Transmission dynamics and control for indoor respiratory infections of measles and influenza
Date Issued
2007
Date
2007
Author(s)
Chen, Szu-Chieh
DOI
en-US
Abstract
The objective of this dissertation is to provide an integrated relevant mathematical model for describing the transmission dynamics, control measures modeling, and cost-effectiveness analysis for indoor respiratory infections including measles and influenza. The empirical evidence of proposed framework is based on the seasonal epidemiological data of influenza and robust age-stratified seroepidemiological data of measles for pre/post-vaccination and setting of nationwide/mountain/rural/urban. In the first phase, three contact patterns of “who acquire infection from who” (WAIFW) matrices are employed to characterize the transmission rate within and between each age group and subsequently the parameters of age-dependent force of infection and age-dependent basic reproduction number (R0) for measles can be quantified. A standard susceptible-exposed-infected-recovery (SEIR) structure can model straightforwardly the dynamics of measles vaccination by using a simple parameterized set of differential equations.
Secondly, Wells-Riley mathematical model is used to predict the influenza infection risk in terms of environmental factors (e.g., room size and ventilation rate) and host factors (e.g., breathing rate and exposure time) and to estimate seasonal-specific age-dependent risk of infection and R0. This study integrates the Wells-Riley mathematical equation and competing-risks model to quantify the impact of combination efforts of indoor air-based engineering and personal protection control measures in containing pandemic influenza within an elementary school. Public health interventions including vaccination and isolation are modeled based on the Von Foerster equation for schoolchildren infected influenza. Then, a critical R0 –θ control line constructed by integrating the Wells-Riley equation, competing-risks model, and the Von Foerster equation, is used to prioritize control measure efforts. The symbol θ,asymptomatic proportion, can be defined as the ratio of the asymptomatic infection over the summation of symptomatic and asymptomatic infection.
In the third phase, an integrated mathematical model linking with the cost-effectiveness-based control methods is developed for preventing from seasonal influenza in an elementary school. The costs and effectiveness of engineering control measurers (ventilation, ultraviolet germicidal irradiation, high-efficiency particulate air filter), personal protection (respiratory masking and handwashing), and public interventions (vaccination and isolation) were collected to perform the cost-effectiveness analysis to minimize the waste of resource and to maximize the health per dollar spent because the seasonal variation in disease transmission may play an important role on modeling the optimal control measures on influenza.
In the present study, the results indicate that the mass regional or nationwide vaccination programmes could greatly reduce the potential for a major measles epidemic. The cost-effectiveness analysis is useful for evaluating the multiple control measures on seasonal influenza. This work can provide a quantitative understanding of the transmission dynamics of measles and influenza. The proposed integrated approach, by employing the mechanism of transmission of indoor respiratory infection, the impact of infectious control programs, and the cost-effectiveness analysis, is a powerful tool for risk profiling prediction of pandemic influenza among schoolchildren.
Subjects
室內呼吸性傳染病
傳輸動態
成本–效益
易感–暴露–感染–復原模式
控制策略
流行性感冒
麻疹
基本再生數
Indoor respiratory infections
Transmission dynamics
Cost-effectiveness
Susceptible-exposed-infected-recovery (SEIR) model
Control strategy
Influenza
Measles
Basic reproduction number (R0)
Type
thesis