Respiratory syncytial virus

Respiratory syncytial virus (RVS) is generally acknowledged as the most important viral respiratory pathogen of early life. RSV infection has been reported in countries which differ widely in geographic location and climate, showing its worldwide distribution. Since its discovery in 1956, several fascinating aspects of RVS infection have been defined. After apparently disappearing from human populations for several months, the virus returns to cause yearly epidemics of respiratory illness. Severe illness due to RSV is seen most commonly in very young infants, despite the presence of pre-existing levels of transplacentally acquired maternal neutralizing antibody. The mechanism by which RSV infection results in severe illness in this particular age group and how RSV infection is associated with the development of clinically evident bronchospasm are still unknown.