The Health & Wellness Show: Some of my best friends are germs

The human body is teeming with billions -- nay, TRILLIONS -- of microbes with over a thousand different species populating the gut alone. We are covered with bacteria, fungi, viruses and parasites from the top of our heads to the bottom of our feet, inside and out. How did we come to be populated with such a vast array of these little beasties and what's their purpose? What influence do they exert on our physical and mental health and, more importantly, what can we do (and what can we avoid...