Cross-regional Transmission Research Articles

Association between toxin-antitoxin system mutations and global transmission of MDR-TB.

The emergence of Multidrug-Resistant Tuberculosis (MDR-TB) poses a significant threat to global tuberculosis control efforts. This study aimed to examine the influence of mutations in Toxin-Antitoxin system genes on the global transmission of MDR-TB caused by Mycobacterium tuberculosis (M. tuberculosis). Whole-genome sequencing was conducted on 13,518 M. tuberculosis isolates. Genes of the Toxin-Antitoxin system were obtained from the National Center for Biotechnology Information (NCBI) Gene database. Techniques such as Random Forest, Gradient Boosting Decision Tree, and Generalized Linear Mixed Models were employed to identify mutation sites in Toxin-Antitoxin system-related genes that facilitated the transmission of MDR-TB. 4,066 (30.08%) were identified as MDR-TB strains of all analyzed isolates. We found significant associations between specific gene mutations and MDR-TB transmission clusters including mutations in Rv0298 (G213A), Rv1959c (parE1, C88T), Rv1960c (parD1, C134T), Rv1991A (maze, G156A), Rv2547 (vapB, C54G), Rv2862A (vapB23, T2C), and Rv3385c (vapB46, G70A). Additionally, several gene mutations associated with MDR-TB transmission clades such as Rv1956 (higA, G445T), Rv1960c (parD1, C134T), and Rv1962A (vapB35, G99A) were noted. Certain gene mutations including vapB35 (G99A), higA (G445T), and parD1 (C134T) correlated with cross-regional transmission clades. This study highlights the significant association between specific gene mutations in the Toxin-Antitoxin system and the global transmission of MDR-TB, providing valuable insights for developing targeted interventions to control MDR-TB.

Virulence plasmid with IroBCDN deletion promoted cross-regional transmission of ST11-KL64 carbapenem-resistant hypervirulent Klebsiella pneumoniae in central China

BackgroundCarbapenem-resistant and hypervirulent Klebsiella pneumoniae (CR-hvKP) caused infections of high mortality and brought a serious impact on public health. This study aims to evaluate the epidemiology, resistance and virulence characteristics of CR-hvKP and to identify potential drivers of cross-regional transmission in different regions of China, in order to provide a basis for developing targeted prevention measures.MethodsClinical K. pneumoniae strains were collected from Jiujiang and Nanchang in Jiangxi province between November 2021 to June 2022. Clinical data of patients (age, sex, source of infection, and diagnosis) were also gathered. We characterized these strains for their genetic relatedness using PFGE, antimicrobial and virulence plasmid structures using whole-genome sequencing, and toxicity using Galleria mellonella infection model.ResultsAmong 609 strains, 45 (7.4%) CR-hvKP were identified, while the strains.isolated from Nanchang and Jiujiang accounted for 10.05% (36/358) and 3.59% (9/251). We observed that ST11-KL64 CR-hvKP had an overwhelming epidemic dominance in these two regions. Significant genetic diversity was identified among all ST11-KL64 CR-hvKP cross-regional transmission between Nanchang and Jiujiang and this diversity served as the primary driver of the dissemination of clonal groups. Virulence genes profile revealed that ST11-KL64 CR-hvKP might harbour incomplete pLVPK-like plasmids and primarily evolved from CRKP by acquiring the hypervirulence plasmid. We found the predominance of truncated-IncFIB/IncHI1B type virulence plasmids with a 25 kb fragment deletion that encoded iroBCDN clusters.ConclusionST11-KL64 is the most cross-regional prevalent type CR-hvKPs in Jiangxi province, which mainly evolved from CRKPs by acquiring a truncated-IncHI1B/IncFIB virulence plasmid with the deletion of iroBCDN. Stricter surveillance and control measures are urgently needed to prevent the epidemic transmission of ST11-KL64 CR-hvKP.

