Transboundary and Emerging Diseases最新文献

The first case of African swine fever (ASF) was confirmed in Sweden in September 2023. This article describes the local epidemiology, including the spatiotemporal dynamics of the outbreak and some of the factors that may have contributed to its apparently successful eradication. Upon detection of the outbreak, strict control measures were put in place in a preliminarily defined infected zone. A carcass search, including geo-localisation, removal, sampling, and destruction of found carcasses, was initiated and a preliminary core area was defined based on the results. Six months after confirmation of the first case, 93 wild boar carcasses had been found in the infected zone, of which 62 tested positive for ASF virus (ASFV). All ASFV-positive carcasses were found inside the core area. Based on two taphonomy methods, it was assumed that the infection was introduced between early May and late June 2023. The data also indicated that the epidemic curve peaked between mid-August and mid-September, with the last death occurring in late September 2023. Based on the average estimated time of death, geo-localisation of carcasses and two-dimensional kernel density estimation, clustering in space and time was identified. An online questionnaire with questions about hunting and the wild boar population was sent to all leaders of hunting groups in the infected zone. The results showed that the wild boar population had increased in the last 10 years but with large variations and geographical heterogeneity in space use. Disease introduction through natural wild boar movements was excluded and it was assumed that the long-distance translocation of the virus had occurred through human activities. A municipal waste collection centre without wild boar-proof fencing is located close to the epicentre of the outbreak, attracting many wild boar and contributing to the spread of the virus once it had been introduced to the population.

The respiratory mucosa serves as a primary entry point for numerous pathogenic microbes, and the respiratory mucosa secretes type I and III interferons (IFNs), the first generation of antiviral cytokines, in response to viral infection. The pseudorabies virus (PRV) causes serious illnesses in many domestic and wild animal species, particularly in pigs and cattle. However, more information is needed about the immunosuppressive properties and evolutionary history of emerging PRV field strains in China’s respiratory system. The PRV field strain JS2022, which was obtained from a cow farm for this investigation, is a spontaneous recombination of early PRV variant strains in the Jiangsu region and is similar to the PRV variations recovered in China in terms of its entire genome sequence. According to sequence analysis, JS2022 has a spontaneous deletion of 1,212 bp in the gE gene, 502 bp in the gI gene, and 192 bp in the glycoprotein (g) C gene. Pathogenicity analysis revealed that intranasal JS2022 causes severe neurological symptoms in calves, but this effect is different from that of ZJ01. In addition, a considerable number of viral antigens in the nasal mucosa were detected by immunohistochemical staining. Therefore, we constructed a bovine nasal mucosal explant model that maintained good cell morphology and activity even after 5 days. In bovine nasal mucosal explants, JS2022 and ZJ01 can cause infection, and the viral load increases dramatically over time. Quantitative research revealed that 24 hr after infection, JS2022 dramatically reduced the expression of downstream interferon-stimulated genes and the innate immune factors IFN-β and IFN-λ3 and bovine nasal mucosal explants. Overall, our results highlight the significance of PRV surveillance in cattle and offer a resource for learning more about the clinical traits and development of PRV.

A PRRSV strain, PRRSV2/CN/FJLX06/2021, with strong homology to an MLV-like strain HeN1201 that evolved from the highly pathogenic PRRSV vaccine virus HuN4-F112, was isolated from a dying piglet in China. BLAST and phylogenetic analyses showed that PRRSV2/CN/FJLX06-2021 was most closely related to HeN1201 and HuN4 (the parental strain of MLV HuN4-F112) and clustered with Chinese HP-PRRSV strains in PRRSV-2 lineage 8.7. Importantly, 29 of the 39 characteristic amino acid mutations in the HuN4-F112 genome were found at the corresponding sites of PRRSV2/CN/FJLX06-2021. Animal studies showed that piglets infected with PRRSV2/CN/FJLX06-2021 had a persistent high fever, higher viremia, presence of interstitial pneumonia, and a higher mortality rate (40%) within 2 weeks than those vaccine-inoculated with HuN4-F112. Taken together, these data suggest that PRRSV2/CN/FJLX06-2021 is an MLV-like strain that has evolved from MLV HuN4-F112 and is highly pathogenic to piglets.

Porcine respiratory and reproductive syndrome (PRRS) caused by Betaarterivirus suid leads to severe economic losses. The emergence of highly pathogenic Betaarterivirus suid 2 (PRRSV-II), such as NADC30 and NADC34, has been reported in the USA and several Asian countries. NADC30-like PRRSV-II was first reported in 2018 in Taiwan. To investigate the PRRSV variants currently circulating in Taiwan, sequences covering ORF2-5 of Taiwan PRRSV isolates collected between 2020 and 2023 were analyzed. Phylogenetic analysis of the ORF5 nucleotide sequence indicated that most of the Taiwan isolates were clustered in lineage 3 and three isolates were grouped in lineage 1 and were closely related to the NADC34 strain. Interestingly, these three NADC34-like Taiwan PRRSV isolates carried amino acid deletions similar to NADC30 and were more closely related to NADC30 strains than the NADC34 strains in the Nsp2 gene. Next-generation sequencing and recombination detection program showed potential recombination of lineage 3 with NADC30- and NADC34-like PRRSV-II. Our results suggest the presence of circulating mosaic recombinants and lineage 3 PRRSV-II in Taiwan during 2020 and 2023.

