Rainfall and dengue occurrences in India during 2010–2016

Background: A changing climate scenario coincided with the emergence and re-emergence of vectorborne diseases such as dengue, chikungunya, and Zika. The worldwide resurgence of dengue since 2005 has affected millions and generated huge disease burden, especially in the tropical developing countries including India. While India has a huge burden of dengue with all four serotypes causing outbreaks in different parts of the country, reports on climate and environmental effects on dengue are sparse. Aims and Objectives: To understand the influence of rainfall on dengue occurrences across India between 2010 and 2016, with emphasis on the most affected states. Methods: Dengue occurrence data was obtained by data mining from the NVBDCP and IDSP websites. Area-weighted-rainfall (ARF) were computed from the division-wise data. Statistical analyses performed to analyze the association between annual ARF and dengue occurrences. Spatio-temporal analyses of dengue outbreaks was conducted. Results: Spatio-temporal analyses revealed that high rainfall was positively associated with the number of cases in the northern states (Indo-gangetic Plains) whereas, the reverse was true for the southern (peninsular) states. The number of rural outbreaks of dengue had also been modulated by annual rainfall. Conclusion: Our study revealed the effect of rainfall on dengue in India. We conclude that rainfall influence the dengue occurrences differently in the northern and the southern states of India.