In this article, the transmission dynamics of a Hand-Foot-Mouth disease model with treatment and vaccination interventions are studied. We calculated the basic reproduction number and proved the global stability of di...In this article, the transmission dynamics of a Hand-Foot-Mouth disease model with treatment and vaccination interventions are studied. We calculated the basic reproduction number and proved the global stability of disease-free equilibrium when R0 R0 > 1. Meanwhile, we obtained the optimal control strategies minimizing the cost of intervention and minimizing the infected person. We also give some numerical simulations to verify our theoretical results.展开更多
Introduction:Since November 2023,influenza has ranked first in reported cases of infectious diseases in China,with the outbreak in both northern and southern provinces exceeding the levels observed during the same per...Introduction:Since November 2023,influenza has ranked first in reported cases of infectious diseases in China,with the outbreak in both northern and southern provinces exceeding the levels observed during the same period in 2022.This poses a serious health risk to the population.Therefore,short to medium-term influenza predictions are beneficial for epidemic assessment and can reduce the disease burden.Methods:A transmission dynamics model considering population migration,encompassing susceptible-exposed-infectious-asymptomatic-recovered(SEIAR)was used to predict the dynamics of influenza before the Spring Festival travel rush.Results:The overall epidemic shows a declining trend,with the peak expected to occur from week 47 in 2023 to week 1 in 2024.The number of cases of A(H3N2)is greater than that of influenza B,and the influenza situation is more severe in the southern provinces compared to the northern ones.Conclusion:Our method is applicable for short-term and medium-term influenza predictions.As the spring festival travel rush approaches.Therefore,it is advisable to advocate for nonpharmaceutical interventions(NPIs),influenza vaccination,and other measures to reduce healthcare and public health burden.展开更多
Background Diphtheria,caused by Corynebacterium diphtheriae,remains a serious public health threat in areas with low vaccination coverage,despite global declines due to widespread immunization and improved clinical ma...Background Diphtheria,caused by Corynebacterium diphtheriae,remains a serious public health threat in areas with low vaccination coverage,despite global declines due to widespread immunization and improved clinical management.A major outbreak in Nigeria from 2022 to 2023 underscored the persistent risk in regions with inadequate vaccination.This study aims to assess the transmission dynamics of diphtheria in Kano State,the epicenter of the outbreak,by estimating key epidemiological parameters,including the generation time(GT),approximated in our study by serial interval,and effective reproduction number(R).Methods We analyzed diphtheria case-based data from Kano State,Nigeria,collected between August 18,2022,and November 29,2023.Generation time was approximated using serial intervals in confirmed cases within the same geographical areas.The effective reproduction number(R)was calculated using four methods:Maximum Likelihood Estimation(MLE),Exponential Growth(EG),Sequential Bayesian(SB),and Time-Dependent(TD),focusing on the period of maximum exponential growth.A sensitivity analysis was conducted to quantify the impact of uncertainties in the GT derived from our data on the estimation of R.Results Over the 469-day outbreak period,13,899 diphtheria cases were reported,with complete data available for 9406 cases.The estimated mean generation time was 2.8 days(SD=3.48 days),with 97%of cases having a GT of less than 21 days.The Restimates varied across methods,with the TD method producing the highest reproduction number of 2.21 during the peak growth period.Sensitivity analysis showed that Restimates increased with longer generation times.The models,except for the SB method,demonstrated a generally strong fit with the outbreak exponential growth period.Conclusion The ongoing diphtheria outbreak in Nigeria highlights the critical threat posed by declining vaccination coverage.This study provides valuable insights into the transmission dynamics of diphtheria during a prolonged and widespread outbreak,enhancing our understanding of disease spread in this context.While certain limitations may influence the interpretation of our estimates,the findings offer valuable information for future diphtheria outbreak preparedness and response in the African context.展开更多
Synergistic interaction between influenza and pneumonia is well established in the literature.In this study,we present a model for the transmission dynamics of co-infection with influenza and pneumococcal pneumonia,wi...Synergistic interaction between influenza and pneumonia is well established in the literature.In this study,we present a model for the transmission dynamics of co-infection with influenza and pneumococcal pneumonia,with the goal of assessing the effects of influenza co-infection on the transmission of pneumonia.We derive an expression for the basic reproductive number R 0=max(R_(f),R_(p))where R_(f) and R_(p) are,respectively,the reproductive numbers for flu and pneumonia.We show that in the case R_(f)≤1≤R_(p),infection with influenza is driven to extinction while pneumonia is endemic,with the endemic state being globally asymptotically stable.The converse result holds in the case where R_(p)≤1≤R_(f).We also show the existence of the co-infection equilibrium.In this case,we show that the presence of co-infection results in a possible backward bifurcation in the system at R 0=1;epidemiologically,this means that the spread of the infection will be harder to control.Numerical simulations are presented to verify the analytic results and gain further insights.展开更多
To investigate the transmission dynamics and temporal and spatial migration characteristics of HIV spread among men who have sex with men(MSM)in China,a total of 1012 HIV-1 partial pol sequences,including five subtype...To investigate the transmission dynamics and temporal and spatial migration characteristics of HIV spread among men who have sex with men(MSM)in China,a total of 1012 HIV-1 partial pol sequences,including five subtypes,were studied.Bayesian analysis were applied for each subtype to infer its dynamic characters including the effective reproductive number(R_(e))and migration process.The mean curve of each R_(e) was almost always greater than 1(even the 95%highest posterior density(HPD)lower value)along with time,which supports the necessity for a comprehensive study about risk behaviors among young MSM group in China.We also should reappraise the free treatment strategy,especially the therapeutic effect during the free treatment policy.展开更多
Ebola virus disease （EVD） has emerged as a rapidly spreading potentially fatal disease. Several studies have been performed recently to investigate the dynamics of EVD. In this paper, we study the transmission dynam...Ebola virus disease （EVD） has emerged as a rapidly spreading potentially fatal disease. Several studies have been performed recently to investigate the dynamics of EVD. In this paper, we study the transmission dynamics of EVD by formulating an SEIR-type transmission model that includes isolated individuals as well as dead individuals that are not yet buried. Dynamical systems analysis of the model is performed, and it is consequently shown that the disease-free steady state is globally asymptotically stable when the basic reproduction number, R0 is less than unity. It is also shown that there exists a unique endemic equilibrium when R0 〉 1. Using optimal control theory, we propose control strategies, which will help to eliminate the Ebola disease. We use data fitting on models, with and without isolation, to estimate the basic reproductive numbers for the 2014 outbreak of EVD in Liberia and Sierra Leone.展开更多
