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

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 is responsible for approximately 40-50% of croup cases and 10-15% of bronchiolitis and bronchitis cases and some pneumonias.

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.

Symptoms vary depending on the type of infection. Cold-like symptoms consisting of a runny nose and mild cough are common. Life-threatening respiratory symptoms can be seen in young infants with bronchiolitis.

In general, symptoms may include:

• Chest pain
• Congestion
• Cough
• Croup
• Runny nose
• Shortness of breath
• Sore throat
• Wheezing

A physical exam may show sinus tenderness, swollen glands, and a red throat. The doctor will listen to the lungs and chest with a stethoscope. Abnormal sounds, such as crackling or wheezing, may be heard.

Tests that may be done include:

• Arterial blood gases
• CBC
• Swab of nose for rapid viral test