Is epiglottitis caused by Haemophilus influenzae type b (HIB)?

Epiglottitis and Haemophilus influenzae type b (HIB)

Yes, Haemophilus influenzae type b (Hib) was historically the leading cause of epiglottitis, particularly in children under 5 years of age before the introduction of effective Hib vaccines. 1

Historical Significance of Hib in Epiglottitis

Before the introduction of effective Hib vaccines in the mid-1980s:

• Hib was the leading cause of bacterial meningitis and other invasive bacterial diseases, including epiglottitis, among children under 5 years of age 1
• Epiglottitis was specifically identified as one of the common invasive diseases caused by Hib 1
• Nearly all Hib infections occurred in children under 5 years of age, with approximately two-thirds occurring in children under 18 months 1

Impact of Hib Vaccination

The introduction of Hib vaccines has dramatically altered the epidemiology of epiglottitis:

• Since the introduction of Hib vaccines in 1985 and conjugate vaccines in 1987-1989, there has been a 99% decrease in invasive Hib disease in children under 5 years 1
• The incidence of epiglottitis has significantly decreased following widespread Hib vaccination 2, 3
• The demographics of epiglottitis have shifted - it is now predominantly seen in adults rather than children 2, 3

Current Etiologic Patterns

In the post-vaccine era:

• Epiglottitis still occurs but is much less commonly caused by Hib 3
• In studies examining epiglottitis cases after widespread Hib vaccination, Hib was rarely identified as the causative organism 3
• Other pathogens such as Streptococcus pneumoniae have been isolated in some cases 3
• Many cases of epiglottitis in the current era have no identified pathogen despite appropriate cultures 3

Vaccine Failures

Despite the overall success of Hib vaccination:

• Rare cases of Hib epiglottitis have been documented in fully vaccinated children 4, 5, 6
• These vaccine failures highlight that vaccination, while highly effective, is not 100% protective 6
• Some vaccine failures have been associated with immunological risk factors such as prematurity or low immunoglobulin levels 6

Clinical Implications

For modern clinical practice:

• Epiglottitis should still be considered in the differential diagnosis of acute upper airway obstruction, even in vaccinated individuals 5, 6
• The classic presentation of epiglottitis includes odynophagia (100%), dysphagia (85%), and voice change (75%) 2
• Warning signs that may indicate need for airway intervention include stridor, respiratory distress, tachycardia, tachypnea, rapid symptom onset, and shortness of breath 2
• Prompt recognition and appropriate management remain essential, as epiglottitis continues to be a potentially life-threatening condition 2, 6

In conclusion, while Hib was historically the predominant cause of epiglottitis, particularly in children, the successful implementation of Hib vaccination programs has dramatically reduced Hib-related epiglottitis. However, epiglottitis continues to occur, now more commonly in adults and often without an identified pathogen.