Transboundary spread of pig diseases: the role of international trade and travel

Predicting and preventing the next viral disease transmitted through food

The ability of viruses to infect humans following oral exposure and disrupt normal physiological or anatomical functions is a hallmark of their potential to cause foodborne disease. While the etiology of the vast majority of foodborne diseases remains undetermined, viruses are often identified as the culprit when the cause is ascertained. Many undiagnosed causes of foodborne illnesses, especially sporadic cases, may go undetected or be caused by yet-to-be-identified viruses. The potential for food to become a transmission vehicle for viral diseases that are not typically acquired following ingestion may be described within the epidemiological paradigm. This model considers the characteristics and interactions of the host (the human), the agent (the virus), and the environment (the food, the food producing animal or the food production environment). Importantly, these factors are not static and evolution of viruses, transformations in agrifood systems, and changes in environmental conditions and human health and behaviour may contribute to increased pathogenicity, virulence, or exposure. In the context of determining the potential for additional viruses to emerge as important causes of foodborne disease, factors that contribute to hazard characterization (e.g., receptor affinity and distribution) and exposure assessment (e.g., prevalence in food animals and food hygiene) are reviewed. Although it is not possible to predict the type, the timing nor the location of the emergence of the next important cause of foodborne viral disease, the deployment and implementation of actions and behaviours related to personal and food hygiene, sanitation, and safe food handling practices can reduce the likelihood and impact of known and emergent viruses on the safety of the food supply and human health.

Evaluating a swine biosecurity website as an education and outreach tool and identifying best practices for end-user engagement: A learning analytics approach

INTRODUCTION

Implementing biosecurity measures on commercial and small-scale swine farms is an ongoing effort to prevent the introduction and spread of infectious diseases. Educating and training swine producers on effective on-farm biosecurity practices is imperative. This study aims to assess a swine biosecurity website as an outreach tool and identify best practices for end-user engagement by tracking and analyzing data on user demographics, engagement, and interaction.

METHODS

User data for a swine biosecurity website were recorded between 5th July 2022 and 31st December 2023 using Google Analytics. A direct interaction between RStudio software and Google Analytics facilitated data export and analysis on user demographics and website traffic. A multivariable negative binomial regression model assessed associations between website event counts (outcome) and predictors representing the type of devices used to access the website and how the website was found. A multivariable linear regression model evaluated associations between the previously described predictor variables and the duration for which the users engaged with the website (outcome). The number of users and event counts in each state was illustrated in choropleth maps, and the Local Moran's I method was used to identify states with a high number of users and event counts to evaluate the website's outreach across the United States of America (US) and worldwide.

RESULTS

Google Analytics reported 768 users with an aggregated event count of 9643. Users were from 78 countries, of which the most users were from the US (708), the Philippines (202), and Canada (49). The website users were distributed across all age categories. The "biosecurity checklist" and "biosecurity protocol of entering the swine farm" were the most downloaded infographics. The website engagement (total events and engagement duration) was significantly higher if users accessed the website on desktop computers compared to mobile phones and tablets, and was higher for users accessing the website through direct links, and search engines. In the US, local clusters of high website users were identified in leading swine production states, including Iowa, Minnesota, Illinois, Nebraska, Indiana, and Missouri.

CONCLUSION

The study findings support the utility of a web-based learning environment, which can provide swine biosecurity education and resources to a broad audience. The website traffic data obtained through Google Analytics helped examine the website users' behavioral patterns, preferences, and engagement tendencies, which can be used to enhance the website in the future. The website tracking and analytical methods presented in this study can be applied to other educational websites.

Anatomo-pathological investigations in pigs of the Piedmont region (Northern Italy) for infectious diseases surveillance in an antimicrobial resistance perspective

Intensive breeding responds to the expanding market demand and animal health must be guaranteed to safeguard human and Public Health. Pig farming has grown in the last decades, leading to increased animal stress, pathogens dissemination, and the consequent use of antibiotics and the spread of antimicrobial-resistant bacteria. The present study aimed to describe the anatomopathological findings observed during necropsies performed from 2019 to 2021 on deceased pigs from five intensive breeding farms in northwestern Italy also reporting bacterial isolations, antimicrobial susceptibility testing, and virological results. Weaned pigs (WP) (N = 143) represented the majority of the carcasses, while the remaining part (N = 49) were fattening pigs (FP). Most of WP were affected by systemic disease (N = 79, 55.2 %), whereas 49 % of FP were affected by respiratory disease (N = 24). Streptococcus suis was the most frequently isolated microorganism in respiratory (around 20 % in both WP and FP) and systemic cases (25.3 % in WP and 33.3 % in FP). Enteric disorders were attributable to Brachyspira spp. and Escherichia coli in WP and FP (44.5 % and 55.5 %, respectively). Escherichia coli was considered to be the second causative agent of systemic disease (22.8 %) in WP. Streptococcus suis and monophasic Salmonella Typhimurium were isolated and demonstrated a high rate of multi-drug resistance (84 % and 100 %, respectively): the first showed resistance mainly against tetracyclines (100 %), lincosamides (88 %) and macrolides (84 %), whereas the latter to tetracyclines, sulfametox-trimethoprim, ampicillin, florfenicol, and enrofloxacin. Necropsy and microbiological assays are powerful tools for disease surveillance programs, highlighting potential risks for public health.

African Swine Fever: Spread and seasonal patterns worldwide

African Swine Fever (ASF) is a viral disease affecting both wild and domestic swine, with the potential for major lethality rates. In addition to direct losses for producers, its notification in a free country or zone leads to international trade restrictions. The disease has spread globally at concerning levels, with outbreaks reported in recent years across five continents. Time series analysis of ASF outbreak notifications indicates an increasing trend in Europe and Asia. For Europe, including both domestic pigs and wild boar, seasonality was pronounced in the summer and autumn (July, August, and October). Wild boar represented 78.00 % (25,017) of the reported outbreaks in the continent, with pronounced seasonality in winter (December, January and February) and a peak in summer (July). In domestic pigs, seasonality was pronounced mainly in the summer (July and August) and autumn (October). Poland and Romania were the countries with the highest number of reported outbreaks on the continent, representing 35.34 % and 22.50 % of the total in Europe, respectively. In Asia, analysis including both domestic pigs and wild boar showed pronounced seasonality in February and March. For domestic animals, a higher number of outbreaks occur in the early months of the year (mainly February, and March), in the third quarter and early fourth (August, September, October and November), with a decrease in the middle (July) and at the end of the year (December). In China, the notifications are predominantly in domestic swine, with 97.21 % (209) of the reported outbreaks in the country. For wild boars, South Korea accounts for 96.46 % (1690) of the notifications in Asia. Seasonality in Europe may be related to increased human movement during these periods and wild boar behavior. In Asia, seasonality coincides with the period immediately following the Chinese New Year, probably related to the increased national demand for pork and the movement of people and by-products in the country. Recent notifications in 2021 and 2022 in the Caribbean region have raised concerns across the Americas.

Evaluating the Global Distribution and Characteristics of Research Studies Focusing on Swine Farm Biosecurity: A Scoping Review

Despite significant advances in swine biosecurity (BS) over the last decade, BS plans have yet to be broadly adopted on swine farms. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScRs) framework was followed to review the literature, describe the worldwide distribution of publications on swine farm BS, and characterize the research methodologies used. The final data extraction and analysis included 157 publications originating from 48 countries. Several publications (n=93) used face-to-face interviews for data collection. An increase in the adoption of online and multimode approaches was detected after 2009. Many publications (n=92) focussed on the impact of BS on the incidence of swine diseases such as porcine reproductive and respiratory syndrome (PRRS) and African swine fever (ASF). Only 16 studies reported proposing incentives for study participation. Regions with high publication numbers were detected in Western and Southern Europe, Northeast of South America, and East Africa. Areas with low publication numbers were in Eastern Europe, North and Central Africa, Central America, and the Northwest of South America. This study identified the most common study methodologies used to assess swine farm BS. Countries with limited swine BS research studies were identified where future investigations are needed.

