What is the most likely diagnosis for an 8-month-old baby presenting with dyspnea, cough, and wheezing?

In an 8-month-old baby presenting with dyspnea, cough, and wheezing, bronchiolitis is the most likely diagnosis. This condition primarily affects infants and is most often caused by viral infections, with respiratory syncytial virus (RSV) being a common culprit.

The symptoms of dyspnea (difficulty breathing), cough, and wheezing are characteristic of bronchiolitis due to the inflammation and obstruction in the small airways that occurs as a result of the viral infection. The age of the patient is crucial; bronchiolitis typically occurs in children under two years of age, and the peak incidence is seen in infants between two and six months, which aligns perfectly with the age of the baby in this scenario.

Other conditions such as asthma, pneumonia, and bronchitis are less likely in this case. Asthma usually presents later and is defined by a pattern of chronic wheezing and airway hyperreactivity, which is uncommon in infants under one year. Pneumonia can cause cough and respiratory distress, but it often presents with fever and signs of systemic illness, and the wheezing is not as prominent as in bronchiolitis. Lastly, bronchitis is generally associated with chronic cough due to bronchial