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There are more sensory neurons in the tongue than in any other part of the body.
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.
Before a vaccine is licensed in the USA, the Food and Drug Administration (FDA) reviews it for safety and effectiveness. The CDC then reviews all studies again, as well as the American Academy of Pediatrics and the American Academy of Family Physicians. Every lot of vaccine is tested before administration to the public, and the FDA regularly inspects vaccine manufacturers' facilities.
There are approximately 3 million unintended pregnancies in the United States each year.
The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.