Parainfluenza virus infections

Abstract The importance of parainfluenza virus types 1, 2, and 3 in childhood respiratory disease has been established. Parainfluenza virus type 1 is the leading cause of laryngotracheobronchitis (croup). Parainfluenza virus type 2, although less common than type 1, is also a major cause of croup. Parainfluenza virus type 3 ranks second only to respiratory syncytial virus as a cause of bronchiolitis and pneumonia in young children. Parainfluenza virus type 4 has been isolated infrequently and its importance as a human pathogen has not been determined. Attempts to develop effective, inactivated, parenterally administered vaccines for the parainfluenza viruses have been unsuccessful. Evidence suggests that the stimulation of local immune responses is more important than serum antibody. Recent efforts in vaccine development have emphasized preparations given intranasally which stimulate local immune response.