A cold is a milder illness than influenza. Influenza typically causes fever, muscle aches, and a more severe cough. However, mild cases of influenza are similar to colds. A dults average 2 to 3 colds per year and children 6 to 10, depending on their age and exposure. Children's noses are the major source of cold viruses.
Rhinoviruses are the most important and cause at least one-half of colds.
When on an environmental surface, cold viruses cannot multiply. However, they are still infectious if they are transported from an environmental site into the nose.