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For about 100 years, scientists thought that peptic ulcers were caused by stress, spicy food, and alcohol. Later, researchers added stomach acid to the list of causes and began treating ulcers with antacids. Now it is known that peptic ulcers are predominantly caused by Helicobacter pylori, a spiral-shaped bacterium that normally exist in the stomach.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
Each year in the United States, there are approximately six million pregnancies. This means that at any one time, about 4% of women in the United States are pregnant.
Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.