Dengue in South Asia: Emerging epidemiological patterns and surveillance obstacles

This systematic review synthesizes current knowledge on dengue epidemiology, serotype distribution, and surveillance systems across four South Asian countries: India, Bangladesh, Sri Lanka, and Bhutan. Through analysis of peer-reviewed literature (2000-2024) and official health reports, the study examines the historical progression from sporadic outbreaks to hyperendemic circulation of multiple dengue virus serotypes (DENV-1 through DENV-4). The findings reveal significant epidemiological shifts across the region, with all countries experiencing increasing case numbers, expanding geographic distribution, and evolving viral genetics. India demonstrates remarkable serotype diversity with all four serotypes circulating nationwide. Bangladesh has transitioned from epidemic to endemic transmission with sequential serotype dominance. Sri Lanka exhibits bimodal seasonal patterns with record outbreaks despite improved case fatality rates. Bhutan presents a unique case…