Serologic response of incividuals infected with para influenza viruses.

Abstract

THE PARA influenza viruses Types 1 (hemadsorption Type 2), 2 (CA), and 3 (hemadsorption Type 1) are newly recognized members of the myxovirus family which have been recovered from persons with various types of respiratory illness.' 2 These agents possess certain biologic and antigenic properties which separate them from the influenza viruses.3'4 The para influenza viruses appear to play an important role in childhood respiratory illness. On a yearround basis, para influenza 1 and 3 viruses have been isolated from 6 per cent of children with all types of respiratory illness, and during certain months the recovery rate from children with upper respiratory illness has been as high as 20 per cent.5'6 Para influenza 1 virus has been the most important single agent associated with acute laryngotracheobronchitis (croup) of infancy and early childhood; this agent has been recovered from 20 per cent of patients with this syndrome.5'7 Recently para influenza 1 virus has been recovered from adults with febrile upper respiratory illness.8'9 During the course of a study of the microbiologic experience of infants and children under three years of age in a welfare nursery, we had the opportunity to observe outbreaks of infection with para influenza 1 virus and with para influenza 3 virus. This report will describe an evaluation of the available serodiagnostic procedures employing specimens derived from the nursery outbreaks. Throat swab specimens were obtained from the nursery children at weekly intervals and at the onset of a febrile illness (temperatures of greater than 100.6 F rectally). These specimens were tested for the presence of virus in monkey kidney tissue culture employing the hemadsorption technic. Neutralization tests were performed with fourfold dilutions of serum which were incubated for one hr at room temperature with 10 TCD50 of para influenza 1 virus or 100 TCD5o of para influenza 3 virus.