Principal Component Analysis to Explore Climatic Variability that Facilitates the Emergence of Dengue Outbreak in Karachi

S. A. Ahmed, J. S. Siddiqi, S. Quaiser


Various studies have reported that global warming causes unstable climate and many serious impact to physical environment and public health. The increasing incidence of dengue incidence is now a priority health issue and become a health burden of Pakistan.  In this study it has been investigated that spatial pattern of environment causes the emergence or increasing rate of dengue fever incidence that effects the population and its health. Principal component analysis is performed for the purpose of finding if there is/are any general environmental factor/structure which could be affected in the emergence of dengue fever cases in Pakistani climate. Principal component is applied to find structure in data for all four periods i.e. 1980 to 2012, 1980 to 1995 and 1996 to 2012. The first four PCs for the period (1980-2012, 1980-1994, 1995-2012 and 20102012) are almost the same. The first three PCs of monthly data for Dengue occurrence period (2010-2012) are also similar to the first three PCs, but for this period PC4 is different from other three. The percentage of variance of PC1 and PC2 are highly different to each other, they are around 44 % and 22 % which shows that there are 66 % of total variation factor of Karachi climate. The third component in the variation of Karachi climate is “reverse of variation of wetness and wind speed “which constitutes 18 % of variation. Whereas the PC4 is the contradiction of “temperature” and “wind speed” which is 11.2 % of variation. In the next stage the study is to establish a relationship between climatic variables and dengue fever

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