A compartmental,epidemiological,mathematical model was developed in order to analyze the transmission dynamics of Delta and Omicron variant,of SARS-CoV-2,in Greece.The model was parameterized twice during the 4th and ...A compartmental,epidemiological,mathematical model was developed in order to analyze the transmission dynamics of Delta and Omicron variant,of SARS-CoV-2,in Greece.The model was parameterized twice during the 4th and 5th wave of the pandemic.The 4th wave refers to the period during which the Delta variant was dominant(approximately July to December of 2021)and the 5th wave to the period during which the Omicron variant was dominant(approximately January to May of 2022),in accordance with the official data from the National Public Health Organization(NPHO).Fitting methods were applied to evaluate important parameters in connection with the transmission of the variants,as well as the social behavior of population during these periods of interest.Mathematical models revealed higher numbers of contagiousness and cases of asymptomatic disease during the Omicron variant period,but a decreased rate of hospitalization compared to the Delta period.Also,parameters related to the behavior of the population in Greece were also assessed.More specifically,the use of protective masks and the abidance of social distancing measures.Simulations revealed that over 5,000 deaths could have been avoided,if mask usage and social distancing were 20%more efficient,during the short period of the Delta and Omicron outbreak.Furthermore,the spread of the variants was assessed using viral load data.The data were recorded from PCR tests at 417 Army Equity Fund Hospital(NIMTS),in Athens and the Ct values from 746 patients with COVID-19 were processed,to explain transmission phenomena and disease severity in patients.The period when the Delta variant prevailed in the country,the average Ct value was calculated as 25.19(range:12.32e39.29),whereas during the period when the Omicron variant prevailed,the average Ct value was calculated as 28(range:14.41e39.36).In conclusion,our experimental study showed that the higher viral load,which is related to the Delta variant,may interpret the severity of the disease.However,no correlation was confirmed regarding contagiousness phenomena.The results of the model,Ct analysis and official data from NPHO are consistent.展开更多
In this paper,an attempt has been made to explore a new delayed epidemiological model assuming that the disease is transmitted among the susceptible population and possessing nonlinear incidence function along with a ...In this paper,an attempt has been made to explore a new delayed epidemiological model assuming that the disease is transmitted among the susceptible population and possessing nonlinear incidence function along with a saturated treatment rate.Due attention is paid to the positivity and boundedness of the solutions and the bifurcation of the dynamical system as well.Basic reproduction number is being calculated,and considering the latent period as a bifurcation parameter,it has been examined that a Hopf-bifurcation occurs near the endemic equilibrium point while the parameter attains critical values.We have also discussed the stability and direction of Hopf-bifurcation near the endemic equilibrium point,the global stability analysis and the optimal control theory.We conclude that the system reveals chaotic dynamics through a specific time-delay value.Numerical simulations are being performed in order to explain the accuracy and effectiveness of the acquired theoretical results.展开更多
Malaria,a devastating disease caused by the Plasmodium parasite and transmitted through the bites of female Anopheles mosquitoes,remains a significant public health concern,claiming over 600,000 lives annually,predomi...Malaria,a devastating disease caused by the Plasmodium parasite and transmitted through the bites of female Anopheles mosquitoes,remains a significant public health concern,claiming over 600,000 lives annually,predominantly among children.Novel tools,including the application of Wolbachia,are being developed to combat malaria-transmitting mosquitoes.This study presents a modified susceptible-exposed-infectious-recovered-susceptible(SEIRS)compartmental mathematical model to evaluate the impact of awareness-based control measures on malaria transmission dynamics,incorporating mosquito interactions and seasonality.Employing the next-generation matrix approach,we calculated a basic reproduction number(R0)of 2.4537,indicating that without robust control measures,the disease will persist in the human population.The model equations were solved numerically using fourth and fifth-order Runge-Kutta methods.The model was fitted to malaria incidence data from Kenya spanning 2000 to 2021 using least squares curve fitting.The fitting algorithm yielded a mean absolute error(MAE)of 2.6463 when comparing the actual data points to the simulated values of infectious human population(Ih).This finding indicates that the proposed mathematical model closely aligns with the recorded malaria incidence data.The optimal values of the model parameters were estimated from the fitting algorithm,and future malaria dynamics were projected for the next decade.The research findings suggest that social media-based awareness campaigns,coupled with specific optimization control measures and effective management methods,offer the most cost-effective approach to managing malaria.展开更多
Since late 2019,the beginning of coronavirus disease 2019(COVID-19)pandemic,transmission dynamics models have achieved great development and were widely used in predicting and policymaking.Here,we provided an introduc...Since late 2019,the beginning of coronavirus disease 2019(COVID-19)pandemic,transmission dynamics models have achieved great development and were widely used in predicting and policymaking.Here,we provided an introduction to the history of disease transmission,summarized transmission dynamics models into three main types:compartment extension,parameter extension and population-stratified extension models,highlight the key contribution of transmission dynamics models in COVID-19 pandemic:estimating epidemiological parameters,predicting the future trend,evaluating the effectiveness of control measures and exploring different possibilities/scenarios.Finally,we pointed out the limitations and challenges lie ahead of transmission dynamics models.展开更多
Mathematical models are increasingly being used in the evaluation of control strategies for infectious disease such as the vaccination program for the Human PapiUomavirus （HPV）. Here, an ordinary differential equati...Mathematical models are increasingly being used in the evaluation of control strategies for infectious disease such as the vaccination program for the Human PapiUomavirus （HPV）. Here, an ordinary differential equation （ODE） transmission dynamic model for HPV is presented and analyzed. Parameter values for a gender and risk structured model are estimated by calibrating the model around the known prevalence of infection. The effect on gender and risk sub-group prevalence induced by varying the epidemiological parameters are investigated. Finally, the outcomes of this model are applied using a classical mathematical method for calculating R0 in a heterogeneous mixing population. Estimates for R0 under various gender and mixing scenarios are presented.展开更多
