A、Through food. B、Through air. C、Through insects. D、Though body fluids. D

A deadly infectious outbreak swept through a small city in Zaire, Africa last spring, killing more than one hundred people. The killer was a rare virus that caused most victims to bleed to death. As scientists rushed to control the outbreak, people in the U.S. wondered "Could it attack here." "We are foolish if we think it couldn’t come to our country," say doctors. The virus can be highly infectious. If you come in contact with a victim’ s blood or other body fluids, you can get
sick, too. All it takes is one infected person to start such a disease. That’ s what scientists believe happened in Zaire. The healthcare workers who treated the first victims there soon fell ill too. The problem was: they had no protective equipment to prevent themselves from being infected. International rescue workers brought equipment to Zaire soon after the out- break occurred. Now the disease appears to be under control. One big mystery is that no one knows where the virus comes from or where it will strike next. Some scientists say that the virus lies inactive in the cells of some kind of plant, insect or other animals, Then it somehow finds a way to infect humans. Scientists are now headed into the jungles of Africa to find out where the virus lives. Once they find the virus, they also hope to find ways to combat it.