Transboundary and Emerging Diseases

Porcine reproductive and respiratory syndrome virus (PRRSV) critically threatens the pig industry in China. Lineage 1 PRRSV, which is divided into L1A–L1F and L1H–L1J, is widely recognized as the most extensively genetically diverse lineage globally. L1A (NADC34-like) and L1C (NADC30-like) PRRSVs have become the current major circulating strains in China. Notably, strains from other branches of L1 have not been reported in China. During our epidemiological investigation of PRRSV, we identified a new strain named HLJDZD55. Phylogenetic analysis of the ORF5 gene revealed that HLJDZD55 belongs to the L1B branch. Alignment of deduced amino acid sequences based on the Nsp2 gene indicated that HLJDZD55 has a discontinuous deletion of 131 amino acids (111 + 1 + 19). We further sequenced the whole genome of HLJDZD55, and phylogenetic analysis based on the whole-genome sequence revealed that HLJDZD55 belongs to the L1C branch. Recombination analysis of the whole genome demonstrated that HLJDZD55 is a recombinant strain of TJZH-1607 (L1C, identified in China) and Minnesota 14 (L1B, identified in the USA). These findings suggested that HLJDZD55 is a newly emerged lineage 1 PRRSV in China and is closely related to L1B PRRSV in the US, which may have been introduced from the U.S. strain and subsequently recombined with the local Chinese strain and underwent evolution. Taken together, these results demonstrated the emergence of L1B PRRSV in China for the first time.

The Korean Demilitarized Zone (DMZ) is one of the world’s most preserved habitats for wild animals and migratory birds. The area also plays a major role in the spread of infectious animal diseases, in particular, African swine fever (ASF) and highly pathogenic avian influenza (HPAI). These outbreaks threaten the livelihood of local livestock farms, not infrequently. In this paper, we explore these relatively under-researched diseases by modeling and mapping ASF and HPAI risks in tandem using MaxEnt, a machine-learning algorithm. The results show robust predictive power with high area under the curve values, of 0.92 and 0.99, respectively. We found that precipitation from spring to early summer and solar radiation in winter were essential in explaining the potential distribution of ASF, but land use contributed little. Thus, understanding only wild boars’ habitat preferences may not be sufficient in preventing ASF epidemics. HPAI risks were shaped by precipitation and mean temperature from winter to spring and land use. Areas with high ASF and HPAI risks were primarily found in forest and agricultural lands, respectively. The DMZ included many high-risk areas, indicating that the DMZ could lead to a broader regional spread of ASF and HPAI in the peninsula. Thus, our results highlight the essential role of cross-border collaboration and the combination of environmental and epidemiological insights in strategies to control ASF and HPAI risks within and surrounding the DMZ.

The dissemination of antimicrobial resistance (AMR) severely degrades the performance of antibiotics and constantly paralyzes the global health system. In particular, plasmid-mediated transfer of antibiotic resistance genes (ARGs) across bacteria is recognized as the primary driver. Therefore, antiplasmid transfer approaches are urgently warranted to resolve this intractable problem. Herein, we demonstrated the potential of azidothymidine (AZT), an FDA-approved anti-HIV drug, as a broad-spectrum horizontal transfer inhibitor to effectively prevent the transmission of multiple ARGs, including mcr-1, bla_NDM−5, and tet(X4), both in vitro and in vivo. It was also noteworthy that the inhibitory effect of AZT was proved to be valid within and across bacterial genera under different mating conditions. Mechanistic studies revealed that AZT dissipated bacterial proton motive force, which was indispensable for ATP synthesis and flagellar motility. In addition, AZT downregulated bacterial secretion systems involving general and type IV secretion systems (T4SS). Furthermore, the thymidine kinase, which is associated with DNA synthesis, turned out to be the potential target of AZT. Collectively, our work demonstrates the broad inhibitory effect of AZT in preventing ARGs transmission, opening new horizons for controlling AMR.

