First Occurence of African Swine Fever in Serbia

Strategic Challenges to the Eradication of African Swine Fever Genotype II in Domestic Pigs in North Italy

African swine fever (ASF) is a severe viral disease characterized by high lethality in suids and caused by the African Swine Fever Virus (ASFV). The ASF genotype I virus was introduced to Europe in 1957, marking the onset of the first European epidemic wave. In 2007, ASFV genotype II was detected in Georgia, affecting domestic pigs and wild boars before spreading to various European and extra-European countries, including Italy. The first case of ASFV in Italy was documented on 7 January 2022, in a wild boar in the Piedmont region. Since then, several ASFV-positive wild boar carcasses have been identified in the Piedmont and Liguria regions. By June 2023, ASFV had spread to Lombardy, one of the major pig-producing regions in northern Italy; the virus was first detected in early summer in wild boar carcasses. Two months later, it was diagnosed in a commercial pig farm as a consequence of the disease's spread amongst wild boars and an increase in the viral environmental load. This report aims to describe the features of ASFV domestic pig outbreaks that occurred in the Zinasco municipality (Lombardy) and the joint efforts to mitigate potential direct and indirect economic impacts on the Italian and global pig industry. The epidemiological investigation and the measures implemented, which were all performed according to national and European regulations, as well as exceptional ad hoc measures aimed at protecting the pig industry, are described in order to provide a practical and effective approach to combating ASF.

The Long-Jumping of African Swine Fever: First Genotype II Notified in Sardinia, Italy

African swine fever (ASF) is a devastating infectious disease of domestic pigs and wild boar that is spreading quickly around the world and causing huge economic losses. Although the development of effective vaccines is currently being attempted by several labs, the absence of globally recognized licensed vaccines makes disease prevention and early detection even more crucial. ASF has spread across many countries in Europe and about two years ago affected the Italian susceptible population. In Italy, the first case of ASF genotype II in wild boar dates back to January 2022, while the first outbreak in a domestic pig farm was notified in August 2023. Currently, four clusters of infection are still ongoing in northern (Piedmont-Liguria and Lombardy), central (Lazio), and southern Italy (Calabria and Campania). In early September 2023, the first case of ASFV genotype II was detected in a domestic pig farm in Sardinia, historically affected by genotype I and in the final stage of eradication. Genomic characterization of p72, p54, and I73R/I329L genome regions revealed 100% similarity to those obtained from isolates that have been circulating in mainland Italy since January 2022 and also with international strains. The outbreak was detected and confirmed due to the passive surveillance plan on domestic pig farms put in place to provide evidence on genotype I's absence. Epidemiological investigations suggest 24 August as the most probable time of ASFV genotype II's arrival in Sardinia, likely due to human activities.

Genetic analysis reveals multiple intergenic region and central variable region in the African swine fever virus variants circulating in Serbia

This study provides the first comprehensive report on the molecular characteristics of African swine fever virus (ASFV) variants in Serbia between 2019 and 2022. Since its first observation in July 2019, the disease has been found in wild boar and domestic swine. The study involved the analysis of 95 ASFV-positive samples collected from 12 infected administrative districts in Serbia. Partial four genomic regions were genetically characterized, including B646L, E183L, B602L, and the intergenic region (IGR) between the I73R-I329L genes. The results of the study suggest that multiple ASFV strains belonging to genotype II are circulating in Serbia, as evidenced by the analysis of the IGR between I73R-I329L genes that showed the most differences. Furthermore, the phylogenetic analysis of the B602L gene showed three different clades within the CVR I group of ASFV strains. Regarding the IGR, 98.4% were grouped into IGR II, with only one positive sample grouped into the IGR III group. These findings provide essential insights into the molecular characteristics of ASFV variants in Serbia and contribute to the knowledge of circulating strains of ASFV in Europe. However, further research is necessary to gain a better understanding of ASFV spread and evolution.

African Swine Fever: The State of the Art in Italy

African swine fever (ASF) is a severe viral disease of domestic pigs and Eurasian wild boars (Sus scrofa) caused by the African swine fever virus (ASFV). ASF is endemic in sub-Saharan Africa, where 24 genotypes of the virus have been reported. Between the late 1950s and the early 1980s, genotype I ASFV emerged in Europe, including Italy. In June 2007, a second ASF epidemic wave caused by genotype II was registered, involving several European and extra-European countries, including Italy in 2022. The present paper aims to provide the state of the art of ASF in Italy, describing the course of ASF in wild boars and domestic pigs as an example of multiple concurring different scenarios. Sardinia is coping with the last phase of the eradication of the disease by applying the exit strategy. Conversely, four clusters of infection located in North, Central, and South Italy are still ongoing. The unique and complex Italian experience in ASF-controlling may be useful to increase know-how on the efficacy of strategies and measures, as well as issues that could be further improved.

