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In 1835 it was discovered that a disease of silkworms known as muscardine could be transferred from one silkworm to another, and was caused by a fungus.
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.
About one in five American adults and teenagers have had a genital herpes infection—and most of them don't know it. People with genital herpes have at least twice the risk of becoming infected with HIV if exposed to it than those people who do not have genital herpes.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.
During pregnancy, a woman is more likely to experience bleeding gums and nosebleeds caused by hormonal changes that increase blood flow to the mouth and nose.