Prevalence and characterization of foodborne pathogens isolated from fresh-cut fruits and vegetables in Beijing, China.

Pre-cut fresh fruits and vegetables are highly appealing to consumers for their convenience, however, as they are highly susceptible to microbial contamination in processing, the potential risks of foodborne illnesses to public health are not negligible. This study aimed to assess the prevalence, antibiotic susceptibility and molecular characteristics of major foodborne pathogens (Listeria monocytogenes, Escherichia coli, Staphylococcus aureus and Salmonella) isolated from fresh-cut fruits and vegetables in Beijing, China. 86 stains were isolated from 326 samples, with S. aureus being the highest prevalence (15.38 %), followed by E. coli (9.23 %) and L. monocytogenes (1.85 %), while no Salmonella was detected. The prevalence by type of food indicated that fruit trays and mixed vegetables were more susceptible to contamination by pathogens. 98 % of S. aureus were resistant to at least of one antibiotic, and showed a high resistance rate to benzylpenicillin (90 %) and oxacillin (48 %). Among 25 E. coli isolates, 57.67 % of which exhibited multi-drug resistance, with common resist to trimethoprim/sulfamethoxazole (66.67 %) and ampicillin (63.33 %). A total of 9 sequence types (STs) and 8 spa types were identified in 35 S. aureus isolates, with ST398-t34 being the predominant type (42.86 %). Additionally, analysis of 25 E. coli isolates demonstrated significant heterogeneity, characterized by 22 serotypes and 18 STs. Genomic analysis revealed that 5 and 44 distinct antibiotic resistance genes (ARGs) in S. aureus and E. coli, respectively. Seven quinolone resistance-determining regions (QRDRs) mutations were identified in E. coli isolates, of which GyrA (S83L) was the most frequently detected. All the S. aureus and E. coli isolates harbored virulence genes. ARGs in S. aureus and E. coli showed a significant positive correlation with plasmids. Furthermore, one L. monocytogenes isolate, which was ST101 and serogroupIIc from watermelon sample, harbored virulence genes (inlA and inlB) and LIPI-1 pathogenic islands (prfA, plcA, hly and actA), which posed potential risks for consumer's health. This study focused on the potential microbial risk of fresh-cut fruits and vegetables associated with foodborne diseases, improving the scientific understanding towards risk assessment related to ready-to-eat foods.

Mitochondrial transfer of α-synuclein mediates carbon disulfide-induced mitochondrial dysfunction and neurotoxicity.

Exposure to carbon disulfide (CS2) is a recognized risk factor in the pathogenesis of Parkinson's disease, yet the underlying mechanisms of deleterious effects on mitochondrial integrity have remained elusive. Here, through establishing CS2 exposure models in rat and SH-SY5Y cells, we demonstrated that highly expressed α-synuclein (α-Syn) is transferred to mitochondria via membrane proteins such as Tom20 and leads to mitochondrial dysfunction and mitochondrial oxidative stress, which ultimately causes neuronal injury. We first found significant mitochondrial damage and oxidative stress in CS2-exposed rat midbrain and SH-SY5Y cells and showed that mitochondrial oxidative stress was the main factor of mitochondrial damage by Mitoquinone intervention. Further experiments revealed that CS2 exposure led to the accumulation of α-Syn in mitochondria and that α-Syn co-immunoprecipitated with mitochondrial membrane proteins. Finally, the use of an α-Syn inhibitor (ELN484228) and small interfering RNA (siRNA) effectively mitigated the accumulation of α-Syn in neurons, as well as the inhibition of mitochondrial membrane potential, caused by CS2 exposure. In conclusion, our study identifies the translocation of α-Syn to mitochondria and the impairment of mitochondrial function, which has important implications for the broader understanding and treatment of neurodegenerative diseases associated with environmental toxins.

Antimicrobial susceptibility and genomic characterization of Vibrio parahaemolyticus isolated from aquatic foods in 15 provinces, China, 2020.

