Invasive pneumococcal disease in Australia, 2006

Enhanced surveillance for invasive pneumococcal disease (IPD) was carried out in all Australian states and territories in 2006 with comprehensive comparative data available since 2002. There were 1,445 cases of IPD notified to the National Notifiable Diseases Surveillance System in Australia in 2006; a notification rate of 7 cases per 100,000 population. The rates varied between states and territories and by geographical region with the highest rates in the Northern Territory, the jurisdiction with the largest proportion of Indigenous people. Invasive pneumococcal disease was reported most frequently in those aged 85 years or over (30.8 cases per 100,000 population) and in children aged one year (26.5 cases per 100,000 population). There were 130 deaths attributed to IPD resulting in an overall case fatality rate of 9%. The overall rate of IPD in Indigenous Australians was 4.3 times the rate in non-indigenous Australians. The rate of IPD in the under two years population continued to fall in 2006, but the rate in Indigenous children (73 cases per 100,000 population) was significantly greater than in non-Indigenous children (21 cases per 100,000 population). The rates of disease caused by serotypes in the 7-valent pneumococcal conjugate vaccine (7vPCV) decreased between 2002 and 2006 by 78% in children aged under two years as a result of the introduction of a universal childhood 7vPCV immunisation program. Significant decreases in IPD caused by 7vPCV serotypes also occurred in the 2-14 years and 65 years or over age groups. Rates of disease caused by non-7vPCV in the same periods were little changed. Serotypes were identified in 94% of all notified cases, with 43% of disease caused by serotypes in the 7vPCV and 85% caused by serotypes in the 23-valent polysaccharide pneumococcal vaccine (23vPPV). The number of invasive pneumococcal isolates with reduced penicillin susceptibility remains low and reduced susceptibility to third generation cephalosporins is rare.