Myxovirus Infections in Acute Laryngotracheobronchitis, Toronto, 1961-62.

Virological investigations were undertaken on nasopharyngeal secretions from 186 children who were admitted to the Hospital for Sick Children, Toronto, with acute laryngotracheobronchitis between December 1961 and March 1962. Patients who required tracheotomy for relief of respiratory obstruction were excluded from this series. Myxoviruses which were isolated from 47 patients included the following antigenic types: 29 Parainfluenza-1, four Parainfluenza-2, five Parainfluenza-3 and nine Influenza B. The average duration of hospitalization, 3.0 days, was identical for the 47 virus-positive patients and the entire group of 186 patients. Ages of 135 patients were less than three years.Between November 1960 and March 1962, myxoviruses were isolated from 150 of 445 laryngotracheobronchitis patients. The dominant strain, Parainfluenza-1, was isolated from 119 patients who became ill between November 1960 and April 1961, and between October 1961 and March 1962. Parainfluenza-3 virus was isolated irregularly from patients during both cool and warm months. Influenza B and Parainfluenza-2 isolations were made only during 1961-62 winter. Rising antibody levels in paired sera from 20 of 23 Parainfluenza-1 virus excretors and in four patients who yielded Parainfluenza-3 virus confirmed infection with these agents.