Rhinoviruses are transmitted through the air or via contact. We might expect this sort of transmission to require a fairly healthy host (one who gets out and comes into contact with others) and, hence, to select against virulent strains. If we take precautions and try to stay away from people or avoid any contact with people, more hand-washing stations, increased attention to sanitization, and isolation of patients will help to reduce the transmission of the disease and, in the process, may favor the evolution of less virulent strains of the virus.
The rate of transmission is more among less virulent viruses. Natural selection adaption processes balances virulence factor and spread of transmission.
A highly virulent virus may be highly pathogenic and effect the host seriously rendering him/her immobile and under bed rest. hence the host will not move to many places which might prevent the spread of disease through contacting other persons.
Less virulent viruses on the other hand will have less pathogenic and will not render the patient immobile. So the host will be free to move around everywhere and even if asymptomatic might be a potential carrier of the virus. Hence the rate of transmission will be more in this case.
