"In 2012, none of America's top killers are contagious. You don't get cancer, diabetes, or heart disease at the swimming pool or just because someone sneezed on you. But a hundred years ago, you probably died from something you caught . While hygiene and modern medicine have thankfully eliminated the deadliest of those bugs, there's still plenty of parasites, bacteria, and viruses hoping to reproduce in the warm, cozy environment of your body. Like it or not, we and these microbes are intimately intertwined.
Climate change is expanding the geographic reach of some diseases, possibly including hantavirus, brain eating amoebas , and at least seven others ."