The recent outbreak of COVID-19 has caused millions of deaths worldwide and a huge societal and economic impact in virtually all countries. A large variety of mathematical models to describe the dynamics of COVID-19 t...The recent outbreak of COVID-19 has caused millions of deaths worldwide and a huge societal and economic impact in virtually all countries. A large variety of mathematical models to describe the dynamics of COVID-19 transmission have been reported. Among them, Bayesian probabilistic models of COVID-19 transmission dynamics have been very efficient in the interpretation of early data from the beginning of the pandemic, helping to estimate the impact of non-pharmacological measures in each country, and forecasting the evolution of the pandemic in different potential scenarios. These models use probability distribution curves to describe key dynamic aspects of the transmission, like the probability for every infected person of infecting other individuals, dying or recovering, with parameters obtained from experimental epidemiological data. However, the impact of vaccine-induced immunity, which has been key for controlling the public health emergency caused by the pandemic, has been more challenging to describe in these models, due to the complexity of experimental data. Here we report different probability distribution curves to model the acquisition and decay of immunity after vaccination. We discuss the mathematical background and how these models can be integrated in existing Bayesian probabilistic models to provide a good estimation of the dynamics of COVID-19 transmission during the entire pandemic period.展开更多
Monte Carlo method was adopted to calculate the meshing error considering the manufacture error and assembly error of the meshing point along the time-varying contact line for helical gear pair. The flexural-torsion-a...Monte Carlo method was adopted to calculate the meshing error considering the manufacture error and assembly error of the meshing point along the time-varying contact line for helical gear pair. The flexural-torsion-axis dynamic model coupled was established under the tooth friction force and solved by the perturbation method to compute real dynamic tooth load. The change laws of the friction force and friction torque were obtained in a meshing period. The transmission error formulation was analyzed to introduce meshing excitations. The maximum dynamic transmission error, the maximum meshing force and the maximum dynamic factor were calculated under different speeds, external loads and damping factors. The conclusions can provide theoretical basis for the gear design especially in tooth profile correction.展开更多
A nonlinear model of anti-backlash gear with time-varying friction and mesh stiffness was proposed for the further study on dynamic characteristics of anti-backlash gear. In order to improve the model precision, appli...A nonlinear model of anti-backlash gear with time-varying friction and mesh stiffness was proposed for the further study on dynamic characteristics of anti-backlash gear. In order to improve the model precision, applied force analysis was completed in detail, and single or double tooth meshing states of two gear pairs at any timing were determined according to the meshing characteristic of anti-backlash gear. The influences of friction and variations of damping ratio on dynamic transmission error were analyzed finally by numerical calculation and the results show that anti-backlash gear can increase the composite mesh stiffness comparing with the mesh stiffness of the normal gear pair. At the pitch points where the frictions change their signs, additional impulsive effects are observed. The width of impulsive in the same value of center frequency is wider than that without friction, and the amplitude is lower. When gear pairs mesh in and out, damping can reduce the vibration and impact.展开更多
Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is involved in aerosol particles and droplets excreted from a coronavirus disease 2019(COVID-19)patient.Such aerosol particles or droplets including infectiou...Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is involved in aerosol particles and droplets excreted from a coronavirus disease 2019(COVID-19)patient.Such aerosol particles or droplets including infectious virions can be attached on fomite,so fomite is not a negligible route for SARS-CoV-2 transmission within a community,especially in indoor environment.This necessarily evokes a need of fomite disinfection to remove virions,but the extent to which fomite disinfection breaks off virus transmission chain in indoor environment is still elusive.In this study,we evaluated the fomite disinfection effectiveness on COVID-19 case number using network analysis that reproduced the reported indoor outbreaks.In the established network,virus can move around not only human but also air and fomite while growing in human and decaying in air and on fomite,and infection success was determined based on the exposed virus amount and the equation of probability of infection.The simulation results have demonstrated that infectious virions on fomite should be kept less than a hundred to sufficiently reduce COVID-19 case,and every-hour disinfection was required to avoid stochastic increase in the infection case.This study gives us a practical disinfection manner for fomite to control SARS-CoV-2 transmission in indoor environment.展开更多
The coronavirus disease 2019(COVID-19)pandemic is a global crisis,and medical systems in many countries are overwhelmed with supply shortages and increasing demands to treat patients due to the surge in cases and seve...The coronavirus disease 2019(COVID-19)pandemic is a global crisis,and medical systems in many countries are overwhelmed with supply shortages and increasing demands to treat patients due to the surge in cases and severe illnesses.This study aimed to assess COVID-19-related essential clinical resource demands in China,based on different scenarios involving COVID-19 spreads and interventions.We used a susceptible–exposed–infectious–hospitalized/isolated–removed(SEIHR)transmission dynamics model to estimate the number of COVID-19 infections and hospitalizations with corresponding essential healthcare resources needed.We found that,under strict non-pharmaceutical interventions(NPIs)or mass vaccination of the population,China would be able to contain community transmission and local outbreaks rapidly.However,under scenarios involving a low intensity of implemented NPIs and a small proportion of the population vaccinated,the use of a peacetime–wartime transition model would be needed for medical source stockpiles and preparations to ensure a normal functioning healthcare system.The implementation of COVID-19 vaccines and NPIs in different periods can influence the transmission of COVID-19 and subsequently affect the demand for clinical diagnosis and treatment.An increased proportion of asymptomatic infections in simulations will not reduce the demand for medical resources;however,attention must be paid to the increasing difficulty in containing COVID-19 transmission due to asymptomatic cases.This study provides evidence for emergency preparations and the adjustment of prevention and control strategies during the COVID-19 pandemic.It also provides guidance for essential healthcare investment and resource allocation.展开更多
