smooth B. suis 1330 antigen, all Brucella-infected domestic pigs, 9/17 FPSR and all seropositive wild boar were positive, while all non-infected pigs and 30/31 seronegative wild boar were negative. The ratio of the readouts from the smooth B. suis antigen and Y. enterocolitica O:9 antigen enabled discriminating all Brucella infected individuals from the FPSR domestic pigs. These results demonstrate the potential of this assay for use in the surveillance of brucellosis, overcoming the cross-reactivity with Y. enterocolitica. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a devastating disease, resulting in the high mortality of domestic and wild pigs, spreading quickly around the world. Ensuring the prevention and early detection of the disease is even more crucial given the absence of licensed vaccines. As suggested by the European Commission, those countries which intend to provide evidence of freedom need to speed up passive surveillance of their wild boar populations. If this kind of surveillance is well-regulated in domestic pig farms, the country-specific activities to be put in place for wild populations need to be set based on wild boar density, hunting bags, the environment, and financial resources. Following the indications of the official EFSA opinion 2021, a practical interpretation of the strategy was implemented based on the failure probabilities of wrongly declaring the freedom of an area even if the disease is still present but undetected. This work aimed at providing a valid, applicative example of an exit strategy based on two different approaches: the first uses the wild boar density to estimate the number of carcasses need to complete the exit strategy, while the second estimates it from the number of wild boar hunted and tested. A practical free access tool, named WBC-Counter, was developed to automatically calculate the number of needed carcasses. The practical example was developed using the ASF data from Sardinia (Italian island). Sardinia is ASF endemic from 43 years, but the last ASFV detection dates back to 2019. The island is under consideration for ASF eradication declaration. The subsequent results provide a practical example for other countries in approaching the EFSA exit strategy in the best choices for its on-field application. [ABSTRACT FROM AUTHOR]

Since the introduction of African swine fever (ASF) to Georgia in 2007, the disease has spread to many other countries including South Korea. Initial detection of ASF from wild boars (WB) in South Korea was reported in early October 2019. Since then, more than a thousand WB samples collected from the northern part of the country have been confirmed as ASF positive (2.9% of ASF positivity among WB samples collected until June 2020), indicating that the disease is endemic in the WB populations. To control the disease, multiple layers of fence‐lines have been erected. Nevertheless, outbreaks continuously occurred across the fence, requiring a better understanding of the spatial transmission mechanism of ASF in WBs. Hence, we developed a novel ASF transmission model to estimate ecological and epidemiological parameters related to the spread of the disease in the WB population of South Korea. The results showed that roads and rivers were effective to prevent the spread, reducing the transmission rate to approximately 37% on average. Only a limited level of reduction was indicated via fence‐lines, implying erection of fences might be considered as a temporary measure to delay the spread. This study also revealed that the probability of ASF transmission to adjacent habitats considerably decreased with increasing distance, supporting the slow spatial transmission speed reported from other European countries. Considering that elucidation of ASF dynamics in WB is crucial to mitigate the impact of the disease, we believe this study provides some useful ecological and epidemiological implications to control the disease in future. [ABSTRACT FROM AUTHOR]

This report provides a descriptive analysis of the African swine fever (ASF) Genotype II epidemic in the affected Member States in the EU and two neighbouring countries for the period from 1 September 2020 to 31 August 2021. ASF continued to spread in wild boar in the EU, it entered Germany in September 2020, while Belgium became free from ASF in October 2020. No ASF outbreaks in domestic pigs nor cases in wild boar have been reported in Greece since February 2020. In the Baltic States, overall, there has been a declining trend in proportions of polymerase chain reaction (PCR)‐positive samples from wild boar carcasses in the last few years. In the other countries, the proportions of PCR‐positive wild boar carcasses remained high, indicating continuing spread of the disease. A systematic literature review revealed that the risk factors most frequently significantly associated with ASF in domestic pigs were pig density, low levels of biosecurity and socio‐economic factors. For wild boar, most significant risk factors were related to habitat, socio‐economic factors and wild boar management. The effectiveness of different control options in the so‐named white zones, areas where wild boar densities have been drastically reduced to avoid further spread of ASF after a new introduction, was assessed with a stochastic model. Important findings were that establishing a white zone is much more challenging when the area of ASF incursion is adjacent to an area where limited control measures are in place. Very stringent wild boar population reduction measures in the white zone are key to success. The white zone needs to be far enough away from the affected core area so that the population can be reduced in time before the disease arrives and the timing of this will depend on the wild boar density and the required population reduction target in the white zone. Finally, establishing a proactive white zone along the demarcation line of an affected area requires higher culling efforts, but has a higher chance of success to stop the spread of the disease than establishing reactive white zones after the disease has already entered in the area. This publication is linked to the following EFSA Journal article: http://onlinelibrary.wiley.com/doi/10.2903/sp.efsa.2022.EN-7320/full [ABSTRACT FROM AUTHOR]

