scholarly journals Analysis and multiple control measures for a typhoid fever disease model

2021 ◽  
Vol 1734 ◽  
pp. 012053
Author(s):  
O C Collins ◽  
J E Okeke
Keyword(s):  
Typhoid Fever ◽  
Disease Model ◽  
Control Measures ◽  
Multiple Control

scholarly journals Estimating Economic Losses Caused by COVID-19 under Multiple Control Measure Scenarios with a Coupled Infectious Disease—Economic Model: A Case Study in Wuhan, China

2021 ◽  
Vol 18 (22) ◽  
pp. 11753
Author(s):  
Xingtian Chen ◽  
Wei Gong ◽  
Xiaoxu Wu ◽  
Wenwu Zhao
Keyword(s):  
Infectious Disease ◽  
Economic Model ◽  
Control Measure ◽  
Central Valley ◽  
Economic Cost ◽  
Assessment Method ◽  
Control Measures ◽  
Economic Losses ◽  
Multiple Control ◽  
Health Crisis

Background: The outbreak of the COVID-19 epidemic has caused an unprecedented public health crisis and drastically impacted the economy. The relationship between different control measures and economic losses becomes a research hotspot. Methods: In this study, the SEIR infectious disease model was revised and coupled with an economic model to quantify this nonlinear relationship in Wuhan. The control measures were parameterized into two factors: the effective number of daily contacts (people) (r); the average waiting time for quarantined patients (day) (g). Results: The parameter r has a threshold value that if r is less than 5 (people), the number of COVID-19 infected patients is very close to 0. A “central valley” around r = 5~6 can be observed, indicating an optimal control measure to reduce economic losses. A lower value of parameter g is beneficial to stop COVID-19 spread with a lower economic cost. Conclusion: The simulation results demonstrate that implementing strict control measures as early as possible can stop the spread of COVID-19 with a minimal economic impact. The quantitative assessment method in this study can be applied in other COVID-19 pandemic areas or countries.

MODELING CHOLERA TRANSMISSION UNDER DISEASE CONTROL MEASURES

2020 ◽  
pp. 1-26
Author(s):  
MARGARET BROWN ◽  
MIKO JIANG ◽  
CHAYU YANG ◽  
JIN WANG
Keyword(s):  
Disease Control ◽  
Disease Transmission ◽  
Control Measures ◽  
Transmission Dynamics ◽  
Threshold Dynamics ◽  
Education Programs ◽  
Multiple Control ◽  
Indirect Transmission ◽  
Transmission Pathways ◽  
The Impact

We present a new mathematical model to investigate the transmission dynamics of cholera under disease control measures that include education programs and water sanitation. The model incorporates the impact of education programs into the disease transmission rates and that of water sanitation into the environmental pathogen dynamics. We conduct a detailed analysis to the autonomous system of the model and establish the local and global stabilities of its equilibria that characterize the threshold dynamics of cholera. We then perform an optimal control study on the general model with time-dependent controls and explore effective approaches to implement the education programs and water sanitation while balancing their costs. Our analysis and simulation highlight the complex interaction among the direct and indirect transmission pathways of the disease, the intrinsic growth of the environmental pathogen and the impact of multiple control measures, and their roles in collectively shaping the transmission dynamics of cholera.

A SATURATED TREATMENT MODEL FOR THE TRANSMISSION DYNAMICS OF RABIES

2019 ◽  
Vol 4 (1) ◽  
pp. 201
Author(s):  
A A Ayoade ◽  
O J Peter ◽  
T A Ayoola ◽  
S Amadiegwu ◽  
A A Victor
Keyword(s):  
Incidence Rate ◽  
Nonlinear Differential Equations ◽  
Viral Disease ◽  
Control Measures ◽  
Transmission Dynamics ◽  
Infectious Agents ◽  
Multiple Control ◽  
Saturated Incidence Rate ◽  
Saturated Incidence ◽  
Saturated Treatment

Rabies is a viral disease that claims about 59 000 lives globally every year. The ignorance of the fact that man can be a carrier of the disease makes every practical and theoretical approach towards the study of the disease a good development. In this work, a mathematical model is designed to incorporate a saturated incidence rate such that the incidence rate is saturated around the infectious agents. The model is studied qualitatively via stability theory of nonlinear differential equations to assess the effects of general awareness, constant vaccination and the saturated treatment on the transmission dynamics of rabies disease. The effective reproduction number is derived and the numerical simulation is carried out to verify the analytical results. It is discovered that while general awareness plays pivotal roles in averting rabies death, multiple control measures have the tendency of driving rabies to extinction.