Association of mutations in Mycobacterium tuberculosis complex (MTBC) respiration chain genes with hyper-transmission

BackgroundThe respiratory chain plays a key role in the growth of Mycobacterium tuberculosis complex (MTBC). However, the exact regulatory mechanisms of this system still need to be elucidated, and only a few studies have investigated the impact of genetic mutations within the respiratory chain on MTBC transmission. This study aims to explore the impact of respiratory chain gene mutations on the global spread of MTBC.ResultsA total of 13,402 isolates of MTBC were included in this study. The majority of the isolates (n = 6,382, 47.62%) belonged to lineage 4, followed by lineage 2 (n = 5,123, 38.23%). Our findings revealed significant associations between Single Nucleotide Polymorphisms (SNPs) of specific genes and transmission clusters. These SNPs include Rv0087 (hycE, G178T), Rv1307 (atpH, C650T), Rv2195 (qcrA, G181C), Rv2196 (qcrB, G1250T), Rv3145 (nuoA, C35T), Rv3149 (nuoE, G121C), Rv3150 (nuoF, G700A), Rv3151 (nuoG, A1810G), Rv3152 (nuoH, G493A), and Rv3157 (nuoM, A1243G). Furthermore, our results showed that the SNPs of atpH C73G, atpA G271C, qcrA G181C, nuoJ G115A, nuoM G772A, and nuoN G1084T were positively correlated with cross-country transmission clades and cross-regional transmission clades.ConclusionsOur study uncovered an association between mutations in respiratory chain genes and the transmission of MTBC. This important finding provides new insights for future research and will help to further explore new mechanisms of MTBC pathogenicity. By uncovering this association, we gain a more complete understanding of the processes by which MTBC increases virulence and spread, providing potential targets and strategies for preventing and treating tuberculosis.

Single-Trial Representations of Decision-Related Variables by Decomposed Frontal Corticostriatal Ensemble Activity.

The frontal cortex-striatum circuit plays a pivotal role in adaptive goal-directed behaviors. However, it remains unclear how decision-related signals are mediated through cross-regional transmission between the medial frontal cortex and the striatum by neuronal ensembles in making decision based on outcomes of past action. Here, we analyzed neuronal ensemble activity obtained through simultaneous multiunit recordings in the secondary motor cortex (M2) and dorsal striatum (DS) in rats performing an outcome-based left-or-right choice task. By adopting tensor component analysis (TCA), a single-trial-based unsupervised dimensionality reduction approach, for concatenated ensembles of M2 and DS neurons, we identified distinct three spatiotemporal neural dynamics (TCA components) at the single-trial level specific to task-relevant variables. Choice-position-selective neural dynamics reflected the positions chosen and was correlated with the trial-to-trial fluctuation of behavioral variables. Intriguingly, choice-pattern-selective neural dynamics distinguished whether the incoming choice was a repetition or a switch from the previous choice before a response choice. Other neural dynamics was selective to outcome and increased within-trial activity following response. Our results demonstrate how the concatenated ensembles of M2 and DS process distinct features of decision-related signals at various points in time. Thereby, the M2 and DS collaboratively monitor action outcomes and determine the subsequent choice, whether to repeat or switch, for action selection.

Analysis of Characteristics and Sensitivity of Photochemical Pollution During High Ozone Season in Shanghai from 2016 to 2020

