Epidemiology of systemic Haemophilus influenzae disease in Korean children

There is a wide variation in the incidence and clinical characteristics of invasive infections by Haemophilus influenzae type b (Hib) among different populations. Characterizing the clinical significance in a particular community is essential for the development of vaccine policy. Data on the clinical significance of Hib in Asian children, including epidemiology and clinical spectrum, are quite limited.

To characterize invasive H. influenzae infections in Korean children in terms of clinical spectrum and frequency as an etiologic agent of bacterial meningitis and to review literature that may be helpful in understanding the epidemiology of H. influenzae disease in Far East Asian children, including Koreans.

Invasive infections by H. influenzae, Streptococcus pneumoniae and Neisseria meningitidis diagnosed at the Seoul National University Children's Hospital from 1986 to 1996 were reviewed. Conventional culture and the latex particle agglutination test were used in addition for diagnosis. A detailed literature review was undertaken to trace relevant information that may be helpful in understanding the epidemiology of invasive Hib disease among Far East Asian children.

A total of 169 invasive infections were identified: 48 H. influenzae; 116 S. pneumoniae; and 5 N. meningitidis. Of the 48 H. influenzae infections 36 developed in apparently healthy children: 25 meningitis; 8 bacteremia; 2 pneumonia; and 1 epiglottitis. Forty-four percent of H. influenzae meningitis developed in infants < 1 year of age, and 92% occurred in children <5 years of age. H. influenzae was the cause of 58% of bacterial meningitis in infants and 62% in children <5 years old.

The limited data suggest that the incidence of H. influenzae meningitis may be lower in Korean than in US children. Prospective population-based studies are needed urgently in Asian countries, including Korea.