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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
Only one in 10 cancer deaths is caused by the primary tumor. The vast majority of cancer mortality is caused by cells breaking away from the main tumor and metastasizing to other parts of the body, such as the brain, bones, or liver.
Vaccines prevent between 2.5 and 4 million deaths every year.
Pubic lice (crabs) are usually spread through sexual contact. You cannot catch them by using a public toilet.
Giardia is one of the most common intestinal parasites worldwide, and infects up to 20% of the world population, mostly in poorer countries with inadequate sanitation. Infections are most common in children, though chronic Giardia is more common in adults.