respiratory syncytial virus (RSV, RS virus), a member of a subgroup of myxoviruses that in tissue culture cause formation of giant cells or syncytia. It is a common cause of epidemics of acute bronchiolitis, bronchopneumonia, and the common cold in young children and sporadic acute bronchitis and mild upper respiratory tract infections in adults. Symptoms of infection with this virus include fever, cough, and severe malaise. The virus occasionally is fatal in infants. Systemic invasion by the virus does not happen, and secondary bacterial invasion is uncommon. Treatment includes rest, high humidity, adequate fluid intake, and, in severe cases, oxygen and ribavirin aerosol. Compare rhinovirus. See also bronchiolitis, bronchitis, bronchopneumonia, cold.
