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Mathematical modelling of dengue epidemics : a numerical approach
Author
Loh, Stephen Wai Kin
Supervisor
Ang, Keng Cheng
Abstract
Dengue fever (DF) and the more severe dengue haemorrhagic fever (DHF) are two of the most serious vector-borne diseases in South East Asia. The disease is transmitted to susceptible humans through the bites of infected species of the Aedes mosquitoes such as Aedes aegypti and Aedes albopictus. Although Singapore has adopted many effective control measures to curb the spread of dengue, there is a resurgence of the disease in recent years. This has initiated a review of current measures, with the aim of minimising or delaying the onset of another epidemic.
The aim of this thesis is to present a plausible model that will highlight the future trend of dengue in Singapore. The model introduces factors such as vector population and rainfall that are known to be significantly associated with increased dengue incidence. These important factors were either assumed to be constant or not taken into consideration at all in past models.
In this model, larvae densities are used to represent a varying vector population. In particular, the model assumes that the proportion of infected vectors is a function of rainfall level since the arrival of rainfall increases potential breeding sites.
The results show that the proportion of infected vectors is approximately 0.9 at the peak of the dengue outbreak in October 1996. It is also shown that increased rainfall and larvae density precede am increase in dengue incidence by 8 and 2 weeks respectively. Consequently, the model compares much better to the actual number of dengue cases during the simulation period than an existing model.
These results are obtained by adopting a numerical approach as an analytical solution is not possible with this model. In addition, the model offers flexibility and ease of control in testing the effect of varying crucial factors related to the spread of dengue.
The aim of this thesis is to present a plausible model that will highlight the future trend of dengue in Singapore. The model introduces factors such as vector population and rainfall that are known to be significantly associated with increased dengue incidence. These important factors were either assumed to be constant or not taken into consideration at all in past models.
In this model, larvae densities are used to represent a varying vector population. In particular, the model assumes that the proportion of infected vectors is a function of rainfall level since the arrival of rainfall increases potential breeding sites.
The results show that the proportion of infected vectors is approximately 0.9 at the peak of the dengue outbreak in October 1996. It is also shown that increased rainfall and larvae density precede am increase in dengue incidence by 8 and 2 weeks respectively. Consequently, the model compares much better to the actual number of dengue cases during the simulation period than an existing model.
These results are obtained by adopting a numerical approach as an analytical solution is not possible with this model. In addition, the model offers flexibility and ease of control in testing the effect of varying crucial factors related to the spread of dengue.
Date Issued
2001
Call Number
QA401 Loh
Date Submitted
2001