Since the introduction in Georgia in 2007 of an African swine fever (ASF) genotype 2 virus strain, the virus has rapidly spread to both Western European and Asian countries. It now constitutes a major threat for the global swine industry. The ongoing European transmission cycle has been related to the 'wild boar habitat' with closed transmission events between wild boar populations and incidental spillovers to commercial and non‐commercial (backyard) pig holdings. During the epidemic in Belgium, only wild boar were infected and although the introduction route has not yet been elucidated, the 'human factor' is highly suspected. While ASF was successfully contained in a small region in the Southern part of Belgium without affecting domestic pigs, the risk of spillover at the wild/domestic interface remains poorly assessed. In this study, we used a semi‐quantitative method, involving national and international experts, to assess the risk associated with different transmission routes for ASF introduction from wild boar to domestic pig holdings and subsequent dissemination between holdings in the Belgian epidemiological context. Qualitative responses obtained by our questionnaire were numerically transformed and statistically processed to provide a semi‐quantitative assessment of the occurrence of the hazard and a ranking of all transmission routes. 'Farmer', 'bedding material', 'veterinarian' and 'professionals from the pig sector' were considered as the most important transmission routes for ASF introduction from the wild reservoir to pig holdings. 'Animal movements', 'farmer', 'veterinarian', 'iatrogenic', 'animal transport truck' and 'animal care equipment' were considered as the most important transmission routes posing a risk of ASF spread between pig holdings. Combined with specific biosecurity checks in the holdings, this assessment helps in prioritizing risk mitigation measures against ASF introduction and further spread in the domestic pig industry, particularly while the ASF situation in Western Europe is worsening. [ABSTRACT FROM AUTHOR]

A mathematical model is developed and analysed to examine the impacts of African swine fever (ASF) introduction into a wild boar population that supports endemic animal tuberculosis (TB). TB is a widespread infectious disease caused by the Mycobacterium tuberculosis bacteria belonging to the Mycobacterium tuberculosis complex (MTC) that can persist in reservoir wildlife hosts. Wild boar (sus scrofa) are a key reservoir for MTC, and an increasing trend in wild boar density is expected to lead to an increase in TB prevalence with spill‐over to livestock. MTC infection is presently controlled through a variety of strategies, including culling. African swine fever (ASF) is a virulent, viral infection which affects wild boar and is spreading across Eurasia and Oceania. ASF infection leads to near 100% mortality at the individual level, can cause a dramatic decrease in population density and may therefore lead to TB control. We extend an established model that captures the key demographic and infection processes for TB in wild boar to consider the impact of ASF introduction on wild boar populations that support different levels of endemic TB. Our model results indicate that an ASF infection will reduce wild boar population density and lead to a decrease in the prevalence of TB. If ASF persists in the local host population the model predicts the long‐term decline of TB prevalence in wild boar. If ASF is eradicated, or fades‐out in the local host population, the model predicts a slower recovery of TB prevalence in comparison to wild boar density after an ASF epidemic. This may open a window of opportunity to apply TB management to maintain low TB prevalence. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is a highly pathogenic viral disease affecting all Suidae, with Ornithodoros moubata complex soft ticks acting as the biological arthropod vectors of the causative agent, African swine fever virus (ASFV). While ASFV is also transmissible via direct contact, pig products and fomites, other arthropods may be involved in virus transmission and persistence. Therefore, we checked various groups of blood‐feeding arthropods collected during summer 2017 in wild boar habitats on the Estonian Island of Saaremaa for the presence of ASFV. Saaremaa had the highest ASF infection prevalences in Estonia in 2017, with an incidence of 9% among hunted wild boar. In addition to ASFV, we tested for other selected pathogens. In total, 784 ticks, 6,274 culicoid biting midges, 77 tabanids and 757 mosquitoes were tested as individuals or pools. No ASFV‐DNA was found in any of them although about 20% of the tick samples tested positive for swine DNA. By contrast, tick‐borne encephalitis virus‐RNA was detected in one out of 37 tick pools (2.7%) and Borrelia burgdorferi s.l.‐DNA in 20 individual ticks and 17 tick pools (25.2% of all samples). No Schmallenberg virus was detected in the Culicoides specimens. In conclusion, we found no evidence for Ixodes ricinus ticks, Culicoides punctatus and Obsoletus complex biting midges, Aedes spp., Anopheles spp. and Culiseta annulata mosquitoes, and Haematopota pluvialis tabanids playing a role in ASFV transmission in the wild boar population in Estonia. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) has spread across many countries in Europe since the introduction into Georgia in 2007. We report here on the first cases of ASF in wild boar detected in Germany close to the border with Poland. In addition to the constant risk of ASF virus (ASFV) spread through human activities, movements of infected wild boar also represent a route of introduction. Since ASF emerged in Western Poland in November 2019, surveillance efforts, in particular examination of wild boar found dead, were intensified in the regions of Germany bordering with Poland. The first case of ASF in wild boar in Germany was therefore detected by passive surveillance and confirmed on 10 September 2020. By 24 September 2020, 32 cases were recorded. Testing of samples from tissues of carcasses in different stages of decomposition yielded cycle threshold values from 18 to 36 in the OIE‐recommended PCR, which were comparable between the regional and national reference laboratory. Blood swabs yielded reliable results, indicating that the method is suitable also under outbreak conditions. Phylogenetic analysis of the ASFV whole‐genome sequence generated from material of the first carcass detected in Germany, revealed that it groups with ASFV genotype II including all sequences from Eastern Europe, Asia and Belgium. However, some genetic markers including a 14 bp tandem repeat duplication in the O174L gene were confirmed that have so far been detected only in sequences from Poland (including Western Poland). Epidemiological investigations that include estimated postmortem intervals of wild boar carcasses of infected animals suggest that ASFV had been introduced into Germany in the first half of July 2020 or even earlier. [ABSTRACT FROM AUTHOR]

