You can also view previously answered questions in the HSW Question Archive . My son had a friend over and the friend was coughing all over the house. A germ can be either a virus or a bacteria, and each virus and bacteria has a different behavior in the environment.
Anthrax is the same way.
Fortunately smallpox has been eradicated and anthrax is not very infectious. The AIDS virus is fragile. According to this page , it is only viable for a few hours. Hepatitis B, on the other hand, may survive up to a week. Some diseases cannot survive outside the human body.