Okay kiddo, let's talk about intentional contagion of infection. It means someone wants to make other people sick on purpose.
Let's pretend you have a little sister who you love very much, but sometimes she annoys you. Now, what if you knew that your sister really didn't like getting sick? You might be tempted to sneak over to her while you have a cold and give her a big sneeze, right?
But that would be very mean and not okay to do. In fact, it's against the law to intentionally make someone sick.
People who intentionally try to spread a virus or disease can be called bioterrorists. They might try to do this by coughing or spitting on other people or by contaminating food or water.
It's important to know that intentional contagion of infection is not a game or a joke. It can make people very sick and even cause death. So, if someone ever tries to do this to you or someone you know, tell an adult right away.