Transboundary and Emerging Diseases最新文献

To date, seven novel parvoviruses have been identified in pigs and designated as porcine parvovirus 2–7 (PPV2–7). The presence of these emerging viruses has been reported in several countries around the world, although their pathogenic role and clinical and economical relevance are largely unknown. Here, we report the estimated prevalence and genetic diversity of novel PPV2–7 in Hungarian pig herds and the detection of these viruses in two Slovakian pig farms. For the comparative prevalence estimation, 2505 serum samples from different age groups, 218 oral fluid samples, and 111 processing fluid samples were collected from 26 large-scale Hungarian farms according to a systematic, cross-sectional sampling protocol. All samples were tested by real-time quantitative polymerase chain reaction (qPCR), and the presence of at least one PPV was detected in 24 of the 26 (92%) Hungarian and both Slovakian farms, suggesting high levels of subclinical circulation in most herds. The estimated PPV2–7 prevalence in Hungary varied from 50% to 89%, with PPV4 being the least and PPV2 being the most prevalent virus. The highest detection rates were observed in oral fluid samples, indicating that this sample type is most suitable for screening PPVs, but all viruses were also detected in serum samples and processing fluids. All novel PPVs were most frequently detected in the serum samples of weaned pigs and fatteners, with slightly higher viral burden in the younger age groups. These results may suggest an age-related susceptibility, which could play a significant role in the epidemiology of these viruses, impacting herd health and productivity.

Foot-and-mouth disease (FMD), which is endemic in 77% of countries globally, is a major threat to the global livestock industry. Knowledge of the reproductive number at the population level (i.e., farm level, herd level, or above) for FMD is important to estimate the magnitude of epidemics and design and implement effective control methods. Different methods, based on disparate assumptions and limitations, have been used interchangeably to compute and report reproductive numbers at the population level without a formal comparison between them. This study compares the results obtained when using alternative methods to compute between populations (R_bp) for FMD using one single dataset collected over 10 years (2007–2017) at the commune-level swine farms in Vietnam. Seven spatial–temporal clusters were identified in the country, and the value of R_bp was computed on each of them using different analytical approaches, namely, epidemic doubling time, nearest neighbor, time-dependent reproductive number (TDR), sequential Bayesian (SB), and birth–death skyline (BDSKY) analysis in Bayesian evolutionary analysis by sampling trees 2 (BEAST2). Estimated R_bp values were relatively similar across methods ranging from 1.25 to 1.61. For the first time, the results here provide a comparison of different methods used to compute R_bp for FMD. Despite differences in assumptions and limitations, results suggest that different methods produce relatively similar outputs. Additionally, the results here provide foundational knowledge to support the evaluation and control of FMD epidemics in a population.

In Africa, livestock production plays a crucial role for sustainable food security and economic growth. However, the development of this sector has been delayed by livestock diseases, one of the main constraints, which can cause important production and economic losses. To overcome these constraints, farmers extensively use antimicrobials, which in turn can lead to antimicrobial resistance (AMR), one of the main threats to global health and food security. Biosecurity has been identified as a key strategy to reduce livestock diseases. Therefore, the current systematic review and meta-analysis, conducted according to the Cochrane guideline, aimed at determining the efficacy of biosecurity in preventing and controlling infectious diseases in livestock farms in Africa. Of the 1408 records retrieved from five different databases, only 16 met the inclusion criteria. These studies were conducted in Egypt (31.2%), Nigeria (31.2%), Uganda (18.8%), Ethiopia (12.5%) and Tunisia (6.3%) and concerned poultry (62.4%), pigs (18.8%) and cattle (18.8%). Investigations focused mainly on avian influenza (AI) (15.0%) and coccidiosis (10.0%) in poultry and African swine fever (ASF) (10.0%) in pigs. In poultry farms, the results of the pairwise meta-analysis showed that biosecurity measures related to visitors and farmworkers could be effective at reducing the risk of introduction and spread of AI viruses (odds ratio [OR] = 0.48; 95% confidence interval [CI] 0.28–0.82). Moreover, inadequate biosecurity seemed to be a factor promoting coccidiosis (OR = 4.20; 95% CI 2.4–7.4) and AI (OR = 1.74; 95% CI 1.23–2.48). Prevention of ASF was significantly associated with the application of biosecurity measures related to animals’ transport, removal of carcasses and manure (OR = 0.33; 95% CI 0.12–0.88). Despite their importance, these findings cannot be translated to the entire African continent, since no studies were available for more than 90% of its countries. More research should be carried out to fill in the gaps identified by this review.