An update on the African swine fever (ASF) situation in the 10 affected Member States (MS) in the EU and in two neighbouring countries from the 1 September 2019 until the 31 August 2020 is provided. The dynamics of the proportions of PCR- and ELISA-positive samples since the first ASF detection in the country were provided and seasonal patterns were investigated. The impact of the ASF epidemic on the annual numbers of hunted wild boar in each affected MS was investigated. To evaluate differences in the extent of spread of ASF in the wild boar populations, the number of notifications that could be classified as secondary cases to a single source was calculated for each affected MS and compared for the earliest and latest year of the epidemic in the country. To evaluate possible risk factors for the occurrence of ASFV in wild boar or domestic pigs, a literature review was performed. Risk factors for the occurrence of ASF in wild boar in Romanian hunting grounds in 2019 were identified with a generalised linear model. The probability to find at least one PCR-confirmed ASF case in wild boar in a hunting ground in Romania was driven by environmental factors, wild boar abundance and the density of backyard pigs in the hunting ground area, while hunting-related variables were not retained in the final model. Finally, measures implemented in white zones (ASF-free zones that are geographically adjacent to an area where ASF is present in wild boar) to prevent further spread of ASF were analysed with a spatially, explicit stochastic individual-based model. To be effective, the wild boar population in the white zone would need to be drastically reduced before ASF arrives at the zone and it must be wide enough. To achieve the necessary pre-emptive culling targets of wild boar in the white zone, at the start of the establishment, the white zone should be placed sufficiently far from the affected area, considering the speed of the natural spread of the disease. This spread is faster in denser wild boar populations. After a focal ASF introduction, the white zone is always close to the infection hence pre-emptive culling measures in the white zone must be completed in short term, i.e. in a few months. [ABSTRACT FROM AUTHOR]

Since the first introduction of African swine fever (ASF) into the European wild boar population in 1957, the question of virus survival in carcasses of animals that succumbed to the disease has been discussed. The causative African swine fever virus (ASFV) is known to be very stable in the environment. Thus, carcasses of infected wild boar could play a major role as ASFV reservoir and thereby help to locally maintain and spread the disease in wild boar populations. To minimize this risk, removal of wild boar carcasses in ASF affected areas is regarded to be crucial for effective disease control. If removal is not feasible, carcasses are usually disposed by burial on the spot to avoid direct contact of wild boar to the infection source. In this study, carcasses of ASFV infected wild boar buried in Lithuania at different time points and locations have been excavated and retested for the presence of infectious ASFV by in vitro assays and for viral genome by qPCR. Soil samples potentially contaminated by body fluids have been additionally tested for viral genome. In seventeen out of twenty burial sites, samples of excavated carcasses were positive for ASFV genome. However, in none of the carcass samples ASFV could be isolated. On seven sites soil samples contained ASF viral DNA. These results unexpectedly negate the long‐term persistence of infectious ASFV in wild boar carcasses independent from the burial time. In this context, sensitivity of ASFV isolation from carcass samples versus susceptibility of animals and doses needed for oral inoculation has to be further investigated. Furthermore, research is required to consider alternative ASF infection sources and drivers in the infection cycle among wild boar. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) has spread widely across China since 2018. It represents a significant threat to the pig production industry, as no treatment or vaccine is available for this disease. In this study, the geographical distribution and epidemiological features of ASF from all endemic regions of China were analyzed. We focused on the epidemiological data from 149 ASF cases among domestic pigs and wild boars, confirmed during 2018‐2019. We found that, in the 1‐year period from August 2018 to July 2019, ASF was reported in most geographical regions of the country, which comprises 31 provinces. The outbreaks were mainly located along the important economic zones and tended to increase southward in general. The southwest region was the most severely affected, with 22% of cases, followed by the Northeast, with 20% of cases. There was no significant difference among other regions. Additionally, the overall mean rate of case‐incidence/fatality was 12.5% and 64%, respectively, in this period and varied significantly different months, with a general trend towards a decrease over time. The highest incidence rate (30.4%) occurred in April‐May 2019, and the highest fatality rate (81.21%) in October‐November 2018, demonstrating the marked seasonality in ASF transmission. Furthermore, anthropogenic effects were a major significant risk factor for the spread of the disease. In summary, this initial epidemiological analysis of ASF provides a global perspective on ASF and facilitates detection of trends and patterns, which will be useful for updating preventive actions at a national level and evaluating their impact on public health. Highlights: The ASF outbreaks located along the economic zones and tended to southward in general.The rates of incidence/fatality varied different months with a general decrease trend.More outbreaks occurring in the warm seasons marked seasonality in ASF transmission.Anthropogenic effects are a major significant risk factor for the spread of ASF. [ABSTRACT FROM AUTHOR]

