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Parainfluenza Viral Infections

Human parainfluenza viruses (HPIVs) are a group of organisms, types 1 through 4, that cause several different respiratory infections. For example, they are the major cause of croup, which is an inflammation of the voice box (larynx) and windpipe (trachea) that makes breathing more difficult.

They also cause some cases of lower respiratory tract diseases, including pneumonia (a lung infection) and bronchiolitis (an infection of the lung’s small breathing tubes). They can make the symptoms of chronic lung disease worse in children.

Parainfluenza viruses have an incubation period of 2 to 6 days. They are spread from person to person by direct contact or exposure to contaminated secretions from the nose or throat. Children are usually exposed to most types of parainfluenza by 5 years of age.

Signs and Symptoms

The following symptoms occur in many types of parainfluenza infections, although they may be different from child to child or one kind of infection to another:

  • A rough, barking cough
  • Rapid, noisy, or labored breathing
  • Hoarseness and wheezing
  • Redness of the eye
  • A runny nose
  • Cough
  • Fever
  • A decline in appetite
  • Vomiting
  • Diarrhea

How Is the Diagnosis Made?

The diagnosis of HPIVs may be made by testing the secretions collected from a sick child’s nose and throat. Viral cultures or tests are taken to look for parts of the virus. An increase in antibodies to parainfluenza may be found in the blood of infected children. As with most infections, it can take several weeks for the antibodies to appear.


The treatment of viral illnesses, including those caused by parainfluenza viruses, should not involve the use of antibacterials, which are not effective against viruses. Most parainfluenza infections do not require specific treatment other than soothing the symptoms and making your child more comfortable until she feels better. The illness goes away on its own. Antibacterials should only be used if a secondary bacterial infection develops.

Talk to your pediatrician about whether your child with a fever should be given acetaminophen to lower her body temperature. Make sure she drinks lots of liquids.

Some supportive therapies are unique to the specific infection that is present. For croup, which is characterized by a barking cough, your child may feel better if you take her into the bathroom, turn on the hot water in the shower, and let the bathroom fill with steam. The warm, moist air should allow her to breathe easier. Breathing in steam is usually helpful, but if it isn’t, take your child outdoors for a few minutes. Inhaling the moist, cool night air may loosen up her airway, and she will be able to breathe easier.

Your pediatrician may prescribe a dose of corticosteroids for croup. Usually a single dose is all that is needed.


In the first few months of life, infants have protection against some parainfluenza types because of antibodies from their mothers.

Keep your child away from youngsters who have viral infections, particularly in the early and most contagious stages. Regular and thorough hand washing is an important way to lower the chances of spreading most viral infections. Your child should not share eating utensils and glasses with a sick youngster.

A vaccine against parainfluenza viruses is not available, although vaccines against viral types 1 and 3 are in development.

Last Updated
Immunizations & Infectious Diseases: An Informed Parent's Guide (Copyright © 2006 American Academy of Pediatrics)
The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
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