Masrani, Afiqah Syamimi
(2020)
Evaluating the effects of climate on dengue cases in Kelantan.
Masters thesis, Universiti Sains Malaysiia.
Abstract
Introduction: Dengue remains endemic in Kelantan despite considerable investment
in vector control activities. Climate plays an integral role in affecting the magnitude
of dengue incidences and has been integrated into some local Early Warning and
Response System for dengue. In order to enhance the proactive usage of climate factors
for a state-specific, time-based estimation of dengue incidence in Kelantan, the effects
of climate on dengue cases needs to be evaluated.
Objective: The study aims to evaluate the effects of climate on dengue cases in
Kelantan from 2016 to 2018 by analysing the trend of dengue cases in Kelantan,
mapping of incidence rate and spatial clustering of dengue by district, and estimating
the effects of temperature, rainfall and wind speed on dengue cases in Kelantan.
Methodology: The study design uses a retrospective secondary data review of daily
dengue case obtained from the eDengue system and daily minimum temperature,
maximum temperature, mean temperature, cumulative rainfall and average wind speed
obtained from Kota Bharu Weather station from the year 2016 to 2018. Universal
sampling of the 10,645 data obtained was applied following sample size calculation of 10,704. The ArcMap application was used to analyse and map the dengue incidence
rate and spatial clustering of dengue cases through hotspot analysis. The effect of
climate on dengue cases was analysed by using a Poisson generalized additive model
in the “mgcv” package of R software.
Results: There was an average of 9.8 dengue cases daily in Kelantan. A cyclical pattern
was observed with peak cases occurring between April and October annually. The
dengue incidence rate shows a reducing trend with the highest incidence and
significant hotspot identified being in Kota Bharu district. The maximum
temperature, mean temperature, rainfall, and wind speed shown significant non-linear
effect on dengue incidence. The highest peak of dengue incidence found at the
maximum temperature between 31.5˚C to 34˚C, the mean temperature between 23˚C
to 26˚C, rainfall between 20mm to 30mm, and wind speed between 0 m/s to 2 m/s.
Conclusion: There is a limited window of opportunity before the start of the intermonsoon
period for enhanced vector control activities in order to reduce the magnitude
of dengue cases. The changing geography of spatial clusters should also be considered
for a targeted approach. Monitoring of climate variables through interagency
collaboration between the Malaysian Meteorology Department and the Ministry of
Health Malaysia provides an improved early warning system for dengue.
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