Prevalent in marine, estuarine and coastal environments, Vibrio parahaemolyticus is one of the major foodborne pathogens which can cause acute gastroenteritis through consumption of contaminated food. This study encompassed antimicrobial resistance, molecular characteristics and phylogenetic relationships of 163 V. parahaemolyticus isolated from aquatic foods across 15 provinces in China. The isolates showed high resistance rates against ampicillin (90.80 %, 148/163) and cefazolin (72.39 %, 118/163). Only 5 isolates demonstrated multi-drug resistance (MDR) phenotypes. A total of 37 different antibiotic resistance genes (ARGs) in correlation with seven antimicrobial categories were identified. tet(34) and tet(35) were present in all 163 isolates. Other most prevalent ARGs were those conferring resistance to ß-lactams, with prevalence rate around 18.40 % (30/163). The virulence genes tdh and trh were found in 17 (10.43 %) and 9 (5.52 %) isolates, respectively. Totally 121 sequence types (STs) were identified through whole genome analysis, among which 60 were novel. The most prevalent sequence type was ST3 (9.20 %, 15/163), which shared the same genotype profile of trh_, tdh+ and blaCARB-22+. Most of the tdh+V. parahaemolyticus isolates was clustered into a distinctive clade by the phylogenetic analysis. Our study showed that the antimicrobial resistance of V. parahaemolyticus in aquatic foods in China was moderate. However, the emerging of MDR isolates implicate strengthened monitoring is needed for the better treatment of human V. parahaemolyticus infections. High genetic diversity and virulence potential of the isolates analyzed in this study help better understanding and evaluating the risk of V. parahaemolyticus posed to public health.

Left ventricular thrombosis caused cerebral embolism during venoarterial extracorporeal membrane oxygenation support: A case report.

BACKGROUND: Venoarterial (VA) extracorporeal membrane oxygenation (ECMO), an effective short-term circulatory support method for refractory cardiogenic shock, is widely applied. However, retrospective analyses have shown that VA-ECMO-assisted cases were associated with a relatively high mortality rate of approximately 60%. Embolization in important organs caused by complications of left ventricular thrombosis (LVT) during VA-ECMO is also an important reason. Although the incidence of LVT during VA-ECMO is not high, the consequences of embolization are disastrous. CASE SUMMARY: A 37-year-old female patient was admitted to hospital because of fever for 4 d and palpitations for 3 d. After excluding the diagnosis of coronary heart disease, we established a diagnosis of "clinically explosive myocarditis". The patient still had unstable hemodynamics after drug treatment supported by VA-ECMO, with heparin for anticoagulation. On day 4 of ECMO support, a left ventricular thrombus attached to the papillary muscle root of the mitral valve was found by transthoracic echocardiography. Left ventricular decompression was performed and ECMO was successfully removed, but the patient eventually died of multiple cerebral embolism. CONCLUSION: LVT with high mobility during VA-ECMO may cause embolism in important organs. Therefore, a "wait and see" strategy should be avoided.

The non-stationary and spatially varying associations between hand, foot and mouth disease and multiple environmental factors: A Bayesian spatiotemporal mapping model study.

The transmission and prevalence of Hand, Foot and Mouth Disease (HFMD) are affected by a variety of natural and socio-economic environmental factors. This study aims to quantitatively investigate the non-stationary and spatially varying associations between various environmental factors and HFMD risk. We collected HFMD surveillance cases and a series of relevant environmental data from 2013 to 2021 in Xi'an, Northwest China. By controlling the spatial and temporal mixture effects of HFMD, we constructed a Bayesian spatiotemporal mapping model and characterized the impacts of different driving factors into global linear, non-stationary and spatially varying effects. The results showed that the impact of meteorological conditions on HFMD risk varies in both type and magnitude above certain thresholds (temperature: 30 °C, precipitation: 70 mm, solar radiation: 13000 kJ/m2, pressure: 945 hPa, humidity: 69%). Air pollutants (PM2.5, PM10, NO2) showed an inverted U-shaped relationship with the risk of HFMD, while other air pollutants (O3, SO2) showed nonlinear fluctuations. Moreover, the driving effect of increasing temperature on HFMD was significant in the 3-year period, while the inhibitory effect of increasing precipitation appeared evident in the 5-year period. In addition, the proportion of urban/suburban/rural area had a strong influence on HFMD, indicating that the incidence of HFMD firstly increased and then decreased during the rapid urbanization process. The influence of population density on HFMD was not only limited by spatial location, but also varied between high and low intervals. Higher road density inhibited the risk of HFMD, but higher night light index promoted the occurrence of HFMD. Our findings further demonstrated that both ecological and socioeconomic environmental factors can pose multiple driving effects on increasing the spatiotemporal risk of HFMD, which is of great significance for effectively responding to the changes in HFMD epidemic outbreaks.

