Childhood Viruses Have you ever had measles, chickenpox, or mumps? These illnesses are called childhood illnesses because most of us get them when we are young. When a person gets one of these illnesses, tiny viruses attack the body. These viruses travel from person to person in the drops of water we make when we sneeze or cough, or they spread through food or water. Viruses need to get into our blood before they can make us feel ill. They do this by attaching themselves to our cells and then entering them. When they are inside the cells, they start to take over. Measles and chickenpox cause red patches on the body. However, our bodies do fight back, so these illnesses are usually not very serious. After we have been ill, our special defense cells will recognize the virus if it tries to attack our bodies again. Hence, people will probably get these illnesses only once in their lives. If any of these viruses make you feel miserable, then remember that most of us get them as well— and that we can have them only once! It is best to stay away from school if one catches such a virus and be sure to get complete rest. 4 Which sentence should be removed from the passage?