Human Parainfluenza Viruses (HPIVs)

Human parainfluenza viruses (HPIVs) are a group of viruses that cause different types of respiratory infections and are most common in children and babies. Most HPIVs usually cause infections of the upper airway, such as a common cold, ear infections, or sore throat. Other infections caused by HPIVs include infections of the lower respiratory tract, such as croup (an infection of the airway below the larynx, or "voice box," that is characterized by a barky cough and harsh, noisy breathing), pneumonia, or bronchiolitis (an inflammation of the lower airways):

• Croup outbreaks usually occur during the fall season and tend to be worse every other year.
• Lower respiratory tract infections occur during the spring and summer and often continue into the fall.
• Children between the ages of 3 months and 5 years are most likely to develop croup.
• Children under the age of 2 are more likely to develop lower respiratory tract infections, such as pneumonia or bronchiolitis.
• Reinfections can occur after the first infection, but are usually less severe.

HPIVs can be spread by either direct contact with respiratory secretions from an infected person or by coming in contact with infectious material and then touching your eyes, nose, or mouth. Most children develop an infection with HPIV before they are 5 years old.

The following are the most common symptoms of HPIV infections. However, each child may experience symptoms differently. Symptoms may include:

• Runny nose
• Redness or swelling of the eyes
• Barky (seal-like) cough 
• Noisy, harsh breathing
• Hoarse voice when speaking or crying 
• Rattling felt over the chest or back when breathing
• Wheezing
• Fever
• Irritability
• Decreased appetite
• Vomiting
• Diarrhea

In addition to a complete medical history, physical examination of your child, and knowledge of regional outbreaks, other diagnostic procedures for HPIV may include:

• Blood work
• Nasal swab of respiratory secretions
• Chest X-ray (a diagnostic test that produces images of internal tissues, bones, and organs)

Once a child is infected, treatment is supportive (aimed at alleviating the symptoms present). Because a virus causes the infection, antibiotics are not useful. Specific treatment will be determined by your child's doctor based on:

• Your child's age, overall health, and medical history
• Extent of the disease with an emphasis on assessing breathing difficulty 
• Your child's tolerance for specific medications, procedures, or therapies
• Expectations for the course of the disease
• Your opinion or preference

HPIVs usually cause mild symptoms of a common cold, but are also a common cause of croup. Croup symptoms can be very scary for parents. Supportive treatment for croup may include:

• Taking your child into cool, night air. A steamy bathroom with the shower running may also help to ease your child's breathing.
• Encouraging your child to drink plenty of fluids.
• Treating a fever with acetaminophen or ibuprofen (as instructed by your child's doctor).
• Keeping your child as quiet and calm as possible to help decrease the breathing effort.

Strict hand-washing is important to prevent the spread of HPIV to other infants and children. If your child is in the hospital, healthcare workers may wear special isolation apparel, such as masks, gowns, and gloves when they enter your child's room. Efforts are underway to develop a vaccine, but currently there are no immunizations for the viruses.