Vector-borne diseases are highly sensitive to environment and to environmental changes. Rift Valley Fever (RFV) is a mosquito-borne zootic virus associated with severe diseases in human beings and economic consequence...Vector-borne diseases are highly sensitive to environment and to environmental changes. Rift Valley Fever (RFV) is a mosquito-borne zootic virus associated with severe diseases in human beings and economic consequences to livestock sector. Animal and human movements have a fundamental impact on RVF transmission. In recent years, there has been a growing interest in the use of mathematics and agent based models to represent and analyze the dynamic of RFV transmission. However, no previous study has taken into consideration animal herds’ mobility and precipitation factors to understand the disease spread. This limitation underlines the necessity to use computational model approach based on multi-agent system in the study of vector-borne diseases transmission and diffusion. In this paper, a multi-agent system combining conceptual model expressiveness is used to study animal herds’ mobility and the precipitation parameter impact on the Rift Valley Fever outbreak in Ferlo Barkedji in Northern Senegal. Simulation scenarios with various parameters, including rain quality, hosts, vectors, camp dispersal around ponds, etc., are unrolled. The different results we have obtained show that the evolution of the number of infected hosts and infected vectors depend on the degree of animal herds’ mobility and on precipitations. Our model provides a framework that permits predicting the spread of the disease associated with the mobility of animal herds.展开更多
A novel mathematical model of the epidemiology of Rift Valley fever (RVF) is studied, which is an ordinary differential equation model for a population of mosquito species and the hosts. A disease-free equilibrium is ...A novel mathematical model of the epidemiology of Rift Valley fever (RVF) is studied, which is an ordinary differential equation model for a population of mosquito species and the hosts. A disease-free equilibrium is discussed as well as its local stability. The prevalence of disease is proved under some conditions. Finally the vertical transmission is considered in a model for such a mosquito population.展开更多
Backgroud:To verify the antipyretic effect and mechanism of Chai Ge fever relief oral liquid,and to provide evidence for the clinical application of Chai Ge fever relief oral liquid.Methods:By designing three groups o...Backgroud:To verify the antipyretic effect and mechanism of Chai Ge fever relief oral liquid,and to provide evidence for the clinical application of Chai Ge fever relief oral liquid.Methods:By designing three groups of experimental models of yeast-induced rat fever model,endotoxin-induced rabbit fever model,and para-influenza virus-induced rabbit fever model,the antipyretic effect and mechanism of Chai Ge fever relief oral liquid were studied by measuring body temperature before and after treatment and the expressions of protein kinase A(PKA),protein kinase C,arginine vasopressin(AVP),prostaglandin E2 and cyclic adenosine monophosphate(cAMP)in hypothalamus after administration.Results:In the yeast-induced fever model of rats,the body temperature and PKA expression levels in different dose groups of Chai Ge fever relief oral liquid were significantly different from those of the model group 1–3 h after treatment.In the rabbit fever model induced by endotoxin,different dosage groups of Chai Ge fever relief oral liquid have obvious antipyretic effect on 1–3 h after the model is established,and can significantly reduce the expression of AVP and cAMP in hypothalamus.In the para-influenza virus-induced rabbit fever model,each dose group of Chai Ge fever relief oral liquid has obvious antipyretic effect on 1–2 h after the model is established.Conclusion:Chai Ge fever relief oral liquid has good antipyretic effect on fever models induced by yeast,endotoxin and parainfluenza by regulating the expression of PKA,AVP,and cAMP.展开更多