Piroplasmosis and anaplasmosis are important zoonotic diseases of animal origin, which can be transmitted by ticks to infect animals. However, there is limited information on the infection of piroplasmosis and anaplasmosis in Tan sheep in Ningxia, China. In order to understand the prevalence of piroplasmosis and anaplasmosis in Tan sheep in Ningxia, 150 blood samples of Tan sheep from farms in five urban areas of Ningxia were detected by PCR, and some positive samples were sequenced to establish a phylogenetic tree. PCR revealed that the prevalence of Anaplasma spp. in Tan sheep in Ningxia was 28.0%. The overall prevalence of Piroplasmids was 33.3%, of which Theileria spp. and Babesia spp. were 20.7% and 12.7%, respectively. Among the samples of different ages, the highest detection rates of Piroplasmids and Anaplasma spp. were found in Tan sheep aged 20–30 months, and the detection rate of Theileria spp., Babesia spp., and Anaplasma spp. were 25.4%, 23.6%, and 36.3%, respectively. In this study, one Theileria species was identified as Theileria uilenbergi, two Babesia species were identified as Babesia molasi and Babesia ovis, and two Anaplasma species were identified as Anaplasma ovis and Anaplasma phagocytophilum, and the dominant species were A. ovis and T. uilenbergi. To the best of our knowledge, this is the first report detailing the infection rate and genotype of Piroplasmids and Anaplasma spp. in Tan sheep in Ningxia, China. The results of this study provide valuable data for understanding the epidemiology of tick-borne disease in Tan sheep in Ningxia, China, and lay a theoretical foundation for the prevention and control of piroplasmosis and anaplasmosis in Tan sheep in Ningxia, northwest China.

The recent high incidence of Mycoplasma pneumoniae (Mp) infections has raised widespread public health concerns. Therefore, rapid and accurate diagnosis of respiratory pathogenic microbial infections is of paramount importance to provide clinicians with accurate diagnostic insights and guide clinical medication. In response to this urgent need, we developed a one-tube Palm CRISPR/Cas12a Diagnostic (PaCD) method. This method facilitates the rapid detection of Mp infections, as well as three other prevalent respiratory pathogens, Chlamydia pneumoniae (Cp), Haemophilus influenzae (Hi), and Streptococcus pneumoniae (SP). In addition, 3D printing was employed to fabricate a compact detection device that includes a temperature control module set at 39°C and a blue light irradiation module, significantly enhancing the feasibility of point-of-care testing. The PaCD diagnostic process takes only 30 min with a detection limit of 50 copies/test, making it suitable for analysis of sputum and throat swab samples. PaCD demonstrated 100% concordance (72/72) with next-generation sequencing and exhibited high concordance with computed tomography test results. These findings demonstrate the clinical feasibility of PaCD for the rapid and accurate diagnosis of infections caused by four prevalent respiratory pathogens, offering theoretical insights into the versatile application of point-of-care tests for the detection of other respiratory pathogens in various clinical scenarios.

Salmonella Dublin is a bovine-adapted bacterial pathogen that primarily affects dairy cattle. The incidence of S. Dublin has been increasing across North America, including strains that are multidrug resistant. In British Columbia, the Ministry of Agriculture’s Animal Health Center (AHC) reported an increase in cases since 2015, warranting an investigation into how S. Dublin is spreading within the province. The objectives of this study were to make use of historical data collected from dairy farms across the province to (1) describe S. Dublin cases diagnosed at the AHC between 2007 and 2021, (2) identify risk factors for S. Dublin transmission across British Columbia dairy farms, and (3) identify any potential biases associated with passive laboratory-based data that may apply to our results. We found that S. Dublin cases diagnosed at the AHC have been increasing over time. Over half of the cases had respiratory symptoms; however, clinical signs tended to be highly variable. The prevalence of respiratory symptoms was mirrored by florfenicol treatment and was suggested to be due to using a first-line antibiotic for more common causes of pneumonia when presented with an S. Dublin case. Calves were 38 times more likely to have S. Dublin when compared to adults (odds ratio = 38.43, confidence interval = 7.26–203.64), and given the sample population (postmortem cases), it is reasonable to conclude clinical disease is most severe in this age group. Farm premise accounted for a large amount of variability within our model (92% of unexplained variance), suggesting that farm-level management practices may be the most important risk factor for S. Dublin infection. In total, only 54% of BC dairy farms submitted to the laboratory between 2007 and 2021; however, proximity to the laboratory did not appear to influence submissions as proportionally; farms within the Fraser Valley submitted as frequently as farms from other regions. We strongly suggest that future work explore factors associated with farm management practices, given our findings regarding the clustering by premises.