Transboundary and Emerging Diseases最新文献

The devastating swine disease, porcine reproductive and respiratory syndrome (PRRS), can only be caused by live PRRS virus (PRRSV) infection. However, the most commonly used detection methods cannot discriminate PRRSV infectivity. Here we developed a triplex propidium monoazide (PMA) qPCR assay for differential detection of infectious PRRSV isolates (NADC34-like PRRSV-2, NADC30-like PRRSV-2, and HP-PRRSV-2) prevalent in China. First, the PRRSV inactivation strategy was selected by comparing distinct inactivation methods. Subsequently, we optimized PMA pretreatment parameters and concentrations of primers and probes. The triplex PMA-qPCR assay displayed favorable specificity, sensitivity, and reproducibility. Moreover, 452 clinical samples (environmental feces, lungs, lymph nodes (LNs), and sera) were submitted to differential detection by triplex qPCR and triplex PMA-qPCR assays. A total of 83 PRRSV-positive samples were detected by the triplex qPCR assay, including 25 NADC34-like, 48 NADC30-like, and 15HP-PRRSV-2-positive samples (two samples were coinfected by NADC34-like and NADC30-like PRRSV-2, while three samples were coinfected by NADC30-like and HP-PRRSV-2). Meanwhile, 65 samples were identified by the PMA-qPCR method, including 21 NADC34-like, 36 NADC30-like, and 9HP-PRRSV-2 positive samples (one sample was coinfected by NADC34-like and NADC30-like PRRSV-2). No PRRSV could be isolated from the 18 qPCR-positive but PMA-qPCR-negative samples. Overall, this study provides the first triplex PMA-qPCR assay for rapid discrimination of live PRRSV isolates in clinical samples, particularly in environmental feces.

Foot-and-mouth disease (FMD) is a highly contagious and serious transboundary disease affecting cloven-hoofed animals. Myanmar is a critical area for FMD outbreaks in Southeast and East Asian regions because of its geographical location bordering South Asian countries and its cattle industry. Phylogenetic characterization and pathogenicity in susceptible animals of circulating viruses in Myanmar are essential to prepare the rapid and accurate diagnosis and implement effective FMD prevention. This study analyzed a total of 34 vesicular epithelial samples collected from FMD cases in northern, central, and southern Myanmar between 2016 and 2022. Phylogenetic analysis of VP1 nucleotide sequences revealed multiple serotypes and topotypes between 2016 and 2019, including serotype O/Middle East-South Asia (ME-SA) topotype (O/ME-SA/Ind-2001e) and Southeast Asia (SEA) topotype, and serotype A/ASIA topotype. Subsequently, all viruses across Myanmar detected from 2019 to 2022 belonged to O/ME-SA/Ind-2001e. Phylogenetic analysis of the whole genome sequence showed that O/ME-SA/Ind-2001e viruses detected after 2019 were classified into a different genetic group with those of 2016 isolates in Myanmar. Based on phylogenetic analysis, one representative strain from 2019 that was genetically similar to viruses detected from 2019 to 2022 and to a 2022 Indonesian isolate was selected for pathogenicity testing in comparison with a 2016 strain closely related to viruses from neighboring countries. Both strains were used for experimental infection in pigs and showed similar pathogenicity. The 2019 strain was additionally tested in cattle and caused typical FMD pathogenicity, including vesicular development and virus excretion. Viral genes and antibodies in infected animals were detectable using existing diagnostic methods, which are considered useful for identifying currently circulating viruses. These results elucidate the subtypes of FMD viruses (FMDVs) circulating in Myanmar, their phylogenetic relationships with viruses from neighboring Asian countries, their pathogenicity, and the applicability of available diagnostic methods. It offers insights into appropriate control strategies against FMD in Southeast and East Asian regions.

Getah virus (GETV), Japanese encephalitis virus (JEV), West Nile virus (WNV), and African horse sickness virus (AHSV) are mosquito-borne viruses threatening the health of racehorses. However, the systematic surveillance of these viruses among Shanghai racehorses remains lacking. Therefore, molecular and serological surveillance was conducted for these viruses in racehorses and mosquitoes at horse farms in Shanghai, China, during 2022 to assess their prevalence. Among 11,140 mosquitoes collected from seven farms across four districts, Culex tritaeniorhynchus and Anopheles sinensis were identified as the dominant species. RT-qPCR detected GETV in four mosquito pools (FX1-6, PD1-32, PD1-45, and PD1-57) and JEV in three pools (SJ1-4, PD1-22, and JS1-9), while WNV and AHSV remained undetected. Two GETV strains (SH202201 and SH202202) were isolated and phylogenetically classified as genotype III (GIII). Serological surveys of 182 horse serum samples revealed an overall GETV antibody positivity rate of 28.6%. The positivity rate demonstrated significant age-dependency (41.7% in horses >15 years) and seasonal variation (45.1% in autumn vs. 12.1% in spring). JEV seroprevalence rates were 12.6%, exhibiting significant seasonal differences. No antibodies positive for WNV and AHSV were detected. These results indicate that the threat of WNV and AHSV to racehorses in Shanghai is currently very small, while GETV represents the primary arboviral risk. Implementing targeted surveillance for GETV during high-risk seasons (autumn) and in key regions (Fengxian), while enhancing surveillance for JEV, WNV, and AHSV, is crucial for safeguarding equine health and promoting the sustainable development of the equestrian industry.