Surveillance is an essential work on infectious diseases prevention and control.When the pandemic occurred,the inadequacy of traditional surveillance was exposed,but it also provided a valuable opportunity to explore ...Surveillance is an essential work on infectious diseases prevention and control.When the pandemic occurred,the inadequacy of traditional surveillance was exposed,but it also provided a valuable opportunity to explore new surveillance methods.This study aimed to estimate the transmission dynamics and epidemic curve of severe acute respiratory syndrome coronavirus 2(SARS-Co V-2)Omicron BF.7 in Beijing under the emergent situation using Baidu index and influenza-like illness(ILI)surveillance.A novel hybrid model(multiattention bidirectional gated recurrent unit(MABG)-susceptible-exposed-infected-removed(SEIR))was developed,which leveraged a deep learning algorithm(MABG)to scrutinize the past records of ILI occurrences and the Baidu index of diverse symptoms such as fever,pyrexia,cough,sore throat,anti-fever medicine,and runny nose.By considering the current Baidu index and the correlation between ILI cases and coronavirus disease 2019(COVID-19)cases,a transmission dynamics model(SEIR)was formulated to estimate the transmission dynamics and epidemic curve of SARS-Co V-2.During the COVID-19 pandemic,when conventional surveillance measures have been suspended temporarily,cases of ILI can serve as a useful indicator for estimating the epidemiological trends of COVID-19.In the specific case of Beijing,it has been ascertained that cumulative infection attack rate surpass 80.25%(95%confidence interval(95%CI):77.51%-82.99%)since December 17,2022,with the apex of the outbreak projected to transpire on December 12.The culmination of existing patients is expected to occur three days subsequent to this peak.Effective reproduction number(Rt)represents the average number of secondary infections generated from a single infected individual at a specific point in time during an epidemic,remained below 1 since December 17,2022.The traditional disease surveillance systems should be complemented with information from modern surveillance data such as online data sources with advanced technical support.Modern surveillance channels should be used primarily in emerging infectious and disease outbreaks.Syndrome surveillance on COVID-19 should be established to following on the epidemic,clinical severity,and medical resource demand.展开更多
Cervical cancer is a common malignancy in women,with persistent human papillomavirus(HPV)infection as its primary cause.Understanding the progression from HPV infection to cervical cancer is crucial.Mathematical model...Cervical cancer is a common malignancy in women,with persistent human papillomavirus(HPV)infection as its primary cause.Understanding the progression from HPV infection to cervical cancer is crucial.Mathematical models play a key role in converting clinical trial data into long-term health forecasts,helping decision-makers tackle challenges posed by limited data and uncertain outcomes.This paper reviews transmission dynamics models and advancements in simulating HPV transmission leading to cervical cancer.It evaluates preventive and control measures,focusing on the impact of HPV vaccination across different vaccine types,doses,age groups,and both genders.These model-based assessments aim to provide insights for developing effective strategies to prevent and control HPV-related cervical cancer.展开更多
Background:HepatitisCvirus(HCV)is a bloodborne virus that causes both acute and chronic hepatitis with the severity from a mild illness to liver airrhosis and cancer.As one of the major infectious diseases in China,th...Background:HepatitisCvirus(HCV)is a bloodborne virus that causes both acute and chronic hepatitis with the severity from a mild illness to liver airrhosis and cancer.As one of the major infectious diseases in China,the monthly surveillance data from the Fujian Provincial Center for Disease Control and Prevention shows the increasing tendency from 2004 to 2011,the stable tendency from 2012 to 2016,and the dedining tendency from 2017 to 2022.The 2004-2022HCV infectiontendency of Fujian Province is affected by nation-wide main control measures of Chinese government,because no control measures for HCV are modified from 2020 to 2022 during the prevalence of COVID-19 in Fujian Province.Methods:The SEACTR(the susceptible,the exposed,the acutely infected,the chronically infected,the treated,the recovered)models with protection awareness are proposed.The next generation matrix method is used to compute basic reproduction number of toy model and dynamic analysis method is used to produce stochastic reproduction number of modified model.The least squares method and toy model are used to perform the optimal fitting against the monthly surveillance data.The positive preserving truncated Euler-Maruyama method is applied in modified model for the positivity of numerical simulations.Results:The optimal fitting is performed using the monthly surveillancedata provided by the Fujian Provincial Center for Disease Control and Prevention from 2004 to 2022.The sensitivities of protection efficiency and conversion rate to basic reproduction number and stochastic reproduction number are analyzed.The reproduction numbers and HCV infec-tion scale with measures(single-measure,double-measure,triple-measure,and none-measure)are compared using toy model and modified model.The impacts of protection efficiency and conversion rate on exposed population,acutely infected population,chronically infectedpopulation,and treated population are analyzed.The tendency predictions for infected population and treated population in Fujian Province from 2023 to 2035 are conducted Conclusions:The HCV infection scale mainly depends on both protection efficiency and conversion rate,in which protection efficiency is the most important contributor.The reproduction numbers show the declining tendendes by phases,which indicate that the prevention and control of HCV in Fujian Province has achieved a remarkable achievement.The 2023-2035tendency predictions of HCV infection scale in Fujian Province grow slowly due to approximately 19-109 monthly infections.The overal HCV growth tendency of Fujian Province is consistent with the nation-wide elimination objective.展开更多
African swine fever(ASF),a fatal disease outbroken in China in August 2018,has widely attracted social concern especially in the information era.The occurrence of ASF led to an imbalance between supply and demand in p...African swine fever(ASF),a fatal disease outbroken in China in August 2018,has widely attracted social concern especially in the information era.The occurrence of ASF led to an imbalance between supply and demand in pork and other meat markets.As a result,meat prices fluctuated greatly during the past year in 2019.To measure ASF quantitatively,the internet public concern index about ASF was created using web crawler methods.The relationships between ASF and meat prices were analyzed based on time-varying parameter vector auto-regressive(TVP-VAR)model.The results showed that there were some differences in the impact size,direction and duration of ASF on the prices of pork,chicken,beef and mutton,and the characteristics of time variability and heterogeneity were obvious.At the same time,the impact of ASF on meat prices is not consistent with the trend and degree of ASF.The impulse intensity is strongly correlated with the strength and duration of ASF,and it is generally weak in the early stage and much stronger in the middle and late periods.The results indicate that macro regulations,monitoring and early-warning system,standardizing production and circulation,and the public opinion monitoring and guidance about ASF should be given more attention in future to stabilize the market expectations and to promote a smooth functioning of the livestock markets.展开更多
文摘In this article, the transmission dynamics of a Hand-Foot-Mouth disease model with treatment and vaccination interventions are studied. We calculated the basic reproduction number and proved the global stability of disease-free equilibrium when R0 R0 > 1. Meanwhile, we obtained the optimal control strategies minimizing the cost of intervention and minimizing the infected person. We also give some numerical simulations to verify our theoretical results.
