Definition of Parainfluenza:

Parainfluenza refers to a group of viruses that lead to upper and lower respiratory infections.

Causes, incidence, and risk factors:

There are four types of parainfluenza virus, all of which can cause upper respiratory infections or lower respiratory infections (pneumonia) in adults and children. The virus can cause croup,bronchiolitis,bronchitis and certain types of pneumonia.

The exact number of cases of parainfluenza is unknown but suspected to be very high. Sometimes the viruses cause only a runny nose and other symptoms that may be diagnosed as a simple cold rather than parainfluenza.

Infections are most common in fall and winter. Parainfluenza infections are most severe in infants and become less severe with age. By school age, most children have been exposed to parainfluenza virus. Most adults have antibodies against parainfluenza although they can get repeat infections.