An imported malaria case with repeated episodes of neurological syndromes resulting from different Plasmodium species.

BACKGROUND: Imported cerebral malaria (CM) cases in non-endemic areas are often misdiagnosed, which delays treatment. Post-malaria neurological syndrome (PMNS) after recovery from severe malaria can also complicate diagnosis. CASE: We report an imported malaria case from West Africa with two sequential episodes with neurological syndromes within about a month. The first episode was diagnosed as CM with microscopy-positive Plasmodium falciparum infection. The second episode, occurring a month after the recovery from the first CM episode, was consistent with PMNS, since malaria parasites were not detected by microscopy in peripheral blood smears. However, this diagnosis was complicated by the detection of Plasmodium vivax in peripheral blood by PCR, suggesting a potential cause of the second episode by P. vivax. CONCLUSION: This study suggests that PMNS often occurs after severe falciparum malaria. Concurrent P. vivax infection with pathogenic biomass being predominantly extravascular further complicates accurate diagnosis.

Resolving Ultraviolet-Visible Spectra for Complex Dissolved Mixtures of Multitudinous Organic Matters in Aerosols.

Light-absorbing organic aerosols, referred to as brown carbon (BrC), play a vital role in the global climate and air quality. Due to the complexity of BrC chromophores, the identified absorbing substances in the ambient atmosphere are very limited. However, without comprehensive knowledge of the complex absorbing compounds in BrC, our understanding of its sources, formation, and evolution mechanisms remains superficial, leading to great uncertainty in climatic and atmospheric models. To address this gap, we developed a constrained non-negative matrix factorization (NMF) model to resolve the individual ultraviolet-visible spectrum for each substance in dissolved organic aerosols, with the power of ultrahigh-performance liquid chromatography-diode array detector-ultrahigh-resolution mass spectrometry (UHPLC-DAD-UHRMS). The resolved spectra were validated by selected standard substances and validation samples. Approximately 40,000 light-absorbing substances were recognized at the MS1 level. It turns out that BrC is composed of a vast number of substances rather than a few prominent chromophores in the urban atmosphere. Previous understanding of the absorbing feature of BrC based on a few identified compounds could be biased. Weak-absorbing substances missed previously play an important role in BrC absorption when they are integrated due to their overwhelming number. This model brings the property exploration of complex dissolved organic mixtures to a molecular level, laying a foundation for identifying potentially significant compositions and obtaining a comprehensive chemical picture.

Combined toxic effects of polystyrene microplastics and 3,6-dibromocarbazole on zebrafish (Danio rerio) embryos.

Microplastics (MPs) and polyhalogenated carbazoles (PHCZs) are widely detected in the aquatic environment, and their ecological risks have become a research focus. Although there is an extensive co-distribution of MPs and PHCZs, their combined toxicity to aquatic organisms is still unclear. This study investigated the toxic effects of polystyrene microplastics (PS-MPs) and 3,6-dibromocarbazole (3,6-DBCZ) on zebrafish embryos by individual/combined exposure. This study showed that individual or combined exposure of PS-MPs (10 mg/L) and 3,6-DBCZ (0.5 mg/L) could significantly increase the rate of zebrafish embryo deformity, whereas no significant effect was observed on mortality and hatching rate. Furthermore, exposure to 3,6-DBCZ or PS-MPs increased reactive oxygen species (ROS) levels in zebrafish embryos, and the resulting oxidative stress induced apoptosis. Comparably, the levels of oxidative stress and apoptosis in zebrafish embryos were significantly reduced with the combined exposure of 3,6-DBCZ and PS-MPs. These observations suggest that the combined exposure of 3,6-DBCZ and PS-MPs has an antagonistic effect on oxidative stress and apoptosis. Fluorescence PS-MPs tracing and 3,6-DBCZ enrichment analysis showed that, with the protection of chorion, the entry of PS-MPs (5 and 50 µm) into the embryonic stage (55 hpf) of zebrafish was prevented. Moreover, after exposure for 96-144 hpf, PS-MPs served as a carrier to promote the 3,6-DBCZ accumulation and its dioxin-like toxicity in zebrafish larvae through ingestion. Compared with 5-µm PS-MPs, 50-µm PS-MPs promoted higher accumulation and dioxin-like toxicity of 3,6-DBCZ in zebrafish larvae. These findings provide that MPs can be used as an important carrier of PHCZs, influencing their toxicity and bioaccumulation in the organisms.