目的了解中缅边境地区景洪市2019年登革热时空分布特征及传播影响因素。方法收集中缅边境地区景洪市2019年登革热本地病例逐日发病数,将人口密度、人均GDP、日平均气温、日平均相对湿度和日照时数等因素作为协变量,构建基于Power-law算...目的了解中缅边境地区景洪市2019年登革热时空分布特征及传播影响因素。方法收集中缅边境地区景洪市2019年登革热本地病例逐日发病数,将人口密度、人均GDP、日平均气温、日平均相对湿度和日照时数等因素作为协变量,构建基于Power-law算法的时空多成分模型,通过赤池信息量(Akaike information criterion,AIC)来评价模型的拟合效果。结果中缅边境地区景洪市2019年累计报告3303例登革热本地病例,发病率为763.44/10万。将人均GDP纳入时间自相关成分,同时将人口密度、日平均气温、日平均最高气温和日平均相对湿度纳入局部特性成分的时空多成分模型的拟合效果最优(AIC=2317),此时时间自相关成分为0.2151[95%CI:(0.0812,0.5702)]、空间流行成分为0.0004[95%CI:(0.0002,0.0010)]、局部特性成分为3.0152[95%CI:(1.6507,5.5078)]。协变量日平均相对湿度、人口密度、人均GDP、日平均气温、日平均最高气温的作用强度依次为2.8159[95%CI:(0.0216,367.1685)]、1.8227[95%CI:(1.4976,2.2183)]、1.2088[95%CI:(1.0577,1.3816)]、0.3561[95%CI:(0.0119,10.6739)]、0.3104[95%CI:(0.0036,126.5482)]。对发病数>20例的区域分析发现,允景洪街道、西双版纳旅游度假区和景洪工业园区时间自相关成分影响较大,嘎洒镇、勐龙镇和勐罕镇局部特性成分影响较大。结论景洪市不同区域登革热时空构成存在差异性,具有不同的时空传播特征。人均GDP会扩大前期疫情对后期疫情传播的影响,人口密度、日平均气温、日平均最高气温和日平均相对湿度则会影响研究区域登革热本地风险水平。展开更多
Global incidence of dengue, a vector-borne tropical disease, has seen a dramatic increase with several major outbreaks in the past few decades. We formulate and analyze a stochastic epidemic model for the transmission...Global incidence of dengue, a vector-borne tropical disease, has seen a dramatic increase with several major outbreaks in the past few decades. We formulate and analyze a stochastic epidemic model for the transmission dynamics of a single strain of dengue virus. The stochastic model is constructed using a continuous time Markov chain (CTMC) and is based on an existing deterministic model that suggests the existence of a backward bifurcation for some values of the model parameters. The dynamics of the stochastic model are explored through numerical simulations in this region of bistability. The mean of each random variable is numerically estimated and these are compared to the dynamics of the deterministic model. It is observed that the stochastic model also predicts the co-existence of a locally asymptotically stable disease-free equilibrium along with a locally stable endemic equilibrium. This co-existence of equilibria is important from a public health perspective because it implies that dengue can persist in populations even if the value of the basic reproduction number is less than unity.展开更多
Objective To explore the associations between the monthly number of dengue fever（DF） cases and possible risk factors in Guangzhou, a subtropical city of China. Methods The monthly number of DF cases, Breteau Index ...Objective To explore the associations between the monthly number of dengue fever（DF） cases and possible risk factors in Guangzhou, a subtropical city of China. Methods The monthly number of DF cases, Breteau Index （BI）, and meteorological measures during 2006-2014 recorded in Guangzhou, China, were assessed. A negative binomial regression model was used to evaluate the relationships between BI, meteorological factors, and the monthly number of DF cases. Results A total of 39,697 DF cases were detected in Guangzhou during the study period. DF incidence presented an obvious seasonal pattern, with most cases occurring from June to November. The current month＇s BI, average temperature （Tare）, previous month＇s minimum temperature （Train）, and Tare were positively associated with DF incidence. A threshold of 18.25℃ was found in the relationship between the current month＇s Tmin and DF incidence. Conclusion Mosquito density, Tove, and Tmin play a critical role in DF transmission in Guangzhou. These findings could be useful in the development of a DF early warning system and assist in effective control and prevention strategies in the DF epidemic.展开更多
Avian Spirochaetosis is an acute endemic tick-borne disease of birds, caused by Borrelia anserins, a species of Borrelia bacteria. In this paper, we present a compartmental mathematical model of the disease for the bi...Avian Spirochaetosis is an acute endemic tick-borne disease of birds, caused by Borrelia anserins, a species of Borrelia bacteria. In this paper, we present a compartmental mathematical model of the disease for the bird population and Tick population. The disease steady-state and the conditions for reaching a stable disease-free steady state are determined. The analysis by Lyapunov method shows both local and global stability. Further investigation involves the introduction of controls to the model;the existence and uniqueness of optimal control are established. Finally, the effect of the controls is investigated using numerical solutions.展开更多
