Viruses need living beings—including you—to survive.
Unlike bacteria, these very tiny germs can’t multiply outside an animal’s body. They survive by spreading from body to body all over the world.
A few viruses, including the cold virus, travel through the air. Most killer viruses do not. These deadly germs spread by direct contact—an infected mosquito bites a human, for example. The germs enter the victim’s bloodstream and cause serious problems. One group of germs, called hemorrhagic (hem-uh-RAJ-ik) fever viruses, causes victims to become feverish and bleed to death internally.
The map below indicates where some hemorrhagic fever viruses began, and it also shows the animals that spread them. Some sites have only infrequent outbreaks. However, these viruses infect people every year, in locations all over the world.
