Climate change will dramatically and adversely affect mankind's relationship to germs, bacteria, and viruses. Examples of these changes are the West Nile Virus and the Zika virus which have recently begun to invade the US. Due to drastic changes in weather where wet regions become arid and dry and once dry regions become tropical and wet, you might see areas of the world that were once relatively free of tropical viruses and diseases experience epidemics or even pandemics.