How do germs spread (and why do they make us sick)?

An animation that explains varying modes of transmission

http://ed.ted.com/lessons/how-do-germs-spread-and-why-do-they-make-us-sick-yannay-khaikin-and-nicole-mideo

"Germs are found on almost every surface we come in contact with, which makes it incredibly common for our bodies to be exposed to them. But why are some of these germs relatively harmless, while others can be fatal? Yannay Khaikan and Nicole Mideo explore this question by examining germs' varying modes of transmission."

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