Modelling and analysis of dengue disease transmission in urban Colombo: a wavelets and cross wavelets approach

Abstract

Transmission of dengue is a complex dynamic
process. Dengue virus is transmitted to humans by the female
Aedes aegypti mosquitoes. Dengue was first identified in
Sri Lanka during 1960s and the risk due to dengue has increased
rapidly during the past few decades mainly in the urban areas.
There are several studies on dengue transmission based on
mathematical and statistical models. However they are not
capable of describing the complex dynamics of transmission
since its transmission mechanism is highly dependent
on various external factors such as climate, demography,
geography and human mobility. Wavelet analysis is a powerful
tool in mathematics, which can be used to reveal useful
information of a highly non-stationary epidemiological time
series. Wavelet theory can be used to obtain vital signals in a
noisy epidemiological time series, which is useful to implement
early warning systems to control the spread of epidemics. This
particular study was aimed at investigating the applicability
of wavelet theory to analyse dengue transmission in urban
Colombo. The wavelet transformation was performed with data
from weekly dengue cases time series from year 2006 to 2012
in the Colombo Municipal Council (CMC) area, and significant
regions were observed in the spectrum that correspond to
approximately 25 week cycles during the time period from year
2009 to 2012. The cross wavelet power spectrum showed that
rainfall was leading the dengue cases in Colombo during the
time period 2010 to 2012.