Towards the end of the disease, there is extensive, generalized virus infection in lymphoid tissues and skin. Both live and killed vaccines exist. First isolated in 1956 and subsequently recognised as a major cause of L.R.T. disease in infants and young children. In culture, causes characteristic syncytial masses - hence the name. Highly infectious, transmission by respiratory secretions.
Primary multiplication occurs in epithelial cells of U.R.T. producing a mild illness.
Has been suggested as a possible factor in cot death.