The prevalence and shedding of porcine epidemic diarrhea virus in intensive swine farms of China from 2022 to 2023

Porcine epidemic diarrhea has emerged as a significant threat to the global swine industry. The shedding and exposure status of porcine epidemic diarrhea virus (PEDV) in intensive farms is not completely understood. In this study, a total of 56,598 clinical samples collected from 256 intensive pig farms in 20 provinces in China from 2022 to 2023, were evaluated for PEDV using quantitative real-time PCR. The overall PEDV prevalence was 11.78 % and 28.45 % at the sample and farm levels, respectively, which are relatively high in Northern China and the fourth and first quarter of the year. The PEDV-positive rates and viral loads in suckling piglet herds were higher than those in growing-finishing pigs and multiparous sows. Meanwhile, 15.61 % of pig pens, 9.51 % of corridors, 9.4 % of office areas, 9.23 % of production personnel, and 8.33 % of pig cart driver samples were positive for PEDV, indicating potential biosafety gaps in intensive pig farms. In addition, 93.41 % of inguinal lymph node tissue samples contained viral nucleic acids, revealing a possible persistent infection of PEDV in pig herds. Our study presents the first report of the large-scale detection of PEDV in intensive pig farms, which constitutes indirect evidence of virus circulation in pig herds. This study provides valuable data for preventing and controlling PEDV infection in the future.

Quantification of wildlife visits to pig farms via camera traps in Japan

Infectious diseases in livestock not only cause significant economic losses but also affect food security. Although wildlife may be involved in these infectious diseases by serving as reservoirs, research has primarily focused on livestock and related species. Moreover, while these species represent a potential threat in wildlife-borne infectious diseases, comprehensive surveys of the presence of various species are limited. In this study, we aimed to quantitatively investigate the occurrence of various mammals and birds at three pig farms in Japan. We conducted camera trap surveys from October 15, 2020, to March 24, 2022, and determined the relative abundance index inside and outside the sanitary control zone. Wild boar (Sus scrofa), sika deer (Cervus nippon), and Japanese serow (Capricornis crispus) were photographed only outside the sanitary control zone. In contrast, small and medium-sized mammals, such as feral cats (Felis catus), raccoons (Procyon lotor), and rodent species (Muridae), and birds, such as the rufous oriental turtle dove (Streptopelia orientalis) and crows of the genus Corvus, were photographed both inside and outside the sanitary control zone. This comprehensive quantitative evidence suggests that various mammals and birds may be in indirect contact with livestock, highlighting the need to improve biosecurity at livestock farms. Moreover, while fences are effective against large mammals, they are inefficient against small to medium-sized mammals and birds. Therefore, the results of this study provide important insights into enhancing biosecurity on livestock farms by strengthening physical fencing, disinfecting clothing and equipment, and complying with standards of hygiene management.

Molecular Epidemiology and Phyloevolutionary Analysis of Porcine Parvoviruses (PPV1 through PPV7) Detected in Replacement Gilts from Colombia

Eight porcine parvovirus (PPV) species, designated as PPV1 through PPV8, have been identified in swine. Despite their similarities, knowledge about their distribution and genetic differences remains limited, resulting in a gap in the genetic classification of these viruses. In this study, we conducted a comprehensive analysis using PPV1 to PPV7 genome sequences from Colombia and others available in the GenBank database to propose a classification scheme for all PPVs. Sera from 234 gilts aged 180 to 200 days were collected from 40 herds in Colombia. Individual detection of each PPV (PPV1 through PPV7) was performed using end-point PCR. Complete nucleotide (nt) sequencing was performed on the PPV1 viral protein (VP), and near-complete genome (NCG) sequencing was carried out for novel porcine parvoviruses (nPPVs) (PPV2 through PPV7). Phylogenetic analyses were conducted by comparing PPV1-VP sequences to 94 available sequences and nPPVs with 565 NCG, 846 nPPV-VP, and 667 nPPV-nonstructural protein (NS) sequences. Bayesian phylogenetic analysis was used to estimate substitution rates and the time to the most recent common ancestor for each PPV. The highest prevalence was detected for PPV3 (40.1%), followed by PPV5 (20.5%), PPV6 (17%), PPV1 (14.5%), PPV2 (9.8%), PPV4 (4.2%), and PPV7 (1.3%). Notably, all tested sera were negative for PPV8 genomes. An analysis of the PPV1-VP sequences revealed two main clades (PPV1-I and PPV1-II), with the sequences recovered in this study grouped in the PPV1-II clade. Comparative analysis showed significant genetic distances for PPV2 to PPV7 at the NCG (>6.5%), NS (>6.3%), and VP (>7.5%) regions, particularly when compared to equivalent regions of PPV genomes recovered worldwide. This study highlights the endemic circulation of nPPVs in Colombian pig herds, specifically among gilts. Additionally, it contributes to the phylogenetic classification and evolutionary studies of these viruses. The proposed method aims to categorize and divide subtypes based on current knowledge and the genomes available in databanks.

Torque Teno Sus Virus 1: A Potential Surrogate Pathogen to Study Pig-Transmitted Transboundary Animal Diseases

Understanding the epidemiology and transmission dynamics of transboundary animal diseases (TADs) among wild pigs (Sus scrofa) will aid in preventing the introduction or containment of TADs among wild populations. Given the challenges associated with studying TADs in free-ranging populations, a surrogate pathogen system may predict how pathogens may circulate and be maintained within wild free-ranging swine populations, how they may spill over into domestic populations, and how management actions may impact transmission. We assessed the suitability of Torque teno sus virus 1 (TTSuV1) to serve as a surrogate pathogen for molecular epidemiological studies in wild pigs by investigating the prevalence, persistence, correlation with host health status and genetic variability at two study areas: Archbold's Buck Island Ranch in Florida and Savannah River Site in South Carolina. We then conducted a molecular epidemiological case study within Archbold's Buck Island Ranch site to determine how analysis of this pathogen could inform transmission dynamics of a directly transmitted virus. Prevalence was high in both study areas (40%, n = 190), and phylogenetic analyses revealed high levels of genetic variability within and between study areas. Our case study showed that pairwise host relatedness and geographic distance were highly correlated to pairwise viral genetic similarity. Molecular epidemiological analyses revealed a distinct pattern of direct transmission from pig to pig occurring within and between family groups. Our results suggest that TTSuV1 is highly suitable for molecular epidemiological analyses and will be useful for future studies of transmission dynamics in wild free-ranging pigs.

Analysis of the swine movement network in Mexico: A perspective for disease prevention and control

Pig farming in Mexico is critical to the economy and food supply. Mexico has achieved advancements in swine health and established an electronic database that records swine movements (Sistema Nacional de Avisos de Movilización, SNAM). In this study, we characterized swine movement patterns in México between 2017 and 2019 to identify specific areas and periods that require concentrated efforts for effective epidemiological surveillance and disease control. We employed a Social Network Analysis (SNA) methodology to comprehensively describe and analyze the intricate patterns of pig movement. In addition, we sought to integrate swine population density into the analysis. We used metrics to characterize the network structure and identify the most critical nodes in the movement network. Cohesion metrics were used to identify commercial communities characterized by a high level of interconnectivity in swine movements between groups of nodes. Of a cumulative count of 662,255 pig shipments, 95.9% were attributed to slaughterhouse shipments. We observed that 54% of all Mexican municipalities were part of the network; however, the density of the movement network was less than 0.14%. We identified four Swine Production Centers in Mexico with high interconnectivity in the movement network. We detected moderate positive correlations (ρ ≥0.4 and <0.6, p < 0.001) between node metrics and swine population indicators, whereas the number of commercial swine facilities showed weak correlations with the node metrics. We identified six large, geographically clustered commercial communities that aligned with the Swine Production Centers. This study provides a comprehensive overview of swine movement patterns in Mexico and their close association with swine production centers, which play a dual role as producers and traders within the swine industry of Mexico. Our research offers valuable insights for policymakers in developing disease prevention and control strategies.

tRF-Gly-GCC in Atretic Follicles Promotes Ferroptosis in Granulosa Cells by Down-Regulating MAPK1

Follicle development refers to the process in which the follicles in the ovary gradually develop from the primary stage to a mature state, and most primary follicles fail to develop normally, without forming a dense granular cell layer and cell wall, which is identified as atretic follicles. Granulosa cells assist follicle development by producing hormones and providing support, and interference in the interaction between granulosa cells and oocytes may lead to the formation of atretic follicles. Ferroptosis, as a non-apoptotic form of death, is caused by cells accumulating lethal levels of iron-dependent phospholipid peroxides. Healthy follicles ranging from 4 to 5 mm were randomly divided into two groups: a control group (DMSO) and treatment group (10 uM of ferroptosis inducer erastin). Each group was sequenced after three repeated cultures for 24 h. We found that ferroptosis was associated with atretic follicles and that the in vitro treatment of healthy follicles with the ferroptosis inducer erastin produced a phenotype similar to that of atretic follicles. Overall, our study elucidates that tRF-1:30-Gly-GCC-2 is involved in the apoptosis and ferroptosis of GCs. Mechanistically, tRF-1:30-Gly-GCC-2 inhibits granulosa cell proliferation and promotes ferroptosis by inhibiting Mitogen-activated protein kinase 1 (MAPK1). tRF-1:30-Gly-GCC-2 may be a novel molecular target for improving the development of atretic follicles in ovarian dysfunction. In conclusion, our study provides a new perspective on the pathogenesis of granulosa cell dysfunction and follicular atresia.

