What is the most likely cause of recurrent wheezing in a 4-year-old associated with viral upper respiratory infections?

Recurrent wheezing in a child, especially one as young as 4 years old, is often indicative of a condition like asthma. In young children, asthma may present as wheezing episodes that are closely tied to viral upper respiratory infections. This can occur because viral infections can trigger bronchial hyperresponsiveness, leading to inflammation and narrowing of the airways, resulting in wheezing.

Asthma is characterized by recurrent wheezing, coughing, and difficulty in breathing due to airway inflammation and hyperreactivity. In children, this condition is commonly exacerbated by respiratory infections, particularly viral ones, which are prevalent in early childhood.

While bronchiolitis is primarily associated with younger infants and often linked to respiratory syncytial virus (RSV), it typically resolves as the child grows. Viral pneumonia might cause wheezing but is more likely to present with additional symptoms like fever and systemic illness. Reactive airway disease is a term that can describe wheezing due to transient factors, but asthma is a more defined diagnosis that encompasses chronic symptoms and recurrent episodes associated with viruses.

Thus, given the pattern of recurrent wheezing specifically connected to viral upper respiratory infections, asthma is the most fitting diagnosis for this scenario.