Risk Factor Impact on African Swine Fever Transmission in Different Extensive Pig Production Settings in Serbia

The first case of ASF in a domestic pig population in Serbia was confirmed in 2019 in a backyard population. Today, outbreaks in wild boar and, more importantly, in domestic pigs are still occurring, although the government measures for ASF prevention are in place. The aim of this study was to determine critical risk factors and identify the possible reasons for ASF introduction into different extensive pig farms. The study was conducted on 26 extensive pig farms with confirmed ASF outbreaks, with data collected from beginning of 2020 to the end of 2022. Collected epidemiological data were divided into 21 main categories. After identifying specific values of variables as critical for ASF transmission, we identified nine important ASF transmission indicators as those variables for which at least 2/3 of the observed farms reported values critical for ASF transmission. Among them were type of holding, distance to hunting ground, farm/yard fencing, and home slaughtering; however, the hunting activity of pig holders, swill feeding, and feeding with mowed green mass were not included. We represented the data in the form of contingency tables to study associations between pairs of variables using Fisher's exact test. All pairs of variables in the group including type of holding, farm/yard fencing, domestic pig-wild boar contact, and hunting activity were significantly related; hunting activity of pig holders, holding pigs in backyards, unfenced yards, and domestic pig-wild boar contact were observed on the same farms. Free-range pig farming led to observed domestic pig-wild boar contact on all farms. The identified critical risk factors need to be strictly addressed to prevent the further spread of ASF to extensive farms and backyards in Serbia and elsewhere.

African Swine Fever Outbreak in an Enclosed Wild Boar Hunting Ground in Serbia

African swine fever (ASF) has been detected in many European countries since its introduction in Georgia in 2007. Serbia suffered its first case of ASF in the domestic pig population in 2019. At the beginning of 2020, ASF was detected in wild boars in open hunting grounds in the southeastern region of the country in districts along the country's borders with Romania and Bulgaria. Since then, all ASF outbreaks in wild boar were clustered in the population located in the same bordering areas. Despite the newly implemented biosecurity protocols for hunters in 2019, ASF was detected for the first time in June 2021 in the wild boar population located in an enclosed hunting ground in the northeast region of the country. In this study, we reported the first ASF outbreak in a wild boar population located in an enclosed hunting ground in close proximity to the Serbian-Romanian border. The epizootiological data on the field investigation of the ASF outbreak, with descriptions of the clinical signs and gross pathological lesions detected, including the total number as well as the estimated age, sex, and postmortem interval, were analyzed. Clinical signs were detected only in nine diseased wild boars, while in total, 149 carcasses were found in the open and enclosed part of the hunting ground. In addition, 99 carcasses from which samples (parts of spleen or long bones) were collected for molecular diagnostics (RT-PCR) were confirmed as ASF-positive. The results of the epidemiological investigations indicate the central role of wild boar movements as well as the constant risk of human-related activities in the countries bordering area.

Innovative Research Offers New Hope for Managing African Swine Fever Better in Resource-Limited Smallholder Farming Settings: A Timely Update

African swine fever (ASF) in domestic pigs has, since its discovery in Africa more than a century ago, been associated with subsistence pig keeping with low levels of biosecurity. Likewise, smallholder and backyard pig farming in resource-limited settings have been notably affected during the ongoing epidemic in Eastern Europe, Asia, the Pacific, and Caribbean regions. Many challenges to managing ASF in such settings have been identified in the ongoing as well as previous epidemics. Consistent implementation of biosecurity at all nodes in the value chain remains most important for controlling and preventing ASF. Recent research from Asia, Africa, and Europe has provided science-based information that can be of value in overcoming some of the hurdles faced for implementing biosecurity in resource-limited contexts. In this narrative review we examine a selection of these studies elucidating innovative solutions such as shorter boiling times for inactivating ASF virus in swill, participatory planning of interventions for risk mitigation for ASF, better understanding of smallholder pig-keeper perceptions and constraints, modified culling, and safe alternatives for disposal of carcasses of pigs that have died of ASF. The aim of the review is to increase acceptance and implementation of science-based approaches that increase the feasibility of managing, and the possibility to prevent, ASF in resource-limited settings. This could contribute to protecting hundreds of thousands of livelihoods that depend upon pigs and enable small-scale pig production to reach its full potential for poverty alleviation and food security.

