Transmission of colds

Rhinorrhea, nasal congestion, and sore throat herald the beginning of the cold season for both children and adults. Although the common cold is a self-limited infection, there are no effective treatments presently available and complications, missed time from work and school, and overall discomfort are not insignificant. Understanding how infections are transmitted may lead to interventions to reduce rates of infection. In order to establish a route of transmission, certain conditions must be met. The virus must be produced and shed at the site of infection. The virus must be deposited in the environment and be able to survive there. The virus must then be able to reach the portal of entry. Finally, interruption of the proposed route of transmission must reduce the incidence of infection under natural conditions. Applying this framework, there is clear evidence in both experimental and home settings that colds can be transmitted via self-inoculation. A small amount of evidence is available relating to large and small particle aerosol transmission. Because rhinovirus is responsible for half of all colds, it has been used as the model to understand how virus is transmitted from one person to another in experimental settings. Rhinovirus has been shown to infect via self-inoculation following hand-to-hand contact with contaminated hands or hand-to-surface contact with contaminated objects in the environment. Similarly, there is convincing evidence that the self-inoculation method of cold virus transmission occurs in the home environment, where colds arre most often transmitted. Aerosol transmission has been studied in the experimental setting and may provide another, albeit less common method for transmission of rhinovirus infection. As more is understood about the transmission of cold viruses, effective methods to interrupt transmission may be devised.