Cold viruses grow mainly in the nose where they multiply in nasal cells and are present in large quantities in the nasal fluid of people with colds
The highest concentration of cold virus in nasal secretions occurs during the first three days of infection. This is when infected persions are most contagius.
Nasal secretions containing cold viruses contaminate the hands of people with colds as a result of nose blowing, covering sneezes, and touching the nose. (3-5) Also, cold viruses may contaminate objects and surfaces in the environment of a cold sufferer. (64-66) Young children are the major reservoir of cold viruses and a particularly good source of virus containing nasal secretions.
Experiments have demonstrated that a cold virus readily transfers from the skin and hands of a cold sufferer to the hands and fingers of another person during periods of brief contact. (3-5, 66) Also, cold viruses readily transfer to the hands as a result of touching contaminated objects and surfaces.
Virus on the fingers is transferred into the nose and eye by finger-to-nose and finger-to-eye contact. (3, 66) Virus deposited in the eye promptly goes down the tear duct into the nose. Once in the nose, a cold virus is transported by mucociliary action to the adenoid area where it starts a cold (7, also see How Cold Virus Infection Occurs).
In some instances, cold virus, which is expelled into the air in coughs and sneezes, may land in the nose or eye and cause infection.