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Malaria was not eliminated in the United States until 1951. The term eliminated means that no new cases arise in a country for 3 years.
A strange skin disease referred to as Morgellons has occurred in the southern United States and in California. Symptoms include slowly healing sores, joint pain, persistent fatigue, and a sensation of things crawling through the skin. Another symptom is strange-looking, threadlike extrusions coming out of the skin.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Many of the drugs used by neuroscientists are derived from toxic plants and venomous animals (such as snakes, spiders, snails, and puffer fish).
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.