基金supported by the Key Research and Development Project in the Health Field of Chongqing(CSTC2021jscx-gksb-N0003)the Provincial Key Research and Development Programof Jiangxi,China(20232BBG70020)+1 种基金the Major Project of Guangzhou National Laboratory(GZNL2024A01004)the National Key Research and Development Program Project(2021YFC2301604).
文摘Introduction:Since November 2023,influenza has ranked first in reported cases of infectious diseases in China,with the outbreak in both northern and southern provinces exceeding the levels observed during the same period in 2022.This poses a serious health risk to the population.Therefore,short to medium-term influenza predictions are beneficial for epidemic assessment and can reduce the disease burden.Methods:A transmission dynamics model considering population migration,encompassing susceptible-exposed-infectious-asymptomatic-recovered(SEIAR)was used to predict the dynamics of influenza before the Spring Festival travel rush.Results:The overall epidemic shows a declining trend,with the peak expected to occur from week 47 in 2023 to week 1 in 2024.The number of cases of A(H3N2)is greater than that of influenza B,and the influenza situation is more severe in the southern provinces compared to the northern ones.Conclusion:Our method is applicable for short-term and medium-term influenza predictions.As the spring festival travel rush approaches.Therefore,it is advisable to advocate for nonpharmaceutical interventions(NPIs),influenza vaccination,and other measures to reduce healthcare and public health burden.
文摘Background Diphtheria,caused by Corynebacterium diphtheriae,remains a serious public health threat in areas with low vaccination coverage,despite global declines due to widespread immunization and improved clinical management.A major outbreak in Nigeria from 2022 to 2023 underscored the persistent risk in regions with inadequate vaccination.This study aims to assess the transmission dynamics of diphtheria in Kano State,the epicenter of the outbreak,by estimating key epidemiological parameters,including the generation time(GT),approximated in our study by serial interval,and effective reproduction number(R).Methods We analyzed diphtheria case-based data from Kano State,Nigeria,collected between August 18,2022,and November 29,2023.Generation time was approximated using serial intervals in confirmed cases within the same geographical areas.The effective reproduction number(R)was calculated using four methods:Maximum Likelihood Estimation(MLE),Exponential Growth(EG),Sequential Bayesian(SB),and Time-Dependent(TD),focusing on the period of maximum exponential growth.A sensitivity analysis was conducted to quantify the impact of uncertainties in the GT derived from our data on the estimation of R.Results Over the 469-day outbreak period,13,899 diphtheria cases were reported,with complete data available for 9406 cases.The estimated mean generation time was 2.8 days(SD=3.48 days),with 97%of cases having a GT of less than 21 days.The Restimates varied across methods,with the TD method producing the highest reproduction number of 2.21 during the peak growth period.Sensitivity analysis showed that Restimates increased with longer generation times.The models,except for the SB method,demonstrated a generally strong fit with the outbreak exponential growth period.Conclusion The ongoing diphtheria outbreak in Nigeria highlights the critical threat posed by declining vaccination coverage.This study provides valuable insights into the transmission dynamics of diphtheria during a prolonged and widespread outbreak,enhancing our understanding of disease spread in this context.While certain limitations may influence the interpretation of our estimates,the findings offer valuable information for future diphtheria outbreak preparedness and response in the African context.
文摘Synergistic interaction between influenza and pneumonia is well established in the literature.In this study,we present a model for the transmission dynamics of co-infection with influenza and pneumococcal pneumonia,with the goal of assessing the effects of influenza co-infection on the transmission of pneumonia.We derive an expression for the basic reproductive number R 0=max(R_(f),R_(p))where R_(f) and R_(p) are,respectively,the reproductive numbers for flu and pneumonia.We show that in the case R_(f)≤1≤R_(p),infection with influenza is driven to extinction while pneumonia is endemic,with the endemic state being globally asymptotically stable.The converse result holds in the case where R_(p)≤1≤R_(f).We also show the existence of the co-infection equilibrium.In this case,we show that the presence of co-infection results in a possible backward bifurcation in the system at R 0=1;epidemiologically,this means that the spread of the infection will be harder to control.Numerical simulations are presented to verify the analytic results and gain further insights.
基金This study is supported by the Natural Science item of China under grant No.11771277.
文摘To investigate the transmission dynamics and temporal and spatial migration characteristics of HIV spread among men who have sex with men(MSM)in China,a total of 1012 HIV-1 partial pol sequences,including five subtypes,were studied.Bayesian analysis were applied for each subtype to infer its dynamic characters including the effective reproductive number(R_(e))and migration process.The mean curve of each R_(e) was almost always greater than 1(even the 95%highest posterior density(HPD)lower value)along with time,which supports the necessity for a comprehensive study about risk behaviors among young MSM group in China.We also should reappraise the free treatment strategy,especially the therapeutic effect during the free treatment policy.
