Original figure, Using information from Haines, 2006

Original figure, Using information from Haines, 2006

Infections that are derived from animals, or zoonotic, are affected when changes with respect to the reservoir animal species (i.e. density and movement of species), and the vectors (i.e. larger species distribution because of new patterns of temperature and humidity) (Franchini, 2015). 

        Chain of infection, Image & description below from CDC

Reservoir

habitat for infectious agent to live, grow, and multiply

includes humans, animals, environment

Transmission

ways the infectious agent can leave reservoir and enter host

Susceptible host

infected individual by the infectious agent due to genetic factors, specific immunity, non-specific

As global temperature increases, reservoir hosts and vector species may spread their habitats into more northern or southern latitudes and/or higher elevations. Because the transmission of many parasites and pathogens depends on free-living wild animal reservoir hosts, a number of vector-borne infectious diseases have recently expanded their geographic range, tracking the range expansion of their hosts whose distribution is tied to climate.
— Simon, 2014 (Article)