In tropical regions, an increase in cases of bronchiolitis is usually observed during the rainy season, but can sometimes occur earlier. This viral illness primarily affects children under the age of 2. In the vast majority of cases, bronchiolitis resolves favorably, either spontaneously or, more often, with the help of physical therapy. In rare cases, this condition requires hospitalization to monitor respiratory function and, if necessary, to administer resuscitation measures. Deaths attributable to acute bronchiolitis are very rare. In more than 7 out of 10 cases, bronchiolitis in children is caused by the respiratory syncytial virus (RSV). Other causative agents include parainfluenza viruses, adenoviruses, and others. The virus spreads through saliva, sneezing, coughing, objects contaminated by a person with a cold, and via hands. Thus, a cold in a child or adult can lead to bronchiolitis in an infant.Bronchiolitis, which is easily diagnosed by a doctor or pediatrician, is treated on an outpatient basis in the vast majority of cases (95%).