Publication Date

3-16-2012

Abstract

Dengue fever is a mosquito-transmitted disease that is endemic in many parts of the tropical world and affects a significant proportion of the human population. Temperature is known to influence aspects of the dengue transmission cycle, which has consequences for disease dynamics. Previous work has explored the effects of temperature on the mortality rate of the mosquito and the resulting population change. However, there is substantial evidence that the extrinsic incubation period (EIP) of the pathogen within the vector host, Aedes aegypti, is also temperature dependent. This dependence has not been thoroughly researched. We present a single serotype compartmental model with a gamma-distributed exposed vector class to account for a temperature-dependent EIP. Where appropriate, temperature-dependent vector mortality is convolved with the temperature dependent EIP using the mortality function presented by Yang et al. [49]. Both seasonal and diurnal temperature changes are examined for their potential effects upon dengue persistence. The mean and range of temperature fluctuations that facilitate persistence are presented based upon the EIP function, initial conditions, seasonal temperature forcing with and without vector mortality, as well as seasonal and diurnal temperature forcing with and without vector mortality. With seasonal forcing and temperature dependence only in the EIP, all simulations with mean temperatures above 26 C show persistence. However, if vector mortality is also variable, persistence is no longer possible in higher temperatures with higher temperature ranges. Diurnal forcing exacerbates this effect limiting persistence to mean temperatures of 23 C to 34 C with variable temperature ranges. It is clear that more data are needed to reduce the uncertainty in estimating the relationships between both EIP and vector mortality because these relationships can have large effects on disease dynamics. Additionally, this work demonstrates that when modeling temperature-dependent effects, it is vital to not only include seasonal variation in temperature but also diurnal variation.

Degree Name

Mathematics

Level of Degree

Masters

Department Name

Mathematics & Statistics

First Advisor

Wearing, Helen

First Committee Member (Chair)

Embid, Pedro

Second Committee Member

Nitsche, Monika

Language

English

Keywords

Dengue--Environmental aspects, Dengue viruses-- Effect of temperature on, Aedes aegypti--Effect of temperature on.

Document Type

Thesis

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