Bronchiolitis is a common lung infection in young children and infants. It causes congestion in the small airways (bronchioles) of the lung. Bronchiolitis is almost always caused by a virus. Typically, the peak time for bronchiolitis is during the winter months.

Bronchiolitis starts out with symptoms similar to those of a common cold but then progresses to coughing, wheezing and sometimes difficulty breathing. Symptoms of bronchiolitis can last for several days to weeks, even a month.

Most children get better with supportive care at home. A very small percentage of children require hospitalization.

Symptoms Causes Risk factors Complications Prevention

For the first few days, the signs and symptoms of bronchiolitis are similar to those of a common cold:

  • Runny nose
  • Stuffy nose
  • Cough
  • Slight fever (not always present)

After this, there may be a week or more of breathing difficulty or a whistling noise when breathing out (wheezing).

Many infants will also have an ear infection (otitis media).

When to see a doctor

If it's difficult to get your child to eat and his or her breathing becomes more rapid or labored, contact your child's doctor. This is especially true if your child is younger than 12 weeks old or has other risk factors for bronchiolitis — including premature birth or a heart or lung condition.

The following signs and symptoms are reasons to seek prompt medical attention:

  • Vomiting
  • Breathing very fast — more than 60 breaths a minute — and shallowly
  • Skin turning blue, especially the lips and fingernails (cyanosis)
  • Lethargy
  • Refusal to drink enough fluids, or breathing too fast to eat or drink
  • Audible wheezing sounds
  • Ribs seem to suck inward when infant inhales

Bronchiolitis occurs when a virus infects the bronchioles, which are the smallest of the airways branching off the main breathing tubes (bronchi) within your lungs. The viral infection makes the bronchioles swell and become inflamed. Mucus collects in these airways, which can make it difficult for air to flow freely into and out from the lungs.

Most cases of bronchiolitis are caused by the respiratory syncytial virus (RSV). RSV is a common virus which infects just about every child by the age of 2. Seasonal outbreaks of RSV infection occur every winter. Bronchiolitis can also be caused by a variety of other viruses, including those that cause the flu or the common cold.

Bronchiolitis is a contagious condition. You contract the virus just as you would a cold or the flu — through droplets in the air when someone who is sick coughs, sneezes or talks. You can also contract bronchiolitis by touching shared objects — such as utensils, towels or toys — and then touching your eyes, nose or mouth.

One of the greatest risk factors for getting bronchiolitis is being younger than 6 months old, because the lungs and immune system aren't yet fully developed.

Other factors that have been associated with an increased risk of bronchiolitis in infants, or more severe illness due to bronchiolitis, include:

  • Never having been breast-fed — breast-fed babies receive immune benefits from the mother
  • Premature birth
  • An underlying heart or lung condition
  • A depressed immune system
  • Exposure to tobacco smoke
  • Contact with multiple children, such as in a child care setting
  • Living in a crowded environment
  • Having siblings who attend school or child care and bring home the infection

Complications of severe bronchiolitis may include:

  • Cyanosis, a condition in which the skin appears blue or ashen, especially the lips, caused by lack of oxygen.
  • In the youngest infants, acute bronchiolitis can sometimes cause long pauses in breathing (apnea).
  • Dehydration.
  • Fatigue and respiratory failure.

If these occur, your child may need hospitalization. Severe respiratory failure may require that a tube be inserted into the trachea to help the child's breathing until the infection has run its course.

If your infant was born prematurely, has a heart or lung condition, or has a compromised immune system, watch closely for beginning signs of bronchiolitis. The infection may rapidly become severe, and signs and symptoms of the underlying condition may become worse. In such cases, your child will usually need hospitalization.

RSV can also cause pneumonia. Sometimes a second infection, such as bacterial pneumonia, can occur at the same time, but this is not common. Reinfections with RSV after the initial episode may occur but typically aren't as severe.

Because bronchiolitis spreads from person to person, one of the best ways to prevent it is to wash your hands frequently — especially before touching your baby when you have a cold. Wearing a face mask at this time is appropriate. If your child has bronchiolitis, keep him or her at home until the illness is past to avoid spreading it to others.

Other effective ways that can help curb spread of the infection include:

  • Limit your child's contact with people who have a fever or cold. If your child is a newborn, especially a premature newborn, avoid exposure to people with colds in the first two months of life.
  • Get a flu shot. An annual influenza vaccination is recommended for everyone older than 6 months. Although it will not prevent the commonest cause of bronchiolitis (respiratory syncytial virus), a flu shot will spare your child from a severe influenza infection.
  • Keep bathroom and kitchen countertops in your home clean. Be especially careful if another family member has a cold. To disinfect the area, you can use a solution of bleach and water made with a tablespoon of bleach per gallon of cool water (14.8 milliliters per 3.8 liters). Don't mix in any other chemicals, as this can create a toxic chemical reaction. Always store homemade mixtures in a labeled container out of the reach of young children or, better, discard unused mixtures.
  • Use a tissue only once. Discard used tissues promptly, then wash your hands or use alcohol hand sanitizer.
  • Use your own drinking glass. Don't share glasses with others.
  • Be prepared away from home. Keep a waterless hand sanitizer handy for yourself and for your child when you're away from home.
  • Wash hands. Frequently wash your own hands and those of your child.
  • Breast-feed. Breast-fed babies receive immunities from their mother.

No vaccine available

There's no vaccine for bronchiolitis. But the medication palivizumab (Synagis) can help decrease the likelihood of RSV infections in infants with high risk of severe disease, as well as decrease the need for hospitalization and limit severity of the illness. Palivizumab is typically given through a single injection into a large muscle, such as the thigh, once a month during the peak RSV season — from November through March.

Palivizumab doesn't interfere with childhood vaccines. Its expense generally limits its use to infants at particularly high risk of RSV infection, such as those born very prematurely or with a heart-lung condition or a depressed immune system.

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