Abstract

Climate change is fundamentally altering the global distribution of vector borne diseases
(VBDs), which account for over 17% of all infectious diseases and cause more than 700,000
deaths annually. Rising temperatures, changing precipitation patterns, and extreme weather
events are expanding the geographic range of disease vectors such as mosquitoes, ticks, sandflies, and fleas into previously cooler latitudes and altitudes. This comprehensive review
synthesizes evidence from 160 studies (2010–2025) examining the mechanisms, observed
expansions, and projected future distributions of major vector borne pathogens, including
malaria, dengue, chikungunya, Zika, West Nile virus, Lyme disease, anaplasmosis, Crimean
Congo hemorrhagic fever, and leishmaniasis. We analyze the thermal biology of vectors
(temperature dependent development, biting rates, pathogen replication), precipitation effects
on vector habitat, and the role of extreme events (floods, droughts, heatwaves) in outbreak
emergence. Observed range expansions include dengue into Europe and the southern United
States; Lyme disease northward into Canada; malaria into highland regions of East Africa and
South America; West Nile virus across the Americas and Europe; and Crimean Congo
hemorrhagic fever into Southern Europe. We recommend climate adaptive vector surveillance, early warning systems, integrated vector management, public health infrastructure
strengthening in expansion zones, and global climate mitigation. Climate driven VBD
expansion is not a future threat; it is already happening