Some viruses, like cold and flu, can live on external surfaces for up to a week. The length of time microbes live outside the body depends on the environment and the characteristics of the microbe itself.
Some germs, such as bacteria, can reproduce and colonize on surfaces around the house. Escherichia coli (E. coli) is an example of a germ that thrives at room temperature. Some germs, such as staphylococcus aureus, can survive for several weeks because they do not require much moisture. While most germs do die, there are some that can lie dormant for months or even years until the right exposure to humidity, air temperature and food allows them to reactivate.