Investigation of Typhoid Fever and Cholera Transmission by Raw Wastewater Irrigation in Santiago, Chile

1993 ◽  
Vol 27 (3-4) ◽  
pp. 167-174 ◽  
Author(s):  
Hillel I. Shuval
Keyword(s):  
Typhoid Fever ◽  
Indirect Evidence ◽  
Salmonella Typhi ◽  
Control Measures ◽  
Capital City ◽  
Irrigation Season ◽  
Main Mode ◽  
Modes Of Transmission ◽  
Irrigated Crops ◽  
Raw Wastewater

Santiago, the capital city of Chile, has suffered for years from high rates of typhoid fever, reaching peaks as high as 210 cases/100,000 in 1977 and 1982. Many officials suspected that the use of raw wastewater to irrigate 13,500 ha of vegetables and salad crops may have been one of the modes of transmission. However, control measures have in general been ineffective. In April, 1991 an outbreak of 41 cases of cholera occurred in Chile probably initiated by the penetration of cholera cases from adjacent Peru which was undergoing an explosive cholera epidemic. Investigations showed that there was strong circumstantial evidence supporting the hypothesis of typhoid and cholera transmission by wastewater irrigated crops. From data gathered it is shown that while there was little seasonal typhoid fever variation in the rest of the country, there was a decided summer peak in Santiago that coincided with the peak irrigation season and harvesting of sewage irrigated vegetables. In the 1991 cholera outbreak, which occurred during the irrigation season, 68% of the cases had consumed wastewater irrigated salad crops eaten uncooked. Salmonella typhi and Vibrio cholerae were isolated by “Moore” pads from raw wastewater in canals leading to irrigated vegetable plots. Other direct and indirect evidence supports the case of wastewater irrigated vegetables as the main mode of transmission. Emergency cholera control measures, including heavy chlorination of raw wastewater, partially settled by flowing in slow moving irrigation canals, are reviewed.

scholarly journals Modeling Yield Losses and Fungicide Profitability for Managing Fusarium Head Blight in Brazilian Spring Wheat

2020 ◽  
Vol 110 (2) ◽  
pp. 370-378
Author(s):  
Maíra Rodrigues Duffeck ◽  
Kaique dos Santos Alves ◽  
Franklin Jackson Machado ◽  
Paul David Esker ◽  
Emerson Medeiros Del Ponte
Keyword(s):  
Fusarium Head Blight ◽  
Disease Model ◽  
Wheat Yield ◽  
Quality Parameters ◽  
Control Measures ◽  
Wheat Crop ◽  
Yield Losses ◽  
Head Blight ◽  
Yield Data ◽  
Profitability Analysis

Fusarium head blight (FHB) and wheat yield data were gathered from fungicide trials to explore their relationship. Thirty-seven studies over 9 years and 11 locations met the criteria for inclusion in the analysis: FHB index in the untreated check ≥ 5% and the range of index in a trial ≥ 4 percentage points. These studies were grouped into two baseline yields, low (Yl ≤ 3,631 kg ha−1) or high (Yh > 3,631 kg ha−1), defined based on the median of maximum yields across trials. Attainable (disease-free) yields and FHB index were predicted using a wheat crop and a disease model, respectively, in 280 simulated trials (10 planting dates in a 28-year period, 1980 to 2007) for the Passo Fundo location. The damage coefficient was then used to calculate FHB-induced yield loss (penalizing attainable yield) for each experiment. Losses were compared between periods defined as before and after FHB resurge during the early 1990s. Disease reduction from the use of one or two sprays of a triazole fungicide (tebuconazole) was also simulated, based on previous meta-analytic estimates, and the response in yield was used in a profitability analysis. Population-average intercepts but not the slopes differed significantly between Yl (2,883.6 kg ha−1) and Yh (4,419.5 kg ha−1) baseline yields and the damage coefficients were 1.60%−1 and 1.05%−1, respectively. The magnitudes and trends of simulated yield losses were in general agreement with literature reports. The risk of not offsetting the costs of one or two fungicide sprays was generally higher (>0.75) prior to FHB resurgence but fungicide profitability tended to increase in recent years, depending on the year. Our simulations allowed us to reproduce trends in historical losses, and may be further adjusted to test the effect and profitability of different control measures (host resistance, other fungicides, etc.) on quality parameters such as test weight and mycotoxin contamination, should the information become available.