Porcine reproductive and respiratory syndrome (PRRS) poses a serious threat to the Chinese swine industry. The etiological agent PRRSV can be classified as either PRRSV-1 or PRRSV-2. Recent studies have revealed an increase in the rates of PRRSV-1 detection and a wider PRRSV-1 distribution. However, the PRRSV-1 genome in China has yet to be fully characterized. In this study, 24 whole PRRSV-1 genomes from different swine farms were assembled and subjected to whole-genome analysis. A phylogenetic analysis based on the complete genome and ORF5 sequences revealed that the PRRSV-1 strains from China belonged to Western European Subtype I and could be classified into seven subgroups. Statistical analysis revealed that BJEU06-1-Like PRRSV is currently the predominant PRRSV-1 strain. Moreover, a similarity analysis showed low pairwise similarity between most PRRSV-1 genomes from different pig farms. Amino acid alignments of the Nsp2 gene revealed that the BJEU06-1-Like subgroup had five discontinued aa deletions (4 + 1). The new subgroup 1 had 11 continued aa deletions and an aa insertion, the new subgroup 2 had two discontinued aa deletions (1 + 1), and, except for in the case of HKEU16, the HKEU16-Like subgroup had five discontinuous aa deletions (1 + 4). Recombination analysis revealed that the BJEU06-1-Like and NMEU09-1-Like strains participated extensively in recent recombination events. The analysis of positive selection suggested that there were 15 positively selected codons in site model, and there were five sites under positive selection in the BJEU06-1-Like subgroup in the branch-site model. The mean rate and tMRCA for PRRSV-1 strains from China were 4.11 × 10⁻³ substitutions/site/year and 1,969.63, respectively. Thus, it is crucial to strengthen epidemiological surveys of PRRSV-1 in China, especially those monitoring BJEU06-1-Like PRRSV.

In many Mediterranean ecosystems, animal tuberculosis (TB), caused by Mycobacterium bovis, is maintained by multi-host communities in which cattle and different wildlife species establish interaction networks contributing to M. bovis transmission and persistence. Most studies have addressed wildlife–cattle disease-relevant interactions, focusing on reservoir hosts, while disregarding the potential contribution of the so-called accidental hosts and/or neglecting wildlife–wildlife interactions. In this work, we aimed to characterise interspecies interactions in an endemic TB risk area and identify the ecological drivers of interaction patterns regardless of the pre-attributed role of host species on TB epidemiology. For that purpose, spatial–temporal indirect interactions between wildlife mammals and cattle, and between different wildlife species, were investigated through camera trapping. Second, five ecological hypotheses potentially driving species pair interactions in the wet and dry seasons were tested covering water and control sites: human presence (H1), landscape composition (H2), topography (H3), weather (H4), and natural food and water resources (H5). Wild boar (Sus scrofa), red deer (Cervus elaphus), and red fox (Vulpes vulpes) were the wildlife species mostly involved in indirect interactions. We found that indirect wildlife–cattle interactions were more frequent than wildlife interactions and, for certain species pairs, interaction rates were higher in the wet season in both wildlife–cattle and wildlife groups. Natural food and water resources (H5) was the most supported hypothesis that influenced the abundance of wildlife–cattle interactions, with positive effects during the dry season and negative effects during the wet season. In contrast, the abundance of indirect interactions between wildlife species was mainly supported by the human disturbance hypothesis (H1), with negative effects exerted on the dry season and variable effects on the wet season. Other tested hypotheses also influenced wildlife–cattle and wildlife–wildlife interactions, depending on the season and host species. These results highlight that indirect interactions, and thus conditions potentially favouring the transmission of M. bovis in shared environments, are determined by different ecological backgrounds.

Leptospirosis is a neglected but reemerging worldwide zoonotic disease. Due to a rise in global temperature, precipitation, and urbanization, the risk of acquiring an infection with Leptospira (L.) spp. increases in Europe. One species affected by leptospirosis living close to the human is the dog. Even though dogs can shed low numbers of leptospires, their value as sentinel animal aiding in understanding environmental reservoirs might be even more important for human and animal health. Therefore, it is crucial to study the prevalence of pathogenic L. spp. in dogs and tailor coordinated protective measures like vaccination. This study aimed to screen a collection of purified DNA extracted from canine field samples (blood and urine, n = 239) collected in Europe from dogs suspected of leptospirosis and found positive by the lipL32 PCR used for diagnostics. A new simple and effective molecular approach was developed to identify different leptospiral serogroups using first a 16S rRNA PCR and 16S rRNA gene sequencing for genomospecies determination followed by a PCR targeting the rfb gene locus responsible for LPS biosynthesis for serogroup classification. In total, 172 DNA samples were successfully tested. Results show that L. Icterohaemorrhagiae was detected as the most prevalent serogroup in Europe (53%), followed by L. Australis serogroup (13%). At lower percentages, L. Pomona (5%), L. Autumnalis (4%), and L. Sejroe (2%) were identified. This work emphasizes that current L4 vaccines are relevant and should confer a high efficacy profile at least against L. Icterohaemorrhagiae and L. Australis serogroups.

