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The first-known contraceptive was crocodile dung, used in Egypt in 2000 BC. Condoms were also reportedly used, made of animal bladders or intestines.
There are more bacteria in your mouth than there are people in the world.
Pubic lice (crabs) are usually spread through sexual contact. You cannot catch them by using a public toilet.
Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
IgA antibodies protect body surfaces exposed to outside foreign substances. IgG antibodies are found in all body fluids. IgM antibodies are the first type of antibody made in response to an infection. IgE antibody levels are often high in people with allergies. IgD antibodies are found in tissues lining the abdomen and chest.