Bronchiolitis
Key points
- Bronchiolitis is an inflammation of the bronchioles (small passages in the lungs) usually caused by a viral infection.
- The disease usually affects children under the age of 2, with a peak age of 3 to 6 months, and is a common, sometimes severe illness.
- Antibiotics are not effective against viral infections.
- Usually, the symptoms have resolved within a week, and difficulty breathing usually improves by the third day.
Definition
Bronchiolitis is an inflammation of the bronchioles (small passages in the lungs) usually caused by a viral infection.
Causes, incidence, and risk factors
The disease usually affects children under the age of 2, with a peak age of 3 to 6 months, and is a common, sometimes severe illness. Respiratory syncytial virus (RSV) is one common cause. Other viruses that can cause bronchiolitis include: parainfluenza, influenza, and adenovirus.
The virus is transmitted from person-to-person by direct contact with nasal secretions or by airborne droplets. Although RSV generally causes only mild symptoms in an adult, it can cause a severe illness in an infant.
Bronchiolitis begins as a mild upper respiratory infection that, over a period of 2 to 3 days, can develop into increasing respiratory distress with wheezing and a "tight", wheezy cough. The infant's breathing rate may increase markedly (tachypnea), and the infant may become irritable or anxious-looking. If the disease is severe enough, the infant may turn bluish (cyanotic), an indication of a critical emergency.
As the effort of breathing increases, parents may see the nostrils flaring with each breath and the muscles between the ribs retracting (intercostal retractions) as the child tries to inhale air. This can be exhausting for the child, and very young infants may become so fatigued that breathing becomes difficult to maintain.
Bronchiolitis is seasonal and appears more frequently in the fall and winter months. It is a very common reason for infants to be hospitalized during winter and early spring. Some children have subclinical infections, that is, few or insignificant symptoms. It is estimated that by the first year, more than half of all infants have been exposed to RSV.
Risk factors include:
- Age (less than 6 months old)
- No history of being breastfed
- Prematurity (born before 37 weeks gestation)
- Exposure to cigarette smoke
- Crowded living conditions
Symptoms
- Cough, wheezing, shortness of breath, or difficulty breathing
- Rapid breathing (tachypnea)
- Intercostal retractions
- Nasal flaring in infants
- Fever (variable)
- Bluish skin due to lack of oxygen (cyanosis)
Signs and tests
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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