African swine fever is a devastating disease of domestic pigs and wild boars caused by African swine fever virus (ASFV). ASFV originates from sub‐Saharan African countries. In the last 10 years, the virus left its endemic range to spread to eastern Europe and Russia. On September 2018, Belgian authorities reported that ASFV had been detected in two wild boars in a southern area of the country. One year later, no domestic pig has been infected, with the last ASFV‐positive wild boar being confirmed in mid‐August 2019, suggesting that the outbreak is now controlled. However, the dispersal dynamics as well as the specific impact of ecological factors and intervention measures on the outbreak remain unknown.In total, 827 positive cases have been reported in wild boar populations. In this study, we exploit the resulting spatio‐temporal distribution of occurrence data to investigate the wavefront progression. We first present the application of recently developed methods to quantify the local wavefront velocity of an invading epidemic. Second, we develop and apply a novel analytical framework that uses occurrence data to investigate the impact of ecological factors on the dispersal dynamics of a wavefront progression.Our analyses highlighted that the network of barriers, involving installed fences, had an impact on both the effective dispersal and the wavefront dispersal velocity. Furthermore, we also demonstrated that the wavefront progression was slower outside forest areas. Together, these results have concrete implications for potential future ASFV epidemics in similar regions.Synthesis and applications. We describe a novel analytical approach that exploits occurrence data to investigate the impact of ecological factors on the wavefront velocity and actual wavefront progression. This methodology has the potential to be quickly applied to outbreak datasets solely made of occurrence data, with key benefits for the epidemiological investigations of external spatial factors impacting pathogen dispersal across non‐endemic areas. Our analytical workflow could also be further applied to investigate the impact of ecological factors on any kind of biological dispersions (pathogen spreads, invasive species). [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is one of the most important and complex viral diseases in domestic pigs and wild boar. Over the last decade, the disease has spread to several European and Asian countries and is now one of the major threats to profitable pig production worldwide. One of the more recently affected western countries is Belgium. To date, only wild boar are affected in a rather defined area in the Luxembourg region close to France, Luxembourg and Germany. While detailed sequence analyses were recently performed, biological characterization was still pending. Here, we report on the experimental inoculation of four sub‐adult wild boar to further characterize the virus and its distribution in different tissues. After oronasal inoculation with the virus strain 'Belgium 2018/1', all animals developed an acute and severe disease course with typical pathomorphological and histopathological lesions. Organs and blood samples were positive in qPCR, haemadsorption test and antigen lateral flow devices (LFD). Virus and viral genome were also detected in genitals and accessory sex glands of two boars. There were no antibodies detectable in commercial antibody ELISAs, antibody LFDs and indirect immunoperoxidase tests. Thus, the genotype II ASF virus isolate 'Belgium 2018/1' showed a highly virulent phenotype in European wild boar similar to parental viruses like Armenia 2007 and other previously characterized ASFV strains. The study also provided a large set of well‐characterized sample materials for test validation and assay harmonization. [ABSTRACT FROM AUTHOR]

Environmental sources of infection can play a primary role in shaping epidemiological dynamics; however, the relative impact of environmental transmission on host‐pathogen systems is rarely estimated. We developed and fit a spatially explicit model of African swine fever virus (ASFV) in wild boar to estimate what proportion of carcass‐based transmission is contributing to the low‐level persistence of ASFV in Eastern European wild boar. Our model was developed based on ecological insight and data from field studies of ASFV and wild boar in Eastern Poland. We predicted that carcass‐based transmission would play a substantial role in persistence, especially in low‐density host populations where contact rates are low. By fitting the model to outbreak data using approximate Bayesian computation, we inferred that between 53% and 66% of transmission events were carcass‐based that is, transmitted through contact of a live host with a contaminated carcass. Model fitting and sensitivity analyses showed that the frequency of carcass‐based transmission increased with decreasing host density, suggesting that management policies should emphasize the removal of carcasses and consider how reductions in host densities may drive carcass‐based transmission. Sensitivity analyses also demonstrated that carcass‐based transmission is necessary for the autonomous persistence of ASFV under realistic parameters. Autonomous persistence through direct transmission alone required high host densities; otherwise re‐introduction of virus periodically was required for persistence when direct transmission probabilities were moderately high. We quantify the relative role of different persistence mechanisms for a low‐prevalence disease using readily collected ecological data and viral surveillance data. Understanding how the frequency of different transmission mechanisms vary across host densities can help identify optimal management strategies across changing ecological conditions. [ABSTRACT FROM AUTHOR]

This report provides an update of the epidemiology of African swine fever (ASF) in the European Union during the period November 2018 to October 2019. In this period, ASF has been confirmed in Slovakia, whereas Czechia became officially ASF-free in March 2019, bringing the number of affected countries in the EU to nine. The report provides a narrative update of the situation in the different countries and an analysis of the temporal and spatial patterns of the disease. There has been no increase in the proportion of seropositive hunted wild boar in the affected areas. In hunted animals, the proportions of wild boar testing polymerase chain reaction-positive and enzyme-linked immunosorbent assay-positive has remained low (< 0.05). In addition to the obvious seasonal peak in summer in domestic pigs, seasonality of ASF in wild boar was statistically confirmed. A network analysis demonstrated that the median velocity of the natural propagation of the disease in wild boar populations was between 2.9 and 11.7 km/year. Human-mediated spread, both in pigs and wild boar, however, remains important. Several wild boar- and domestic pig-related risk factors for ASF occurrence in non-commercial farms in Romania were identified with a case–control study. This report also updates an extensive literature review on control measures to stop the spread of the disease in wild boar and on measures to separate wild boar populations. Several new studies have been identified in this reporting period, but these did not alter the conclusions of the previous reporting period. Field experience with the use of fences as part of the control strategy deployed in the Belgian focal outbreak of ASF in wild boar is described. So far, the measures have proven effective to keep ASF virus inside the affected area. This strategy included a combination of different measures, namely zoning, carcass removal, a complete feeding ban, specific hunting regulations and depopulation actions depending on the zone, a partial ban of people and logging, and setting up a network of concentric fences. [ABSTRACT FROM AUTHOR]

