Transboundary and Emerging Diseases最新文献

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.

Examining both long-term and short-term effects can enhance the precision and reliability of time series analysis. This study aimed to delve into the asymmetric effects of weather conditions on hemorrhagic fever with renal syndrome (HFRS) in the long and short terms and build a forecasting system. Data comprising monthly HFRS incidents and weather factors in Heilongjiang from January 2004 to December 2019 were extracted. Subsequently, the long- and short-term asymmetric impacts were examined using the autoregressive distributed lag (ARDL) and nonlinear ARDL (NARDL) models. Next, the samples were partitioned into training and testing subsets to evaluate the predictive potential of both models. From 2004 to 2019, HFRS exhibited a declining trend (average annual percentage change = −6.744%, 95% CI: −13.52%–0.563%) and a dual seasonal pattern, with a prominent peak in June and a secondary one in October–December. This study identified long-term asymmetric effects of rainfall (Wald long-run asymmetry (WLR) = 3.292, p = 0.001), wind velocity (WLR = −3.271, p = 0.001), and air pressure (WLR = −6.453, p < 0.001) on HFRS. Additionally, this study observed short-term asymmetric impacts of relative humidity (Wald short-run symmetry (WSR) = −1.547, p = 0.001), rainfall (WSR = −1.984, p = 0.049), and air pressure (WSR = −2.33, p = 0.021) on HFRS. A unit increase in relative humidity, sunshine hours, and air pressure resulted in about 10.9%, 1.9%, and 13.6% decreases in HFRS, respectively; a unit decrease in relative humidity, rainfall, and sunshine hours led to about 6.7%, 1.8%, and 2% decreases in HFRS, respectively. When temperature increased and decreased by one unit, the HFRS incidence increased by 11.6% and 22.5%, respectively. HFRS also varied significantly with the positive and negative changes in differenced (D) temperature, D (relative humidity), D (wind velocity), D (rainfall), D (air pressure), and D (sunshine hours) at 0−3-month delays over the short term. The NARDL model exhibited notably lower error rates in forecasting compared to the ARDL model. Meteorological parameters affect HFRS in both the long and short term, often showing asymmetric effects. The NARDL model, capable of incorporating various weather parameters, proves to be valuable in predicting HFRS epidemic and guiding strategies for prevention and control.

Lumpy skin disease (LSD) is an economically important and notifiable transboundary viral disease of cattle and water buffalo, predominantly transmitted by arthropod vectors. In recent times, LSD has emerged as a notable concern in Nepal, with the first outbreak reported in June 2020, in Morang district. In 2022, outbreaks of LSD were observed in several districts with Nawalpur district being the hard-hit district. The objective of this study is to provide insights into the epidemiological characteristics of LSD, to identify potential sources and associated risk factors for LSD outbreak in Nawalpur, and its financial impact. The overall morbidity rate was observed to be 28.02% (n = 431/1,538) and the mortality rate was 3.06% (n = 47/1,538), resulting in a case fatality rate of 10.90% (n = 47/431). The predominant clinical symptoms were skin nodules, lameness, and decreased milk production in milking animals. Dry cattle, including pregnant cows and cattle heifers were the most affected. Univariable logistic regression analysis identified factors linked to disease outbreaks, such as importing animals from disease prevalent regions, sharing feed and water, herd size, and the presence of clinical signs in neighboring farms. Multivariable analysis highlighted the significance of neighboring farms having sick animals in resulting disease outbreaks. Because of the substantial economic impact due to LSD, it is imperative to implement effective control and preventive measures. These include animal movement control and quarantine, following biosecurity protocols during nearby outbreaks, and targeted vaccination of susceptible populations to prevent further disease spread.

The H6N6 avian influenza virus (AIV) subtype is one of the most frequently isolated subtypes in poultry, and it has a broad host range. Some strains can overcome species barriers for transmission and infect humans. Increased affinity for human-type receptors is a key factor in this process. In this study, two H6N6 AIV strains originating from five different clades, in which amino acid 226 of hemagglutinin was mutated from glutamine to lysine, were isolated from ducks. The receptor-binding preference and pathogenicity of the two strains in poultry and mice were evaluated. The results indicated that the DK/GD/W3 strain can bind to both α-2,6 and α-2,3 receptors, whereas the DK/GD/L31 strain maintained affinity toward avian-origin α-2,3 receptors, highlighting differences in receptor tropism and pathogenicity to different hosts for two H6N6 strains with the same genetic background. These findings have revealed the complex recombination characteristics and molecular characteristics of H6N6 circulating strains in the environment and underscored the importance of continuous surveillance of this subtype for livestock and poultry health as well as human safety.

