An outbreak of serotype-1 sequence type 306 invasive pneumococcal disease in an Australian Indigenous population.

Between 2010 and 2013, an outbreak of serotype-1 sequence type 306 (ST306) invasive pneumococcal disease (IPD) occurred primarily in remote locations of Northern and Central Australia. This is a descriptive study of the epidemiology of the outbreak using nationwide IPD surveillance data, supplemented with more detailed data held by affected jurisdictions, and of the response to the outbreak, including vaccination strategies. In the year the outbreak peaked (2011), serotype-1 IPD incidence was over 30-fold higher in the affected regions than in the rest of Australia (incidence rate ratio: 30.7 [95% CI 20.1-48.9]). The study includes 245 cases of serotype-1 IPD from the outbreak regions, with 75.5% identified as Indigenous. No reported cases of serotype-1 IPD occurred in young children who had completed either a 10- or 13-valent pneumococcal conjugate vaccine schedule. However serotype-1 IPD did occur in older children who had previously received 23-valent pneumococcal polysaccharide vaccine. Development of public-health-focused national IPD management guidelines, including suitable vaccine strategies for consistent use nationwide, could potentially decrease the duration and intensity of similar outbreaks in the future.

Invasive pneumococcal disease in Australia 2007 and 2008.

Enhanced surveillance for invasive pneumococcal disease (IPD) was conducted in all Australian states and territories in 2007 and 2008 with comprehensive comparative data available since 2002. There were 1,477 cases of IPD notified to the National Notifiable Diseases Surveillance System in Australia in 2007; a notification rate of 7.0 cases per 100,000 population. In 2008 there were 1,628 cases; a notification rate of 7.6 cases per 100,000 population. The overall rate of IPD in Indigenous Australians was almost 6 times the rate in non-Indigenous Australians in 2007 and almost 5 times in 2008. By 2008, the 4th year of a funded universal infant 7-valent pneumococcal conjugate vaccine (7vPCV) program in Australia with a 3+0 schedule, vaccine serotype IPD notification rates in those identified as non-Indigenous decreased in all age groups compared with 2002 levels, most significantly by 96% in children aged less than 5 years. However, rates of disease in non-vaccine serotypes increased by 168% in children aged less than 5 years, including a four-fold increase in the number of cases due to serotype 19A. For the Aboriginal and Torres Strait Islander population, national pre-vaccination data are not available, as the vaccine program was funded for this group from 2001. From 2002 to 2008, the proportion of disease due to 7vPCV serotypes in children aged less than 5 years decreased by 77%, while disease due to non-7vPCV serotypes increased by 76%. In Indigenous adults (≥50 years), rates of 23vPPV serotypes increased by 92%. There were 120 deaths attributed to IPD in 2007 and 113 in 2008, although it should be noted that deaths may be under-reported. The number of invasive pneumococcal isolates with reduced penicillin susceptibility remains low and reduced susceptibility to third-generation cephalosporins is rare.