Transboundary and Emerging Diseases最新文献

African swine fever (ASF) is a virulent and lethal disease affecting domestic pigs and wild boars, with serious implications for biodiversity, food security, and the economy. Since its reemergence in Europe, ASF has become widespread, and Singapore reported its first ASF outbreak in its wild boar population. To understand the transmission dynamics in Singapore’s urban landscape, an agent-based spatiotemporal model was designed to mechanistically model the wild boar dispersal and their interactions for ASF transmission. We investigated the impacts of wild boar dispersal capacity and carcass removal actions on the spatiotemporal dynamics of disease transmission. The model predictions were validated using observed wild boar mortality reports in Singapore and suggested multiple disease entry points into our wild boar population. Our simulations estimated that the ASF outbreak in Singapore would peak within 3 weeks and lasts for less than 70 days. Carcass-mediated transmission was evident with epidemic reoccurrence through infectious carcasses accounting for 18%–75% of the iterations. Increasing wild boar dispersal capacity expanded the geographic extent of ASF infection, potentially spreading further inland. Simulated carcass removal and decontamination measures slightly reduced the epidemic duration by up to 13.5 days and reoccurrence through infectious carcass by 10.8%. Carcass removal and decontamination efforts, along with identifying and blocking high-risk areas (e.g., dispersal corridors), are important in controlling the transmission of ASF through contaminated fomites and limiting the dispersal of infected animals. Establishing surveillance programmes and enhancing detection capabilities are also crucial for the successful management and control of infectious diseases.

The 2009 influenza A H1N1 pandemic (pdm09) originated from the influenza A virus of swine (IAV-S) through multiple reassortment events with avian and human IAVs. The pdm09 reportedly reintroduced the virus to pigs, contributing to the evolution and diversity of IAV-S through frequent reassortment and drifts. Surveillance and whole-genome sequencing of IAV-S from conventional pig farms in Korea during 2021–2022 revealed that the genetic diversity of H1 and H3 IAV-S was continuously enriched after human-to-swine spillover of pdm09 viruses with long-term maintenance, persistence, and reassortment of virus lineages. Evidence of additional human-to-swine spillover of viruses that are different from the 2009 virus but close to that of the recent H1N1pdm09 human vaccine was identified in this study. The identification of swine-adapted pdm09 viruses, which have accumulated amino acid mutations with potentially altered antigenicity and a unique potential N-glycosylation site within the haemagglutinin (HA) gene, suggests the distinctive evolution of spillover pdm09 viruses in swine. The genetic constellation of the recently emerging Eurasian avian-like swine lineage and the preexisting classical swine lineage H1 viruses in Korea has been expanded through reassortment with cocirculating pdm09 viruses and/or H3N2 IAV-S harboring the pdm09 M gene (H3N2pM). Collectively, after the major shift of Korean IAV-S from the classical swine lineage to the pdm09 lineage in 2009, the frequent spillover of pdm09 viruses and the circulation of IAV-S harboring pdm09 gene segments led to the continuous diversification of IAV-S through antigenic drift and shift, raising concerns about the potential reintroduction of these viruses to humans.

Feline panleukopenia (FP) is a highly prevalent and consequential disease that poses a substantial threat to both adult and juvenile cats across all geographical regions. The causative agent responsible for this disease is the feline panleukopenia virus (FPV). Therefore, it is imperative to develop a facile, efficient, and accurate detection method for FPV. Hence, a recombinase polymerase amplification–lateral flow dipstick assay (RPA–LFDA) method was specifically designed for the detection of FPV. The amplification process was optimized. This investigation focused on evaluating the expansion temperature detection system and revealed an optimal reaction temperature of 39°C. Then, primer combination screening involving nine groups identified F3R2 as the most effective primer set, while dilution ratio experiments determined that a 10-fold dilution yielded the best amplification products. Our findings demonstrated that the RPA-LFDA assay had an analytical sensitivity that was capable of detecting as low as 10 target copies per reaction. Furthermore, cross-reactivity tests demonstrated no interference between feline herpesvirus-1 (FHV-1) and feline calicivirus (FCV). To validate our newly developed method against existing techniques in clinical samples from three common sources on the market, we observed superior sensitivity and specificity compared to those of the colloidal gold method (CGM), with a higher positive detection rate using our nucleic acid detection system than CGM. Compared to qPCR as a reference standard, RPA-LFDA detected 39 out of 44 positive samples (including one false positive), whereas CGM detected 26 out of 44 positive samples. Based on the RPA-LFDA, the sensitivity was calculated to be 100%, the specificity was 83.33%, the mistake diagnostic rate was 16.67%, the omission diagnostic rate was 0%, and the overall accuracy reached 97.73%. Moreover, the positive coincidence rate was 97.44%, while the negative coincidence rate reached 100%. The agreement κ value was 0.8962. In conclusion, this approach exhibits greater sensitivity than CGM and offers greater convenience and cost-effectiveness than the qPCR methodology, making it a viable option for the clinical detection of FPV.

