Climate Change and Parasite Epidemiology: Impacts on Vector Distribution, Transmission Dynamics, and Disease Emergence

Abstract

Climate change is increasingly reshaping the epidemiology of parasitic and vector-borne diseases by altering the environmental conditions that govern vector distribution, parasite development, transmission seasonality, and host exposure. Rising temperatures, shifting rainfall, humidity, drought, flooding, vegetation change, and altered land use affect the survival, reproduction, activity, and establishment of arthropod vectors such as mosquitoes and ticks, expanding vector suitability into cooler temperate, highland, or higher-latitude regions while reducing transmission where heat or moisture becomes unfavourable. Climate change thus redistributes parasitic disease risk rather than uniformly increasing it. Transmission dynamics are further shaped by changes in vectorial capacity, extrinsic incubation period, seasonal activity, environmental survival of parasite stages, grazing patterns, reservoir-host distribution, and human-animal-environment contact. In livestock and wildlife systems, temperature and moisture influence free-living parasite stages on pasture and modify host exposure to infective stages. Climate change may also drive the emergence or re-emergence of parasitic diseases by creating newly suitable ecological niches for vectors, parasites, intermediate hosts, and reservoirs, although emergence rarely results from climate alone, depending instead on interactions with land use, animal movement, urbanisation, travel, trade, and surveillance capacity. This review synthesises key pathways linking climate change to parasite epidemiology, emphasizing vector distribution, transmission dynamics, and disease emergence, and argues for a One Health approach integrating climate-informed surveillance, preparedness, vector monitoring, and adaptive control strategies.