Definition

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

Alternative Names

Human parainfluenza virus; HPIVs

Causes

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

The exact number of parainfluenza cases is unknown. The number is suspected to be very high. 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 the parainfluenza virus. Most adults have antibodies against parainfluenza, although they can get repeat infections.

Symptoms

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 and those with weak immune system.

In general, symptoms may include:

• Sore throat
• Fever
• Runny or stuffy nose
• Chest pain, shortness of breath, wheezing
• Cough or croup

Exams and Tests

A physical exam may show sinus tenderness, swollen glands, and a red throat. The health care provider 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
• Blood cultures (to rule out other causes of pneumonia)
• Chest x-ray
• CT scan of the chest
• Complete blood count (CBC)
• Swab of nose for rapid viral test including the virus that causes COVID-19

Treatment

There is no specific treatment for the viral infection. Certain treatments are available for the symptoms of croup and bronchiolitis to make breathing easier.

Outlook (Prognosis)

Most infections in adults and older children are mild and recovery takes place without treatment, unless the person is very old or has an abnormal immune system. Medical intervention may be necessary if breathing difficulties develop.

Possible Complications

Secondary bacterial infections are the most common complication. Airway obstruction in croup and bronchiolitis can be severe and even life threatening, especially in younger children.

When to Contact a Medical Professional

Contact your provider if:

• You or your child develops croup, wheezing, or any other type of breathing difficulty.
• A child under 18 months develops any type of upper respiratory symptom.

Prevention

There are no vaccines available for parainfluenza. A few preventive measures that may help include:

• Avoid crowds to limit exposure during peak outbreaks.
• Wash your hands often.
• Limit exposure to day care centers and nurseries, if possible.

References

Ison MG. Parainfluenza viruses. In: Bennett JE, Dolin R, Blaser MJ, eds. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 9th ed. Philadelphia, PA: Elsevier; 2020:chap 156.

Weinberg GA, Edwards KM. Parainfluenza viral disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 339.

Welliver Sr RC. Parainfluenza viruses. In: Cherry JD, Harrison GJ, Kaplan SL, Steinbach WJ, Hotez PJ, eds. Feigin and Cherry's Textbook of Pediatric Infectious Diseases. 8th ed. Philadelphia, PA: Elsevier; 2019:chap 179.