Determining environmental and socioeconomic risk factors for dengue infection among the resident population of Kandy District, Sri Lanka

Dengue is a frequently debilitating and potentially life-threatening flaviviral infection of humans that is transmitted via Aedes spp. mosquitoes. The global incidence of dengue has escalated dramatically during and since the second half of the twentieth century to the point where today there are estimated to be some 400 million infections per annum, of which a quarter produce clinical symptoms. Currently, over 22,000 fatalities are attributed directly to severe disease complications, while many more suspected cases go unconfirmed. The increasing worldwide incidence of dengue correlates with the expanding distribution of vector mosquitoes in tropical and subtropical regions, together with other contributing factors such as rising urbanization and accelerated changes in climate. Like elsewhere in South Asia the disease has become endemic to Sri Lanka. All four authenticated dengue virus serotypes (DENV 1-4) co-circulate in the island nation, thereby posing a major public health risk. The country regularly experiences seasonal outbreaks of infection, usually following the monsoon rains that trigger an explosion of local mosquito populations. Kandy, the main city of the Central Highlands, is a hot spot for dengue incidence and was a regional focus of the 2016-17 epidemic. This significant outbreak highlighted the susceptibility of resident communities to dengue haemorrhagic fever and dengue shock syndrome, for which timely and accurate clinical diagnosis is required to enable implementation of an appropriate treatment regimen. Therapeutic intervention is a later step of an integrated approach to control and prevention of dengue. Here, we discuss environmental and socioeconomic risk factors for dengue pertaining to Kandy District, identify local knowledge gaps and propose ways in which these earlier steps should be explored. A deeper understanding of the variables affecting dengue prevalence and distribution will facilitate better disease management, vector surveillance and infection control in this increasingly endemic area.