文摘Ebola virus disease （EVD） has emerged as a rapidly spreading potentially fatal disease. Several studies have been performed recently to investigate the dynamics of EVD. In this paper, we study the transmission dynamics of EVD by formulating an SEIR-type transmission model that includes isolated individuals as well as dead individuals that are not yet buried. Dynamical systems analysis of the model is performed, and it is consequently shown that the disease-free steady state is globally asymptotically stable when the basic reproduction number, R0 is less than unity. It is also shown that there exists a unique endemic equilibrium when R0 〉 1. Using optimal control theory, we propose control strategies, which will help to eliminate the Ebola disease. We use data fitting on models, with and without isolation, to estimate the basic reproductive numbers for the 2014 outbreak of EVD in Liberia and Sierra Leone.
文摘A compartmental,epidemiological,mathematical model was developed in order to analyze the transmission dynamics of Delta and Omicron variant,of SARS-CoV-2,in Greece.The model was parameterized twice during the 4th and 5th wave of the pandemic.The 4th wave refers to the period during which the Delta variant was dominant(approximately July to December of 2021)and the 5th wave to the period during which the Omicron variant was dominant(approximately January to May of 2022),in accordance with the official data from the National Public Health Organization(NPHO).Fitting methods were applied to evaluate important parameters in connection with the transmission of the variants,as well as the social behavior of population during these periods of interest.Mathematical models revealed higher numbers of contagiousness and cases of asymptomatic disease during the Omicron variant period,but a decreased rate of hospitalization compared to the Delta period.Also,parameters related to the behavior of the population in Greece were also assessed.More specifically,the use of protective masks and the abidance of social distancing measures.Simulations revealed that over 5,000 deaths could have been avoided,if mask usage and social distancing were 20%more efficient,during the short period of the Delta and Omicron outbreak.Furthermore,the spread of the variants was assessed using viral load data.The data were recorded from PCR tests at 417 Army Equity Fund Hospital(NIMTS),in Athens and the Ct values from 746 patients with COVID-19 were processed,to explain transmission phenomena and disease severity in patients.The period when the Delta variant prevailed in the country,the average Ct value was calculated as 25.19(range:12.32e39.29),whereas during the period when the Omicron variant prevailed,the average Ct value was calculated as 28(range:14.41e39.36).In conclusion,our experimental study showed that the higher viral load,which is related to the Delta variant,may interpret the severity of the disease.However,no correlation was confirmed regarding contagiousness phenomena.The results of the model,Ct analysis and official data from NPHO are consistent.
文摘In this paper,an attempt has been made to explore a new delayed epidemiological model assuming that the disease is transmitted among the susceptible population and possessing nonlinear incidence function along with a saturated treatment rate.Due attention is paid to the positivity and boundedness of the solutions and the bifurcation of the dynamical system as well.Basic reproduction number is being calculated,and considering the latent period as a bifurcation parameter,it has been examined that a Hopf-bifurcation occurs near the endemic equilibrium point while the parameter attains critical values.We have also discussed the stability and direction of Hopf-bifurcation near the endemic equilibrium point,the global stability analysis and the optimal control theory.We conclude that the system reveals chaotic dynamics through a specific time-delay value.Numerical simulations are being performed in order to explain the accuracy and effectiveness of the acquired theoretical results.
文摘Malaria,a devastating disease caused by the Plasmodium parasite and transmitted through the bites of female Anopheles mosquitoes,remains a significant public health concern,claiming over 600,000 lives annually,predominantly among children.Novel tools,including the application of Wolbachia,are being developed to combat malaria-transmitting mosquitoes.This study presents a modified susceptible-exposed-infectious-recovered-susceptible(SEIRS)compartmental mathematical model to evaluate the impact of awareness-based control measures on malaria transmission dynamics,incorporating mosquito interactions and seasonality.Employing the next-generation matrix approach,we calculated a basic reproduction number(R0)of 2.4537,indicating that without robust control measures,the disease will persist in the human population.The model equations were solved numerically using fourth and fifth-order Runge-Kutta methods.The model was fitted to malaria incidence data from Kenya spanning 2000 to 2021 using least squares curve fitting.The fitting algorithm yielded a mean absolute error(MAE)of 2.6463 when comparing the actual data points to the simulated values of infectious human population(Ih).This finding indicates that the proposed mathematical model closely aligns with the recorded malaria incidence data.The optimal values of the model parameters were estimated from the fitting algorithm,and future malaria dynamics were projected for the next decade.The research findings suggest that social media-based awareness campaigns,coupled with specific optimization control measures and effective management methods,offer the most cost-effective approach to managing malaria.
基金the National Natural Science Foundation of China(No.82041024 to F.C.,81973142 to Y.W.)the Bill&Melinda Gates Foundation(Investment ID:INV-006371).
文摘Since late 2019,the beginning of coronavirus disease 2019(COVID-19)pandemic,transmission dynamics models have achieved great development and were widely used in predicting and policymaking.Here,we provided an introduction to the history of disease transmission,summarized transmission dynamics models into three main types:compartment extension,parameter extension and population-stratified extension models,highlight the key contribution of transmission dynamics models in COVID-19 pandemic:estimating epidemiological parameters,predicting the future trend,evaluating the effectiveness of control measures and exploring different possibilities/scenarios.Finally,we pointed out the limitations and challenges lie ahead of transmission dynamics models.
文摘Mathematical models are increasingly being used in the evaluation of control strategies for infectious disease such as the vaccination program for the Human PapiUomavirus （HPV）. Here, an ordinary differential equation （ODE） transmission dynamic model for HPV is presented and analyzed. Parameter values for a gender and risk structured model are estimated by calibrating the model around the known prevalence of infection. The effect on gender and risk sub-group prevalence induced by varying the epidemiological parameters are investigated. Finally, the outcomes of this model are applied using a classical mathematical method for calculating R0 in a heterogeneous mixing population. Estimates for R0 under various gender and mixing scenarios are presented.
