What diagnosis is most likely in a child with sudden onset difficulty breathing, stridor, high fever, and drooling, especially if unimmunized?

In this scenario, the diagnosis of acute epiglottitis is strongly indicated by the constellation of symptoms: sudden onset difficulty breathing, stridor, high fever, and drooling, particularly in an unimmunized child.

Acute epiglottitis is most commonly caused by infection, with Haemophilus influenzae type b being a significant pathogen, especially in children who have not received the recommended vaccinations. The infection leads to inflammation and swelling of the epiglottis, resulting in airway obstruction, which explains the child's acute breathing difficulties and stridor, a high-pitched sound indicative of airway narrowing. The high fever aligns with the infectious nature of the condition, while drooling can occur due to difficulty swallowing and the pain associated with throat involvement.

The age group and clinical presentation point toward a serious condition that requires immediate attention, as acute epiglottitis can lead to rapid deterioration and requires urgent medical intervention.

In contrast, croup typically presents with a more gradual onset of a "barking" cough, hoarseness, low-grade fever, and is usually associated with viral infections. Pneumonia might cause difficulty in breathing and fever but usually does not cause stridor or drooling. An asthma attack could lead to difficulty breathing