Background: We examined temporal trends and demographic influences on infectious disease notifications made to Australia's National Notifiable Diseases Surveillance System (NNDSS).
Methods: Cases notified to NNDSS from 1991–2011 were analyzed by disease group (blood-borne viruses [BBVs], gastrointestinal, sexually transmitted infections [STIs], vaccine preventable diseases [VPDs] and other), jurisdiction (six states and two territories), Indigenous status, time period (1991–1997, 1998–2004 and 2005–2011), age-group (<5 years, 5–19 years, 20–64 years and ≥65 years), and social disadvantage using the Australian Bureau of Statistic's Index of Relative Socioeconomic Disadvantage (IRSD) quintiles.
Results: From 1991–2011, 2,437,602 cases were notified of which 32% were STIs, 21% gastrointestinal infections, 21% VPDs, and 18% BBVs. Eight pathogens (Chlamydia trachomatis, hepatitis C, Campylobacter, pertussis, Salmonella, influenza, hepatitis B, and Neisseria gonorrhoeae) accounted for 81% of notifications. Indigenous Australians comprise 2.4% of the Australian population but 8.4% of notified cases. Notification incidence more than doubled between the earliest and latest time period, driven by increased STI and VPD notifications (Fig 1) and addition of 30 notifiable conditions to NNDSS including chlamydial infection, hepatitis C and influenza. The average annual notification incidence for all diseases was 577 cases/100,000 people; this was highest for the Northern Territory (2,632/100,000), children <5 years (740 cases/100,000, Fig 2) and the most disadvantaged IRSD quintile (692 cases/100,000, Fig 3).
Conclusion: Notification incidence increased throughout the study period, influenced by the addition of high-incidence conditions to NNDSS, improvements in diagnostics and changes in testing practices. Identification of diseases with increasing notification rates and social groups with higher disease burden highlight priority areas for public health intervention in Australia.
Figure 1: Notification incidence by period, Australia 1991–2011
Figure 2: Notification incidence by age-group, Australia 1991–2011
Figure 3: Notification incidence by index of relative socioeconomic disadvantage quintile, Australia 1991–2011
R. Hall, None
A. C. Cheng, None