Torque teno sus virus k2a (TTSuVk2a) in wild boars from northeastern Patagonia, Argentina

Torque teno sus virus k2a (TTSuVk2a) is a member of the family Anelloviridae that can establish persistent infections in both domestic pigs and wild boars. Its association with diseases has not been precisely elucidated, and it is often considered only as a commensal virus. This infectious agent has been reported in herds throughout the world. In this study, we investigated the detection rate and diversity of TTSuVk2a in free-living wild boars from northeastern Patagonia, Argentina. Total DNA was extracted from tonsil samples of 50 animals, nested PCR assays were carried out, and infection was verified in 60% of the cases. Sequence analysis of the viral non-coding region revealed distinct phylogenetic groups. These clusters showed contrasting patterns of spatial distribution, which presented statistically significant differences when evaluating spatial aggregation. In turn, the sequences were compared with those available in the database to find that the clusters were distinguished by having similarity with TTSuVk2a variants of different geographic origin. The results suggested that Patagonian wild boar populations are bearers of diverse viral strains of Asian, European, and South American provenance.

Investigation of Risk Factors Associated with the African Swine Fever Outbreaks in the Nizhny Novgorod Region of Russia, 2011-2022

African swine fever (ASF) is a transboundary viral disease that affects both domestic pigs and wild boar, causing enormous damage to the pig production. Numerous studies are devoted to elucidating the role of domestic and wild pigs in ASF outbreaks. The identification of the risk factors contributing to the spread of disease in previously unaffected regions is of special interest. We conducted a retrospective analysis of sporadic ASF outbreaks in the Nizhny Novgorod region of the Russian Federation from 2011 to 2022 among both domestic pig and wild boar populations. Methods of spatiotemporal cluster analysis, mathematical modeling with logistic and negative binomial regressions, as well as the cross-correlation analysis of time series, were used to identify the most significant factors associated with the ASF outbreaks' presence and intensity. Regression analysis did not reveal a statistically significant correlation between ASF outbreaks in wild boar and their population density over the entire study period. However, the spatial and temporal coincidence between outbreaks and increased wild boar density was observed at the beginning of the ASF epidemic in the region. We identified the significant environmental and sociodemographic factors contributing to the spread of ASF in both domestic pig and wild boar populations. The number of small-scale farms (backyards) and summary road length were determined as the main factors contributing to the spread of ASF among domestic pigs in the Nizhny Novgorod region. The regression model for ASF outbreaks in the wild boar population revealed the presence of water bodies, number of hunting farms, and the occurrence of ASF outbreaks in the domestic pig population to be the main explanatory factors. A statistically significant coincidence was identified between the monthly volume of pork products imported to the region from the rest of Russia and the occurrence of ASF outbreaks in both domestic and wild populations. Thus, the identified spatiotemporal patterns may be useful to determine areas with an elevated risk of ASF outbreaks emergence for better resource management, disease control, and prevention. The importance of intensified monitoring and control measures in the pig products supply chain is strongly needed. The obtained models can be applied not only by the veterinary service of the Nizhny Novgorod region but to other regions with similar environmental and sociodemographic conditions.

Porcine Macrophage Markers and Populations: An Update

Besides its importance as a livestock species, pig is increasingly being used as an animal model for biomedical research. Macrophages play critical roles in immunity to pathogens, tissue development, homeostasis and tissue repair. These cells are also primary targets for replication of viruses such as African swine fever virus, classical swine fever virus, and porcine respiratory and reproductive syndrome virus, which can cause huge economic losses to the pig industry. In this article, we review the current status of knowledge on porcine macrophages, starting by reviewing the markers available for their phenotypical characterization and following with the characteristics of the main macrophage populations described in different organs, as well as the effect of polarization conditions on their phenotype and function. We will also review available cell lines suitable for studies on the biology of porcine macrophages and their interaction with pathogens.

Biosecurity and Mitigation Strategies to Control Swine Viruses in Feed Ingredients and Complete Feeds

No system nor standardized analytical procedures at commercial laboratories exist to facilitate and accurately measure potential viable virus contamination in feed ingredients and complete feeds globally. As a result, there is high uncertainty of the extent of swine virus contamination in global feed supply chains. Many knowledge gaps need to be addressed to improve our ability to prevent virus contamination and transmission in swine feed. This review summarizes the current state of knowledge involving: (1) the need for biosecurity protocols to identify production, processing, storage, and transportation conditions that may cause virus contamination of feed ingredients and complete feed; (2) challenges of measuring virus inactivation; (3) virus survival in feed ingredients during transportation and storage; (4) minimum infectious doses; (5) differences between using a food safety objective versus a performance objective as potential approaches for risk assessment in swine feed; (6) swine virus inactivation from thermal and irradiation processes, and chemical mitigants in feed ingredients and complete feed; (7) efficacy of virus decontamination strategies in feed mills; (8) benefits of functional ingredients, nutrients, and commercial feed additives in pig diets during a viral health challenge; and (9) considerations for improved risk assessment models of virus contamination in feed supply chains.

Detection of porcine circovirus 2, porcine parvovirus 1, and torque teno sus virus k2a in wild boars from northeastern Patagonia, Argentina

Wild boars can act as a reservoir of pathogenic viruses that affect the pig industry. Here, we assessed the presence of porcine circovirus 2, porcine parvovirus 1, and torque teno sus virus k2a in wild boars in northeastern Patagonia (Argentina). Total DNA was extracted from the tonsils of 27 animals (collected between early 2016 and mid-2019) and used to prepare sample pools, which were subjected to viral detection through two-round PCR assays. Sequencing of the amplification products and phylogenetic analysis confirmed the occurrence of all of the aforementioned infectious agents.

Network analysis of pig movement data as an epidemiological tool: an Austrian case study

Animal movements represent a major risk for the spread of infectious diseases in the domestic swine population. In this study, we adopted methods from social network analysis to explore pig trades in Austria. We used a dataset of daily records of swine movements covering the period 2015-2021. We analyzed the topology of the network and its structural changes over time, including seasonal and long-term variations in the pig production activities. Finally, we studied the temporal dynamics of the network community structure. Our findings show that the Austrian pig production was dominated by small-sized farms while spatial farm density was heterogeneous. The network exhibited a scale-free topology but was very sparse, suggesting a moderate impact of infectious disease outbreaks. However, two regions (Upper Austria and Styria) may present a higher structural vulnerability. The network also showed very high assortativity between holdings from the same federal state. Dynamic community detection revealed a stable behavior of the clusters. Yet trade communities did not correspond to sub-national administrative divisions and may be an alternative zoning approach to managing infectious diseases. Knowledge about the topology, contact patterns, and temporal dynamics of the pig trade network can support optimized risk-based disease control and surveillance strategies.