The global outbreak of highly pathogenic avian influenza (HPAI) H5N1 Eurasian lineage goose/Guangdong clade 2.3.4.4b virus that was detected in North America in 2021 is the largest in history and has significantly impacted wild bird populations and domestic poultry across the continent. Synanthropic birds may play an important role in transmitting the virus laterally to other wild bird species and domestic poultry. Understanding the dynamics of HPAI in atypical, or nonreservoir, wild bird hosts may help inform management decisions and potential risk factors to both wild and domestic bird populations. Following the confirmation of infections of HPAI H5N1 in domestic poultry at two commercial premises in Indiana, United States, we sampled and tested 266 Columbiformes and Passeriformes birds and found no detections of the virus at either location. We further queried laboratories within the National Animal Health Laboratory Network for avian influenza (AI) virus diagnostic test results for wild birds submitted from morbidity/mortality events, for a total of 9,368 birds tested across eight orders and 1,543 avian influenza virus detections between February 2022 and March 2023. Query results were assessed for viral prevalence by taxonomic group and suggested that the virus most often was observed in predatory and scavenging birds. The highest prevalence was observed in raptors (0.2514), with prevalence rates in exclusively scavenging Cathartidae reaching up to 0.5333. There is evidence that the consumption of infected tissues is a key pathway for transmission of AI viruses in predatory and scavenging birds. Although detections were found in nonpredatory synanthropic birds, including orders Columbiformes and Passeriformes, the risk of transmission from and between these groups appears comparatively low. Understanding the dynamics of AI viruses in synanthropic bird orders during the global HPAI H5N1 outbreak in wild bird populations can provide pertinent information on viral transmission, disease ecology, and risk to humans and agriculture.

In 2021, a pregnant Rottweiler dog living on a sheep farm was diagnosed with clinical bluetongue (BT) infection. This study reports on the investigation of this farm where bluetongue virus (BTV) infection was diagnosed in this atypical host species. Samples were collected during farm visits 14, 28, 60, and 89 days after the onset of clinical signs in the pregnant Rottweiler. Blood was collected from all farm dogs (n = 6) and tested for BTV genome using a reverse-transcriptase quantitative PCR (RT-qPCR) assay and BTV antibodies with the competitive ELISA (cELISA) and dogs positive by RT-qPCR were further tested using virus neutralization (VN) serological testing. Blood was also collected from 16 sick sheep and tested using RT-qPCR. Midges were trapped on the study farm using an Onderstepoort UV light trap placed above a sheep pen for 36 hr at the first farm (14 days) visit. Parous/gravid midges were tested by BTV RT-qPCR in batches of up to 200 midges per species. Blood-fed midges (n = 308) were tested using a PCR species probe (KAPA Multiplex Master Mix) to identify the host species on which the midge had fed. Three dogs (n = 3/6) had detectable BTV RNA with RT-qPCR and high VN antibody titers to BTV. All RT-qPCR-positive dogs and one additional dog tested cELISA seropositive (n = 4/6). Bluetongue virus RNA was detected in 5/16 sheep tested. The most abundant midge species was Culicoides imicola (99.3%) and BTV was only detected in this species (n = 3/4 batches of 200 parous midges). Dog blood was not detected in any blood-fed midges tested. The occurrence of natural BT viraemia in exposed dogs creates a potential risk of BTV entry into BT-free countries through dog importation. It remains unclear whether BT viremia in dogs is capable of onward transmission.