Patterns of ASFV Transmission in Domestic Pigs in Serbia

The first case of African swine fever in domestic pigs in Serbia was in 2019. The following year, the disease was confirmed in wild boar. Thenceforth, ASF has been continuously reported in both wild and domestic pigs. The outbreaks in domestic pigs could not be linked directly to wild boars, even though wild boars were endemically infected, and reservoirs for ASF. This study aimed to investigate outbreaks and routes of transmission in domestic pigs in a region of central Serbia where no outbreaks in wild boar were reported. Fourteen outbreaks of ASF on backyard farms with low biosecurity were traced back, and no connection to wild boar was found. The epidemic investigation covered 2094 holdings, with 24,368 pigs, out of which 1882 were tested for ASF. In surrounding hunting grounds, field searches were conducted. Dead wild boars were found, and 138 hunted wild boars were negative for ASFV. It was concluded that outbreaks in 2021 were provoked by the illegal trade of live animals and pig products. Even though infective pressure from wild boars is assumed, no positive cases have been found, while the ASFV spreads within the domestic swine population evidenced in four recent outbreaks in 2022.

A Novel Tool to Assess the Risk for African Swine Fever in Hunting Environments: The Balkan Experience

In Europe, African swine fever (ASF) can be sustained within wild boar populations, thus representing a constant source of virus and a huge challenge in the management of the disease. Hunters are the key stakeholders for the prevention, detection and control of ASF in wild boar. Their behavior and the biosecurity standards applied in infected or at-risk hunting grounds have a huge impact on disease dynamics and management. The Food and Agriculture Organization (FAO) has developed a semi-quantitative survey-based novel tool to assess the risk of ASF in hunting grounds (namely the risks of introduction and spread into and between hunting grounds, and the risk of not detecting the infection) and how such risks could be reduced if mitigation or corrective measures were applied at low, medium and high effort. The weight of risk factors was determined through an expert knowledge elicitation (EKE). The surveys for each hunting ground were filled in by their respective managers. The tool's outputs allow users to visualize the different ASF risks of hunting grounds, whether as numerical values or color-coded maps, at sub-national, national and regional levels. These outputs can be used to guide policy makers, highlighting gaps or geographical areas to prioritize. The tool was used to assess hunting grounds in Kosovo¹ (¹ As per United Nations Security Council resolution 1244). Montenegro and Serbia, showing overall a high risk.

Review of the Pig-Adapted African Swine Fever Viruses in and Outside Africa

The region in eastern, central and southern Africa (ECSA) where African swine fever (ASF) originated in a sylvatic cycle is home to all the p72 genotypes of ASF virus identified so far. While 20 of the 24 genotypes have been isolated from outbreaks in domestic pigs in the region, only five of the genotypes (I, II, VIII, IX, X) have an extended field presence associated with domestic pigs. Of the genotypes that appear to be strongly adapted to domestic pigs, two have spread beyond the African continent and have been the focus of efforts to develop vaccines against ASF. Most of the experimental ASF vaccines described do not protect against a wider spectrum of viruses and may be less useful in the event of incursions of different strains or where multiple genotypes co-exist. The other three pig-adapted strains that are currently restricted to the ECSA region might spread, and priority should be given to understanding not only the genetic and antigenic characteristics of these viruses but also their history. We review historic and current knowledge of the distribution of these five virus genotypes, and note that as was the case for genotype II, some pig-associated viruses have the propensity for geographical range expansion. These features are valuable for prioritizing vaccine-development efforts to ensure a swift response to virus escape. However, whilst ASF vaccines are critical for high-production systems, global food security relies on parallel efforts to improve biosecurity and pig production in Africa and on continued ASFV surveillance and characterisation in the ECSA region.

Key risk factors and impact of African swine fever spreading on pig production in Serbia

African swine fever (ASF) is a viral disease of domestic pigs and wild boars and currently represents a major threat to the swine industry worldwide. Disease control is impaired by a lack of an effective vaccine and currently, it is dependent on biosecurity measures in pig production, rapid diagnosis, and stamping out of infected herds. Consequently, this swine disease has considerable social-economic significance on national or even regional level. In 2019 for the first time ASF was detected in the domestic swine population (backyards) in the central region of Serbia. From then on, there have been continuous outbreaks of new cases in the population of domestic and wild boars. Considering domestic pig population, in the majority of cases, ASF was detected in small holdings and backyards. The biosecurity measures are not officially required by veterinary regulation and are only given in a form of recommendations. On the other hand, it is not always possible to implement biosecurity measures that are recognized today as essential for sustainable pig production in the old type of industrial pig facilities. Nowadays, in 2021, it became obvious that the domestic pig cycle, human activities involving pigs, or pig-derived meat products are the dominant driver of virus transmission. Additionally, human activities are frequently a risky connection between domestic pigs and wild boars both directly or indirectly. Traditional, culture-related aspects and facts that politicians failed to recognise ASF as a serious issue that causes great economical losses were found to be very important obstacles in disease control.