High-fat diet exacerbated motor dysfunction via necroptosis and neuroinflammation in acrylamide-induced neurotoxicity in mice.

Health risks associated with acrylamide (ACR) or high-fat diet (HFD) exposure alone have been widely concerned in recent years. In a realistic situation, ACR and HFD are generally co-existence, and both are risk factors for the development of neurological diseases. The purpose of the present study was to investigate the combined effects of ACR and HFD on the motor nerve function. As a result, neurobehavioral tests and Nissl staining disclosed that long-term HFD exacerbated motor dysfunction and the damage of spinal cord motor neurons in ACR-exposed mice. Co-exposure of ACR and HFD resulted in morphological changes in neuronal mitochondria of the spinal cord, a significantly reduced mitochondrial subunits NDUFS1, UQCRC2, and MTCO1, released the mitochondrial DNA (mtDNA) into the cytoplasm, and promoted the production of reactive oxygen species (ROS). Combined exposure of HFD and ACR activated the calpain/CDK5/Drp1 axis and caused the mitochondrial excessive division, ultimately increasing MLKL-mediated necroptosis in spinal cord motor neurons. Meanwhile, HFD significantly exacerbated ACR-induced activation of NFkB, NLRP3 inflammasome, and cGAS-STING pathway. Taken together, our findings demonstrated that combined exposure of ACR and HFD aggravated the damage of spinal cord motor neurons via neuroinflammation and necroptosis signaling pathway, pointing to additive effects in mice than the individual stress effects.

Deletion of prolyl hydroxylase domain-containing enzyme 3 (phd3) in zebrafish facilitates hypoxia tolerance.

Prolyl hydroxylase domain (PHD)-containing enzyme 3 (PHD3) belongs to the Caenorhabditis elegans gene egl-9 family of prolyl hydroxylases. PHD3 catalyzes proline hydroxylation of hypoxia-inducible factor α (HIF-α) and promotes HIF-α proteasomal degradation through coordination with the pVHL complex under normoxic conditions. However, the relationship between PHD3 and the hypoxic response is not well understood. In this study, we used quantitative real-time PCR assay and O-dianisidine staining to characterize the hypoxic response in zebrafish deficient in phd3. We found that the hypoxia-responsive genes are upregulated and the number of erythrocytes was increased in phd3-null zebrafish compared with their wild-type siblings. On the other hand, we show overexpression of phd3 suppresses HIF-transcriptional activation. In addition, we demonstrate phd3 promotes polyubiquitination of zebrafish hif-1/2α proteins, leading to their proteasomal degradation. Finally, we found that compared with wild-type zebrafish, phd3-null zebrafish are more resistant to hypoxia treatment. Therefore, we conclude phd3 has a role in hypoxia tolerance. These results highlight the importance of modulation of the hypoxia signaling pathway by phd3 in hypoxia adaptation.

Effects of the polyhalogenated carbazoles 3-bromocarbazole and 1,3,6,8-tetrabromocarbazole on soil microbial communities.

