Distribution Expansion of Dengue Vectors and Climate Change in India

Abstract

Dengue is the most widespread arthropod-borne disease, that has become endemic in more than 100 countries (World Health Organization, 2020). It is usually found in tropical and sub-tropical climates, with a vast majority of dengue cases occurring in the Americas and in South-East Asia (World Health Organization, 2020). In India, dengue has witnessed an alarming upsurge in the past decade, with more than fivefold increase from 28,066 cases in 2010 (NVBDCP, 2010) to 157,315 cases in 2019 (NVBDCP, 2020).The two arthropod vectors of dengue are Aedes (Stegomyia) aegypti (L.) and Aedes (Stegomyia) albopictus (Skuse), which are also responsible for the transmission of several other arboviruses such as the chikungunya virus, yellow fever virus and Zika virus. Aedes aegypti exhibits an indoor resting behavior and primarily feeds on humans during the day (Scott & Takken, 2012). It is mostly found in urban areas and usually breeds in man-made water receptacles such as plastic containers and rubber tyres (Vijayakumar et al., 2014). Aedes albopictus prefers to rest outdoors and is an opportunistic feeder (Paupy et al., 2009), though strong anthropophagic behavior has also been observed in some studies (Delatte et al., 2010;Ponlawat & Harrington, 2005). The presence and population size of these arthropod vectors is highly dependent on climatic factors such as temperature, rainfall and relative humidity. The poikilothermic physiology of mosquitoes renders them sensitive to temperature extremities, which affects larval development as well as vector mortality (Farjana et al., 2012). Rainfall also supports vector populations by providing suitable habitat for development of the aquatic larval stages (Farjana et al., 2012).