Incidence of invasive pneumococcal disease in Sydney children, 1991-96.

Objective: Few data are available on invasive disease due to Streptococcus pneumoniae in representative Australian childhood populations. This study aimed to determine the age-specific incidence of invasive pneumococcal disease in Sydney children.

Methodology: Population-based prospective study where isolates of Streptococcus pneumoniae from normally sterile sites were identified through an established laboratory surveillance network. Isolates came from children aged under 15 years living within the boundaries of Central, Eastern. Southern, Western and South-western Sydney Area Health Services from 1 July 1991 to 30 June 1996.

Results: Invasive pneumococcal disease was identified in 320 children during a 5-year period, of whom 193 (60%) were under 2 years of age. The incidence per 100,000 children was 12.7 per 100,000 (95% CI: 11.4-14.2/100,000) under 15 years; 31.7 (95% CI 28.1-35.7) under 5 years, and 45.5 (95% CI 38.9-53.3) under 2 years. The incidence of pneumococcal meningitis in children aged under 2 years was 10.5 per 100,000 (95% CI: 7.4-14.5/100,000).

Conclusions: The incidence of childhood invasive pneumococcal disease in Sydney was stable during 1991-96 and comparable to rates reported from other industrialized countries. There was no evidence of any change in pneumococcal disease incidence with reduction in invasive Haemophilus influenzae type b (Hib) disease following introduction of Hib immunization.