Bronchiolitis Symptoms & Causes

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What causes bronchiolitis?

Bronchiolitis is most often caused by a virus, usually the respiratory syncytial virus (RSV). But many other viruses have been involved, including:

Some bacteria can also cause bronchiolitis, such as:

  • mycoplasma pneumoniae
  • chlamydia pneumoniae

Initially, the virus causes an infection in the upper respiratory tract, and then spreads downward into the lower tract. Here, the virus inflames or even kills cells inside the respiratory tract. This leads to obstructed airflow in and out of your child's lungs.

What risk factors are associated with bronchiolitis?

Risk factors that increase the likelihood that your child may develop bronchiolitis include:

  • exposure to smoke
  • day care attendance
  • having older children in the home
  • not having been breast-fed

What are the symptoms of bronchiolitis?

While each child may experience symptoms of bronchiolitis differently, your child might experience:

  • common cold symptoms, including:
    • runny nose
    • congestion
    • fever
    • cough (this may become more severe as the condition progresses)
  • changes in breathing patterns (your child may be breathing fast or hard and/or you may hear wheezing or a high-pitched sound)
  • decreased appetite (your infant may not eat well)
  • irritability
  • vomiting

Can bronchiolitis be prevented?

There is an injection that can help decrease your baby’s chance of getting RSV, the most common cause of bronchiolitis in children under 5 years of age. It is currently recommended only for high-risk infants, including premature infants (age at birth less than 35 weeks) and infants with chronic lung disease.

The medication is called either Palivizumab (Synagis), or respiratory syncytial immune globulin (RSV-IGIV). Your baby’s physician will be able to talk with you about whether this may be an option.

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