Effective porcine health management relies majorly on diagnostic tests, vaccination, treatment strategies, and a proper biosecurity management plan. However, understanding the link between circulating microbes and biosecurity measures on a pig farm is not evident. Substantial progress has been made in recent years with the availability of new diagnostic tools (e.g., sequencing-based diagnostics) and extensive biosecurity management questionnaires. However, the interpretation and correlation of these results are hampered by the abundance of gained (meta)data. Therefore, we aimed to cross-correlate viral and bacterial pathogens with respiratory tropism detected by third-generation nanopore metagenomic sequencing with biosecurity measures assessed by Biocheck.UGent™. The study was conducted on 25 sow farms with attached nurseries in Germany with known respiratory distress. The biosecurity level of the study farms complied with the European averages. Interestingly, the farms with the highest biosecurity score showed the lowest overall prevalence of porcine reproductive and respiratory syndrome virus (PRRSV) and Actinobacillus sp.; the circulation of well-studied pathogenic viruses, such as PRRSV, was correlated with overall lower biosecurity scores, a higher number of stillborn piglets, and cocirculation of porcine parvovirus type 7. Moreover, potential risk factors for lesser-known agents (e.g., porcine hemagglutinating and encephalomyelitis virus, porcine respiratory coronavirus, and porcine polyomavirus) could also be addressed. For the bacterial pathogen Glaesserella sp., a correlation with increased clinical signs was observed, whereas Lactobacillus sp. and Moraxella sp. are putative biomarkers for pig farms with better biosecurity scores. In conclusion, in-depth cross-correlation of (meta)data from new diagnostic platforms with biosecurity measures on pig farms may contribute to a better understanding of new actions in adapting biosecurity measures. This will not only contribute to improved animal welfare and economic productivity but also helping to address (new) zoonotic disease threats and potential treatments.

Various domestic and wildlife species have been found susceptible to and infected with SARS-CoV-2, the causative agent of COVID-19, around the globe, raising concerns about virus adaptation and transmission to new animal hosts. The virus circulation in the white-tailed deer population in North America has further called to action for virus surveillance in the wildlife. Here, we report on the first SARS-CoV-2 survey of wild animals in Japan, where frequent wildlife invasions of urban areas have occurred due to the limited predation, field abandonment, the increase of human acclimatization. Genetic testing using nasal swabs and serological screening have been conducted for sika deer, brown bears, raccoons, and raccoon dogs captured in Hokkaido prefecture from the end of the Delta variant wave to the spread of the Omicron variant, between March 2022 and February 2023. No viral RNA was detected in raccoons (0/184), sika deer (0/107), and brown bears (0/14) indicating that the virus was unlikely to spread within the population of these animal species. Among 171 raccoons, 20 raccoon dogs, 100 sika deer, and 13 brown bears, one raccoon, one brown bear, and two deer tested positive in the antibodies screening with multispecies SARS-CoV-2 N-protein ELISA. Still, ELISA-positive samples tested negative in three other serological tests, emphasizing the importance of confirming serological screening results. Our results suggested that SARS-CoV-2 was unlikely to spillback from humans to wildlife in Hokkaido during the study period, with the emergence of new variants, continuous surveillance is of utmost importance.

African swine fever (ASF), caused by African swine fever virus (ASFv), is a highly contagious disease of domestic and wild pigs with a mortality rate that can reach 100%. Continuous spread of the virus into ASF-free regions, including the Caribbean island of Hispaniola in 2021, is causing socioeconomic burdens and presents a threat to food security. Pork-producing countries, including the United States and Canada, are urgently looking for efficient tools for early detection to reduce spread of the virus in the event of an outbreak. Previous experimental infection studies evaluated the utility of aggregate porcine oral fluids (OFs) as a sample type with a highly sensitive ASFv real-time PCR for individual blood and tissue-based diagnosis. In this study, real-time PCR with porcine OFs was further evaluated to better understand diagnostic performance using samples from three Romanian farms with an ongoing ASF outbreak. In this limited dataset using a Bayesian latent class model, no statistical difference in diagnostic sensitivity was found between the real-time PCR using aggregate OFs and the process of determining pen disease status by testing individual blood samples collected from a subset of pigs from the same pen. Known negative aggregate OF samples from pigs in the United States had no occurrences of false positives, suggesting reliable diagnostic specificity of the sample matrix used for this study. Until results are produced from further studies with sufficient sample size, aggregate OF testing using real-time PCR could cautiously be used as a supplementary sample type for ASF diagnosis alongside currently approved sample types, including blood and lymphoid tissues.

