In One Health, climate change can influence transmission by altering which components?

• A. Vector distributions, reservoir dynamics, and contact rates across species.
• B. Only human behavior with no ecological changes.
• C. Insurance coverage for livestock.
• D. Global trade policies.

Answer: (D)

Climate change shifts the ecological context in which pathogens spread, changing how infections move through populations. Warmer temperatures and altered rainfall patterns can expand the geographic range of vectors like mosquitoes and ticks, and can lengthen their breeding seasons, which increases the number of transmission events. It can also influence reservoir hosts—wildlife that maintain pathogens—by altering their populations, health, and interactions with vectors and domestic animals. Additionally, climate-driven changes in habitat and movement can modify how often species come into contact across ecosystems, creating new opportunities for pathogens to jump between species. These ecological and interspecies interaction changes are the main ways climate change influences transmission. Socio-economic factors such as insurance coverage or trade policies may affect outbreak response or exposure risk indirectly, but they do not describe the direct biological pathways by which climate affects transmission.