They may remain dormant for years, suddenly erupt back into lytic or shedding cycle as a result of stress. The most common of all infectious diseases. Over 200 different viruses may cause cold. Most are RNA viruses in rhinovirus family. Reproduce best at temperatures cooler than body temp.
Infection usually last a week or so, until antibodies to virus are made.
Hand contact much more frequent, and rubbing eyes after contact is most effective way of getting virus into body. No cure available. Virus attacks mucous membranes of upper respiratory tract, sometimes lungs. Most serious problems due to bacteria that invade while defences are weak. Death may occur in infants, elderly.