In fact, they are so small that they defy our imagination. Even the largest virus is billions of times smaller than a speck of dust. Actually a virus is such a strange creature that scientists are not sure whether to call it dead or alive. That s because sometimes it acts as if it were as dead as a stone, while other times it acts as if were truly alive. This very strange creature sometimes displays the properties of the living, while at other times it displays the properties of the dead.
Viruses come in all shapes and sizes and contain different types of genetic material inside.
Yet, as small as it is, it can be far more deadly than even an atom bomb. A few drops of anthrax virus spread in the air is enough to kill billions of people. This is why we are so concerned with biological warfare. America is afraid that some mad scientist will make some deadly virus with which he can terrorize the world. The world is afraid that some crazy dictator will make the anthrax virus and use it to threaten the world.