Objective: Paediatric epiglottitis is a serious, potentially life-threatening condition. Since the widespread introduction of the Haemophilus influenzae type b (Hib) conjugate vaccine in the UK in October 1992, there has been a dramatic reduction in its incidence. Vaccine failure is rare. The purpose of this study is to examine the failure rate of H. influenzae type b vaccine as measured by the number of cases of Haemophilus epiglottitis in fully vaccinated children presenting to a tertiary paediatric centre. A secondary aim is to provide a retrospective review of all cases of epiglottitis over a 13-year period.
Methods: A retrospective case-note review identifying all cases of epiglottitis presenting to Alder Hey Hospital was undertaken covering the time period December 1987-January 2001. Details of patient age, sex, source of referral, clinical presentation, management and complications along with microbiological and serological findings were obtained. There were 21 males and 19 females. The mean age was 36 months (range 6-125 months). A provisional diagnosis was made on the basis of the clinical features, confirmed by direct laryngoscopy in all but two cases and further supported in 28 cases by a positive blood culture. Of the 40 children presenting with epiglottitis, eight (20%) presented after the introduction of the Hib conjugate vaccine. H. influenzae antibody titres were measured both in the acute and convalescent phases of illness by the central Haemophilus Reference Unit in Oxford.
Results: We present the clinical features, management and complications of 40 cases of acute epiglottitis. H. influenzae was isolated from blood cultures in 28 cases (70%). In 12 of these cases, H. influenzae type b was identified, seven prior to 1993 and five thereafter. Four of these five cases presenting after introduction of the Hib vaccine were known to have been fully vaccinated. One child had a history of prematurity and serum immunoglobulin estimation was abnormally low in another child. Acute Hib antibody titre was less than 1 microg/ml in two of the three cases in which this was available.
Conclusion: Whilst the incidence of Haemophilus type b epiglottitis has significantly diminished, vaccine failure does occur. We discuss the current understanding of clinical and immunological risk factors for vaccine failure and the significance of the Hib antibody titre. Further evaluation of vaccine failure would be of benefit. The series that we present highlights the importance of considering acute epiglottitis in the differential diagnosis of the child presenting with acute upper airway obstruction. This is particularly relevant when in future there will be fewer doctors familiar with the symptoms and signs of the disease.