Objective A diagnostic model was established to discriminate infectious diseases from non-infectious diseases. Methods The clinical data of patients with fever of unknown origin(FUO) hospitalized in Xiangya Hospital C...Objective A diagnostic model was established to discriminate infectious diseases from non-infectious diseases. Methods The clinical data of patients with fever of unknown origin(FUO) hospitalized in Xiangya Hospital Central South University, from January, 2006 to April, 2011 were retrospectively analyzed. Patients enrolled were divided into two groups. The first group was used to develop a diagnostic model: independent variables were recorded and considered in a logistic regression analysis to identify infectious and non-infectious diseases(αin = 0.05, αout = 0.10). The second group was used to evaluate the diagnostic model and make ROC analysis.Results The diagnostic rate of 143 patients in the first group was 87.4%, the diagnosis included infectious disease(52.4%), connective tissue diseases(16.8%), neoplastic disease(16.1%) and miscellaneous(2.1%). The diagnostic rate of 168 patients in the second group was 88.4%, and the diagnosis was similar to the first group. Logistic regression analysis showed that decreased white blood cell count(WBC < 4.0×109/L), higher lactate dehydrogenase level(LDH > 320 U/L) and lymphadenectasis were independent risk factors associated with non-infectious diseases. The odds ratios were 14.74, 5.84 and 5.11(P ≤ 0.01), respectively. In ROC analysis, the sensitivity and specificity of the positive predictive values was 62.1% and 89.1%, respectively, while that of negative predicting values were 75% and 81.7%, respectively(AUC = 0.76, P = 0.00).Conclusions The combination of WBC < 4.0×109/L, LDH > 320 U/L and lymphadenectasis may be useful in discriminating infectious diseases from non-infectious diseases in patients hospitalized as FUO.展开更多
In this paper, we build an epidemiological model to investigate the dynamics of the spread of dengue fever in human population. We apply optimal control theory via the Pontryagins Minimum Principle together with the R...In this paper, we build an epidemiological model to investigate the dynamics of the spread of dengue fever in human population. We apply optimal control theory via the Pontryagins Minimum Principle together with the Runge-Kutta solution technique to a “simple” SEIRS disease model. Controls representing education and drug therapy treatment are incorporated to reduce the latently infected and actively infected individual populations. The overall thrust is the minimization of the spread of the disease in a population by adopting an optimization technique as a guideline.展开更多
文摘Vector-borne diseases are highly sensitive to environment and to environmental changes. Rift Valley Fever (RFV) is a mosquito-borne zootic virus associated with severe diseases in human beings and economic consequences to livestock sector. Animal and human movements have a fundamental impact on RVF transmission. In recent years, there has been a growing interest in the use of mathematics and agent based models to represent and analyze the dynamic of RFV transmission. However, no previous study has taken into consideration animal herds’ mobility and precipitation factors to understand the disease spread. This limitation underlines the necessity to use computational model approach based on multi-agent system in the study of vector-borne diseases transmission and diffusion. In this paper, a multi-agent system combining conceptual model expressiveness is used to study animal herds’ mobility and the precipitation parameter impact on the Rift Valley Fever outbreak in Ferlo Barkedji in Northern Senegal. Simulation scenarios with various parameters, including rain quality, hosts, vectors, camp dispersal around ponds, etc., are unrolled. The different results we have obtained show that the evolution of the number of infected hosts and infected vectors depend on the degree of animal herds’ mobility and on precipitations. Our model provides a framework that permits predicting the spread of the disease associated with the mobility of animal herds.
