Climate change and the rising threat of vector-borne diseases in the Andes.

Vector-borne diseases such as dengue, malaria, leishmaniasis, and Chagas disease continue to cause millions of infections and thousands of deaths each year, particularly in low- and middle-income regions of South America. In recent years, climate change has profoundly altered the distribution and behavior of arthropod vectors, promoting their expansion into new ecological niches, including high-altitude areas of the Andes once considered unsuitable for transmission. Countries such as Colombia, Ecuador, Peru, and Bolivia have reported outbreaks of dengue and malaria in populations residing above 2000 m above sea level, revealing an unprecedented epidemiological shift. Importantly, this emerging scenario reflects more than an environmental process: it also exposes deep social vulnerabilities linked to poverty, deforestation, and limited access to health services, which can magnify outbreak impacts and constrain timely response. Within this context, the climate-vector-inequity triad offers an integrative perspective to understand how climatic and structural factors converge to amplify risk. Addressing this challenge requires altitude-sensitive surveillance systems, ecosystem restoration, and health policies grounded in the One Health approach to strengthen prevention, diagnosis, and response capacity in highland regions of the Andes, particularly in vulnerable indigenous and rural communities across Ecuador, Colombia, Peru, and Bolivia where socioeconomic disparities exacerbate transmission risks.