1. About 7 billion people live on Earth today, but there are more germs than that on and inside your body right now. They’re on your skin and under your fingernails. They’re inside your mouth, nose, and intestines. They’re even in your eyelashes.
2. Between 1914 and 1918, about 20 million people had died in World War I. Just as the war was ending, Spanish flu swept across Europe. It killed 25 million people in 6 months.
3. Some bacteria divide every twenty minutes. In just three days, one of them could produce enough new bacteria to equal the mass of the entire Earth.
4. Almost every illness you can think of is caused by a germ. Scientists have identified at least 5,000 kinds of viruses and 30,000 kinds of bacteria. There are probably thousands more left to discover.
5. You can’t catch a cold from a dog or cat, but you can get the flu from a horse, a pig, or even a duck.