Emerging infectious diseases (sometimes called new diseases) are illnesses caused by germs (like bacteria, viruses, or parasites) that spread to people who weren't affected before. These diseases often start in animals and can spread to humans. Examples include Zika virus, SARS, and Ebola. Germs can spread between people very quickly and cause a lot of people to get sick, so it is important to try to stop them from spreading. This includes washing your hands, not touching animals you don't know, and staying away from people who are sick. Vaccines are another way to prevent the spread of infectious diseases. Vaccines introduce a germ that is similar to the germ causing the disease, which helps your body recognize and fight the germ if you ever get exposed.