Usually caused by the common cold, influenza, can also be caused by bacterial infection after the inflammation of the tiny bronchi of the lungs, mostly occurs in children under 2.5 years of age, 80.% occurs in children under 1 year old, most of them are infants within 6 months. The treatment of hairy branch: treatment is best to use nebulized inhalation, serious hospitalization, timely nebulized treatment effect is better, the disease is easy to re-emerge after the improvement, just like asthma, is due to viral infection of the airway mucosa will appear hyper-reactive state, once the cold is easy to induce coughing and wheezing. Nebulized treatment drugs preferred hormone, such as imported budesonide, specifically for airway mucosa, good effect, less side effects, in addition to the expansion of the bronchial drugs, such as salbutamol sulfate aerosol. In severe cases, hospitalization is required for infusion therapy. Gammaglobulin can regulate immunity and close antigens to achieve rapid treatment.