Soil ecosystems are being more contaminated with polyhalogenated carbazoles (PHCZs), which raising much attention about their impact on soil microorganisms. 3-Bromocarbazole (3-BCZ) and 1,3,6,8-tetrabromocarbazole (1,3,6,8-TBCZ) are two typical PHCZs with high detection rates in the soil environment. However, ecological risk research on these two PHCZs in soil is still lacking. In the present study, after 80 days of exposure, the ecological influence of 3-BCZ and 1,3,6,8-TBCZ was investigated based on 16S rDNA sequencing, ITS sequencing, gene (16S rDNA, ITS, amoA, nifH, narG and cbbL) abundance and soil enzyme activity. The results showed that the bacterial 16S rDNA gene abundance significantly decreased under 3-BCZ and 1,3,6,8-TBCZ exposure after 80 days of incubation. The fungal ITS gene abundance significantly decreased under 1,3,6,8-TBCZ (10 mg/kg) exposure. PHCZs contributed to the alteration of bacteria and fungi community abundance. Bacteria Sphingomonas, RB41 and fungus Mortierella, Cercophora were identified as the most dominant genera. The two PHCZs consistently decreased the relative abundance of Sphingomonas, Lysobacter, Dokdonella, Mortierella and Cercophora etc at 80th day. These keystone taxa are related to the degradation of organic compounds, carbon metabolism, and nitrogen metabolism and may thus have influence on soil ecological functions. Bacterial and fungal functions were estimated using functional annotation of prokaryotic taxa (FAPROTAX) and fungi functional guild (FUNGuild), respectively. The nitrogen and carbon metabolism pathway were affected by 3-BCZ and 1,3,6,8-TBCZ. The soil nitrogen-related functions of aerobic ammonia oxidation were decreased but the soil carbon-related functions of methanol oxidation, fermentation, and hydrocarbon degradation were increased at 80th day. The effects of 3-BCZ and 1,3,6,8-TBCZ on the abundances of the amoA, nifH, narG, and cbbL genes showed a negative trend. These results elucidate the ecological effects of PHCZs and extend our knowledge on the structure and function of soil microorganisms in PHCZ-contaminated ecosystems.

COVID-19 transmission driven by age-group mathematical model in Shijiazhuang City of China.

Background: A COVID-19 outbreak in the rural areas of Shijiazhuang City was attributed to the complex interactions among vaccination, host, and non-pharmaceutical interventions (NPIs). Herein, we investigated the epidemiological characteristics of all reported symptomatic cases by picking Shijiazhuang City, Hebei Province in Northern China as research objective. In addition, we established a with age-group mathematical model to perform the optimal fitting and to investigate the dynamical profiles under three scenarios. Methods: All reported symptomatic cases of Shijiazhuang epidemic (January 2-February 3, 2021) were investigated in our study. The cases were classified by gender, age group and location, the distributions were analyzed by epidemiological characteristics. Furthermore, the reported data from Health Commission of Hebei Province was also analyzed by using an age-group mathematical model by two phases and three scenarios. Results: Shijiazhuang epidemic caused by SARS-CoV-2 wild strain was recorded with the peak 84 cases out of 868 reported symptomatic cases on January 11, 2021, which was implemented with strong NPIs by local government and referred as baseline situation in this study. The research results showed that R0 under baseline situation ranged from 4.47 to 7.72, and Rt of Gaocheng Distinct took 3.72 with 95% confidence interval from 3.23 to 4.35 on January 9, the declining tendencies of Rt under baseline situation were kept till February 3, the value of Rt reached below 1 on January 19 and remained low value up to February 3 for Gaocheng District and Shijiazhuang City during Shijiazhuang epidemic. This indicated Shijiazhuang epidemic was under control on January 19. However, if the strong NPIs were kept, but remote isolation operated on January 11 was not implemented as of February 9, then the scale of Shijiazhuang epidemic reached 9482 cases from age group who were 60 years old and over out of 31,017 symptomatic cases. The investigation also revealed that Shijiazhuang epidemic reached 132,648 symptomatic cases for age group who were 60 years old and over (short for G2) under risk-based strategies (Scenario A), 58,048 symptomatic cases for G2 under late quarantine strategies (Scenario B) and 207,124 symptomatic cases for G2 under late quarantine double risk strategies (Scenario C), and that the corresponding transmission tendencies of Rt for three scenarios were consistently controlled on Jan 29, 2021. Compared with baseline situation, the dates for controlling Rt below 1 under three scenarios were delayed 10 days. Conclusions: Shijiazhuang epidemic was the first COVID-19 outbreak in the rural areas in Hebei Province of Northern China. The targeted interventions adopted in early 2021 were effective to halt the transmission due to the implementation of a strict and village-wide closure. However we found that age group profile and NPIs played critical rules to successfully contain Shijiazhuang epidemic, which should be considered by public health policies in rural areas of mainland China during the dynamic zero-COVID policy.