Risk Factors and Spatiotemporal Analysis of Classical Swine Fever in Ecuador

Classical swine fever (CSF) is one of the most important re-emergent swine diseases worldwide. Despite concerted control efforts in the Andean countries, the disease remains endemic in several areas, limiting production and trade opportunities. In this study, we aimed to determine the risk factors and spatiotemporal implications associated with CSF in Ecuador. We analysed passive surveillance and vaccination campaign datasets from 2014 to 2020; Then, we structured a herd-level case-control study using a logistic and spatiotemporal Bayesian model. The results showed that the risk factors that increased the odds of CSF occurrence were the following: swill feeding (OR 8.53), time until notification (OR 2.44), introduction of new pigs during last month (OR 2.01) and lack of vaccination against CSF (OR 1.82). The spatiotemporal model showed that vaccination reduces the risk by 33%. According to the priority index, the intervention should focus on Morona Santiago and Los Rios provinces. In conclusion, the results highlight the complexity of the CSF control programs, the importance to improve the overall surveillance system and the need to inform decision-makers and stakeholders.

Estimation of R0 for the Spread of the First ASF Epidemic in Italy from Fresh Carcasses

After fifty years of spread in the European continent, the African swine fever (ASF) virus was detected for the first time in the north of Italy (Piedmont) in a wild boar carcass in December, 2021. During the first six months of the epidemic, the central role of wild boars in disease transmission was confirmed by more than 200 outbreaks, which occurred in two different areas declared as infected. The virus entered a domestic pig farm in the second temporal cluster identified in the center of the country (Lazio). Understanding ASF dynamics in wild boars is a prerequisite for preventing the spread, and for designing and applying effective surveillance and control plans. The aim of this work was to describe and evaluate the data collected during the first six months of the ASF epidemic in Italy, and to estimate the basic reproduction number (R0) in order to quantify the extent of disease spread. The R0 estimates were significantly different for the two spatio-temporal clusters of ASF in Italy, and they identified the two infected areas based on the time necessary for the number of cases to double (td) and on an exponential decay model. These results (R0 = 1.41 in Piedmont and 1.66 in Lazio) provide quantitative knowledge on the epidemiology of ASF in Italy. These parameters could represent a fundamental tool for modeling country-specific ASF transmission and for monitoring both the spread and sampling effort needed to detect the disease early.

Description of electroencephalographic data gathered using water-based medium-expansion foam as a depopulation method for nursery pigs

The United States' swine industry is under constant threat of foreign animal diseases, which may emerge without warning due to the globalized transportation networks moving people, animals, and products. Therefore, having disease control and elimination protocols in place prior to pathogen introduction is paramount for business continuity and economic recovery. During extraordinary circumstances, it may become necessary to depopulate large populations of animals, including swine, as a disease containment measure. Currently approved depopulation methods for swine present significant logistical challenges when scaled to large populations or performed in field conditions. In the United States, water-based foam is currently approved for poultry depopulation, and recent field studies demonstrate water-based foam is an effective depopulation alternative for swine. While effective, the speed at which water-based foam induces loss of consciousness prior to death, a major welfare consideration, has not been adequately investigated. In this study, 12 nursery pigs were terminated using water-based medium-expansion foam to quantify the time to induce loss of consciousness and ultimately brain death. Each pig was implanted with subdermal electrodes to capture electroencephalographic data, placed in a body sling, and suspended in a plastic bulk container that was subsequently filled with water-based foam. Electroencephalographic data was recorded for 15 min, during which the pigs remained immersed in the water-based foam. Conservatively, average (± SD) time to unconsciousness and brain death was 1 min, 53 s ± 36 s and 3 min, 3 s ± 56 s, respectively. The relatively rapid loss of consciousness compared to other methods limits the amount of distress and is overall a positive finding for the welfare of the pigs that might be depopulated with water-based foam. The findings of this study add additional evidence supporting the use of water-based medium-expansion foam for an emergency depopulation of swine.

Welfare of pigs during transport

In the framework of its Farm to Fork Strategy, the Commission is undertaking a comprehensive evaluation of the animal welfare legislation. The present Opinion deals with protection of pigs during transport. The welfare of pigs during transport by road is the main focus, but other means of transport are also covered. Current practices related to transport of pigs during the different stages (preparation, loading/unloading, transit and journey breaks) are described. Overall, 10 welfare consequences were identified as highly relevant for the welfare of pigs during transport based on the severity, duration and frequency of occurrence: group stress, handling stress, heat stress, injuries, motion stress, prolonged hunger, prolonged thirst, restriction of movement, resting problems and sensory overstimulation. These welfare consequences and their animal-based measures are described. A variety of hazards were identified, mainly relating to factors such as mixing of unfamiliar pigs, inappropriate handling methods and devices, the use of pick-up pens, inexperienced/untrained handlers, structural deficiencies of vehicles and facilities, poor driving conditions, unfavourable microclimatic and environmental conditions and poor husbandry practices leading to these welfare consequences. The Opinion contains general and specific conclusions relating to the different stages of transport of pigs. Recommendations to prevent hazards and to correct or mitigate welfare consequences are made. Recommendations were also developed to define quantitative thresholds for microclimatic conditions and minimum space allowance within means of transport. The development of the welfare consequences over time was assessed in relation to maximum journey duration. The Opinion covers specific animal transport scenarios identified by the European Commission relating to transport of cull sows and 'special health status animals', and lists welfare concerns associated with these.

Network analysis of live pig movements in North Macedonia: Pathways for disease spread

Globalization of trade, and the interconnectivity of animal production systems, continues to challenge efforts to control disease. A better understanding of trade networks supports development of more effective strategies for mitigation for transboundary diseases like African swine fever (ASF), classical swine fever (CSF), and foot-and-mouth disease (FMD). North Macedonia, bordered to the north and east by countries with ongoing ASF outbreaks, recently reported its first incursion of ASF. This study aimed to describe the distribution of pigs and pig farms in North Macedonia, and to characterize the live pig movement network. Network analyses on movement data from 2017 to 2019 were performed for each year separately, and consistently described weakly connected components with a few primary hubs that most nodes shipped to. In 2019, the network demonstrated a marked decrease in betweenness and increase in communities. Most shipments occurred within 50 km, with movements <6 km being the most common (22.5%). Nodes with the highest indegree and outdegree were consistent across years, despite a large turnover among smallholder farms. Movements to slaughterhouses predominated (85.6%), with movements between farms (5.4%) and movements to market (5.8%) playing a lesser role. This description of North Macedonia's live pig movement network should enable implementation of more efficient and cost-effective mitigation efforts strategies in country, and inform targeted educational outreach, and provide data for future disease modeling, in the region.

First Expert Elicitation of Knowledge on Drivers of Emergence of Bovine Besnoitiosis in Europe

Bovine besnoitiosis (BB) is a chronic and debilitating parasitic disease in cattle caused by the protozoan parasite Besnoitia besnoiti. South European countries are affected and have reported clinical cases of BB. However, BB is considered as emerging in other countries/regions of central, eastern and northern Europe. Yet, data on drivers of emergence of BB in Europe are scarce. In this study, fifty possible drivers of emergence of BB in cattle were identified. A scoring system was developed per driver. Then, the scoring was elicited from eleven recognized European experts to: (i) allocate a score to each driver, (ii) weight the score of drivers within each domain and (iii) weight the different domains among themselves. An overall weighted score was calculated per driver, and drivers were ranked in decreasing order of importance. Regression tree analysis was used to group drivers with comparable likelihoods to play a role in the emergence of BB in cattle in Europe. Finally, robustness testing of expert elicitation was performed for the seven drivers having the highest probability to play a key role in the emergence of BB: i.e., (i) legal/illegal movements of live animals from neighbouring/European Union member states or (ii) from third countries, (iii) risk of showing no clinical sign and silent spread during infection and post infection, (iv) as a consequence, difficulty to detect the emergence, (v) existence of vectors and their potential spread, (vi) European geographical proximity of the pathogen/disease to the country, and (vii) animal density of farms. Provided the limited scientific knowledge on the topic, expert elicitation of knowledge, multi-criteria decision analysis, cluster and sensitivity analyses are very important to prioritize future studies, e.g., the need for quantitative import risk assessment and estimation of the burden of BB to evidence and influence policymaking towards changing (or not) its status as a reportable disease, with prevention and control activities targeting, firstly, the top seven drivers. The present methodology could be applied to other emerging animal diseases.