Strongyloidiasis caused by Strongyloides papillosus is a significant parasitic disease affecting the health and productivity of small ruminants globally. In this study, a novel recombinase-aided amplification (RAA) combined with lateral flow dipstick (LFD) assay was developed and validated for the rapid and specific detection of S. papillosus infection in goats and sheep, targeting the 18S ribosomal RNA (18S rRNA) gene. A total of 815 fecal samples were collected from nine provinces in China, encompassing major goats and sheep production regions. The RAA-LFD assay exhibited high sensitivity, with a minimum detection limit of 15 eggs per gram (EPG) of feces. Clinical fecal examination yielded a positive rate of 62.30% (433/695), while the RAA-LFD assay achieved a positive rate of 58.28% (475/815), indicating that the diagnostic accuracy of the RAA-LFD assay is consistent with that of fecal examination. Compared with conventional fecal examination, the RAA-LFD assay offers superior rapidity, portability, and sensitivity, presenting a valuable diagnostic tool for large scale epidemiological surveillance and point-of-care applications, particularly in resource constrained environments.

Bartonella species are known as candidates for zoonotic transmission, and cats serve as the main reservoir for Bartonella henselae, the primary causative agent of cat scratch disease (CSD). However, research on the transmission of bartonellosis to humans remains very limited. In East Asia, there is a lack of comprehensive studies regarding the prevalence of B. henselae infection and its associated risk factors among companion cats, their owners, and individuals working in veterinary professions. This study aimed to investigate both the molecular and seroprevalence of B. henselae in veterinary personnel and companion cats in South Korea, along with a questionnaire-based analysis of transmission risk factors. Blood and saliva samples were collected from humans, whereas blood, saliva, claw, and fecal samples were obtained from cats. Seroprevalence and molecular prevalence were measured for all these samples. Additionally, participants were required to complete an epidemiological information questionnaire related to CSD. The study enrolled 300 veterinary professionals and 126 companion cats owned by them. The serum IgG prevalence in humans was 64.6% (190/294), whereas, in cats, it was 5.5% (6/108). The molecular prevalence in human blood and saliva was 3% (9/298) and 1.7% (5/298), respectively. In cats, it was 10.1% (12/119) for blood, 0% (0/123) for saliva, 1.7% (2/119) for nails, and 4.5% (5/112) for feces. Phylogenetic analysis of the PCR-positive samples confirmed that all of them were B. henselae. This study demonstrates that Bartonella species are widespread among veterinary professionals in South Korea, highlighting their significance as zoonotic pathogens. Given the potential for indirect transmission from cats, enhancing awareness of Bartonella exposure risk among veterinary personnel is warranted, along with emphasizing preventive education for cat owners, including strict ectoparasite control.

African swine fever (ASF) genotype II has severely impacted the Philippine swine industry since 2019, affecting backyard and commercial farms as well as native wild boar populations, with significant economic and food security implications. Understanding ASF transmission dynamics is crucial for effective control and management strategies. However, farm-level transmission patterns remain unclear, and a comprehensive analysis incorporating both national and island-specific estimates has yet to be conducted. Using ASF outbreak data from 2019 to 2022, we estimated the herd-level basic reproduction number (R_h) for the Philippines and its three major islands—Luzon, Visayas, and Mindanao—using deterministic and stochastic models. Epidemic descriptive analysis and Spearman’s correlation results indicate that Luzon’s data most accurately reflect national epidemic trends. Our estimation model for R_h shows that while the long-term trend of ASF approaches a threshold near 1, indicating a shift toward endemicity, the R_h value does not consistently remain below 1 during the study period, suggesting ongoing outbreaks. Luzon, the outbreak’s origin with the highest swine farm density, mirrors national trends, whereas Mindanao and Visayas exhibit distinct transmission patterns influenced by local production systems and swine demographics. These results highlight the need for region-specific ASF management strategies, including enhanced biosecurity in Luzon and community-based surveillance in Visayas and Mindanao. Adapting control measures to regional transmission patterns can improve ASF management and support the long-term recovery of the Philippine swine industry.