Classical swine fever (CSF) is an important viral disease of domestic pigs and wild boar. The structural proteins E2 and Erns of classical swine fever virus (CSFV), which participate in the attachment of the virion to the host cell surface and its subsequent entry, are immunogenic. The E2 and Erns proteins are used for diagnosis and the development of vaccines against CSFV infection in swine. Newcastle disease virus (NDV) has been successfully used as a viral vector to express heterologous proteins. In the present study, the E2 and Erns proteins of CSFV were expressed in cell culture as well as embryonated chicken eggs, using recombinant NDV (rNDV). Rescued rNDV expressing the E2 and Erns proteins induced the production of CSFV-neutralizing antibodies upon intranasal vaccination of pigs. Serum samples from vaccinated animals were found to neutralize both homologous and heterologous CSFV strains. Furthermore, rNDV expressing the E2 and Erns proteins of CSFV was used to develop an indirect ELISA, which was used to measure the the antibody titers of randomly collected serum samples. The results suggested that the ELISA based on rNDV-expressed E2 and Erns proteins could be used to screen for CSFV infections. This study shows that rNDV-based expression of CSFV antigens is potentially applicable for development of vaccines and diagnostic tests for CSFV infection. This approach could be an economically favorable alternative to the existing vaccine and diagnostics for CSFV in pigs. [ABSTRACT FROM AUTHOR]

Understanding the drivers underlying disease dynamics is still a major challenge in disease ecology, especially in the case of long‐term disease persistence. Even though there is a strong consensus that density‐dependent factors play an important role for the spread of diseases, the main drivers are still discussed and, more importantly, might differ between invasion and persistence periods.Here, we analysed long‐term outbreak data of classical swine fever, an important disease in both wild boar and livestock, prevalent in the wild boar population from 1993 to 2000 in Mecklenburg‐Vorpommern, Germany. We report outbreak characteristics and results from generalized linear mixed models to reveal what factors affected infection risk on both the landscape and the individual level.Spatiotemporal outbreak dynamics showed an initial wave‐like spread with high incidence during the invasion period followed by a drop of incidence and an increase in seroprevalence during the persistence period. Velocity of spread increased with time during the first year of outbreak and decreased linearly afterwards, being on average 7.6 km per quarter.Landscape‐ and individual‐level analyses of infection risk indicate contrasting seasonal patterns. During the persistence period, infection risk on the landscape level was highest during autumn and winter seasons, probably related to spatial behaviour such as increased long‐distance movements and contacts induced by rutting and escaping movements. In contrast, individual‐level infection risk peaked in spring, probably related to the concurrent birth season leading to higher densities, and was significantly higher in piglets than in reproductive animals.Our findings highlight that it is important to investigate both individual‐ and landscape‐level patterns of infection risk to understand long‐term persistence of wildlife diseases and to guide respective management actions. Furthermore, we highlight that exploring different temporal aggregation of the data helps to reveal important seasonal patterns, which might be masked otherwise. [ABSTRACT FROM AUTHOR]

The European Commission requested EFSA to compare the reliability of wild boar density estimates across the EU and to provide guidance to improve data collection methods. Currently, the only EU-wide available data are hunting data. Their collection methods should be harmonised to be comparable and to improve predictive models for wild boar density. These models could be validated by more precise density data, collected at local level e.g. by camera trapping. Based on practical and theoretical considerations, it is currently not possible to establish wild boar density thresholds that do not allow sustaining African swine fever (ASF). There are many drivers determining if ASF can be sustained or not, including heterogeneous population structures and human-mediated spread and there are still unknowns on the importance of different transmission modes in the epidemiology. Based on extensive literature reviews and observations from affected Member States, the efficacy of different wild boar population reduction and separation methods is evaluated. Different wild boar management strategies at different stages of the epidemic are suggested. Preventive measures to reduce and stabilise wild boar density, before ASF introduction, will be beneficial both in reducing the probability of exposure of the population to ASF and the efforts needed for potential emergency actions (i.e. less carcass removal) if an ASF incursion were to occur. Passive surveillance is the most effective and efficient method of surveillance for early detection of ASF in free areas. Following focal ASF introduction, the wild boar populations should be kept undisturbed for a short period (e.g. hunting ban on all species, leave crops unharvested to provide food and shelter within the affected area) and drastic reduction of the wild boar population may be performed only ahead of the ASF advance front, in the free populations. Following the decline in the epidemic, as demonstrated through passive surveillance, active population management should be reconsidered. [ABSTRACT FROM AUTHOR]

Summary: Classical swine fever (CSF) represents a major health and trade problem for the pig industry. In endemic countries or those with a wild boar reservoir, CSF remains a priority for Veterinary Services. Surveillance as well as stamping out and/or vaccination are the principle tools of prevention and control, depending on the context. In the past decades, marker vaccines and accompanying diagnostic tests allowing the discrimination of infected from vaccinated animals have been developed. In the European Union, an E2 subunit and a chimeric live vaccine have been licensed and are available for the use in future disease outbreak scenarios. The implementation of commonly accepted and globally harmonized concepts could pave the way to replace the ethically questionable stamping out policy by a vaccination‐to‐live strategy and thereby avoid culling of a large number of healthy animals and save food resources. Although a number of vaccines and diagnostic tests are available worldwide, technological advancement in both domains is desirable. This work provides a summary of an analysis undertaken by the DISCONTOOLS group of experts on CSF. Details of the analysis can be downloaded from the web site at http://www.discontools.eu/. [ABSTRACT FROM AUTHOR]

