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Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
About 3.2 billion people, nearly half the world population, are at risk for malaria. In 2015, there are about 214 million malaria cases and an estimated 438,000 malaria deaths.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
The top five reasons that children stay home from school are as follows: colds, stomach flu (gastroenteritis), ear infection (otitis media), pink eye (conjunctivitis), and sore throat.