The sensitivity analysis of ozone generation in key ozone-polluted regions and cities is an important basis for the prevention and control of near-surface ozone （O3） pollution. Based on the five-year data of ozone, VOCs, and NOx from three typical stations in Shanghai, namely Dianshan Lake Station （suburban area）, Pudong Station （urban area）, and Xinlian Station （industrial area） from 2016 to 2020, the nonlinear relationship between ozone and precursors （VOCs and NOx） during the high-ozone season in the five years was quantitatively analyzed using an observation model. The results showed that the peak months of near-surface ozone in Shanghai were from April to September during 2016 to 2020, with the highest values appearing from June to August. The volume fraction of VOCs and NO2 concentration had a strong indicative significance for the O3 concentration at Pudong Station. The O3 concentration at Dianshan Lake Station was mainly influenced by regional environment, meteorological factors, and cross-regional transmission. The ozone concentration at Xinlian Station was a combination of environmental background concentration and industrial area photochemical pollution. Pudong Station and Dianshan Lake Station were in the VOCs control zone. Xinlian Station was gradually closer to the NOx control zone from 2016 to 2019, transitioning to the VOCs control zone since 2020. The L·OH of Pudong Station, Dianshan Lake Station, and Xinlian Station were： NOx control area>collaborative control area>VOCs control area.

Prediction method for power fluctuations in cross regional consumption and transportation under the integration of new energy

Against the backdrop of the increasing development of the new energy industry, the volatility of new energy output poses significant challenges to regional power grid balance and energy absorption. Therefore, this article proposes a prediction method for cross regional transmission power fluctuations under new energy integration conditions. A comprehensive and representative sample dataset was constructed by comprehensively considering factors such as fluctuations in new energy output, capacity confidence, and peak shaving characteristic parameters, combined with numerical weather forecast data. Normalize the sample data to eliminate dimensional differences between parameters. The sparrow search algorithm is used to optimize the weights and thresholds of the double hidden layer BP neural network, effectively avoiding local optimization problems caused by over training. The experimental results show that this method has significant advantages in predicting power fluctuations in cross regional absorption and transportation of new energy, with a predicted power to power ratio of over 0.85.

A Low-carbon Dispatching Method for Cascade Hydropower via HVDC Flexible Delivery

Abstract As a country rich in hydropower resources, the transmission of Southwest hydropower through HVDC system can achieve a large range of optimal allocation of resources, but the traditional HVDC transmission plan is often operated in high and low binary value, which is difficult to give full play to the flexibility of HVDC transmission, and increase the carbon emission and operation cost of the power system. In order to fully explore the flexibility of HVDC transmission mode to reduce system carbon emissions, this paper builds a mixed integer programming model based on the scenario of hydropower being sent to the receiving system through the HVDC system, taking into account such factors as low operating costs and carbon dioxide emissions of thermal power units at the receiving end, overload capacity of the HVDC system, and reactive power compensation cost of the HVDC system. A low carbon scheduling method for cascade hydropower HVDC flexible delivery system is proposed. Finally, taking the cross-regional transmission system of cascade hydropower station as an example, the model proposed in this paper is compared with the high-low binary transmission of traditional HVDC system. The results show that the dispatch mode proposed in this paper and the flexible operation of the HVDC system can promote the consumption of new energy, reduce the CO2 emissions of the system and achieve the dispatch goal of both low carbon and economic operation.

Contextualizing Transnational Chinese Christianity: A Relational Approach

In recent years, the number of Chinese Christian organizations in Europe has grown considerably compared to other overseas Chinese community organizations. They can mobilize transnational networks and resources to expand religious space in host societies and form a highly visible social force. Although the rise of early Christianity in the Western world has been considered an outcome of inherent religious strength, especially in terms of its central doctrines and religious ethics, this article suggests that in the diasporic Chinese world where Christianity constitutes a non-indigenous religious tradition, social relatedness based on native place, family, and kinship ties provides a more useful context for understanding its dynamic expansion and cross-regional transmission. Drawing on anthropological fieldwork conducted in Europe among overseas Chinese Christian traders and entrepreneurs, this research seeks an alternative framework for understanding the religious-cultural dynamics of Chinese Christianity in the context of transnational migration.

Multidrug-resistant Mycobacterium tuberculosis transmission in Shandong, China.