African swine fever ( ASF) is considered a major threat to the production of pigs worldwide. The ASF aetiological agent, ASFV, is the sole member of the Asfivirus genus, belonging to the Asfarviridae family. An effective ASF vaccine is not currently available, thus the only measures of ASF spread control include, reliable and fast diagnosis. Officially approved, diagnostic methods include, virus isolation, serological assays, including enzyme-linked immunosorbent assay and immunoperoxidase assay ( IPT) and different modifications of the polymerase chain reaction ( PCR). This paper describes the first development and application of a cross-priming amplification method ( CPA) for the direct detection of genetic ASFV material, in blood and sera from pigs and wild boars. This method is specific only to ASFV DNA. The study showed that CPA had equal sensitivity, in comparison to the official, universal probe library ( UPL) real-time PCR and reached 7·2 copies of standard plasmid DNA, containing a p72 gene fragment. This method was capable of detecting ASFV DNA in all examined blood samples, originating from pigs; n = 10 and wild boars; n = 76. The obtained results were also confirmed by the officially approved, real-time PCR. The developed CPA might be further used by local and county veterinary officers, hunters or pig farmers, for preliminary ASF diagnosis. Significance and Impact of the Study The spread of the African swine fever virus ( ASFV) among infected pigs and wild boars, is currently one of the most important facets of virus transmission in eastern Europe. Cross-priming amplification ( CPA) has been developed, for fast and direct development of genetic ASFV material in the blood and sera of infected pigs and wild boars. It has been shown that CPA is a rapid, sensitive and specific isothermal method for the detection of ASFV DNA, in directly collected blood or sera from pigs and wild boars. [ABSTRACT FROM AUTHOR]

Classical swine fever (CSF) is among the most detrimental diseases for the swine industry worldwide. Infected wild boar populations can play a crucial role in CSF epidemiology and controlling wild reservoirs is of utmost importance for preventing domestic outbreaks. Oral mass vaccination (OMV) has been implemented to control CSF in wild boars and limit the spill over to domestic pigs. This retrospective overview of vaccination experiences illustrates the potential for that option. The C-strain live vaccine was confirmed to be highly efficacious and palatable baits were developed for oral delivery in free ranging wild boars. The first field trials were performed in Germany in the 1990's and allowed deploying oral baits at a large scale. The delivery process was further improved during the 2000's among different European countries. Optimal deployment has to be early regarding disease emergence and correctly designed regarding the landscape structure and the natural food sources that can compete with oral baits. OMV deployment is also highly dependent on a local veterinary support working closely with hunters, wildlife and forestry agencies. Vaccination has been the most efficient strategy for CSF control in free ranging wild boar when vaccination is wide spread and lasting for a sufficient period of time. Alternative disease control strategies such as intensified hunting or creating physical boundaries such as fences have been, in contrast, seldom satisfactory and reliable. However, monitoring outbreaks has been challenging during and after vaccination deployment since OMV results in a low probability to detect virus-positive animals and the live-vaccine currently available does not allow serological differentiation of infected from vaccinated animals. The development of a new marker vaccine and companion test is thus a promising option for better monitoring outbreaks during OMV deployment as well as help to better determine when to stop vaccination efforts. After rabies in red fox, the use of OMV against CSF in European wild boar can be considered as a second example of successful disease control in wildlife. The 30 years of disease control experience included in this review may provide options for improving future disease management within wild populations. [ABSTRACT FROM AUTHOR]

Background: Viral agents associated with reproductive failure such as Aujeszky's disease virus (ADV), encephalomyocarditis virus (EMCV), and porcine parvovirus (PPV) have also been identified in European wild boar. To screen for the presence of antibodies against ADV, EMCV, and PPV from wild boar (Sus scrofa) in South Korea, 481 serum samples were collected from wild boar hunted between December 2010 and May 2011. Results: Of the 481 serum samples tested, 47 (9.8%) and 37 (7.7%) were seropositive for ADV and EMCV antibodies, respectively, based on a neutralization test (VNT), and 142 (29.5%) were seropositive for PPV antibodies based on a hemagglutination inhibition (HI) test. Conclusions: This was the first survey to identify the seroprevalence of the three major viruses associated with reproductive failure in the wild boar population of South Korea. Wild boar may act as a reservoir for many viruses that cause infectious diseases in domestic pigs. Thus, strict prevention and control measures, such as continuous wildlife disease surveillance and strategic methods of downsizing the population density, should be implemented to prevent disease transmission from wild boar to domestic pigs. [ABSTRACT FROM AUTHOR]

