Invasive pneumococcal disease in the population of Victoria.

OBJECTIVES: To estimate morbidity and mortality rates for invasive Streptococcus pneumoniae (pneumococcal) disease in the non-Indigenous population of Victoria.

DESIGN AND SETTING: Survey using data from a statewide voluntary laboratory surveillance scheme (1989-1998), statewide hospital discharge database (1995-1998), medical records of notified patients (1994-1995) and serotyping of notified isolates (1994-1998).

MAIN OUTCOME MEASURES: Incidence of pneumococcal bacteraemia and pneumonia; predisposing factors; serotypes of isolates.

RESULTS: Minimum estimates of annual incidence of invasive disease, based on laboratory surveillance data for 1995-1998, were 59 per 100,000 for children aged < 2 years, 25 per 100,000 for people aged > or = 65 years, and 8 per 100,000 overall. Annual incidence of pneumococcal pneumonia, calculated from hospital discharge data, was 99 per 100,000 for those aged > or = 65 years. Manifestations of invasive pneumococcal disease varied with age, with meningitis more common in infants, and pneumonia most common in older patients. A predisposing factor for pneumococcal infection was present in 48% of patients. Most isolates from infants (83%) belonged to serotypes in the proposed seven-valent infant vaccine, and 91% of isolates from people aged > or = 2 years belonged to serotypes in the current 23-valent adult vaccine.

CONCLUSIONS: S. pneumoniae continues to be a major cause of morbidity and mortality in young children and the elderly in Victoria. More widespread use of the currently available pneumococcal vaccine in adults and introduction of an effective vaccine for infants should greatly reduce incidence of the disease.