Lumpy skin disease (LSD) is an important infectious disease caused by lumpy skin disease virus (LSDV) in bovine. LSDV, sheep pox virus (SPPV), and goat pox virus (GTPV) from the same genus Capripoxvirus (CaPV) of the Poxviridae family exhibit a nucleotide sequence similarity of up to 97%. Therefore, attenuated vaccines of GTPV and SPPV are often used to vaccinate cattle against LSD. However, available serological testing methods cannot accurately differentiate cattle vaccinated with GTPV from those infected with LSDV, posing a significant risk for disease spread. In this study, we developed a synthesized gene unique to LSDV as a differential antigen to detect serum antibodies specific to LSDV and differentiate naturally infected from vaccinated animals (DIVA). We used it for an in-house indirect enzyme-linked immunosorbent assay (iELISA), and no cross-reaction with positive sera for bovine viral diarrhea virus (BVDV), infectious bovine rhinotracheitis virus (IBRV), Mycobacterium bovis (M. Tb), Pasteurella multocida (P. multocida), and Mycoplasma bovis (M. bovis). The cut-off value (S/P%) was 30% for in-house iELISA. The corresponding diagnostic specificity was 100% (95% CI: 88.43–100), and the diagnostic sensitivity was 93.3% (95% CI: 77.93–99.18). The intra-assay coefficient of variation (CV) ranged from 1.08% to 4.11%, and the interassay CV was 0.00%–8.90%. Furthermore, 200 clinical serum samples were examined, in the vaccinated herd, there were no positive samples (0/141) indicating the strong differentiation ability of this method. On the other hand, in the infected herds, the overall positivity was 33.90% (20/59) (95% CI: 22.08–47.39). In summary, a valuable synthesized protein unique to LSDV was developed and showed a promising application in an iELISA with high specificity and sensitivity in differentiating cattle infected with LSDV from those vaccinated with GTPV.

Salmonella enterica is one of the most important foodborne pathogens worldwide, and the emergence of multidrug resistance (MDR) clones can aggravate its public health importance. Wildlife species may act as reservoirs of these clones, but their role is not well understood. In this study, faecal samples from shorebirds, with a focus on the endangered Humboldt penguin (Spheniscus humboldti), collected from five sites in central Chile with different levels of anthropogenic pressure were analysed to characterize antimicrobial resistant S. enterica serovars. Overall, Salmonella was isolated from 22 of the 595 samples (3.7%), with positivity ranging between 1.6% and 9.5%, depending on the sampling site. Four of the Salmonella isolates were retrieved from Humboldt penguin samples (1.4% positive samples in this species). Serovars Infantis (nine isolates), Typhimurium (six), Goldcoast (four), and Enteritidis, Agona, and Give (one isolate each) were identified. Resistance levels were the highest for sulphamethoxazole (13/21 isolates with a non-wild-type phenotype), ciprofloxacin, tetracycline, and trimethoprim (11/21 each). Whole-genome sequencing performed on eight S. Infantis strains revealed that seven carried the plasmid replicon IncFIB (pN55391), indicating the presence of the pESI-like megaplasmid, harbouring resistance determinants to multiple antimicrobial classes as well as heavy metal, biocides, and virulence-related genes. Furthermore, five S. Infantis isolates that showed an ESBL phenotype carried the bla_CTX-M−65 gene, three of which were detected in Humboldt penguin faeces. The finding of an international emerging S. Infantis clone in protected wildlife is of concern to environmental, animal, and public health specialists, supporting initiatives for an active surveillance of resistance and virulence traits in wildlife exposed to anthropogenic areas.

Whole genome sequencing (WGS) plays an important role in the advanced characterization of pathogen transmission and is widely used in studies of major bacterial and viral diseases. Although protozoan parasites cause serious diseases in humans and animals, WGS data on them are relatively scarce due to the large genomes and lack of cultivation techniques for some. In this review, we have illustrated bioinformatic analyses of WGS data and their applications in studies of the genomic epidemiology of apicomplexan parasites. WGS has been used in outbreak detection and investigation, studies of pathogen transmission and evolution, and drug resistance surveillance and tracking. However, comparative analysis of parasite WGS data is still in its infancy, and available WGS data are mainly from a few genera of major public health importance, such as Plasmodium, Toxoplasma, and Cryptosporidium. In addition, the utility of third-generation sequencing technology for complete genome assembly at the chromosome level, studies of the biological significance of structural genomic variation, and molecular surveillance of pathogens has not been fully exploited. These issues require large-scale WGS of various protozoan parasites of public health and veterinary importance using both second- and third-generation sequencing technologies.