Multidrug-resistant tuberculosis (MDR-TB) has imposed a significant economic and health burden worldwide, notably in China. Using whole genome sequence, we sought to understand the mutation and transmission of MDR-TB in Shandong. A retrospective study of patients diagnosed with pulmonary tuberculosis in Shandong from 2009 to 2018 was conducted. To explore transmission patterns, we performed whole genome sequencing on MDR-TB isolates, identified genomic clusters, and assessed the drug resistance of TB isolates. Our study analyzed 167 isolates of MDR-TB, finding that 100 were clustered. The predominant lineage among MDR-TB isolates was lineage 2, specifically with a notable 88.6% belonging to lineage 2.2.1. Lineage 4 constituted a smaller proportion, accounting for 4.2% of the isolates. We discovered that Shandong has a significant clustering percentage for MDR-TB, with Jining having the highest percentage among all Shandong cities. The clustering percentages of MDR-TB, pre-extensively drug-resistant tuberculosis, and extensively drug-resistant tuberculosis were 59.9%, 66.0%, and 71.4%, respectively, and the clustering percentages increased with the expansion of the anti-TB spectrum. Isolates from genomic clusters 1 and 3 belonged to lineage 2.2.1 and showed signs of cross-regional transmission. The distribution of rrs A1401G and katG S315T mutations in lineage 2.2.1 and 2.2.2 strains differed significantly (P < .05). MDR-TB isolates with rpoB I480V, embA-12C > T, and rrs A1401G mutations showed a higher likelihood of clustering (P < .05). Our findings indicate a significant problem of local transmission of MDR-TB in Shandong, China. Beijing lineage isolates and some drug-resistant mutations account for the MDR-TB transmission in Shandong.

Global spread characteristics of CTX-M-type extended-spectrum β-lactamases: A genomic epidemiology analysis

BackgroundExtended-spectrum β-lactamases (ESBLs) producing bacteria have spread worldwide and become a global public health concern. Plasmid-mediated transfer of ESBLs is an important route for resistance acquisition. MethodsWe collected 1345 complete sequences of plasmids containing CTX-Ms from public database. The global transmission pattern of plasmids and evolutionary dynamics of CTX-Ms have been inferred. We applied the pan-genome clustering based on plasmid genomes and evolution analysis to demonstrate the transmission events. FindingsTotally, 48 CTX-Ms genotypes and 186 incompatible types of plasmids were identified. The geographical distribution of CTX-Ms showed significant differences across countries and continents. CTX-M-14 and CTX-M-55 were found to be the dominant genotypes in Asia, while CTX-M-1 played a leading role in Europe. The plasmids can be divided into 12 lineages, some of which forming distinct geographical clusters in Asia and Europe, while others forming hybrid populations. The Inc types of plasmids are lineage-specific, with the CTX-M-1_IncI1-I (Alpha) and CTX-M-65_IncFII (pHN7A8)/R being the dominant patterns of cross-host and cross-regional transmission. The IncI-I (Alpha) plasmids with the highest number, were presumed to form communication groups in Europe-Asia and Asia-America-Oceania, showing the transmission model as global dissemination and regional microevolution. Meanwhile, the main kinetic elements of blaCTX-Ms showed genotypic preferences. ISEcpl and IS26 were most frequently involved in the transfer of CTX-M-14 and CTX-M-65, respectively. IS15 has become a crucial participant in mediating the dissemination of blaCTX-Ms. Interestingly, blaTEM and blaCTX-Ms often coexisted in the same transposable unit. Furthermore, antibiotic resistance genes associated with aminoglycosides, sulfonamides and cephalosporins showed a relatively high frequency of synergistic effects with CTX-Ms. ConclusionsWe recognized the dominant blaCTX-Ms and mainstream plasmids of different continents. The results of this study provide support for a more effective response to the risks associated with the evolution of blaCTX-Ms-bearing plasmids, and lay the foundation for genotype-specific epidemiological surveillance of resistance, which are of important public health implications.