Prevalence of Porcine Circoviruses in Slaughterhouses in Central Shanxi Province, China

Background

Porcine circovirus disease is currently the greatest threat to pig farming. Four main porcine circovirus genotypes are circulating worldwide.

Objective

The study aimed to assess the prevalence of porcine circovirus genotypes in the central part of Shanxi province.

Methods

We investigated the prevalence of porcine circovirus type 2 (PCV2), porcine circovirus type 3 (PCV3), and porcine circovirus type 4 (PCV4). Porcine circoviruses were analyzed by polymerase chain reaction (PCR) in the lung tissues of 180 pigs from 7 slaughterhouses in central Shanxi, China.

Results

The prevalence of PCV2, PCV3, and PCV4 were 56.8, 80, and 9.4%, respectively, and the negative rate was 10% for all three pathogens. The co-infection with PCV2 + PCV3, PCV2 + PCV4, PCV3 + PCV4, and PCV2 + PCV3 + PCV4 were 47.2, 7.4, 7.4, and 5.6%, respectively. Among PCV4-positive samples, the positive rate of PCV4 + PCV2 was 52.9% (9/17), whereas that of PCV4 + PCV3 was 100% (17/17). On the other hand, PCV2 and PCV3 were detected in 57.1% (93/163) and in 78.5% (128/163) of PCV4-negative samples, respectively. Phylogenetic analysis demonstrated that PCV2, PCV3, and PCV4 were not in the same clade and were distant from each other.

Conclusion

The high positive rates of PCV3, PCV2 + PCV3, and PCV3 + PCV4 suggest that PCV3 may play a decisive role in PCV2 and PCV4 infections. Therefore, further control of PCV3 is needed to reduce the spread of the virus.

African Swine Fever Survey in a European Context

African swine fever (ASF) is currently the most threatening disease for domestic and wild pigs worldwide. Wild boar has been the main affected species in all EU countries except for Romania, where most notifications occur in domestic pigs. The spread of ASF in wild boar is challenging to control; risk factors are harder to identify and establish than in domestic pigs, which, together with an underestimation of the disease and the lack of treatment or an effective vaccine, are hindering control and eradication efforts. We distributed two online questionnaires, one for domestic pigs and one for wild boar, to experts of different background and countries in Europe, to explore risk factors in relation to ASF control connected to farming, hunting, trade, the environment, and domestic pig and wild boar populations. Overall, wild boar movements were estimated to pose the highest risk of ASF introduction and spread. The movement of pork and pork products for own consumption also ranked high. Here we explored, in addition to the assessment of risk pathways, the identification of risks of transmission at the domestic/wild boar interface, the importance of biosecurity practices and improved control efforts, and controversial opinions that require further attention.

Stem cell-derived porcine macrophages as a new platform for studying host-pathogen interactions

BACKGROUND

Infectious diseases of farmed and wild animals pose a recurrent threat to food security and human health. The macrophage, a key component of the innate immune system, is the first line of defence against many infectious agents and plays a major role in shaping the adaptive immune response. However, this phagocyte is a target and host for many pathogens. Understanding the molecular basis of interactions between macrophages and pathogens is therefore crucial for the development of effective strategies to combat important infectious diseases.

RESULTS

We explored how porcine pluripotent stem cells (PSCs) can provide a limitless in vitro supply of genetically and experimentally tractable macrophages. Porcine PSC-derived macrophages (PSCdMs) exhibited molecular and functional characteristics of ex vivo primary macrophages and were productively infected by pig pathogens, including porcine reproductive and respiratory syndrome virus (PRRSV) and African swine fever virus (ASFV), two of the most economically important and devastating viruses in pig farming. Moreover, porcine PSCdMs were readily amenable to genetic modification by CRISPR/Cas9 gene editing applied either in parental stem cells or directly in the macrophages by lentiviral vector transduction.

CONCLUSIONS

We show that porcine PSCdMs exhibit key macrophage characteristics, including infection by a range of commercially relevant pig pathogens. In addition, genetic engineering of PSCs and PSCdMs affords new opportunities for functional analysis of macrophage biology in an important livestock species. PSCs and differentiated derivatives should therefore represent a useful and ethical experimental platform to investigate the genetic and molecular basis of host-pathogen interactions in pigs, and also have wider applications in livestock.

Models to assess the risk of introduction of selected animal viral diseases through the importation of live animals as a key part of risk analysis

Introduction of an animal viral disease, especially a notifiable disease, into an importing country or region free from the disease may lead to serious epidemiological consequences and economic losses. Trade in live animals is historically considered one of the most important risk pathways. To estimate the magnitude of such risk, the likelihood of a virus’ entry into a country and the consequences of this event should be jointly evaluated. Depending on data availability, the urgency of the problem and the detail level of the objectives, a risk assessment may be conducted in a qualitative, semi-quantitative or quantitative way. The purpose of this review was firstly to provide a brief description of each step of the risk analysis process, with particular emphasis on the risk assessment component, and subsequently to supply examples of different approaches to the assessment of the risk of the introduction of selected animal viral diseases. Based on the reviewed models, the overall likelihood of introduction of particular diseases was generally estimated as low. The output risk value was strongly dependent on the duration of the silent phase of the epidemic in the country of origin. Other parameters with some bearing upon the risk derived from the epidemiological situation in the country of origin and the biosecurity or mitigation measures implemented in the country of destination. The investigated models are universal tools for conducting assessment of the risk of introduction of various animal diseases to any country. Their application may lead to timely implementation of appropriate measures for the prevention of the spread of a disease to another country or region.

AgSecure Africa ProgrammeTM: A Blended Training Approach for Africa

An innovative training program entitled "AgSecure Africa Programme^TM" was developed in partnership with the South African Agricultural Research Council-Onderstepoort Veterinary Research (ARC-OVR) to train veterinarians, animal health technicians, researchers and laboratory personnel. Three blended courses consisting of both virtual and in-person delivery were provided with the intent of contributing to the better prevention, detection and control of infectious diseases of livestock and poultry of significant importance for the region with a strong emphasis on transboundary animal diseases. A "train the trainer" model of instruction was employed to equip participants with the ability to train and share knowledge with colleagues and small-holder farmers in their various communities and regions. The design of this program was to increase the capacity of veterinarians and veterinary diagnosticians to safely and accurately diagnose infectious livestock diseases and to also empower small-holder farmers with the knowledge needed to safely and securely manage their livestock and be a first line defense in the prevention and control of infectious livestock diseases. Quantitative and qualitative evaluations were used to measure the impact of the trainings which revealed significant increases in knowledge gains. Course materials were submitted and approved for accreditation by the South African Veterinary Council (SAVC) becoming the first international training program to achieve this. Approval of these courses led to licensed veterinarians and animal health technicians being awarded continuing professional development credits upon their successful completion of courses. A larger goal was to build training capacity, not only for South Africa, but also for the region.

African Swine Fever Virus (ASFV): Biology, Genomics and Genotypes Circulating in Sub-Saharan Africa

African swine fever (ASF) is a highly infectious and fatal haemorrhagic disease of pigs that is caused by a complex DNA virus of the genus Asfivirus and Asfarviridae African suids family. The disease is among the most devastating pig diseases worldwide including Africa. Although the disease was first reported in the 19th century, it has continued to spread in Africa and other parts of the world. Globally, the rising demand for pork and concomitant increase in transboundary movements of pigs and pork products is likely to increase the risk of transmission and spread of ASF and pose a major challenge to the pig industry. Different genotypes of the ASF virus (ASFV) with varying virulence have been associated with different outbreaks in several countries in sub-Saharan Africa (SSA) and worldwide, and understanding genotype circulation will be important for ASF prevention and control strategies. ASFV genotypes unique to Africa have also been reported in SSA. This review briefly recounts the biology, genomics and genotyping of ASFV and provides an account of the different genotypes circulating in SSA. The review also highlights prevention, control and progress on vaccine development and identifies gaps in knowledge of ASFV genotype circulation in SSA that need to be addressed.

Influenza A Viruses and Zoonotic Events-Are We Creating Our Own Reservoirs?