Chronic carbon disulfide exposure induces parkinsonian pathology via α-synuclein aggregation and necrosome complex interaction.

Exposure to carbon disulfide (CS2) has been associated with an increased incidence of parkinsonism in workers, but the mechanism underlying this association remains unclear. Using a rat model, we investigated the effects of chronic CS2 exposure on parkinsonian pathology. Our results showed that CS2 exposure leads to significant motor impairment and neuronal damage, including loss of dopaminergic neurons and degeneration of the substantia nigra pars compacta (SNpc). The immunoassays revealed that exposure to CS2 induces aggregation of α-synuclein and phosphorylated α-synuclein, as well as activation of necroptosis in the SNpc. Furthermore, in vitro and in vivo experiments demonstrated that the interaction between α-synuclein and the necrosome complex (RIP1, RIP3, and MLKL) is responsible for the loss of neuronal cells after CS2 exposure. Taken together, our results demonstrate that CS2-mediated α-synuclein aggregation can induce dopaminergic neuron damage and parkinsonian behavior through interaction with the necrosome complex.

Identification of potential pathogenic targets and survival strategies of Vibrio vulnificus through population genomics.

Vibrio vulnificus, a foodborne pathogen, has a high mortality rate. Despite its relevance to public health, the identification of virulence genes associated with the pathogenicity of currently known clinical isolates of V. vulnificus is incomplete and its synergistic pathogenesis remains unclear. Here, we integrate whole genome sequencing (WGS), genome-wide association studies (GWAS), and genome-wide epistasis studies (GWES), along with phenotype characterization to investigate the pathogenesis and survival strategies of V. vulnificus. GWAS and GWES identified a total of six genes (purH, gmr, yiaV, dsbD, ramA, and wbpA) associated with the pathogenicity of clinical isolates related to nucleotide/amino acid transport and metabolism, cell membrane biogenesis, signal transduction mechanisms, and protein turnover. Of these, five were newly discovered potential specific virulence genes of V. vulnificus in this study. Furthermore, GWES combined with phenotype experiments indicated that V. vulnificus isolates were clustered into two ecological groups (EGs) that shared distinct biotic and abiotic factors, and ecological strategies. Our study reveals pathogenic mechanisms and their evolution in V. vulnificus to provide a solid foundation for designing new vaccines and therapeutic targets.

The short and long-term impact of nonpharmaceutical interventions on the prevalence of varicella in Xi'an during the COVID-19 pandemic.

Varicella is a highly prevalent infectious disease with a similar transmission pathway to coronavirus disease 2019 (COVID-19). In the context of the COVID-19 pandemic, anti-COVID-19 nonpharmaceutical interventions (NPIs) have been implemented to prevent the spread of the infection. This study aims to analyze varicella's epidemiological characteristics and further investigate the effect of anti-COVID-19 NPIs on varicella in Xi'an, northwestern China. Based on the varicella surveillance data, search engine indices, meteorological factors from 2011 to 2021 in Xi'an, and different levels of emergency response to COVID-19 during the pandemic, we applied Bayesian Structural Time Series models and interrupted time series analysis to predict the counterfactual incidence of varicella and quantify the impact of varying NPIs intensities on varicella. From 2011 to 2021, varicella incidence increased, especially in 2019, with a high incidence of 111.69/100 000. However, there was a sharp decrease of 43.18% in 2020 compared with 2019, and the peak of varicella incidence in 2020 was lower than in previous years from the 21st to the 25th week. In 2021, the seasonality of varicella incidence gradually returned to a seasonal pattern in 2011-2019. The results suggest that anti-COVID-19 NPIs effectively reduce the incidence of varicella, and the reduction has spatiotemporal heterogeneity.

