Myxovirus dissemination by air.

Myxoviruses including 150 strains of parainfluenza 1, 15 of parainfluenza 3 and five of influenza B virus were isolated from nasopharyngeal secretions obtained from 300 children less than 3 years of age who developed acute laryngotracheobronchitis during the preceding 48 hours. The patients were examined between October 1966 and January 1967, the peak monthly rate of virus isolation (67%) occurring during January. Parainfluenza 1 virus was isolated from air obtained in the vicinity of one of 30 children whose nasopharyngeal secretions yielded this agent. Samples comprising 150 litres of air were collected for virus assay by placing an Andersen sampler about 60 cm. from the child's face inside an oxygen tent which surrounded the patient. These findings confirm previous observations that parainfluenza 1 virus is the dominant agent associated with acute laryngotracheobronchitis in children in Toronto, and they show that this virus is disseminated in the air.