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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.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.
Nearly 31 million adults in America have a total cholesterol level that is more than 240 mg per dL.
When blood is exposed to air, it clots. Heparin allows the blood to come in direct contact with air without clotting.
More than 50% of American adults have oral herpes, which is commonly known as "cold sores" or "fever blisters." The herpes virus can be active on the skin surface without showing any signs or causing any symptoms.