Zoonotic infections of humans with influenza A viruses (IAVs) from animal reservoirs can result in severe disease in individuals and, in rare cases, lead to pandemic outbreaks; this is exemplified by numerous cases of human infection with avian IAVs (AIVs) and the 2009 swine influenza pandemic. In fact, zoonotic transmissions are strongly facilitated by manmade reservoirs that were created through the intensification and industrialization of livestock farming. This can be witnessed by the repeated introduction of IAVs from natural reservoirs of aquatic wild bird metapopulations into swine and poultry, and the accompanied emergence of partially- or fully-adapted human pathogenic viruses. On the other side, human adapted IAV have been (and still are) introduced into livestock by reverse zoonotic transmission. This link to manmade reservoirs was also observed before the 20th century, when horses seemed to have been an important reservoir for IAVs but lost relevance when the populations declined due to increasing industrialization. Therefore, to reduce zoonotic events, it is important to control the spread of IAV within these animal reservoirs, for example with efficient vaccination strategies, but also to critically surveil the different manmade reservoirs to evaluate the emergence of new IAV strains with pandemic potential.

Rethinking the uncertainty of African swine fever virus contamination in feed ingredients and risk of introduction into the United States

Economically relevant pathogens, such as African swine fever virus (ASFV), have been shown to survive when experimentally inoculated in some feed ingredients under the environmental conditions in transoceanic transport models. However, these models did not characterize the likelihood of virus survival under various time and temperature processes that feed ingredients undergo before they are added to swine diets. Here, we developed a quantitative risk assessment model to estimate the probability that one or more corn or soybean meal ocean vessels (25,000 tonnes) contaminated with ASFV would be imported into the United States annually. This final probability estimate was conditionally based on five likelihoods: the probability of initial ASFV contamination (p0), ASFV inactivation during processing (p1) and transport (p2), recontamination (pR), and ASFV inactivation while awaiting customs clearance at United States entry (p3). The probability of ASFV inactivation was modelled using corn and soybean (extruded or solvent extracted) processing conditions (times and temperatures), D-values (time to reduce 90% or 1-log) estimated from studies of ASFV thermal inactivation in pork serum (p1), and survival in feed ingredients during transoceanic transport (p2 and p3). 'What-if' scenarios using deterministic values for p0 and pR (1%, 10%, 25%, 50%, 75%, and 100%) were used to explore their impact on risk. The model estimated complete inactivation of ASFV after extrusion or solvent extraction processes regardless of the initial ASFV contamination probability assumed. The value of recontamination (ranging from 1% to 75%) was highly influential on the risk of one ASFV-contaminated soybean meal vessel entering the United States. Median risk estimates ranged from 0.064% [0.006%-0.60%; 95% probability interval (PI)], assuming a pR of 1.0%, up to 4.67% (0.45%-36.50% 95% PI) assuming a pR of 75.0%. This means that at least one vessel with ASFV-contaminated soybean meal would be imported once every 1563-21 years, respectively. When all raw corn was assumed to be contaminated (p0 = 100%), and no recontamination was assumed to occur (pR = 0%), the median probability of one vessel with ASFV-contaminated corn entering the United States was 2.02% (0.28%-9.43% 95% PI) or once every 50 years. Values of recontamination between 1% and 75% did not substantially change the risk of corn. Days of transport, virus survival during transport (D-value), and number of vessels shipped were the parameters most influential for increased likelihood of a vessel with ASFV-contaminated soybean meal or corn entering the United States. The model helped to identify knowledge gaps that are most influential on output values and serves as a framework that could be updated and parameterized as new scientific information becomes available. We propose that the quantitative risk assessment model developed in this study can be used as a framework for estimating the risk of ASFV entry into the United States and other ASFV-free countries through other types of imported feed ingredients that may potentially become contaminated. Ultimately, this model can be used to develop risk mitigation strategies and critical control points for inactivating ASFV during feed ingredient processing, storage, and transport, and contribute to the design and implementation of biosecurity measures to prevent the introduction of ASFV into the United States and other ASFV-free countries.

Evaluation of an automated insulated isothermal polymerase chain reaction system for rapid and reliable, on-site detection of African swine fever virus

OBJECTIVE

To evaluate the utility of an automated insulated isothermal PCR (iiPCR) system for rapid and reliable on-site detection of African swine fever virus (ASFV) in swine biological samples.

SAMPLE

Lymph node, tissue homogenate, whole blood, serum, spleen, and tonsil samples collected from swine in North and South Vietnam.

PROCEDURES

Analytic sensitivity of the iiPCR system was determined by serial dilution and analysis of 2 samples (swine tissue homogenate and blood) predetermined to be positive for ASFV. Analytic specificity was assessed by analysis of 2 samples predetermined to be negative for ASFV and positive or negative for other swine pathogens (classical swine fever virus, porcine reproductive and respiratory syndrome virus, foot-and-mouth disease virus, and porcine circovirus type 2). Diagnostic performance of the iiPCR system for detection of ASFV was determined by analysis of the various tissue sample types. For all tests, a real-time PCR assay was used as the reference method.

RESULTS

The iiPCR system was able to detect ASFV in swine blood or tissue homogenate at dilutions up to 10⁶, whereas the real-time PCR assay was able to detect dilutions of up to 10⁵ or 10⁶. The iiPCR system had high analytic specificity for detection of ASFV versus other swine pathogens. Between 97% and 100% agreement was found between results of the iiPCR system for the various tissue samples and results of real-time PCR assay.

CONCLUSIONS AND CLINICAL RELEVANCE

The evaluated iiPCR system was found to be a rapid, reliable, and sample-flexible method for ASFV detection and may be useful for disease surveillance and quarantine in national strategies for early ASF control.

Modeling the Spread of Porcine Reproductive and Respiratory Syndrome Among Pig Farms in Lira District of Northern Uganda

Porcine Reproductive and Respiratory Syndrome (PRRS) is a viral swine disease that causes reproductive failure in breeding sows and respiratory distress in growing pigs. The main objectives were to simulate the transmission patterns of PRRS in Uganda using North American Animal Disease Spread Model (NAADSM) and to evaluate the potential effect of prevention and control options such as vaccination and movement control. The median number of infectious farms at the end of 52 weeks for the baseline scenario was 735 (36.75% of the 2,000 farms). The best effects of vaccination were observed in scenarios 60% farm coverage and 80% farm coverage, which resulted in 82 and 98.2% reduction in the median number of infectious farms at the end of the simulation, respectively. Vaccination of all medium and large farms only (33% of the farms) resulted in a 71.2% decrease in the median number of infectious farms at the end of 52 weeks. Movement control (MC) results showed that the median number of infectious farms at the end of 52 weeks decreased by 21.6, 52.3, 79.4, and 92.4% for scenarios MC 20, MC 40, MC 60, and MC 80%, respectively. This study provides new insights to the government of Uganda on how PRRS can be controlled. The large and medium farms need to be prioritized for vaccination, which would be a feasible and effective way to limit the spread of PRRS in Uganda. Scavenging pigs should be confined at all times, whether in the presence or absence of any disease outbreaks.

African swine fever risk and plant-based feed ingredients: Canada's approach to risk management of imported feed products

As a result of unprecedented spread of African swine fever (ASF) since 2018, Canada has taken additional steps to prevent introduction of the virus. While the role of plant‐based feed in the transmission of ASF is not completely understood, it was identified that no mitigation measures were in place to address this uncertain risk. A risk analysis process was conducted with collaboration between government and industry, including an assessment of the costs and benefits of various risk mitigation options. Using existing legislative tools, requirements must now be met before the importation of plant‐based feed ingredients of concern is permitted. Even with an uncertain risk, countries such as Canada that would suffer severe consequences should ASF be introduced, need to consider appropriate, risk‐based mitigation measures.