Modelling the pulse population-wide nucleic acid screening in mitigating and stopping COVID-19 outbreaks in China.

BACKGROUND: During 2021-2022, mainland China experienced multiple times of local COVID-19 outbreaks in several cities, including Yangzhou, Xi'an etc., and the Chinese government persistently adopted the zero-COVID policy in combating with the local outbreaks. METHODS: We develop a mathematical model with pulse population-wide nucleic acid screening, part of the zero-COVID policy, to reveal its role in controlling the spread of COVID-19. We calibrate the model by fitting the COVID-19 epidemic data of the local outbreaks in Yangzhou and Xi'an, China. Sensitivity analysis is conducted to investigate the impact of population-wide nucleic acid screening on controlling the outbreak of COVID-19. RESULTS: Without the screening, the cumulative number of confirmed cases increases by [Formula: see text] and [Formula: see text] in Yangzhou and Xi'an, respectively. Meanwhile, the screening program helps to shorten the lockdown period for more than one month when we aim at controlling the cases into zero. Considering its role in mitigating the epidemics, we observe a paradox phenomenon of the screening rate in avoiding the runs on medical resource. That is, the screening will aggravate the runs on medical resource when the screening rate is small, while it helps to relieve the runs on medical resource if the screening rate is high enough. We also conclude that the screening has limited effects on mitigating the epidemics if the outbreak is in a high epidemic level or there has already been runs on medical resources. Alternatively, a smaller screening population per time with a higher screening frequency may be a better program to avoid the runs on medical resources. CONCLUSIONS: The population-wide nucleic acid screening strategy plays an important role in quickly controlling and stopping the local outbreaks under the zero-COVID policy. However, it has limited impacts and even increase the potential risk of the runs on medical resource for containing the large scale outbreaks.

Study on the COVID-19 epidemic in mainland China between November 2022 and January 2023, with prediction of its tendency.

The prediction system EpiSIX was used to study the COVID-19 epidemic in mainland China between November 2022 and January 2023, based on reported data from December 9, 2022, to January 30, 2023, released by The Chinese Center for Disease Control and Prevention on February 1, 2023. Three kinds of reported data were used for model fitting: the daily numbers of positive nucleic acid tests and deaths, and the daily number of hospital beds taken by COVID-19 patients. It was estimated that the overall infection rate was 87.54% and the overall case fatality rate was 0.078%-0.116% (median 0.100%). Assuming that a new COVID-19 epidemic outbreak would start in March or April of 2023, induced by a slightly more infectious mutant strain, we predicted a possible large rebound between September and October 2023, with a peak demand of between 800,000 and 900,000 inpatient beds. If no such new outbreak was induced by other variants, then the current COVID-19 epidemic course in mainland China would remain under control until the end of 2023. However, it is suggested that the necessary medical resources be prepared to manage possible COVID-19 epidemic emergencies in the near future, especially for the period between September and October 2023.

Genetic diversity of Plasmodium vivax populations from the China-Myanmar border identified by genotyping merozoite surface protein markers.

BACKGROUND: Parasite diversity and population structure influence malaria control measures. Malaria transmission at international borders affects indigenous residents and migrants, defying management efforts and resulting in malaria re-introduction. Here we aimed to determine the extent and distribution of genetic variations in Plasmodium vivax populations and the complexity of infections along the China-Myanmar border. METHODS: We collected clinical P. vivax samples from local and migrant malaria patients from Laiza and Myitsone, Kachin State, Myanmar, respectively. We characterized the polymorphisms in two P. vivax merozoite surface protein markers, Pvmsp-3α and Pvmsp-3ß, by PCR-restriction fragment length polymorphism (PCR-RFLP) analysis. We sought to determine whether these genetic markers could differentiate these two neighboring parasite populations. RESULTS: PCR revealed three major size variants for Pvmsp-3α and four for Pvmsp-3ß among the 370 and 378 samples, respectively. PCR-RFLP resolved 26 fragment-size alleles by digesting Pvmsp-3α with Alu I and Hha I and 28 alleles by digesting Pvmsp-3ß with Pst I. PCR-RFLP analysis of Pvmsp-3α found that infections in migrant laborers from Myitsone bore more alleles than did infections in residents of Laiza, while such difference was not evident from genotyping Pvmsp-3ß. Infections originating from these two places contained distinct but overlapping subpopulations of P. vivax. Infections from Myitsone had a higher multiplicity of infection as judged by the size of the Pvmsp-3α amplicons and alleles after Alu I/Hha I digestion. CONCLUSIONS: Migrant laborers from Myitsone and indigenous residents from Laiza harbored overlapping but genetically distinct P. vivax parasite populations. The results suggested a more diverse P. vivax population in Myitsone than in the border town of Laiza. PCR-RFLP of Pvmsp-3α offers a convenient method to determine the complexity of P. vivax infections and differentiate parasite populations.