文摘The recent outbreak of COVID-19 has caused millions of deaths worldwide and a huge societal and economic impact in virtually all countries. A large variety of mathematical models to describe the dynamics of COVID-19 transmission have been reported. Among them, Bayesian probabilistic models of COVID-19 transmission dynamics have been very efficient in the interpretation of early data from the beginning of the pandemic, helping to estimate the impact of non-pharmacological measures in each country, and forecasting the evolution of the pandemic in different potential scenarios. These models use probability distribution curves to describe key dynamic aspects of the transmission, like the probability for every infected person of infecting other individuals, dying or recovering, with parameters obtained from experimental epidemiological data. However, the impact of vaccine-induced immunity, which has been key for controlling the public health emergency caused by the pandemic, has been more challenging to describe in these models, due to the complexity of experimental data. Here we report different probability distribution curves to model the acquisition and decay of immunity after vaccination. We discuss the mathematical background and how these models can be integrated in existing Bayesian probabilistic models to provide a good estimation of the dynamics of COVID-19 transmission during the entire pandemic period.
基金Supported by National Basic Research Program of China("973"Program,No.2013CB632305)
文摘Monte Carlo method was adopted to calculate the meshing error considering the manufacture error and assembly error of the meshing point along the time-varying contact line for helical gear pair. The flexural-torsion-axis dynamic model coupled was established under the tooth friction force and solved by the perturbation method to compute real dynamic tooth load. The change laws of the friction force and friction torque were obtained in a meshing period. The transmission error formulation was analyzed to introduce meshing excitations. The maximum dynamic transmission error, the maximum meshing force and the maximum dynamic factor were calculated under different speeds, external loads and damping factors. The conclusions can provide theoretical basis for the gear design especially in tooth profile correction.
基金Project(51175505)supported by the National Natural Science Foundation of China
文摘A nonlinear model of anti-backlash gear with time-varying friction and mesh stiffness was proposed for the further study on dynamic characteristics of anti-backlash gear. In order to improve the model precision, applied force analysis was completed in detail, and single or double tooth meshing states of two gear pairs at any timing were determined according to the meshing characteristic of anti-backlash gear. The influences of friction and variations of damping ratio on dynamic transmission error were analyzed finally by numerical calculation and the results show that anti-backlash gear can increase the composite mesh stiffness comparing with the mesh stiffness of the normal gear pair. At the pitch points where the frictions change their signs, additional impulsive effects are observed. The width of impulsive in the same value of center frequency is wider than that without friction, and the amplitude is lower. When gear pairs mesh in and out, damping can reduce the vibration and impact.
基金supported by MHLW Research on Health Security Control Program Grant Number JPMH21LA1007.
文摘Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is involved in aerosol particles and droplets excreted from a coronavirus disease 2019(COVID-19)patient.Such aerosol particles or droplets including infectious virions can be attached on fomite,so fomite is not a negligible route for SARS-CoV-2 transmission within a community,especially in indoor environment.This necessarily evokes a need of fomite disinfection to remove virions,but the extent to which fomite disinfection breaks off virus transmission chain in indoor environment is still elusive.In this study,we evaluated the fomite disinfection effectiveness on COVID-19 case number using network analysis that reproduced the reported indoor outbreaks.In the established network,virus can move around not only human but also air and fomite while growing in human and decaying in air and on fomite,and infection success was determined based on the exposed virus amount and the equation of probability of infection.The simulation results have demonstrated that infectious virions on fomite should be kept less than a hundred to sufficiently reduce COVID-19 case,and every-hour disinfection was required to avoid stochastic increase in the infection case.This study gives us a practical disinfection manner for fomite to control SARS-CoV-2 transmission in indoor environment.
基金supported by the following fundings:Chinese Academy of Medical Sciences(CAMS)Innovation Fund for Medical Sciences(2020-I2M-1-001,2020-I2M-2-015,and 2016-I2M-1-014)National Social Science Fund of China(20&ZD201).
文摘The coronavirus disease 2019(COVID-19)pandemic is a global crisis,and medical systems in many countries are overwhelmed with supply shortages and increasing demands to treat patients due to the surge in cases and severe illnesses.This study aimed to assess COVID-19-related essential clinical resource demands in China,based on different scenarios involving COVID-19 spreads and interventions.We used a susceptible–exposed–infectious–hospitalized/isolated–removed(SEIHR)transmission dynamics model to estimate the number of COVID-19 infections and hospitalizations with corresponding essential healthcare resources needed.We found that,under strict non-pharmaceutical interventions(NPIs)or mass vaccination of the population,China would be able to contain community transmission and local outbreaks rapidly.However,under scenarios involving a low intensity of implemented NPIs and a small proportion of the population vaccinated,the use of a peacetime–wartime transition model would be needed for medical source stockpiles and preparations to ensure a normal functioning healthcare system.The implementation of COVID-19 vaccines and NPIs in different periods can influence the transmission of COVID-19 and subsequently affect the demand for clinical diagnosis and treatment.An increased proportion of asymptomatic infections in simulations will not reduce the demand for medical resources;however,attention must be paid to the increasing difficulty in containing COVID-19 transmission due to asymptomatic cases.This study provides evidence for emergency preparations and the adjustment of prevention and control strategies during the COVID-19 pandemic.It also provides guidance for essential healthcare investment and resource allocation.