Research on demand forecasting and distribution of emergency medical supplies using an agent-based model

The global health crisis caused by SARS-CoV-2 since 2019 has emphasized the critical significance of effective disease detection and treatment in minimizing infection rates and fatalities, as well as halting the spread of pandemics. During an outbreak, individuals suspected of being infected require a significant amount of testing resources, while those confirmed to be infected demand substantial treatment resources. Hence, this paper is dedicated to presenting a new pandemic model that enables joint forecasting and allocation of resources for testing and treatment. The proposed model in this paper is an innovative agent-based epidemic compartmental model, which also incorporates a mixed integer model. It integrates novel features based on crucial disease characteristics, such as self-healing for asymptomatic or mild-symptomatic cases, varying infection risk levels among different groups, and the inclusion of secondary infections. Moreover, the solutions of the joint allocation model are compared with those of the independent allocation model, which entails considering resource interactions rather than allocating each resource independently. Furthermore, the validity of this model was confirmed through real-world data obtained during the SARS-CoV-2 outbreak in China. The findings offer valuable insights into the impact of intervention levels and duration, joint allocation schemes, as well as optimal allocation of test and treatment resources on cross-regional transmission of the pandemic.

Analysis of Spatio-temporal Characteristics of Air Quality, Meteorological Impact, and Emission Reduction Effect During the Winter Olympics in Beijing-Tianjin-Hebei and Its Surrounding Areas

From January 31st to February 20th, 2015 to 2022, the spatio-temporal characteristics of the PM2.5 pollution evolution of 44 cities in the Beijing-Tianjin-Hebei Region and its surrounding areas were analyzed. The contribution of simultaneous meteorology, coordinated emission reduction, and cross-regional transmission to PM2.5 concentration and chemical component changes were quantified, respectively, with the aim to provide scientific reference for regional air quality joint prevention and control under adverse meteorological conditions. The results showed that the mean value of PM2.5 concentration of 44 cities in 2022 was the lowest(46 μg·m-3) without heavy pollution in the same period of the lunar calendar since 2015, whereas the proportion of days with good air quality was the highest(83.3%). PM2.5 pollution was more serious in the southern region than that in the northern region, and the high values were mainly concentrated along the Taihang Mountains and Yanshan transmission channel cities. In 2016, under the unregulated emission of fireworks in the Spring Festival, the proportion of unpolluted days was 93.5%, which means that the strong atmospheric diffusion ability was crucial to improve air quality. In 2022, the static weather index(SWI) increased by 2.1 compared with that in 2021, indicating unfavorable atmospheric diffusion capacity. The average and peak values of PM2.5 decreased by 14 μg·m-3 and 76 μg·m-3, respectively. The reduction in PM2.5 concentration in Beijing owing to emission reduction measures increased by 96% compared with that before one month. Under the adverse atmospheric background in the Shanxi-Shandong-Henan Region, which contributed to the increase in PM2.5 concentration, the peak value of PM2.5 concentration decreased by 87 μg·m-3, indicating that the peak clipping effect of regional collaborative pollution emission reduction was significant. From 2019 to 2022, the concentration of PM2.5 chemical components decreased yearly with narrowed spatial differences, and the high value was concentrated in the central and southern regions. The descending order of PM2.5 secondary component concentration decrease was as follows:organic matter(21.9%)>sulfate(20%)>ammonium salt(16.7%)>nitrate(9.7%). The proportion of nitrate in PM2.5 increased yearly to 30.1%, indicating that the contribution of traffic pollution was relatively prominent. In 2022, the SNA concentration in the Shanxi-Shandong-Henan Region increased. Pollution from external sources accounted for the main contribution in the Beijing-Tianjin-Hebei Region(>50%). Liaoning Province contributed significantly to the PM2.5 concentration in cities along the Bohai(>10%), and nitrate and sulfate were easy to transport over long distances. It is necessary to strengthen the coordinated control of precursors of secondary chemical components SO2, NOx, and NH3.