Is transportation a risk factor for African swine fever transmission in Australia: a review

African swine fever (ASF) is a viral disease of the pigs that was first described in Africa during the early part of the twentieth century. The disease has periodically occurred outside of Africa, including an ongoing epidemic in Europe and Asia that started in 2007; the disease has never occurred in Australia or New Zealand. Once introduced into a country, spread can occur through direct and indirect routes of transmission. Infected feral pig populations have the potential to act as a long-term reservoir for the virus, making eradication difficult. Just before and throughout the period of clinical signs, ASF virus is shed in oronasal fluids, urine, faeces and blood. This results in contamination of the pig's environment, including flooring, equipment and vehicles. Transportation-related risk factors therefore are likely to play an important role in ASF spread, though evidence thus far has been largely anecdotal. In addition to the existing AUSVETPLAN ASF plan, efforts should be made to improve transportation biosecurity, from the time a pig leaves the farm to its destination. Collection of data that could quantify the capabilities and capacity of Australia to clean and disinfect livestock trucks would help to determine if private and/or public sector investment should be made in this area of biosecurity. No peer-reviewed research was identified that described a specific process for cleaning and disinfecting a livestock truck known to be contaminated with ASF virus, though literature suggests that transportation is an important route of transmission for moving the virus between farms and countries.

Detection of African swine fever virus in pigs in Southwest Nigeria

BACKGROUND AND AIM

Nigeria experienced repeated outbreaks of African swine fever (ASF) in pig herds between 1997 and 2005 in the southwest region of the country. ASF is believed to currently be enzootic in this region. The status of enzootic transmission of ASF virus strain to pigs is; however, unknown. Twenty-three genotypes of the ASF virus based on the p72 gene are found across Africa. This study aimed to identify the current circulating field strain(s) of the ASF virus in Southwest Nigeria and characterized evolutionary trends.

MATERIALS AND METHODS

DNA samples were extracted from 144 pooled blood samples obtained from 2012 to 2013 following the manufacturer's instructions. DNA was used for conventional polymerase chain reaction using primers targeting the p72 gene and amplified products sequenced with Sanger's sequencing. Sequences were analyzed for homology and phylogenetic relationships.

RESULTS

Eleven of 144 samples (7.6%) showed bands at 950 bp. A new field strain of ASF virus of genotype I that shared ancestry with ASF virus strains or isolates from Spain and Brazil was identified among pig herds. The new strain differs phylogenetically in amino acid composition compared with previously identified ASF virus field strains.

CONCLUSION

The currently circulating field strain of ASF virus suggests a mutation responsible for decreased morbidity and mortality recorded in sporadic cases.

Development of a transboundary model of livestock disease in Europe

Epidemiological models of notifiable livestock disease are typically framed at a national level and targeted for specific diseases. There are inherent difficulties in extending models beyond national borders as details of the livestock population, production systems and marketing systems of neighbouring countries are not always readily available. It can also be a challenge to capture heterogeneities in production systems, control policies, and response resourcing across multiple countries, in a single transboundary model.

In this paper, we describe EuFMDiS, a continental‐scale modelling framework for transboundary animal disease, specifically designed to support emergency animal disease planning in Europe. EuFMDiS simulates the spread of livestock disease within and between countries and allows control policies to be enacted and resourced on a per‐country basis. It provides a sophisticated decision support tool that can be used to look at the risk of disease introduction, establishment and spread; control approaches in terms of effectiveness and costs; resource management; and post‐outbreak management issues.

Can we effectively manage parasites, prions, and pathogens in the global feed industry to achieve One Health?

Prions and certain endoparasites, bacteria, and viruses are internationally recognized as types of disease-causing biological agents that can be transmitted from contaminated feed to animals. Historically, foodborne biological hazards such as prions (transmissible spongiform encephalopathy), endoparasites (Trichinella spiralis, Toxoplasma gondii), and pathogenic bacteria (Salmonella spp., Listeria monocytogenes, Escherichia coli O157, Clostridium spp., and Campylobacter spp.) were major food safety concerns from feeding uncooked or improperly heated animal-derived food waste and by-products. However, implementation of validated thermal processing conditions along with verifiable quality control procedures has been effective in enabling safe use of these feed materials in animal diets. More recently, the occurrence of global Porcine Epidemic Diarrhea Virus and African Swine Fever Virus epidemics, dependence on international feed ingredient supply chains, and the discovery that these viruses can survive in some feed ingredient matrices under environmental conditions of trans-oceanic shipments has created an urgent need to develop and implement rigorous biosecurity protocols that prevent and control animal viruses in feed ingredients. Implementation of verifiable risk-based preventive controls, traceability systems from origin to destination, and effective mitigation procedures is essential to minimize these food security, safety, and sustainability threats. Creating a new biosafety and biosecurity framework will enable convergence of the diverging One Health components involving low environmental impact and functional feed ingredients that are perceived as having elevated biosafety risks when used in animal feeds.

Molecular detection of porcine circovirus type 3 in Shanxi Province, China

Porcine circovirus type 3 (PCV3), which was first detected in the United States of America in 2015, is a potential threat to the swine industry. However, the prevalence of PCV3 in Shanxi Province, China, is unclear. In this research, the prevalence and genetic diversity of PCV3 were investigated in above area. Lung tissue samples (n = 491) from 19 pig slaughterhouses across 11 cities throughout Shanxi Province were analyzed for PCV3 infection by PCR in 2019. The results showed that PCV3 positive rates in slaughterhouses and individuals were 100% (19/19) and 86.76% (426/491), respectively. PCV2 and PCV3 double-positive rates in slaughterhouses and individuals were 100% (19/19) and 59.27% (291/491), respectively. PCR positive samples were further sequenced and 8 PCV3 isolates were identified. The nucleotide homology of these isolates with other PCV3 isolates in NCBI database was 97.45–99.90%. A phylogenetic analysis, based on the complete genomic sequence and ORF2, divided these PCV3 strains into 2 major groups. Based on A24/V and R27/K amino acid mutations of capsid protein, the 8 identified PCV3 strains were separated to 2 clades. This was the first detailed investigation into the epidemiology of PCV3 in Shanxi Province. Our findings enabled us to assess the possibility of widespread transmission from this region. Thus, current findings establish a basis for further studies of genetic variations in PCV3 strains circulating in China.

The first genotype II African swine fever virus isolated in Africa provides insight into the current Eurasian pandemic

African swine fever (ASF) caused by the African swine fever virus (ASFV) is ranked by OIE as the most important source of mortality in domestic pigs globally and is indigenous to African wild suids and soft ticks. Despite two ASFV genotypes causing economically devastating epidemics outside the continent since 1961, there have been no genome-level analyses of virus evolution in Africa. The virus was recently transported from south-eastern Africa to Georgia in 2007 and has subsequently spread to Russia, eastern Europe, China, and south-east Asia with devastating socioeconomic consequences. To date, two of the 24 currently described ASFV genotypes defined by sequencing of the p72 gene, namely genotype I and II, have been reported outside Africa, with genotype II being responsible for the ongoing pig pandemic. Multiple complete genotype II genome sequences have been reported from European, Russian and Chinese virus isolates but no complete genome sequences have yet been reported from Africa. We report herein the complete genome of a Tanzanian genotype II isolate, Tanzania/Rukwa/2017/1, collected in 2017 and determined using an Illumina short read strategy. The Tanzania/Rukwa/2017/1 sequence is 183,186 bp in length (in a single contig) and contains 188 open reading frames. Considering only un-gapped sites in the pairwise alignments, the new sequence has 99.961% identity with the updated Georgia 2007/1 reference isolate (FR682468.2), 99.960% identity with Polish isolate Pol16_29413_o23 (MG939586) and 99.957% identity with Chinese isolate ASFV-wbBS01 (MK645909.1). This represents 73 single nucleotide polymorphisms (SNPs) relative to the Polish isolate and 78 SNPs with the Chinese genome. Phylogenetic analysis indicated that Tanzania/Rukwa/2017/1 clusters most closely with Georgia 2007/1. The majority of the differences between Tanzania/Rukwa/2017/1 and Georgia 2007/1 genotype II genomes are insertions/deletions (indels) as is typical for ASFV. The indels included differences in the length and copy number of the terminal multicopy gene families, MGF 360 and 110. The Rukwa2017/1 sequence is the first complete genotype II genome from a precisely mapped locality in Africa, since the exact origin of Georgia2007/1 is unknown. It therefore provides baseline information for future analyses of the diversity and phylogeography of this globally important genetic sub-group of ASF viruses.