文摘A novel mathematical model of the epidemiology of Rift Valley fever (RVF) is studied, which is an ordinary differential equation model for a population of mosquito species and the hosts. A disease-free equilibrium is discussed as well as its local stability. The prevalence of disease is proved under some conditions. Finally the vertical transmission is considered in a model for such a mosquito population.
基金National Natural Science Foundation of China(81773977).
文摘Backgroud:To verify the antipyretic effect and mechanism of Chai Ge fever relief oral liquid,and to provide evidence for the clinical application of Chai Ge fever relief oral liquid.Methods:By designing three groups of experimental models of yeast-induced rat fever model,endotoxin-induced rabbit fever model,and para-influenza virus-induced rabbit fever model,the antipyretic effect and mechanism of Chai Ge fever relief oral liquid were studied by measuring body temperature before and after treatment and the expressions of protein kinase A(PKA),protein kinase C,arginine vasopressin(AVP),prostaglandin E2 and cyclic adenosine monophosphate(cAMP)in hypothalamus after administration.Results:In the yeast-induced fever model of rats,the body temperature and PKA expression levels in different dose groups of Chai Ge fever relief oral liquid were significantly different from those of the model group 1–3 h after treatment.In the rabbit fever model induced by endotoxin,different dosage groups of Chai Ge fever relief oral liquid have obvious antipyretic effect on 1–3 h after the model is established,and can significantly reduce the expression of AVP and cAMP in hypothalamus.In the para-influenza virus-induced rabbit fever model,each dose group of Chai Ge fever relief oral liquid has obvious antipyretic effect on 1–2 h after the model is established.Conclusion:Chai Ge fever relief oral liquid has good antipyretic effect on fever models induced by yeast,endotoxin and parainfluenza by regulating the expression of PKA,AVP,and cAMP.
文摘目的了解中缅边境地区景洪市2019年登革热时空分布特征及传播影响因素。方法收集中缅边境地区景洪市2019年登革热本地病例逐日发病数,将人口密度、人均GDP、日平均气温、日平均相对湿度和日照时数等因素作为协变量,构建基于Power-law算法的时空多成分模型,通过赤池信息量(Akaike information criterion,AIC)来评价模型的拟合效果。结果中缅边境地区景洪市2019年累计报告3303例登革热本地病例,发病率为763.44/10万。将人均GDP纳入时间自相关成分,同时将人口密度、日平均气温、日平均最高气温和日平均相对湿度纳入局部特性成分的时空多成分模型的拟合效果最优(AIC=2317),此时时间自相关成分为0.2151[95%CI:(0.0812,0.5702)]、空间流行成分为0.0004[95%CI:(0.0002,0.0010)]、局部特性成分为3.0152[95%CI:(1.6507,5.5078)]。协变量日平均相对湿度、人口密度、人均GDP、日平均气温、日平均最高气温的作用强度依次为2.8159[95%CI:(0.0216,367.1685)]、1.8227[95%CI:(1.4976,2.2183)]、1.2088[95%CI:(1.0577,1.3816)]、0.3561[95%CI:(0.0119,10.6739)]、0.3104[95%CI:(0.0036,126.5482)]。对发病数>20例的区域分析发现,允景洪街道、西双版纳旅游度假区和景洪工业园区时间自相关成分影响较大,嘎洒镇、勐龙镇和勐罕镇局部特性成分影响较大。结论景洪市不同区域登革热时空构成存在差异性,具有不同的时空传播特征。人均GDP会扩大前期疫情对后期疫情传播的影响,人口密度、日平均气温、日平均最高气温和日平均相对湿度则会影响研究区域登革热本地风险水平。
文摘Global incidence of dengue, a vector-borne tropical disease, has seen a dramatic increase with several major outbreaks in the past few decades. We formulate and analyze a stochastic epidemic model for the transmission dynamics of a single strain of dengue virus. The stochastic model is constructed using a continuous time Markov chain (CTMC) and is based on an existing deterministic model that suggests the existence of a backward bifurcation for some values of the model parameters. The dynamics of the stochastic model are explored through numerical simulations in this region of bistability. The mean of each random variable is numerically estimated and these are compared to the dynamics of the deterministic model. It is observed that the stochastic model also predicts the co-existence of a locally asymptotically stable disease-free equilibrium along with a locally stable endemic equilibrium. This co-existence of equilibria is important from a public health perspective because it implies that dengue can persist in populations even if the value of the basic reproduction number is less than unity.
