Staying home from work every time you are sick could add up to a lot of missed days. In fact, it has been reported that up to 40% of lost time from work is due to the common cold, totaling about 23 million missed days per year.
Germs can spread from direct contact with a sick person or his or her secretions (such as from handshakes or touching shared objects like doorknobs). Some viruses can live on the skin or other surfaces for at least a few hours and continue to infect others.
In addition, viruses can spray a few feet following a cough or sneeze. Especially in the earliest part of illness, when you are most contagious, stay home if you work in close quarters with other people or if you handle food.
Source: CNN