What Is Parainfluenza?

Parainfluenza is a common virus that can cause both upper and lower respiratory infections, including colds, bronchitis, croup, and pneumonia. Despite the name, it is not related to influenza (the flu). It is caused by an entirely different virus known as the human parainfluenza virus (HPIV).

This article looks at parainfluenza and its symptoms, causes, and treatments.

Parainfluenza Types

Parainfluenza viruses are common causes of respiratory illness. Parainfluenza infections are most likely to occur in the spring, summer, and fall. Most cases of parainfluenza occur in young children, but you can get parainfluenza at any age.

There are four different types of HPIV:

• HPIV-1: The leading cause of croup in children
• HPIV-2: Also a common cause for croup; typically seen in autumn
• HPIV-3: Associated with pneumonia, bronchitis, and bronchiolitis
• HPIV-4: A less common type associated with more severe illness

Symptoms vary depending on both the viral type and the individual.

Parainfluenza Symptoms

After exposure, it takes between two to seven days for symptoms to develop. Most of the time, the virus causes an upper respiratory infection, which may include the following symptoms:

• Sore throat
• Cough
• Sneezing
• Fever
  
• Congestion
• Ear pain
• Lack of appetite
  

In most cases, symptoms are not severe and may be similar to the common cold. Sometimes, however, symptoms can progressively worsen and may lead to lower respiratory infections in the main bronchial tube of the lungs (bronchitis), the smaller air passages (bronchiolitis), or the lung itself (pneumonia).

Symptoms of lower respiratory infection may include:

• Shortness of breath
• Wheezing
• Chest pain
• A barking cough
• Noisy or rattling breath

What Causes Parainfluenza?

The parainfluenza virus is transmitted by coughing and sneezing or by touching objects that have HPIV on them and then transmitting the virus to your nose, mouth, or eyes.

As with the cold and flu, parainfluenza can be easily passed from person to person. The virus itself is quite robust and can live on surfaces for up to 10 hours. As a result, it can spread rapidly through places where people spend a lot of time in close quarters, such as daycares and elementary schools.

Diagnosis

In otherwise healthy people, parainfluenza is typically diagnosed by reviewing symptoms and ruling out other causes. Those with compromised immune systems may undergo additional testing to determine the strain affecting them. Your healthcare provider may also take a throat culture or nasal swab to rule out other pathogens, such as influenza A.

After examining you and listening to your lungs, your healthcare provider may order imaging tests, such as a chest X-ray or computed tomography (CT) scan, to check for pneumonia and determine the right course of treatment for you.

How Is Parainfluenza Treated?

If symptoms are mild, there is usually no need for medical intervention. In cases of fever or body aches, Tylenol (acetaminophen) or an over-the-counter cold and flu remedy may be used. (Children and adolescents should not take aspirin; read other product labels for the recommended age for use.)

For moderate to severe croup, steroids (typically dexamethasone) are given orally or intravenously. is only possible if the patient is not intubated or vomiting. Epinephrine, if given, is administered by inhalation via a nebulizer. For adults with pneumonia caused by parainfluenza, treatment is supportive (i.e., supplemental oxygen and/or ventilator support) and sometimes includes inhaled bronchodilators, such as albuterol and/or corticosteroids.

Secondary pneumonia is typically treated with antibiotics.

Prevention

Parainfluenza transmission is prevented the same way as the cold or flu:

• Wash your hands after coming in contact with someone who has a cold or the flu.
• Sanitize any objects and surfaces the ill person may have touched.
• If you are sick, cover your mouth when you cough or sneeze.
• If someone is sick, they should stay home and not attend school or work until they are better.

Long-Term Outlook

Parainfluenza is not usually serious. Most people start to feel better in about seven to 10 days. 

Infants, older adults, and people with weakened immune systems are more vulnerable to experiencing serious illness, including bronchitis and pneumonia. If you or your child develop a barking cough, wheezing, chest pain, or shortness of breath, seek medical attention. 

A Word From Verywell

Parainfluenza is more common than most people realize and, in most cases, is not of great concern. In fact, most people won't know whether they've caught a cold or HPIV—and it usually doesn't matter. However, if symptoms worsen or persist, don't hesitate to seek medical attention.