Abstract:
Climate change which is the ultimate outcome of global warming is now universally recognised
as the fundamental human development challenge of the 21st century. Impact of climate change
include extremes in weather events and increase in the ambient temperatures. Among many
adverse consequences, health impacts are also very significant. The impact of climate change
had been studied using dengue incidence as an indicator in the present study since the vector of
the dengue fever, the Aedes mosquito is highly sensitive to climatic variations. Seven out of 25
administrative districts of Sri Lanka were randomly selected representing all climatic zones; wet
zone, intermediate zone, dry zone for this study. The districts thus selected were Colombo,
Gampaha, Kurunegala, Ratnapura, Batticaloa, Kandy and Nuwara-Eliya. Monthly dengue
incidence data for selected seven districts were collected over a 10 years period from 2006 to
2015 from the Epidemiology Unit of the Ministry of Health. Monthly minimum and maximum
temperature and mean rainfall data for the selected seven districts were collected from the
Department of Meteorology. The significance of the impact of climatic parameters such as
rainfall, temperature were tested on the incidence of dengue across years, across months in each
year and across the districts. Poisson regression model was tested for all the 7 districts and the
best model was fitted using the parameters; number of dengue cases in the previous month,
number of dengue cases in the same month of the previous year, rainfall of the given month of
the given year, minimum temperature of the given month of the given year, average temperature
of the given month of the given year, difference of the maximum and minimum temperature of
the given month of the given year. The results revealed that the incidence of dengue is at the
highest in Colombo District, followed by Gampaha and then Kurunegala. Nuwara-Eliya District
showed the lowest. In all the districts, the incidence showed a leap from 2009. There was a
significant difference between the years and the districts in dengue cases. The incident rate of
number of dengue cases of all the 7 districts in the given month of the given year increased by
0.03% for every unit increase in the rainfall of the given month of the given year. Similarly, the
incident rate of the number of dengue cases of all the 7 districts in the given month of the given
year increased by 4% for every unit increase in the difference of the temperature of the given
month of the given year. This study concludes that the incidence of dengue is related to the
climatic variations such as rainfall and temperature which are used as indictors of climatic
change impact.
