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Every 10 seconds, a person in the United States goes to the emergency room complaining of head pain. About 1.2 million visits are for acute migraine attacks.
There are more nerve cells in one human brain than there are stars in the Milky Way.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
Cytomegalovirus affects nearly the same amount of newborns every year as Down syndrome.