Feline coronavirus (FCoV) is an enveloped, positive-sense RNA virus, which is widespread among feline populations, and can cause a fatal serious disease called feline infectious peritonitis (FIP). According to the differences of antigen and genetic composition, FCoV consists of two genotypes, FCoV I and FCoV II. In this study, we have isolated and identified a FCoV I strain named HL2019. Based on the complete genome of HL2019, phylogenetic analysis showed that HL2019 strain formed in the cluster FCoV I which is more closed to human coronavirus 229E (HCoV 229E) and HCoV NL63, while the FCoV I stains is distantly related to FCoV II strains. Analyzing with RDP4 and Simplot software showed that the virus HL2019 is recombinant by the FCoV I China/ZJU1709 and FCoV I Netherlands/UU16 strains. Furthermore, the pathogenicity of HL2019 was evaluated in 9–12-month-old cats. Two of three challenged cats developed serious clinical signs and died at 28-day postchallenge (dpc). Real-time polymerase chain reaction (PCR) analysis showed that HL2019 has broad tissue tropism, especially in the duodenum with viral load up to 10⁴ copies/mg. In summary, our data show that we have successfully isolated a strain of FCoV I named HL2019 that is highly pathogenic to cats.

A high pathogenicity avian influenza (HPAI) subtype H7N6 virus emerged in South African poultry in 2023 and later spread to Mozambique, the first documented emergence of H7 HPAI in the African continent. A total of 6.82 million birds succumbed to the disease or were culled, representing about 20% of the South African egg-laying flock and almost 30% of the broiler breeder flock. The complete genomes of 68 outbreak viruses were sequenced and analyzed, tracing the phylogenetic origins of the ancestral H7N6 virus to a reassortment of various subtypes that circulated in southern African wild birds. Molecular clock analysis determined that the virus emerged in the first week of May 2023, probably in a smallholder chicken flock, before spreading to commercial farms, where the disease was first reported in early June. The multibasic hemagglutinin protein cleavage site (HA₀) was derived from a nonhomologous recombination event with chicken 28S ribosomal ribonucleic acid (RNA). Few genetic markers associated with an increased risk to humans were present in the translated viral proteins. The intravenous pathogenicity index (IVPI) value of the index case isolate was 1.67, reflecting that 50% of the specific pathogen-free chickens died within 4 days of infection. Surviving birds showing mostly mild clinical signs and recovered by day 10 postinfection. Prior to death, chickens shed the virus primarily through the respiratory route, with lower amounts shed from the cloaca, but in the survivors, the virus was still being shed from the cloaca on day 10. Fomites were the likely source of disease spread between farms, and the amount of H7N6 HPAI virus per gram of feces was calculated at ~383,193 (5.58 log₁₀) egg infectious dose 50 (EID₅₀) equivalents, chicken feather follicles contained on average 739,712.43 (5.87 log₁₀) EID₅₀ equivalents, and 20 µg of feather dust contained 14,976.96 (4.175 log₁₀) EID₅₀ equivalents.

Wild rodents and their ectoparasites are known reservoirs for various zoonotic pathogens, highlighting the need for detailed studies into their roles in disease transmission. Our research investigated the spatial distribution of rodents and their ectoparasites to better understand the epidemiology of vector-borne zoonotic diseases (VBZDs), including severe fever with thrombocytopenia syndrome (SFTS), Lyme disease, Q fever, and scrub typhus. We analyzed samples from 540 rodents and 6785 mites, detecting the presence of Borrelia spp., the causative agent of Lyme disease, in 0.9% of rodents and SFTS virus (SFTSV) in 1.0%. In mites, Borrelia spp. and Orientia tsutsugamushi, the bacteria causing scrub typhus, were detected in 0.3% of samples each. Phylogenetic analysis identified the SFTSV sequence as type B3, the Borrelia spp. sequence as B. afzelii, and the O. tsutsugamushi sequence as Karp-related. Notably, SFTSV was detected for the first time in mites in South Korea, and B. afzelii was found in mites for the first time globally. These findings emphasize the critical need for continuous analysis of VBZDs to anticipate future trends and develop a comprehensive monitoring system. Further research into the rodent and mite populations in South Korea is essential to fully assess the potential risks of VBZDs.

Coronaviruses (CoVs) belonging to the Gamma-CoV and Delta-CoV genera are widespread in poultry and wildfowl. Migratory birds, particularly duck species, serve as hosts for CoVs and play a pivotal role in transmitting the viruses to other species, including mammals. Despite the potential risks to animals and humans, there remains a narrow knowledge of the genetic and epidemiological properties of CoVs in wild birds. The current research aimed to detect and characterize CoVs present in migratory duck species (Anas acuta, Anas platyrhynchos, and Anas poecilorhyncha) from South Korea. Employing two rounds of pan-CoV real-time reverse transcription-polymerase chain reaction (RT-PCR) and nested PCR (nPCR) assays amplifying the conserved RNA-dependent RNA polymerase (RdRp) portion common to all known CoVs, we screened 2120 duck fecal samples collected during 2022–2023. The results indicated the presence of CoVs in 4.2% (91/2120) of samples from migratory ducks. Nucleotide sequencing of the RdRp gene revealed that all identified CoVs were clustered within the Gamma-CoV genus. Further phylogenetic analysis suggested that South Korean gamma-CoVs belong to the Igacovirus subgenus and share similarities with those found worldwide, highlighting the critical role of migratory ducks in introducing and exporting avian CoVs. We discovered two clade VII igacovirus strains in wild ducks closely related to those in pigeons, implying potential cross infection between these avian species. Overall, our study underscores the importance of active surveillance and monitoring of avian CoVs in wild birds as a preemptive response against the forthcoming emergence of new CoV species that can threaten both animal and human health.