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

The first confirmed case of African Swine Fever (ASF) in Serbia occurred in 2019. Since then, numerous outbreaks in domestic pigs and wild boars have been reported. Until April 2021, all the detected ASF cases were in backyard pigs. Beside backyard and smallholders farming systems as a dominant pig production system in Serbia, large commercial pig farms can also be found, located mostly in villages. In the beginning of April 2021, a large commercial farrow-to-finish pig farm in Serbia with almost 19,000 animals was affected with the ASF virus. The pig farm analysed in this paper is located in an area where ASF was confirmed earlier in both backyard and wild boars. In this study, we describe the overall epidemiological course of the ASF outbreak. Epidemiological investigation using a hypothesis-based approach was conducted in order to reconstruct the disease course until the official notification. All the available data from the farm were analysed with the aim to determine the high-risk period (HRP). Some of the key points to consider when it comes to the sources of infection and entry route of ASF are the following: contamination of the area in the immediate vicinity of the farm, risky human activities, irregularities and some omissions in the external farm biosecurity and immediate proximity of the city waste-yard where the communal waste is disposed of. It was concluded that when commercial pig farms are surrounded by villages with a large number of backyards, hence the anthropogenic factor is the key risk factor for ASF spreading.

Risk and Mitigation of African Swine Fever Virus in Feed

Simple Summary

African swine fever is the most significant disease threat to swine globally, and recent introductions into previously negative countries has heightened the risk for disease spread. Without an effective vaccine or treatment, the primary objective of negative countries is to prevent African swine fever virus infection in pigs. Significant quantities of feed ingredients used for swine diets are traded worldwide and may be imported from countries with African swine fever. If feed ingredients are contaminated with the virus, they can serve as potential routes for the introduction and transmission of African swine fever virus. This review provides information on the risk of African swine fever virus in feed and the mitigation strategies that may help protect the global swine population from introduction and spread through feed.

Abstract

Since the 2013 introduction of porcine epidemic diarrhea virus into the United States (U.S.), feed and feed ingredients have been recognized as potential routes for the introduction and transmission of foreign animal diseases of swine. Feed ingredients for swine diets are commodities traded worldwide, and the U.S. imports thousands of metric tons of feed ingredients each year from countries with circulating foreign animal diseases. African swine fever (ASF) is the most significant foreign animal disease threat to U.S. swine production, and the recent introduction of ASF into historically negative countries has heightened the risk for further spread. Laboratory investigations have characterized the stability of the ASF virus (ASFV) in feed ingredients subjected to transoceanic shipment conditions, ASFV transmissibility through the natural consumption of plant-based feed, and the mitigation potential of certain feed additives to inactivate ASFV in feed. This review describes the current knowledge of feed as a risk for swine viruses and the opportunities for mitigating the risk to protect U.S. pork production and the global swine population from ASF and other foreign animal diseases.

Current Swine Respiratory Diseases Morphology in Intensive Swine Production in Serbia

Swine respiratory diseases represent one of the most frequent health issues in pig production worldwide. Despite the great progress that has been made in the field of diagnostics, control and prophylaxis, respiratory diseases still remain the most challenging health problem in modern commercial pig production. The list of infectious agents that cause respiratory diseases in swine is extensive and includes both, bacterial and viral pathogens. In Serbia, more than fifteen years after the introduction of modern vaccines, the list of bacterial pathogens related to swine respiratory infections still include Mycoplasma hyopneumoniae, Actinobacillus pleuropneumoniae, Haemophilus parasuis and Pasteurella multocida. On the other hand, most commonly involved viral pathogens are Porcine Reproductive and Respiratory Syndrome Virus, Swine influenza virus, Porcine circovirus type 2 and Pseudorabies virus. The morphological features of pneumonia where several agents are involved, depend on the predominant etiological agent. Expanding knowledge of the main pathogens associated with swine respiratory diseases and the effects of their interactions on the disease outcome is important for further investigations of lung diseases and implementation of control strategies in commercial pig populations in Serbia. This review discusses the latest findings on swine respiratory disease and current trends in Serbian pig production.

Characteristics of African Swine Fever Virus Isolated from Domestic Pigs and Wild Boars in the Russian Federation and South Ossetia

The article presents the results of a comparative study of the biological, molecular and genetic characteristics of African swine fever virus (ASFV) isolates, obtained from domestic pigs and wild boars in the Russian Federation and South Ossetia from 2016 to 2018. The studied isolates caused the death of pigs manifesting, as a rule, signs of an acute or subacute form of the disease when using various methods of infection including intramuscular, direct contact, intranasal and oral routes. The virus was hemadsorbing, belonging to serotype 8 and genotype II, and accumulated in the blood with a titer of 6.5 to 7.5 lg HAU50/cm3. The ASFV isolates circulating in the central region of Russia were found to have an insertion of 10 base pairs in the intergenic region I73R/I329L. However, the ASFV isolated in the Irkutsk region and South Ossetia, as well as Georgia 2007/1 (FR682468.1), lacked this insertion.