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Vaccines cause herd immunity. If the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get the disease since others are less likely to become sick from it and spread the disease.
Asthma cases in Americans are about 75% higher today than they were in 1980.
Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.
In the ancient and medieval periods, dysentery killed about ? of all babies before they reach 12 months of age. The disease was transferred through contaminated drinking water, because there was no way to adequately dispose of sewage, which contaminated the water.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.