Definition

Bronchiolitis is a childhood disease that affects the lungs. It occurs when a virus enters the breathing system. The virus causes the tiny airways in the lungs to become swollen. As a result, a thick fluid called mucus collects in the airways. This makes it hard for air to flow freely in the lungs.

Usually, the infection goes away after 7-10 days. Some children show very mild symptoms. In others, the disease can be severe. Older children are less at risk. If they get bronchiolitis, they don’t get as sick as younger children.

Bronchioles

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