基金supported by grants from the National Institutes of Health,USA(R01 AI083202,D43 TW009527)National Nature Science Foundation of China(81273139)+1 种基金the Project for Key Medicine Discipline Construction of Guangzhou Municipality(2013-2015-07)Technology Planning Project of Guangdong Province,China(2013B021800041)
文摘Objective To explore the associations between the monthly number of dengue fever（DF） cases and possible risk factors in Guangzhou, a subtropical city of China. Methods The monthly number of DF cases, Breteau Index （BI）, and meteorological measures during 2006-2014 recorded in Guangzhou, China, were assessed. A negative binomial regression model was used to evaluate the relationships between BI, meteorological factors, and the monthly number of DF cases. Results A total of 39,697 DF cases were detected in Guangzhou during the study period. DF incidence presented an obvious seasonal pattern, with most cases occurring from June to November. The current month＇s BI, average temperature （Tare）, previous month＇s minimum temperature （Train）, and Tare were positively associated with DF incidence. A threshold of 18.25℃ was found in the relationship between the current month＇s Tmin and DF incidence. Conclusion Mosquito density, Tove, and Tmin play a critical role in DF transmission in Guangzhou. These findings could be useful in the development of a DF early warning system and assist in effective control and prevention strategies in the DF epidemic.
文摘Avian Spirochaetosis is an acute endemic tick-borne disease of birds, caused by Borrelia anserins, a species of Borrelia bacteria. In this paper, we present a compartmental mathematical model of the disease for the bird population and Tick population. The disease steady-state and the conditions for reaching a stable disease-free steady state are determined. The analysis by Lyapunov method shows both local and global stability. Further investigation involves the introduction of controls to the model;the existence and uniqueness of optimal control are established. Finally, the effect of the controls is investigated using numerical solutions.
文摘Objective A diagnostic model was established to discriminate infectious diseases from non-infectious diseases. Methods The clinical data of patients with fever of unknown origin(FUO) hospitalized in Xiangya Hospital Central South University, from January, 2006 to April, 2011 were retrospectively analyzed. Patients enrolled were divided into two groups. The first group was used to develop a diagnostic model: independent variables were recorded and considered in a logistic regression analysis to identify infectious and non-infectious diseases(αin = 0.05, αout = 0.10). The second group was used to evaluate the diagnostic model and make ROC analysis.Results The diagnostic rate of 143 patients in the first group was 87.4%, the diagnosis included infectious disease(52.4%), connective tissue diseases(16.8%), neoplastic disease(16.1%) and miscellaneous(2.1%). The diagnostic rate of 168 patients in the second group was 88.4%, and the diagnosis was similar to the first group. Logistic regression analysis showed that decreased white blood cell count(WBC < 4.0×109/L), higher lactate dehydrogenase level(LDH > 320 U/L) and lymphadenectasis were independent risk factors associated with non-infectious diseases. The odds ratios were 14.74, 5.84 and 5.11(P ≤ 0.01), respectively. In ROC analysis, the sensitivity and specificity of the positive predictive values was 62.1% and 89.1%, respectively, while that of negative predicting values were 75% and 81.7%, respectively(AUC = 0.76, P = 0.00).Conclusions The combination of WBC < 4.0×109/L, LDH > 320 U/L and lymphadenectasis may be useful in discriminating infectious diseases from non-infectious diseases in patients hospitalized as FUO.
文摘In this paper, we build an epidemiological model to investigate the dynamics of the spread of dengue fever in human population. We apply optimal control theory via the Pontryagins Minimum Principle together with the Runge-Kutta solution technique to a “simple” SEIRS disease model. Controls representing education and drug therapy treatment are incorporated to reduce the latently infected and actively infected individual populations. The overall thrust is the minimization of the spread of the disease in a population by adopting an optimization technique as a guideline.