African horse sickness (AHS) is a viral disease transmitted by arthropods that impacts Equidae, specifically horses and related species. Recognized as a notifiable disease by the World Organisation for Animal Health (WOAH), AHS is associated with a high mortality rate of 80%–90% in susceptible hosts and exhibits rapid transmission dynamics. Historical records document numerous instances of mass horse deaths attributed to AHS, with recent occurrences in Thailand and Malaysia in 2020 causing heightened concerns within the local horse industry. The lack of a comprehensive global perspective on the distribution and transmission of AHS poses challenges in comprehending and implementing effective prevention and control strategies. This study marks a pioneering effort in analyzing the global epidemiological patterns of AHS across different regions. By employing predictive modeling with a comprehensive set of environmental variables, we uncovered overarching global patterns in AHS dynamics, a first in this field. Our analysis revealed significant regional differences influenced by specific climatic conditions, highlighting the disease’s complexity. The study also identifies new high-risk areas for AHS, underscoring the necessity for regionally tailored disease management strategies. Despite some limitations, such as the exclusion of wild equine data, this research offers critical insights for global AHS intervention and prevention, setting a path for future research incorporating broader datasets and socioeconomic factors.

Seneca Valley virus (SVV) and foot-and-mouth disease virus (FMDV) belong to the Picornaviridae family, which can cause similar symptoms. After infection, pigs will develop fever; loss of appetite; blister lesions on the skin and mucous membrane of the mouth, nose, and hoof; and other similar diseases, and the spread is very fast, causing major economic losses to the pig industry. Therefore, a rapid, accurate, and sensitive diagnostic method is necessary to enable rapid prevention and control measures for preventing the spread of these diseases. Here, a fluorescent immunochromatography test strip, using Eu-doped fluorescence beads and monoclonal antibody, was developed for the simultaneous determination of FMDV and SVV. The test process for the assay could be completed in 12 min, which avoided the time cost of the current methods for FMDV/SVV detection. Under optimized conditions, the limit of detection of SVV is 5 × 10⁴ PFU/mL, and that of FMDV is 5 × 10⁴ PFU/mL under the Fluorescence Immunoassay Analyzer. Our assay results showed a good linear correlation with RT-PCR installed in the clinical laboratory. The species design has a promising application prospect in the surveillance and control of the outbreak of idiopathic blister.

A strain of porcine reproductive and respiratory syndrome virus (PRRSV) was isolated from lung tissue of a pig showing severe respiratory clinical signs from a farm in Gyeongsang province of South Korea. This PRRSV strain, designated as SNUVR220803, was classified within the lineage Korean clade C (LKC) based on a phylogenetic analysis of the ORF5 gene. A whole-genome analysis was conducted on the SNUVR220803 strain, which appears to be a recombinant between the PRRSV strains K07-2273 (part of LKC lineage) and Ingelvac MLV (part of Lineage 5). The Nsp2 amino acid sequence of this strain features a deletion of four additional amino acids, setting it apart from the typical Korean clades A, B, and C lineages. An animal inoculation experiment was conducted with 24 pigs divided into three groups: 12 pigs in the inoculated group, six in the sentinel group, and six in the negative control group. Inoculated pigs exhibited persisting hyperthermia (≥40.3°C) for 5 days, palpebral edema, and cyanosis. Subsequently, these pigs suffered from severe respiratory distress and cachexia, leading to a mortality rate of 58.3% (7 out of 12 pigs) at 14 days postinoculation (dpi). Body weight decreased post-SNUVR220803 strain infection in both the inoculated and sentinel groups. Gross pathology revealed noncollapsed lungs and serous effusion in the pericardial and peritoneal cavities. Microscopic analysis revealed severe interstitial pneumonia, while immunohistochemistry confirmed the presence of PRRSV antigen in the lungs, lymph nodes, thymus, kidneys, and the heart. Additionally, the levels of cytokines such as tumor necrosis factor-α (TNF-α), interferon-α (IFN-α), and IL-10 were significantly elevated in the plasma of infected pigs. These observations indicate that the LKC recombinant strain, combined with Lineage 5, possesses high virulence and infectivity as characterized by distinctive exudative lesions.

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