Background. Brucellosis is a major worldwide public health problem with economic and zoonotic implications. Despite the importance of vaccines in preventing brucellosis, no previous systematic evaluation of vaccination in sheep has been conducted. Materials and Methods. Articles were searched in databases such as PubMed, Science Direct, Cochrane, VIP, Wan Fang, and CNKI by screening the articles, and articles reporting Brucella vaccination in sheep were included in the study. Meta-analysis was performed using random effects models to calculate pooled risk ratios for vaccines and to calculate vaccine effectiveness. Results. A total of 2,605 articles were retrieved, and 17 articles were obtained through screening for analysis. The effectiveness of vaccination was 65% (RR = 0.35, 95% CI: 0.27–0.36; VE = 65%), with the M5 vaccine being significantly more effective at 84% (RR = 0.1587, 95% CI: 0.0256–0.9858; VE = 84%) than the other vaccines, and intramuscular injection could be the best route of immunization. Rev.1 was indicated for female sheep, especially for pregnant ewes (RR = 0.2016, 95% CI: 0.1139–0.3569; VE = 80%), and for reduced abortions (RR = 0.0978, 95% CI: 0.0459–0.2085). Conclusion. This meta-analysis was conducted to identify the relevant factors affecting vaccine efficacy. We recommend that sheep be inoculated intramuscularly with Rev.1, different inoculation protocols be adopted for sheep of different ages, and pregnant ewes be inoculated with Rev.1 to prevent abortion.

Erysipelothrix rhusiopathiae is responsible for erysipelas infection in pigs. Outbreaks of E. rhusiopathiae have increased in several countries, including China, over the past two decades. An E. rhusiopathiae strain (ML101) was isolated and characterized from dead pig tissue sample collected from a farm experiencing an outbreak of E. rhusiopathiae, which was responsible for the deaths of 146 sows and 308 fattening pigs within a week. Spleen swelling, gastric and bladder mucosa bleeding, and submandibular lymph node swelling and bleeding were observed through necropsy. ML101 was identified as serotype 1a via molecular analysis and immunological assays. Studies in mice demonstrated that the minimal lethal dose per animal was less than 10 colony-forming units (CFU). Notably, the minimal lethal dose in piglets was also less than 10 CFU, which is lower than that of any E. rhusiopathiae strain reported to date. The challenged piglets showed typical acute erysipelas symptoms, such as pyrexia, hemorrhage, depression, complete inappetence, reddening, and purpling skin on the buttock. Evidence of efficient horizontal transmission was observed, as healthy pigs were infected and died when cohoused with challenged piglets. Whole-genome sequencing revealed that ML101 contained a 77 kb genomic island (GI), carrying a Tn916 transposon and a multidrug resistance gene cluster (aadE-apt-spw-lsa(E)-lnu(B)-aadE-sat4–aphA3). A retrospective analysis of E. rhusiopathiae isolates via PCR indicated that the GI has been widely distributed since 2010, when outbreaks were more frequently reported in China. This study demonstrated that the highly virulent E. rhusiopathiae is responsible for the erysipelas outbreak and indicates that relevant genes located within the transmissible genetic elements may play roles in virulence. Therefore, epidemiological monitoring needs to be emphasized to better prevent and control erysipelas in the swine industry, and live attenuated vaccines should be used with caution.

Outbreaks of zoonotic Streptococcus equi subsp. zooepidemicus (SEZ) have caused severe epidemics in the pig sector since the 1970s in Southeastern Asia, China, and more recently North America. Cases of high mortality caused by peracute septicaemia were all attributed to strains of a highly virulent clonal lineage belonging to the sequence type (ST) 194. In Europe, only two outbreaks have been reported with similar features, caused by other sequence types. In August 2023, a febrile disease followed by abortion and subsequent death was observed among sows kept in a small-scale organic pig farm in West Hungary. Symptoms, pathological lesions, and microbiological findings were suggestive of septicaemia from bacterial origin caused by SEZ. According to the results of the routine laboratory testing, no other relevant infectious agents were involved. Whole-genome sequence analysis assigned the examined strains to ST138, unrelated to any of the European isolates. It also revealed a few common SEZ virulence genes, compared to the highly virulent ST194 strains. A sudden weather change and subsequent extremely high average daily temperature before the outbreak could be identified as the only predisposing factor. The immediate antibiotic treatment and applied biosecurity measures might have helped to restrict and terminate the outbreak. To our knowledge, this is the first report on abortion and lethal septicaemia in sows from Central and Eastern Europe. The results call attention to the potential of non-ST194 SEZ strains to cause outbreaks in pig farms.