Bovine viral diarrhea (BVD) represents a serious threat to the cattle sector in Chile, indicating the need for a regionally defined control program. Ex-ante evaluations of program options using simulation modeling have proven to be a successful approach in providing decision-makers with relevant supporting insights in that respect. Given the complexity of bovine viral diarrhea virus (BVDV) infection dynamics, simulation of BVD spread in a metapopulation requires detailed consideration of both within and between herd transmission dynamics. The aims of the study are (i) to investigate the dynamics of BVDV transmission in cattle herds in southern Chile by linking a within-herd transmission model (WHM) that accounts for the BVDV’s unique characteristics with a between-herd model (BHM) that meets the demands for further regional control strategy evaluation; (ii) to suggest and discuss criteria for evaluation of the model approach and plausibility for later research and for support decision-making. This resulted in bringing forth a modeling rationale for complex disease spread simulation in metapopulations. BHM simulations under this approach show outcomes that agree with BVDV’s known situation in Chile; dairy herds prevalence at endemic equilibrium reaches and maintains 75%, which agrees with estimations of BVDV active infection in dairy herds in southern Chile (77%). For the entire herd population, the infection always reaches endemic levels with a large proportion of infected herds (median = 60%), where herd prevalence was higher in the dairy herd class than in the remaining categories. Transmission probability variation affects the new infections picked, prevalence at endemic levels, and the velocity in which the infection spreads between herds. The fact that the presented approach was able to model a complex infection dynamic such BVDV, with sufficient confidence, provides evidence that this approach can be used to explore mitigation strategies to control BVDV in southern Chilean herds.

Porcine reproductive and respiratory syndrome virus (PRRSV) is a significant pathogen in the worldwide swine industry. The virus shows high genetic variation coupled with a broad range of virulence in pigs. Although multiple lineages of the virus have been prevalent throughout in Korea, the characteristics of lineage-wise pathogenicity are largely unknown. Therefore, this study was designed to analyze and compare the pathogenicity of 11 representative Korean PRRSV-2 isolates selected from PRRSV-2 lineages circulating in Korea, NADC30-like, VR2332-like, and three nation-specific lineages (lineage KOR A (LKA), lineage KOR B (LKB), and lineage KOR C (LKC)), which have been continuously prevalent in the nation. Eleven groups of pigs were experimentally infected with one Korean PRRSV-2 isolate through four consecutive animal experiments. Body weight and body temperature were recorded during each 4-week challenge experiment period, and virological, serological, and histopathological tests were performed on the collected samples. The data from the animal experiments were integrated into two indicators—excretion and clinical signs—through correlation and principal component analysis (PCA). Meta-analysis was used to compare PRRSV-2 isolates using each indicator. Based on these analyses, while L1C viruses used in this study (JB15-N-P31-GB and JB15-N-PJ73-GN, similar to NADC30-like strains) exhibited low or moderate levels of excretion and clinical signs, lineage 5 (L5) or modified live vaccine (MLV)-variant strains exhibited high levels of excretion compared to other PRRSV-2 isolates. However, the L5 variants all caused mild clinical signs, except for JB15-N-PJ4-GN, which showed the 4th highest clinical sign indicator. Among the Korean lineages (LKA, LKB, and LKC), two LKB strains (GGYC45 and JB15-N-PJ10-GN) were the most virulent as they showed the highest mortality after the challenge. On the other hand, the LKA and LKC viruses displayed lower excretion indicators than L5 strains, but they had higher-ranked clinical sign indicators than low-virulence L5 MLV variants. In conclusion, PRRSV prevalent in Korea has diverse excretion and clinical characteristics, and certain lineage is highly pathogenic. These results will offer useful insights to prevent spread of PRRSV and improve the efficacy of vaccines in the future.

This study is the first report in Italy on the molecular characterization by whole-genome sequencing (WGS) analysis of a Streptococcus suis strain isolated from a human case of meningitis in Italy. The characterized S. suis strain was classified as a serotype 2 (SS2), multilocus sequence typing (MLST) sequence type ST1. The strain exhibited the presence of several virulence genes and resistance to penicillin, tetracycline and macrolide–lincosamide–streptogramin. Finally, we found a frameshift mutation in the gene mrp determining the translation of two truncated forms of the corresponding muramidase-release protein. These results highlight the importance of complete genomic data to understand the pathogenesis and epidemiology of this bacterium, capable to pose serious risks to human health.