In the United States, hantaviruses can cause hantavirus pulmonary syndrome (HPS) in humans, an acute respiratory illness with a high mortality rate. Most people contract HPS from exposure to infected rodent excrement. The interannual dynamics of hantavirus transmission are tied to both environmental and human-related factors, including changes in annual climate conditions, rodent populations, and the built environment in which humans are more likely to be exposed. Similar environmental conditions and socioeconomic factors also likely determine the long-term risk of hantavirus exposure. Here, we use ecological niche models and human cases of HPS in the U.S. from 1993 to 2022 to assess hantavirus risk using four socioeconomic variables, 17 land use variables, one variable of rodent richness, and seven climate variables to determine both the geographical locations of highest exposure risk and leading environmental predictors. We found that areas with higher relative risk tend to be where it is drier, higher social vulnerability, increased rodent richness, and more open to low levels of development—this largely mapped to the western U.S. We found evidence that fringe ecosystems may be important areas of hantavirus transmission, similar to other emerging diseases. Increased rodent richness was associated with increased hantavirus risk, warranting further investigation into how the abundance and community composition of rodents could impact long-term risk. These risk maps can help public health officials develop plans for mitigating hantavirus, especially for the most susceptible populations. They can also be used to further investigate regions estimated to be at high risk for hantavirus where disease cases have not been as common but may be underreported.

Prediction of dengue continues to be valuable in endemic countries. Time series forecasting methods have been widely employed for predicting future dengue trends and outbreaks. The study aimed to determine the spatial distribution, trends, and seasonality of dengue cases and compare the predictive accuracy of seasonal autoregressive integrated moving average (SARIMA), neural network autoregression (NNAR), random forest (RF), long–short term memory (LSTM), trigonometric exponential smoothing state–space model with Box–Cox transformation, ARMA errors, trend and seasonal components (TBATS), and Prophet in forecasting dengue cases in the Philippines. Monthly data from 2017 to 2024 across all provinces were obtained and were partitioned into training (January 2017–December 2023) and testing segments (January 2024–December 2024). Model performance was assessed by analyzing the training data using time series techniques and comparing the resulting forecasts with empirical values from the test dataset. In total, 3-year projections were generated by implementing the models on the entire dataset. The study analyzed 1,903,425 dengue cases with a mean monthly incidence of 17.66 ± 15.97 per 100,000 population. Regular seasonal epidemics were identified, peaking from July to September. NNAR outperformed the other models and predicted an annual average of 444,678 cases from 2025 to 2027. This is the first study to apply SARIMA, RF, LSTM, TBATS, and Prophet in forecasting dengue cases in the Philippines at a national scale. The study offers new insights into disease forecasting, particularly in the application of advanced time series methodologies. These findings should be considered to strengthen surveillance, prevention, and control against dengue.

Coronaviruses (CoVs) can cross species barriers and endanger public health. Despite reports on their circulation and evolution in companion animals during the pandemic, postpandemic surveillance remains crucial. Therefore, during the first postpandemic year, 309 samples from 263 companion animals (cats and dogs) in Chengdu, China, were detected for CoVs using a universal assay based on Rdrp genes combined with one-generation sequencing. Four kinds of CoVs, including feline CoV (FCoV), canine CoV (CCoV), CRCoV, and SARS-CoV-2 (the first reported case of SARS-CoV-2 in a dog in mainland China, confirmed by viral nucleic acid detection and analysis), were detected with an overall positive rate of 21.7% (57/263); FCoV-I and CCoV-IIa were the dominant genotypes, and of these 57 positive cases, 71.9% (41/57) were in pets ≤12 months old. In CCoV-positive dogs, 72.2% (13/18) were coinfected with other viruses (primarily canine parvovirus [CPV], 76.9%; 10/13), while 13.9% (5/36) codetection with feline parvovirus (FPV). A 21-nt deletion in two FCoV S genes and a 145-nt deletion in one FCoV ORF3abc gene were identified, and recombination events at positions 919 and 1639 nt in two S genes were noticed. Notably, the amino acid variations in FCoV and CCoV S genes revealed distinct regional adaptations: FCoV strains showed unique substitutions (e.g., Ala/Ser129Leu) and a shift from RSRR to RARR furin cleavage motifs; CCoV strains in China exhibited significant differences from those in other countries. Phylogenetic analysis demonstrated that the S genes of FCoV and CCoV were closely related to those of the prevalent strains in China, whereas the S genes of CRCoV were closely related to that of human CoV (HCoV) OC43. These findings highlight the need for continued surveillance of CoV infection in companion animals (especially ≤12 months old) in the postpandemic era.

Ticks serve as critical viral vectors, and border regions, acting as convergence zones of complex ecosystems, provide diverse habitats for ticks and their hosts, thereby underscoring the need to investigate the tick-borne virome composition in such areas. In this study, metatranscriptomic analysis of five tick species, namely Haemaphysalis longicornis, Haemaphysalis concinna, Haemaphysalis japonica, Ixodes persulactus, and Dermacentor silvarum, collected from the China–Russia–North Korea border region identified 10 viral families and 22 viral species. Among these, five were confirmed human pathogens, while nine exhibited potential zoonotic risks. Moreover, significant variations in virome composition across sampling sites revealed associations between tick-borne viruses and ecological-geographical factors. These findings highlight the diversity and spatiotemporal distribution patterns of tick-borne viruses in the region, offering critical insights for safeguarding border biosecurity and public health.