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Parainfluenza is a group of viruses that causes an infection in the respiratory system and closely resembles the common cold.

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What Is Parainfluenza?

Parainfluenza refers to a group of viruses called the human parainfluenza viruses (HPIVs). There are four viruses in this group, and each one causes different symptoms and illnesses. All forms of HPIV cause an infection in either the upper or lower respiratory area of the body.

Symptoms of HPIVs are similar to those of the common cold. When cases are mild, the viruses are often misdiagnosed. Most healthy people infected with an HPIV recover with no treatment. On the other hand, a person with a weakened immune system is at risk for developing a serious and life-threatening infection.

What Are the Types of Parainfluenza Viruses?

There are four different types of HPIV. Although they all cause a respiratory infection, the exact type of infection, the symptoms, and the location of the infection depend on the type of virus you have. The four types of HPIV can infect anyone.


HPIV-1 is the leading cause of croup in children. Croup is a swelling near the vocal cords and in other parts of the upper respiratory system. According to the Centers for Disease Control and Prevention (CDC), HPIV-1 is responsible for biennial outbreaks of croup in the autumn. In the United States, the outbreaks tend to be more widespread in odd-numbered years.


HPIV-2 also causes croup in children, but doctors detect it much less often than HPIV-1. It’s seen mostly in the autumn but to a lesser degree than HPIV-1.


An infection by HPIV-3 is mostly associated with pneumonia and bronchiolitis, which is a swelling in the airways that leads to the lungs. It causes infections largely in the spring and early summer, but it appears in people throughout the year.


There two subtypes of HPIV-4 are HPIV-4A and HPIV-4B. HPIV-4 is rarely included in screening panels for acute respiratory infections. This omission may be making it hard to understand its prevalence and its role in serious respiratory infections. Any pattern in HPIV-4 outbreaks is currently unknown.

How Is Parainfluenza Transmitted?

An HPIV can infect you in a few ways. An HPIV can survive on a hard surface for up to 10 hours. If you touch a contaminated surface with your hands and then touch your nose or mouth, you can become infected. The viruses can also infect you through droplets or close contact with an infected person. It usually takes between two and seven days after infection for symptoms to occur.

What Are the Symptoms of Parainfluenza?

Common symptoms of the four types of HPIV are very similar to those of the common cold. They include:

  • fever
  • cough
  • runny nose
  • stuffy nose
  • chest pain
  • sore throat
  • shortness of breath
  • wheezing
  • general difficulty breathing

Most often, the symptoms of parainfluenza viruses aren’t severe enough to cause concern in healthy adults. They can, however, be life-threatening in an infant, older persons, or anyone else with a compromised or weakened immune system. If you have HPIV symptoms, you should see a doctor or go to the emergency room.

How Is Parainfluenza Diagnosed?

In most cases, your doctor won’t bother to diagnose your particular HPIV. Because healthy adults can recover normally without any treatment, there’s no need for an exact diagnosis. If, however, you have a compromised immune system, your doctor may want to confirm that you have a particular HPIV.

Your doctor may simply do a physical exam to determine if your symptoms match those of HPIVs. For a more accurate diagnosis, your doctor may take a throat or nose swab to detect the presence of a virus and to identify it in a cell culture. Your doctor can also diagnose a specific virus by detecting antigens that your body has made to fight the virus.

Your doctor may order a chest X-ray or a CT scan of your chest. These are both imaging techniques that allow your doctor to see what’s happening in your respiratory system. They can help your doctor determine the extent of symptoms and whether or not you have complications such as pneumonia.

What Are the Treatments for Parainfluenza?

There’s no treatment that can eliminate HPIV from the body. When infected with HPIV, you just have to let it run its course.

Symptoms, however, can be treated with over-the-counter medications like saline nose drops and analgesics like aspirin or acetaminophen. Don’t give aspirin to a child or teenager who has a fever and a viral infection. When given as treatment for a viral illness, aspirin has been associated with Reye’s syndrome, a serious and potentially deadly disorder.

How Can I Prevent Parainfluenza?

There are steps you can take to prevent infection with an HPIV. You should wash your hands regularly and disinfect surfaces that can harbor the viruses. Avoiding close contact with infected people can also lower your risk of becoming infected. There’s currently no vaccine that prevents HPIVs.

What Is the Long-Term Outlook for Parainfluenza?

An HPIV isn’t a serious illness for most people. The symptoms can be very uncomfortable for several days, but as long as your immune system is functioning properly, you should be able to fight off the infection.

The following people are at an increased risk of an HPIV infection:

  • infants
  • very young children
  • older persons
  • anyone with a weakened immune system

With medical treatment, however, recover is possible.

Written by: Mary Ellen Ellis
Edited by:
Medically Reviewed by:
Published: Jul 9, 2012
Published By: Healthline Networks, Inc.
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