Constitutive humoral immunity (CHI) is thought to be a first-line of protection against pathogens invading vertebrate hosts. However, clear evidence that CHI correlates with host fitness in natural conditions is still lacking. This study explores the relationship between CHI, measured using a haemagglutination-haemolysis assay (HAHL), and resistance to classical swine fever virus (CSFV) among wild boar piglets. The individual dynamics of HAHL during piglet growth was analysed, using 423 serum samples from 92 piglets repeatedly captured in the absence of CSFV (in 2006) within two areas showing contrasting food availability. Natural antibody levels increased with age, but, in the youngest piglets antibody levels were higher in individuals from areas with the highest food availability. Complement activity depended on natural antibody levels and piglets' body condition. In the presence of CSFV (i.e., in 2005 within one area), serum samples from piglets that were repeatedly captured were used to assess whether piglet HAHL levels affected CSFV status at a later capture. The correlation between CHI and resistance to CSFV was tested using 79 HAHL measures from 23 piglets captured during a CSFV outbreak. Both natural antibodies and complement activity levels measured at a given time correlated negatively to the subsequent probability of becoming viremic. Finally, capture-mark-recapture models showed that piglets with medium/high average complement activity, independently of their age, were significantly less at risk of becoming viremic and more likely to develop a specific immune response than piglets with low complement activity. Additionally, piglets with high average complement activity showed the highest survival prospects. This study provides evidence linking CHI to individual fitness within a natural mammal population. The results also highlight the potential of HAHL assays to explore the dynamics and co-evolution between wildlife mammal hosts and blood-borne parasites interacting with the CHI. [ABSTRACT FROM AUTHOR]

Background: The understanding of host-parasite systems in wildlife is of increasing interest in relation to the risk of emerging diseases in livestock and humans. In this respect, many efforts have been dedicated to controlling classical swine fever (CSF) in the European Wild Boar. But CSF eradication has not always been achieved even though vaccination has been implemented at a large-scale. Piglets have been assumed to be the main cause of CSF persistence in the wild since they appeared to be more often infected and less often immune than older animals. However, this assumption emerged from laboratory trials or cross-sectional surveys based on the hunting bags. Methodology/Principal Findings: In the present paper we conducted a capture-mark-recapture study in free-ranging wild boar piglets that experienced both CSF infection and vaccination under natural conditions. We used multi-state capture recapture models to estimate the immunization and infection rates, and their variations according to the periods with or without vaccination. According to the model prediction, 80% of the infected piglets did not survive more than two weeks, while the other 20% quickly recovered. The probability of becoming immune did not increase significantly during the summer vaccination sessions, and the proportion of immune piglets was not higher after the autumn vaccination. Conclusions/Significance: Given the high lethality of CSF in piglets highlighted in our study, we consider unlikely that piglets could maintain the chain of CSF virus transmission. Our study also revealed the low efficacy of vaccination in piglets in summer and autumn, possibly due to the low palatability of baits to that age class, but also to the competition between baits and alternative food sources. Based on this new information, we discuss the prospects for the improvement of CSF control and the interest of the capture-recapture approach for improving the understanding of wildlife diseases. [ABSTRACT FROM AUTHOR]

Simple Summary: Biosecurity breaches have been shown to play a major role in the introduction and spread of African swine fever (ASF) in domestic pig populations. The aim of the study was to describe the biosecurity levels and management practices of ASF outbreak and uninfected herds and to identify potential risk factors for ASF introduction. The biosecurity score of ASF outbreak herds was significantly lower compared to uninfected herds. This may reflect general improvement in the application of biosecurity measures over time in Estonian pig farms as the data on uninfected herds were collected later, at a time when intensified official controls may have had their effect. Larger herds were more at risk of being 'outbreak herds' compared to smaller herds. The biosecurity parameters significantly associated with 'outbreak herd' status in statistical analysis were mostly related to indirect contacts with the outside farm environment. The biosecurity barriers applied in Estonian pig farms have not been sufficient to avoid the introduction of ASF and need critical evaluation and improvement. Reduction of all contacts between the farm and the external environment should be emphasized in a situation where ASF is circulating in wild boar populations close to pig farms. Risk factors related to external biosecurity have been considered to play a major role in the introduction and spread of African swine fever (ASF) in domestic pig populations. The aim of the study was to describe the biosecurity levels and management practices of ASF outbreak and uninfected herds and to identify potential risk factors for ASF introduction. Data collected from the outbreak herds during outbreak investigations and from the randomly selected uninfected herds were analyzed. The biosecurity score in ASF outbreak herds was significantly lower compared to uninfected herds. However, this may reflect general improvement in the application of biosecurity measures in pig farms over time as the data on uninfected herds were collected later, at a time when intensified official controls may have had their effect. Larger herds were more at risk of being outbreak herds compared to smaller herds. The biosecurity parameters significantly associated with the outbreak herd status in multiple correspondence analysis were mostly related to indirect contacts with the outside farm environment. The biosecurity barriers applied in Estonian pig farms have not been sufficient to avoid ASF introduction and need critical evaluation and improvement. Reduction of all contacts between the farm and the external environment should be emphasized in a situation where ASF is circulating in wild boar populations close to pig farms. [ABSTRACT FROM AUTHOR]

In 2002 and 2003, two successive outbreaks of classical swine fever were declared in wild boar in northern France. The first was in Moselle, near the town of Thionville and the border with Luxembourg, and the second was in the northern Vosges area, near the German border. The outbreaks were investigated by serological and virological diagnosis of dead or shot animals. Hunting restrictions were applied to limit the spread of the outbreaks. The virus was detected eight times between April and July 2002 in the Thionville area, an area well delimited by natural or artificial barriers such as rivers or highways. Cooperation between the authorities concerned was good, and hunting restrictions were applied for one year. No virus was detected after July 2002 and the Thionville outbreak was officially considered over in March 2005. In the northern Vosges the situation was different, with no barriers to animal movements, continuous forest, difficulties in establishing hunting restrictions in this huge area, and the circulation of the virus in Germany close to the frontier. Virus of a different strain from that isolated in the Thionville outbreak was still being isolated in the northern Vosges in 2004, and owing to the failure of the hunting restrictions, the French health authorities decided to vaccinate wild boar. [ABSTRACT FROM AUTHOR]

