Effects of the Weather on Dengue Infections in Kolkata, India

Environmental elements including weather variables may play important role in the transmission of dengue. The present study has examined the impact of weather variation on dengue transmission in Kolkata, India in the year 2014. The study is conducted on impact of weather variants like various parameters of temperature, rainfall and relative humidity on dengue transmission in the city of Kolkata. Data on monthly-reported cases of dengue in 2014 have been obtained from Gautam Laboratories Imaging and Research Centre, Kolkata. Seasonal variability parameters include maximum, minimum and mean temperature ( ° C), monthly rainfall (mm), rainy days, total in wetting months (mm) and relative humidity (%). Chi-square test is used to find the differences relating to seasonal variability data. Poisson regression analysis is performed using data on monthly weather variables and dengue cases. In the month of August dengue infection started to disseminate which is found to reach its peak in the month of October. Relative humidity and monthly rainfall are found to be the significant predictors of dengue incidence in Kolkata. Maximum rainfall and humidity during the month of July may trigger the dissemination of dengue and the infections breakout in successive months in Kolkata. Number of dengue cases in Kolkata increased with increase in the number of rainy days as well as relative humidity and a fall of ambient temperature.