Symptoms:

Some children have infections with few or minor symptoms.

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 a lot (tachypnea), and the infant may become irritable or anxious-looking. If the disease is severe enough, the infant may turn bluish (cyanotic), which is an emergency.

As the effort of breathing increases, parents may see the child's nostrils flaring with each breath and the muscles between the ribs retracting (intercostal retractions) as the child tries to breathe in air. This can be exhausting for the child, and very young infants may become so tired that they have difficulty maintaining breathing.

Symptoms include:

• Bluish skin due to lack of oxygen (cyanosis)
• Cough, wheezing, shortness of breath, or difficulty breathing
• Fever
• Intercostal retractions
• Nasal flaring in infants
• Rapid breathing (tachypnea)

Signs and tests:

Signs include:

• Decreased blood oxygen
• Wheezing and crackling sounds heard through stethoscope exam of chest

Tests include:

• Blood gases
• Chest x-ray
• Nasal fluid cultures (to determine which virus is present)