Respiratory syncytial and other viruses associated with respiratory disease in infants.

Diagnosis by virus isolation and serology was attempted in 377 cases of respiratory-tract infection in infants under one year of age admitted to hospital during two winters. A diagnosis of infection with respiratory syncytial (R.S.) virus was made in 40%, rhinovirus in 6·1%, adenovirus in 3·7%, parainfluenza in 2·1%, enterovirus in 1·9%, and influenza in 1·3%. R.S.-virus infections were more severe than others and occurred mostly in the first five months of life, with a peak at two months. Rhinovirus infections occurred at all ages, and often involved the lower respiratory tract. Of the 12 deaths, only 1 (due to R.S. virus) was not associated with a contributory cause. Maternal antibody to R.S. virus did not notably affect the incidence or severity of R.S.-virus infections.