Most viruses are frail little things (unlike bacteria and fungi, viruses aren’t even alive) that can multiply only inside a living host (including animals, plants, and even bacteria). There they spread, overwhelming and attacking the host’s immune system and causing all sorts of nasty, symptoms. Colds, flus, chickenpox, immune disorders, and measles are caused by viruses. Among the worst is Ebola, which triggers bleeding and is fatal to more than half the people who catch it.
When viruses invade a body’s cells and begin to multiply, they make the host sick. Viruses can cause all sorts of diseases. Viruses are very small and lightweight. They can float through the air; survive in water, or even on the surface of your skin. Viruses can be passed from one person to another by shaking hands, touching food, through water, or through the air when a person coughs or sneezes. Viruses can also be passed on by insect bites, animals, or through bad food.
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