The goal of this study was to evaluate the efficacy of the chimeric marker vaccine candidate CP7_E2alf in different formulations for oral immunization against classical swine fever (CSF). In the first experiment, three wild boars were vaccinated orally with the liquid chimeric virus CP7_E2alf, whereas in the second experiment, four wild boars and four domestic pigs were immunized with the lyophilized chimera administered in gelatine capsules and new baits. The chimera was safe for wild boars and domestic pigs. All animals vaccinated orally with the liquid chimera were seropositive 21 days after vaccination, and neither viraemia nor virus shedding were observed after challenge with a highly virulent CSF virus. At necropsy, viral genome of the challenge virus was detected in some organs of all surviving wild boars. Lyophilized chimera administered orally did not protect the animals. The reasons for the inefficacy of the lyophilized vaccine virus are discussed. Irrespective of the negative result with lyophilized virus, the study and previous experiences (Reimann et al., Virology, 307:213–227, 2004) suggest that the chimera CP7_E2alf is a potential CSF marker vaccine candidate. [ABSTRACT FROM AUTHOR]

1. Classical swine fever has increased in economic importance since it has become endemic in some wild boar Sus scrofa populations in Europe. The mechanism of disease persistence is still not well understood, and several aspects of both the ecology of boar and the virus are claimed to be responsible for disease persistence. 2. We review literature on the spread and persistence of the disease in free-ranging wild boar. We determine whether the available knowledge can explain the observed patterns via mechanistic processes and their interactions, and assemble knowledge in a conceptual model. 3. We speculate that the most important factor explaining disease persistence is an alteration in disease outcome, resulting in individual courses with prolonged infectiousness or a sustained reproductive population through immunity. This effect is reinforced by high wild boar numbers either within sites or scattered over larger areas. 4. We highlight the sparse knowledge of disease transmission between wild boar. We derive management suggestions for different phases of an outbreak based on the conceptual model and advocate the use of model-based investigations to test alternative management options. [ABSTRACT FROM AUTHOR]

Simple Summary: High wild boar population densities lead to human–wildlife conflicts. For proper wildlife management, knowledge of wildlife biology as well as human attitudes is needed. We conducted inquiries on hunting methods and on hunters' attitudes in the German Federal State of Lower Saxony to better understand hunting strategies. Single hunt, especially at bait, is still the most widely used method for hunting wild boar. The proportion of drive hunts within the hunting bag is increasing. The proportions of hunting methods vary regionally due to wild boar densities, geographical conditions and hunters' practices. Private hunting is important for wild boar management, although it is just insufficient. Besides promoting more efficient hunting methods and motivating hunters, in the future, additionally, administrative wildlife managers could be established as coordinators of wild boar management, and as such, could manage hunting, the incorporation of regional conditions and investigating hunters' attitudes and abilities. High wild boar population densities lead to demands for a population reduction to avoid crop damages or epidemic diseases. Along with biological studies, a better understanding of the human influence on wildlife and on wildlife management is important. We conducted inquiries on hunting methods and on hunters' attitudes in the Federal State of Lower Saxony, Germany, to better understand hunting strategies and the influence on increasing wild boar population, as well as to underpin game management concepts. Single hunt, especially at bait, is still the most widely used method for hunting wild boar. The proportion of drive hunts within the hunting bag is increasing. The proportions of hunting methods vary regionally due to wild boar densities, geographical features (vegetation, terrain, etc.) and hunters' practices. Hunters increased the proportion of conjoint hunts on wild boar. Baiting remains an important hunting method in wild boar management and the proportion of drive hunts should be fostered. Private hunting is important for wild boar management, although it is just insufficient. Additionally, administrative wildlife managers are recommended for the near future as coordinators of wild boar management, and as such, could manage hunting, the incorporation of regional conditions and investigating hunters' attitudes and abilities. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the diagnostic performance of a multiplex bead assay for the simultaneous detection of antibodies against Mycobacterium bovis, Brucella suis, and Trichinella spiralis. Sera from Eurasian wild boar of known serological status for TB (64 seropositive, 106 seronegative), Brucella (30 seropositive, 39 seronegative), and Trichinella (21 seropositive, 97 seronegative) were used for the development and evaluation of the assay. Magnetic beads coated with recombinant MPB83 antigen (TB), a whole-cell B. suis 1330 antigen, and an E/S T. spiralis antigen were used for the detection of specific antibodies using Bio-Rad Bio-Plex technology. The sensitivities (Se) and specificities (Sp) of the multiplex assay were, for M. bovis, 0.98 and 0.86; for B. suis, 1.00 and 0.97; and for T. spiralis, 0.90 and 0.99 (Se and Sp, respectively). The results show the diagnostic potential of this assay for the simultaneous detection of antibodies against M. bovis, B. suis, and T. spiralis in wild boar. [ABSTRACT FROM AUTHOR]