Sustainable Cross-Regional Transmission Control for the Industrial Augmented Intelligence of Things

Sustainable connectivity between an Augmented Intelligence of Things (AIoT) system and terminal devices can provide a strong guarantee for an enterprise's continuity of production. To ensure sustainable data interaction in emergency situations such as damage to communication infrastructure facilities in a postdisaster period, a pyramidal air–space–ground network model is proposed in this paper, and its transmission performance is investigated. The space network, constructed of geostationary (GEO) satellites and medium and low Earth orbit (MEO and LEO) satellites, is heterogeneously fused with the terrestrial AIoT network to ensure around-the-clock network service for enterprise production. Then, bandwidth–delay product (BDP) analysis is performed for this heterogeneous network. The proposed scheme improves the data transmission efficiency of the network model by mitigating the impact of a long round-trip time (RTT) and improving the congestion window optimization in the case of data loss. The proposed scheme increases the transmission rate in the network model by a factor of 3.72 compared to the traditional transmission scheme in the case of a 5-hop terrestrial AIoT network and has a 3.94-fold advantage in download time.

Native circulating Brucella melitensis lineages causing a brucellosis epidemic in Qinghai, China.

Since 2010, the cases and incidences of human brucellosis have been increasing annually in Qinghai (QH) Province. Molecular epidemiology and phylogenetic analyses of strains from this region are crucial to better understand the transmission of the disease and the evolutionary patterns of Brucella strains. In this study, classical bio-typing assay, multilocus variable-number tandem repeat analysis, and the whole-genome sequencing-single-nucleotide polymorphism approach were used to illustrate the epidemiological and evolutionary patterns of Brucella melitensis. A total of 54 B. melitensis bv. 3 strains were isolated and molecularly characterized, with all strains belonging to the East Mediterranean lineages. Cross-regional transmission events (i.e., between counties) were caused by common sources of infection, suggesting that predominant circulating genotypes are endemic in different regions. Strengthening surveillance in animal brucellosis and controlling infected animals' cross-border movement are necessary. Two strains isolated from humans and marmots were clustered in the same sub-clade, implying the possible existence of direct and/or indirect contact between sheep (and goats) and wildlife (marmots), but this needs to be verified by further investigations. The global-scale phylogenetic analysis indicated that 54 strains sorted into six subclades, four of which formed independent lineages, suggesting that the increase in the incidence rate of human brucellosis may be caused by local circulating lineages. Further strengthening the serology and pathogen surveillance of animals (wildlife) and humans will contribute to an in-depth understanding of the transmission chain of human brucellosis in this region.

Estimating the Importation Risk of Mpox Virus in 2022 to Hong Kong, China

International air travel has been recognized as a crucial factor in the cross-regional transmission of monkeypox (now known as mpox) since this disease rapidly spread across the globe in May 2022. On September 6, 2022, Hong Kong SAR (HK) reported its first imported mpox case with travel history of the United States (US), Canada, and the Philippines. In this study, we estimated the importation risk to HK from 25 international departure regions from May 1 to September 6, 2022, based on the prevalence of presymptomatic mpox cases in the study regions, and time-varying flight mobility evaluated by aggregating multiple open-access air travel datasets (e.g., OpenSky and Aviation Edge). The results of the study indicated that during the study period, the highest risk of mpox importation was from the US, at 63% (95% CI: 32% and 95%), followed by the United Kingdom (UK) and Canada, with risks of 29% (95% CI: 10% and 63%), and 17% (95% CI: 8% and 32%), respectively. The importation risk of mpox from the US and Canada was substantially higher than from the other regions, which was aligned with the travel history of the first reported case in HK. Our study introduces a simplified computational method that estimates the risk of importation mpox virus by combining air travel mobility, disease prevalence, and observed real-world scenarios to achieve accurate outcome estimates. Estimating the cross-regional importation risk of mpox would be beneficial in designing and adjusting inbound measures appropriately, which are essential for emergency public health policies.