基金supported by grants from the Chinese Academy of Medical Sciences(CAMS)Innovation Fund for Medical Sciences(2021I2M-1-044)。
文摘Surveillance is an essential work on infectious diseases prevention and control.When the pandemic occurred,the inadequacy of traditional surveillance was exposed,but it also provided a valuable opportunity to explore new surveillance methods.This study aimed to estimate the transmission dynamics and epidemic curve of severe acute respiratory syndrome coronavirus 2(SARS-Co V-2)Omicron BF.7 in Beijing under the emergent situation using Baidu index and influenza-like illness(ILI)surveillance.A novel hybrid model(multiattention bidirectional gated recurrent unit(MABG)-susceptible-exposed-infected-removed(SEIR))was developed,which leveraged a deep learning algorithm(MABG)to scrutinize the past records of ILI occurrences and the Baidu index of diverse symptoms such as fever,pyrexia,cough,sore throat,anti-fever medicine,and runny nose.By considering the current Baidu index and the correlation between ILI cases and coronavirus disease 2019(COVID-19)cases,a transmission dynamics model(SEIR)was formulated to estimate the transmission dynamics and epidemic curve of SARS-Co V-2.During the COVID-19 pandemic,when conventional surveillance measures have been suspended temporarily,cases of ILI can serve as a useful indicator for estimating the epidemiological trends of COVID-19.In the specific case of Beijing,it has been ascertained that cumulative infection attack rate surpass 80.25%(95%confidence interval(95%CI):77.51%-82.99%)since December 17,2022,with the apex of the outbreak projected to transpire on December 12.The culmination of existing patients is expected to occur three days subsequent to this peak.Effective reproduction number(Rt)represents the average number of secondary infections generated from a single infected individual at a specific point in time during an epidemic,remained below 1 since December 17,2022.The traditional disease surveillance systems should be complemented with information from modern surveillance data such as online data sources with advanced technical support.Modern surveillance channels should be used primarily in emerging infectious and disease outbreaks.Syndrome surveillance on COVID-19 should be established to following on the epidemic,clinical severity,and medical resource demand.
基金Supported by grants from The Department of Science and Technology of Hunan Province(No:2020SK1010)the National Health Commission of the Hunan Province(No:202212054651).
文摘Cervical cancer is a common malignancy in women,with persistent human papillomavirus(HPV)infection as its primary cause.Understanding the progression from HPV infection to cervical cancer is crucial.Mathematical models play a key role in converting clinical trial data into long-term health forecasts,helping decision-makers tackle challenges posed by limited data and uncertain outcomes.This paper reviews transmission dynamics models and advancements in simulating HPV transmission leading to cervical cancer.It evaluates preventive and control measures,focusing on the impact of HPV vaccination across different vaccine types,doses,age groups,and both genders.These model-based assessments aim to provide insights for developing effective strategies to prevent and control HPV-related cervical cancer.
基金supported by Natural Science Foundation of Fujian Province of China(2021J01621)supported by National Natural Science Foundation of China(12231012)+3 种基金supported by Royal Society of Edinburgh(RSE1832)Engineering and Physical Sciences Research Council(EP/W522521/1)supported by The Major Health Research Project of Fujian Province(2021ZD01001)Fujian Research and Training Grants for Young and Middle-aged Leaders in Healthcare(202501140018).
文摘Background:HepatitisCvirus(HCV)is a bloodborne virus that causes both acute and chronic hepatitis with the severity from a mild illness to liver airrhosis and cancer.As one of the major infectious diseases in China,the monthly surveillance data from the Fujian Provincial Center for Disease Control and Prevention shows the increasing tendency from 2004 to 2011,the stable tendency from 2012 to 2016,and the dedining tendency from 2017 to 2022.The 2004-2022HCV infectiontendency of Fujian Province is affected by nation-wide main control measures of Chinese government,because no control measures for HCV are modified from 2020 to 2022 during the prevalence of COVID-19 in Fujian Province.Methods:The SEACTR(the susceptible,the exposed,the acutely infected,the chronically infected,the treated,the recovered)models with protection awareness are proposed.The next generation matrix method is used to compute basic reproduction number of toy model and dynamic analysis method is used to produce stochastic reproduction number of modified model.The least squares method and toy model are used to perform the optimal fitting against the monthly surveillance data.The positive preserving truncated Euler-Maruyama method is applied in modified model for the positivity of numerical simulations.Results:The optimal fitting is performed using the monthly surveillancedata provided by the Fujian Provincial Center for Disease Control and Prevention from 2004 to 2022.The sensitivities of protection efficiency and conversion rate to basic reproduction number and stochastic reproduction number are analyzed.The reproduction numbers and HCV infec-tion scale with measures(single-measure,double-measure,triple-measure,and none-measure)are compared using toy model and modified model.The impacts of protection efficiency and conversion rate on exposed population,acutely infected population,chronically infectedpopulation,and treated population are analyzed.The tendency predictions for infected population and treated population in Fujian Province from 2023 to 2035 are conducted Conclusions:The HCV infection scale mainly depends on both protection efficiency and conversion rate,in which protection efficiency is the most important contributor.The reproduction numbers show the declining tendendes by phases,which indicate that the prevention and control of HCV in Fujian Province has achieved a remarkable achievement.The 2023-2035tendency predictions of HCV infection scale in Fujian Province grow slowly due to approximately 19-109 monthly infections.The overal HCV growth tendency of Fujian Province is consistent with the nation-wide elimination objective.
基金This study was supported by the National Natural Science Foundation of China(72073131)the Central Public-Interest Scientific Institution Basal Research Fund,China(2020JKY025)the Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(CAAS-ASTIP-2016-AII).
文摘African swine fever(ASF),a fatal disease outbroken in China in August 2018,has widely attracted social concern especially in the information era.The occurrence of ASF led to an imbalance between supply and demand in pork and other meat markets.As a result,meat prices fluctuated greatly during the past year in 2019.To measure ASF quantitatively,the internet public concern index about ASF was created using web crawler methods.The relationships between ASF and meat prices were analyzed based on time-varying parameter vector auto-regressive(TVP-VAR)model.The results showed that there were some differences in the impact size,direction and duration of ASF on the prices of pork,chicken,beef and mutton,and the characteristics of time variability and heterogeneity were obvious.At the same time,the impact of ASF on meat prices is not consistent with the trend and degree of ASF.The impulse intensity is strongly correlated with the strength and duration of ASF,and it is generally weak in the early stage and much stronger in the middle and late periods.The results indicate that macro regulations,monitoring and early-warning system,standardizing production and circulation,and the public opinion monitoring and guidance about ASF should be given more attention in future to stabilize the market expectations and to promote a smooth functioning of the livestock markets.