Enhanced Detection of Major Pathogens and Toxins in Poultry and Livestock With Zoonotic Risks Using Nanomaterials-Based Diagnostics

Nanotechnology has gained prominence over the recent years in multiple research and application fields, including infectious diseases in healthcare, agriculture, and veterinary science. It remains an attractive and viable option for preventing, diagnosing, and treating diseases in animals and humans. The apparent efficiency of nanomaterials is due to their unique physicochemical properties and biocompatibility. With the persistence of pathogens and toxins in the poultry and livestock industries, rapid diagnostic tools are of utmost importance. Though there are many promising nanomaterials-based diagnostic tests specific to animal disease-causing agents, many have not achieved balanced sensitivity, specificity, reproducibility, and cost-effectiveness. This mini-review explores several types of nanomaterials, which provided enhancement on the sensitivity and specificity of recently reported diagnostic tools related to animal diseases. Recommendations are also provided to facilitate more targeted animal populations into the development of future diagnostic tools specifically for emerging and re-emerging animal diseases posing zoonotic risks.

New perspectives for evaluating relative risks of African swine fever virus contamination in global feed ingredient supply chains

There are no published reports indicating that the African swine fever virus (ASFV) has been detected in feed ingredients or complete feed. This is primarily because there are only a few laboratories in the world that have the biosecurity and analytical capabilities of detecting ASFV in feed. Several in vitro studies have been conducted to evaluate ASFV concentration, viability and inactivation when ASFV was added to various feed ingredients and complete feed. These inoculation studies have shown that some feed matrices support virus survival longer than others and the reasons for this are unknown. Current analytical methodologies have significant limitations in sensitivity, repeatability, ability to detect viable virus particles and association with infectivity. As a result, interpretation of findings using various measures may lead to misleading conclusions. Because of analytical and technical challenges, as well as the lack of ASFV contamination data in feed supply chains, quantitative risk assessments have not been conducted. A few qualitative risk assessments have been conducted, but they have not considered differences in potential scenarios for ASFV contamination between various types of feed ingredient supply chains. Therefore, the purpose of this review is to provide a more holistic understanding of the relative potential risks of ASFV contamination in various global feed ingredient supply chains and provide recommendations for addressing the challenges identified.

Prevalence of porcine respiratory pathogens in slaughterhouses in Shanxi Province, China

Background

Porcine respiratory diseases remain the biggest challenge in pig‐based food production and are a public health concern. Despite control measures, persistent outbreaks have been reported worldwide.

Objective

To establish an early detection mechanism for pig farm disease outbreaks based on slaughterhouse risk and environmental assessment.

Methods

We investigated the prevalence and risk factors of porcine respiratory disease‐causing pathogens including Mycoplasma hyopneumoniae (MHP), porcine circovirus type 2 (PCV2), porcine reproductive and respiratory syndrome virus (PRRSV) and Haemophilus parasuis (HPS). Polymerase chain reaction (PCR) was used to analyse the lungs of 491 pigs from 19 slaughterhouses across 11 cities in Shanxi Province, China.

Results

PCR detected MHP, PCV2, PPRSV and HPS in 76.99%, 67.00%, 11.82% and 19.55% of the samples, respectively; 10.12% were negative for all four pathogens. Co‐positivity rates for two and three pathogens were identified. The results confirmed significant correlations between PCV2 and MHP (p = .001, p < .05), HPS and PCV2 (p = .01, p < .05) and MHP and PRRSV (p = .01, p < .05). No significant correlation was observed between HPS and MHP (p = .067, p > .05). Positive MHP and PCV2 rates were low in areas with high vegetation coverage. The overall pathogen positivity rate was higher in both lower and higher temperature environments.

Conclusions

Interactions among pathogens may increase disease severity. Furthermore, environmental assessment and pathogen surveillance within pig slaughterhouses can be an effective approach for early detection and mitigation of new disease threats before broad dissemination occurs among a herd.

Global Comprehensive Literature Review and Meta-Analysis of Brucella spp. in Swine Based on Publications From 2000 to 2020

Background: Brucellosis, a zoonotic disease, infects various hosts, including swine and humans. It has reemerged in recent years as a public health concern, and current studies on brucellosis infection in swine have been conducted worldwide. However, no meta-analyses of global brucellosis infection in swine have been published. The aim of this study was to provide an overview of Brucella species (spp.) in swine worldwide and the factors associated with its persistence.

Results: We searched seven databases for published epidemiological studies on brucellosis in pigs, including the Chinese National Knowledge Infrastructure, Wanfang Data, SpringerLink, ScienceDirect, Web of Science, the VIP Chinese Journal Database and PubMed. We selected 119 articles published from January 1, 2000 to January 3, 2020 for inclusion in the meta-analysis and analyzed the data using a random-effects model. Funnel plots and Egger's test showed significant publication bias in the included studies. The results of the sensitivity analysis showed that our study was relatively stable and reliable. The prevalence of brucellosis in swine was 2.1% (95% CI: 1.6–2.6), of which the highest infection rate, which was found in Europe, was 17.4% (95% CI: 11.1–24.9). The prevalence in feral pigs (15.0%, 95% CI: 8.4–23.2) was higher than that in domestic pigs (1.1%, 95% CI 0.2–2.5). The prevalence in high-income countries (15.7%, 95% CI 8.0–25.3) was significantly higher than that in middle- (0.8%, 95% CI 0.5–1.1), and low-income countries (0.1%, 95% CI 0.0–0.2). The prevalence was highest in finishing pigs at 4.9% (95% CI 0.9–11.0), and lowest among suckling pigs at 0% (95% CI 0.0–0.5).

Conclusion: The Brucella prevalence in pig herds currently is distributed widely throughout the world. In some countries, swine brucellosis may be a neglected zoonotic disease. We recommend long-term monitoring of the prevalence of brucellosis in domestic and wild pig herds. Attention should also be paid to animal welfare on intensive pig farms; controlling the breeding density may play an important role in reducing the spread of brucellosis among pigs.

Measures Matter-Determining the True Nutri-Physiological Value of Feed Ingredients for Swine

Many types of feed ingredients are used to provide energy and nutrients to meet the nutritional requirements of swine. However, the analytical methods and measures used to determine the true nutritional and physiological ("nutri-physiological") value of feed ingredients affect the accuracy of predicting and achieving desired animal responses. Some chemical characteristics of feed ingredients are detrimental to pig health and performance, while functional components in other ingredients provide beneficial health effects beyond their nutritional value when included in complete swine diets. Traditional analytical procedures and measures are useful for determining energy and nutrient digestibility of feed ingredients, but do not adequately assess their true physiological or biological value. Prediction equations, along with ex vivo and in vitro methods, provide some benefits for assessing the nutri-physiological value of feed ingredients compared with in vivo determinations, but they also have some limitations. Determining the digestion kinetics of the different chemical components of feed ingredients, understanding how circadian rhythms affect feeding behavior and the gastrointestinal microbiome of pigs, and accounting for the functional properties of many feed ingredients in diet formulation are the emerging innovations that will facilitate improvements in precision swine nutrition and environmental sustainability in global pork-production systems.

A Novel E2 Glycoprotein Subunit Marker Vaccine Produced in Plant Is Able to Prevent Classical Swine Fever Virus Vertical Transmission after Double Vaccination

The efficacy of a novel subunit vaccine candidate, based in the CSFV E2 glycoprotein produced in plants to prevent classical swine fever virus (CSFV) vertical transmission, was evaluated. A Nicotiana benthamiana tissue culture system was used to obtain a stable production of the E2-glycoprotein fused to the porcine Fc region of IgG. Ten pregnant sows were divided into three groups: Groups 1 and 2 (four sows each) were vaccinated with either 100 μg/dose or 300 μg/dose of the subunit vaccine at 64 days of pregnancy. Group 3 (two sows) was injected with PBS. Groups 1 and 2 were boosted with the same vaccine dose. At 10 days post second vaccination, the sows in Groups 2 and 3 were challenged with a highly virulent CSFV strain. The vaccinated sows remained clinically healthy and seroconverted rapidly, showing efficient neutralizing antibodies. The fetuses from vaccinated sows did not show gross lesions, and all analyzed tissue samples tested negative for CSFV replication. However, fetuses of non-vaccinated sows had high CSFV replication in tested tissue samples. The results suggested that in vaccinated sows, the plant produced E2 marker vaccine induced the protective immunogenicity at challenge, leading to protection from vertical transmission to fetuses.