Re-emergence and global expansion of chikungunya virus: Climate change, vector adaptation, and urbanization

Abstract

Chikungunya Fever has re-emerged over the last two decades as one of the most important arboviral threats to global public health. Once considered a geographically restricted tropical disease, chikungunya virus (CHIKV) has expanded across Africa, Asia, Europe, and the Americas, driven by complex interactions among climate change, globalization, vector adaptation, urbanization, and increasing human mobility. The expansion of competent mosquito vectors, particularly Aedes aegypti and Aedes albopictus, has facilitated sustained transmission in regions previously unsuitable for CHIKV circulation. Climate-associated changes in temperature, rainfall, humidity, and extreme weather events have altered vector ecology and enhanced transmission potential in both tropical and temperate settings. Urbanization, population growth, inadequate sanitation, and expanding peri-urban settlements have further amplified mosquito breeding and human-vector contact. Additionally, adaptive viral mutations, including the E1-A226V mutation, have improved CHIKV fitness in the alternative vector Aedes albopictus, accelerating global spread. Recent outbreaks in Europe, the Americas, and parts of Asia demonstrate the increasing potential for autochthonous transmission outside traditional endemic zones. This review synthesizes current evidence regarding the epidemiological resurgence of CHIKV, emphasizing the interplay between environmental change, vector adaptation, and urbanization. The review also discusses future projections, surveillance challenges, integrated vector management, and the need for climate-informed public health preparedness. Understanding the multifactorial drivers of CHIKV emergence is critical for developing sustainable prevention and control strategies in an increasingly interconnected and warming world.