Different In Vitro Drug Susceptibility Profile of Plasmodium falciparum Isolates from Two Adjacent Areas of Northeast Myanmar and Molecular Markers for Drug Resistance.

The Greater Mekong Subregion (GMS) is the epicenter of antimalarial drug resistance. We determined in vitro susceptibilities to 11 drugs of culture-adapted Plasmodium falciparum isolates from adjacent areas (Laiza and Muse) along the China−Myanmar border. Parasites from this region were highly resistant to chloroquine and pyrimethamine but relatively sensitive to other antimalarial drugs. Consistently, the Dd2-like pfcrt mutations were fixed or almost fixed in both parasite populations, and new mutations mediating piperaquine resistance were not identified. Similarly, several mutations related to pfdhfr and pfdhps were also highly prevalent. Despite their geographical proximity, malaria parasites from Laiza showed significantly higher in vitro resistance to artemisinin derivatives, naphthoquine, pyronaridine, lumefantrine, and pyrimethamine than parasites from Muse. Likewise, the pfdhfr N51I, pfdhps A581G, pfmrp1 H785N, and pfk13 F446I mutations were significantly more frequent in Laiza than in Muse (p < 0.05). For the pfmdr1 mutations, Y184F was found only in Laiza (70%), whereas F1226Y was identified only in Muse (31.8%). Parasite isolates from Laiza showed a median RSA value of 5.0%, significantly higher than the 2.4% in Muse. Altogether, P. falciparum parasite populations from neighboring regions in the GMS may diverge substantially in their resistance to several antimalarial drugs. This information about different parasite populations will guide antimalarial treatment policies to effectively manage drug resistance during malaria elimination.

Study and prediction of the 2022 global monkeypox epidemic.

The World Health Organization (WHO) declared monkeypox as a public health emergency of international concern (PHEIC) on July 23, 2022, their highest level of alert. This raised concerns about the management of the global monkeypox outbreak, as well as the scientific analysis and accurate prediction of the future course of the epidemic. This study used EpiSIX (an analysis and prediction system for epidemics based on a general SEIR model) to analyze the monkeypox epidemic and to forecast the major tendencies based on data from the USA CDC (https://www.cdc.gov) and the WHO (https://www.who.int/health-topics/monkeypox). The global outbreak of monkeypox started in the UK on May 2, 2022, which marked the beginning of an epidemic wave. As of October 28, 2022, the cumulative number of reported cases worldwide was 77,115, with 36 deaths. EpiSIX simulations predict that the global monkeypox epidemic will enter a low epidemic status on March 1, 2023 with the cumulative number of confirmed cases ranging from 85,000 to 124,000, and the total number of deaths ranging from 60 to 87. Our analysis revealed that the basic reproduction number (R0) of monkeypox virus (MPXV) is near to 3.1 and the percentage of asymptomatic individuals is 13.1 %-14.5 %, both of which are similar to the data for SARS. The vaccination efficiency against susceptibility (VEs) of individuals who have had monkeypox is âˆ¼ 79 %, and the vaccination efficiency against infectiousness (VEi) of individuals who have had monkeypox is âˆ¼ 76 %-82 %. The mean incubation period for monkeypox is 8 days. In total, 94.7 % of infected individuals develop symptoms within 20 days and recover within 2 weeks after the confirmation of symptoms. Simulation results using EpiSIX showed that ring vaccination was remarkably effective against monkeypox. Our findings confirmed that a 20-day isolation for close contacts is necessary.