Discrete Switching Host-Parasitoid Models with Integrated Pest Control

2014 ◽  
Vol 24 (09) ◽  
pp. 1450114 ◽  
Author(s):  
Changcheng Xiang ◽  
Zhongyi Xiang ◽  
Sanyi Tang ◽  
Jianhong Wu
Keyword(s):  
Pest Control ◽  
Complex Dynamics ◽  
Control Measures ◽  
Switching Frequency ◽  
Multiple Attractors ◽  
Multiple Control ◽  
Different Types ◽  
Existence And Stability ◽  
Numerical Bifurcation ◽  
Integrated Pest Control

The switched discrete host-parasitoid model concerning integrated pest management (IPM) has been proposed in the present work, and the economic threshold (ET) is chosen to guide the switches. That is, if the density of host (pest) population increases and exceeds the ET, then the biological and chemical tactics are applied together. Those multiple control measures are suspended once the density of host falls below the ET. Firstly, the existence and stability of several types of equilibria of switched system have been discussed briefly, and two- or three-parameter bifurcation diagrams reveal the regions of different types of equilibria including regular and virtual equilibria. Secondly, numerical bifurcation analyses show that the switched discrete system may have very complex dynamics including the co-existence of multiple attractors and switched-like behavior among attractors. Finally, we address how the key parameters and initial values of both host and parasitoid populations affect the host outbreaks, switching frequencies or mean switching frequency, and consequently the relative biological implications with respect to pest control are discussed.

scholarly journals Analysis of Control Interventions against Malaria in communities with Limited Resources

2021 ◽  
Vol 29 (2) ◽  
pp. 71-91
Author(s):  
E.A. Bakare ◽  
B.O. Onasanya ◽  
S. Hoskova-Mayerova ◽  
O. Olubosede
Keyword(s):  
Optimal Control ◽  
Malaria Transmission ◽  
Control Strategies ◽  
Indoor Residual Spraying ◽  
Control Measures ◽  
Limited Resources ◽  
Effective Control ◽  
Bed Nets ◽  
Multiple Control ◽  
Potential Impact

Abstract The aim of this paper is to analyse the potential impact of multiple current interventions in communities with limited resources in order to obtain optimal control strategies and provide a basis for future predictions of the most effective control measures against the spread of malaria. We developed a population-based model of malaria transmission dynamics to investigate the effectiveness of five different interventions. The model captured both the human and the mosquito compartments. The control interventions considered were: educational campaigns to mobilise people for diagnostic test and treatment and to sleep under bed nets; treatment through mass drug administration; indoor residual spraying(IRS) with insecticide to reduce malaria transmission; insecticide treated net (ITN) to reduce morbidity; and regular destruction of mosquito breeding sites to reduce the number of new mosquito and bites/contact at dusks and dawn. Analysis of the potential impact of the multiple control interventions were carried out and the optimal control strategies that minimized the number of infected human and mosquito and the cost of applying the various control interventions were determined.

scholarly journals Shigellosis Dynamics: Modelling the Effects of Treatment, Sanitation, and Education in the Presence of Carriers

2020 ◽  
Vol 2020 ◽  
pp. 1-19
Author(s):  
Stephen Edward ◽  
Eunice Mureithi ◽  
Nyimvua Shaban
Keyword(s):  
Potential Role ◽  
Control Strategies ◽  
Control Measure ◽  
Control Measures ◽  
Reproductive Number ◽  
Direct Transmission ◽  
Multiple Control ◽  
Globally Asymptotically Stable ◽  
Indirect Transmission ◽  
Dynamics Modelling

A mathematical model for Shigellosis including disease carriers with multiple control strategies is developed. We compute the effective reproductive number Re, which is used to analyze the local stability of the equilibria, while the comparison theorem is used to prove global stability. By constructing a suitable Lyapunov function, the model endemic equilibrium is globally asymptotically stable when Re>1. Sensitivity analysis is performed to investigate the parameters that have a high impact on the transmission dynamics of the disease with direct transmission contributing more infections than indirect transmission. The effects of control measures are then investigated both analytically and numerically. Numerical results show that there is a reduction in the number of infections when at least a single control measure is applied efficiently. However, as the number of control interventions increases, Shigellosis elimination is more possible. Results also show that carriers play a potential role in the prevalence of Shigellosis and ignoring these individuals could potentially undermine the efforts of containing this epidemic.

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