Rainfall and Chikungunya incidences in India during 2010-2014.

Changing climate scenario has resulted in recent emergence and re-emergence of various arboviral diseases including Chikungunya. This disease is caused by Chikungunya virus (CHIKV), which belongs to Togaviridae family of viruses and spread by Aedes mosquitoes. A resurgence of CHIKV and its rapid global spread has been observed since 2004. The disease reemerged in India in 2005, after a gap of 32 years, causing massive outbreaks in some states and circulating thereafter. In the present paper we analyze CHIKV incidence data from India (2010-2014) with a view to understand association with environmental parameters, if any. Data on country-wide occurrences of CHIKV cases were considered from the National Vector Borne Disease Control Board, India. Meteorological data for different climatic subdivisions of India were obtained and processed mathematically. State-wise association of number of cases with rainfall, if any, were studied by statistical analyses. We observe that prevailing temperature range was favorable for CHIKV propagation and the occurrences were modulated by average rainfall. Most affected states were West Bengal, Maharashtra and Karnataka. Overall for India, favorable climatic conditions have contributed to incidences of CHIKV during the study period. There is strong positive association between rainfall variations and occurrence of CHIKV cases.