Wind resource droughts in China

With the rising share of wind energy in power generation, the occurrence of low-wind-power events (termed ‘wind resource droughts’) are becoming critical in understanding the national electricity supply and the security of power systems. We use hourly wind speed data (2428 meteorological stations; in the years 2010–2020) to analyze the occurrence of wind resource droughts in seven onshore wind energy planning regions over China. We find that wind resource droughts tend to occur in warm season (summer and autumn) in most regions (i.e., Northeast China, East China, Central China, South China and Tibetan Plateau). In these regions, the number of moderate wind resource drought events (wind capacity factor below 10%) in the warm season (summer and autumn) was about 3–13 times higher than in the cold season (spring and winter). By contrast, for North China and Northwest China, the wind resource droughts mainly occurred in the autumn and winter. Averaged over 11 years, Northeast China experienced the most moderate wind resource droughts with 30 d yr−1, while Northwest China had only 1 d yr−1. Some of these wind resource drought events occurred consecutively, in which Northeast China experienced nine wind resource drought events that lasted for at least five days (where the longest reached 9 d) across the 11 years from 2010 to 2020; North China and South China exhibited one five-day wind resource drought events; while Northwest China, East China, Central China and Tibetan Plateau had none. Moreover, we found that increasing the aggregated area of wind resource can reduce the volatilities of wind energy. Therefore, improving the cross-regional transmission capacity can substantially help reduce the number of wind resource drought events. These findings should assist decision-makers to establish the counterplan to mitigate the energy shortages and instability in power supply caused by the uncertainty of wind resource droughts.

The impact of multiple non-pharmaceutical interventions for China-bound travel on domestic COVID-19 outbreaks.

Non-pharmaceutical interventions (NPIs) implemented on China-bound travel have successfully mitigated cross-regional transmission of COVID-19 but made the country face ripple effects. Thus, adjusting these interventions to reduce interruptions to individuals' daily life while minimizing transmission risk was urgent. An improved Susceptible-Infected-Recovered (SIR) model was built to evaluate the Delta variant's epidemiological characteristics and the impact of NPIs. To explore the risk associated with inbound travelers and the occurrence of domestic traceable outbreaks, we developed an association parameter that combined inbound traveler counts with a time-varying initial value. In addition, multiple time-varying functions were used to model changes in the implementation of NPIs. Related parameters of functions were run by the MCSS method with 1,000 iterations to derive the probability distribution. Initial values, estimated parameters, and corresponding 95% CI were obtained. Reported existing symptomatic, suspected, and asymptomatic case counts were used as the training datasets. Reported cumulative recovered individual data were used to verify the reliability of relevant parameters. Lastly, we used the value of the ratio (Bias2/Variance) to verify the stability of the mathematical model, and the effects of the NPIs on the infected cases to analyze the sensitivity of input parameters. The quantitative findings indicated that this improved model was highly compatible with publicly reported data collected from July 21 to August 30, 2021. The number of inbound travelers was associated with the occurrence of domestic outbreaks. A proportional relationship between the Delta variant incubation period and PCR test validity period was found. The model also predicted that restoration of pre-pandemic travel schedules while adhering to NPIs requirements would cause shortages in health resources. The maximum demand for hospital beds would reach 25,000/day, the volume of PCR tests would be 8,000/day, and the number of isolation rooms would reach 800,000/day within 30 days. With the pandemic approaching the end, reexamining it carefully helps better address future outbreaks. This predictive model has provided scientific evidence for NPIs' effectiveness and quantifiable evidence of health resource allocation. It could guide the design of future epidemic prevention and control policies, and provide strategic recommendations on scarce health resource allocation.

