The capsular antigen in type b is polyribose-ribotol phosphate. Hemophilus influenzae type b is the most common cause of invasive bacterial disease in children in the United States. The most common infection is meningitis, followed by epiglottitis, cellulitis, arthritis, pneumonia, and a variety of abscesses. Absence of cough is an important symptom that helps distinguish supraglottitis from croup. Classically, in order to lessen the airway obstruction, the child sits erect, flexed at the waist, with the chin forward, mouth open and the tongue protruding from the mouth.
Many children are toxemic with high fever.
Symptoms progress rapidly, often in less than 24 hours. Because of the severity of this disease, the diagnosis of supraglottitis should be made quickly and as early as possible. In a review of 155 children presenting to the emergency room with stridor, Mauro et al found absence of spontaneous cough, and the presence of drooling and agitation to be most commonly associated with supraglottitis. Vigorous examination or stimulation of a child with supraglottitis may lead to laryngospasm and airway obstruction. For this reason, the common teaching has been not to examine or stimulate any child suspected of having supraglottitis.