Epidemiology of sexually transmissible infections in New South Wales: are case notifications enough?

Surveillance of sexually transmissible infections (STI)s is important to assess the disease burden in the population and to monitor and evaluate changes in trends over time. Routinely collected surveillance data in New South Wales are reliant on case reporting, which for many infections is an inadequate mechanism for capturing incidence and prevalence. Increasing rates of chlamydia over the past decade have sparked intense debate as to whether the current notification system is optimal and whether the true burden of infection are being measured. This study describes the current surveillance for STIs in New South Wales.

New South Wales-specific data for the years 2000-2009 were analysed. Notification data were used to examine the rate of the 4 STIs that are notifiable in New South Wales; chlamydia, gonorrhoea, infectious syphilis and HIV notifications. Hospital admissions and chlamydia-associated pelvic inflammatory disease were analysed using admitted patient data.

Chlamydia was the most frequently reported of the notifiable STIs in New South Wales. Despite the higher rates of notification compared with other STIs, chlamydia-related hospitalisations contribute less than a 5th of all STI-related hospital admissions. Infectious syphilis contributed to the highest proportion of all STI-related hospitalisations in New South Wales and rates increased from 2000 to 2009. For other STIs such as anogenital herpes and gonorrhoea, hospital admissions remained stable for the same period.

Notifications data for STIs should be complemented with hospital admission and other data sources to better describe STI morbidity. A synthesis of these data sources is needed to improve current surveillance and allow for better comparisons and trend analysis of STIs in New South Wales.