Genomic epidemiology and transmission characteristics of mcr1-positive colistin-resistant Escherichia coli strains circulating at natural environment

MCR-positive Escherichia coli (MCRPEC) have been reported in humans worldwide. The high prevalence of mcr-1 poses clinical and environmental risks due to its diverse genetic mechanisms. Given the vital role of animals and the environment in the spread of antibiotic resistance, a “One Health” perspective should be taken when addressing antimicrobial resistance issues. This study conducted a prospective study in six farms (located in Jiaxing City, Zhejiang province, China) in 2019. MCRPEC strains were screened from samples of different sources. The molecular epidemiological surveys and transmission potential were investigated by whole-genome sequencing and phylogenetic analysis. MCRPEC were detected in different farms with various sources. Sequence type complex 10 was dominant and distributed widely in multiple sources. Core-genome multilocus sequence type (cgMLST) analysis indicated that clonal transmission could occur within and between farms. In addition, mcr-1 genes with different locations showed different transmission tendencies. The study indicated that interspecies and cross-regional transmission of MCRPEC could occur between different sectors in farms. Further surveillance and research of non-clinical MCRPEC strains are necessary to reduce the threat of MCRPEC.

Drug resistance and genomic characteristics of Salmonella enterica serovar London from clinical and food sources in Hangzhou City from 2017 to 2021

Objective: To analyze the drug resistance and genomic characteristics of Salmonella enterica serovar London isolated from clinical and food sources in Hangzhou City from 2017 to 2021. Methods: A total of 91 Salmonella enterica serovar London strains isolated from Hangzhou City from 2017 to 2021 were analyzed for drug susceptibility, pulsed field gel electrophoresis (PFGE) typing and whole genome sequencing. Multilocus sequence typing (MLST), core genome multilocus sequence typing (cgMLST) and detection of drug resistance genes were performed by using the sequencing data. Phylogenetic analysis was conducted to compare the 91 genomes from Hangzhou City with 347 genomes from public databases. Results: No significant difference in the drug resistance rate was observed between clinical strains and food strains to 18 drugs in Hangzhou City(all P>0.05), and the multidrug resistance (MDR) rate was 75.8% (69/91). Most strains were resistant to 7 drug classes simultaneously. One strain was resistant to Polymyxin E as well as positive for mcr-1.1, and 50.5% (46/91) of the strains were resistant to Azithromycin and were positive for mph(A). All 91 Salmonella enterica serovar London strains were ST155, which were subdivided into 44 molecular types by PFGE and 82 types by cgMLST. Phylogenetic analysis showed that most strains from Hangzhou City (83/91) were clustered together, and a small number of human isolates from Europe, North America and pork isolates from Hubei and Shenzhen were mixed in the cluster. Other strains from Hangzhou City (8/91) were closely related to strains from Europe, America and Southeast Asia. Strains isolated from pork were the most closely related to clinical strains. Conclusion: The epidemic of Salmonella enterica serovar London in Hangzhou City is mainly caused by the spread of ST155 strains, which is mainly transmitted locally. At the same time, cross-region transmission to Europe, North America, Southeast Asia, and other provinces and cities in China may also occur. There is no significant difference in the drug resistance rate between clinical strains and food strains, and a high level of MDR is found in the strains. Clinical infection of Salmonella enterica serovar London may be closely related to pork consumption in Hangzhou City.

Dynamic analysis of pandemic cross-regional transmission considering quarantine strategies in the context of limited medical resources

This work aims to quantitatively analyze the effect of quarantine strategies on controlling the spread of the pandemic in multiple regions under limited medical resources. First, a multi-regional discrete-time susceptible-infected-quarantined -recovered (SIQR) pandemic model considering intra-regional and inter-regional quarantine strategies is proposed. The basic reproduction number of the model is derived and shown to be a non-increasing function of the quarantine control parameters. Due to the limited medical resources, a multi-period model of resource allocation coupled with quarantine control is developed. Numerical results demonstrate that quarantine strategies reduce the speed and size of pandemic spreading. In the context of limited medical resources, intra-regional control is less effective at reducing infected individuals than inter-regional control, and most of the resources are allocated to high-risk regions.