It occurs in outbreaks chiefly during the cooler months. In and of itself it is a harmless cold virus but is sometimes mentioned in news stories as a terrible new plague. These respiratory infections cause an estimated 120,000 hospital admissions in young children in the US annually. RSV is a member of the paramyxovirus family. The infection is transmitted directly from person to person, usually hands to nose or eyes.
Large droplets produced by coughing are also infectious.
The virus survives on toy surfaces, and on unwashed hands for up to an hour. Incubation is 2 to 8 days, average 5 days. Babies younger than a month of age shed the most active virus particles, and infants tend to shed the virus for up to a month or longer. Older children and adults only spread the virus for 3 or 4 days of illness. Symptoms of RSV infection are mild to severe upper respiratory tract symptoms, with runny nose, cough and fever.