Tuberculosis, public health and gathering new evidence to guide control efforts

Abstract

Aim: To describe the epidemiology of tuberculosis in NSW between 2009 and 2011 and comparewith previous years.Methods:Data from all cases of tuberculosis notified in NSW during this period were extracted from the Notifiable Conditions Information Management System. Descriptive analyses of notification data were undertaken. Incidence rates were calculated per 100 000 population. Results: Between 2009 and 2011, there were 1548 cases of tuberculosis notified in NSW, translating to an average annual notification rate of 7.2 per 100 000 population for this period. A total of 89% (n1⁄4 1371) of notified cases were overseas-born, and 1.6% (n1⁄4 24) of cases were recorded as Aboriginal persons. The most common site of infection was the lung (60% of cases). Of notified cases, 68% were reported as having been tested for HIV, of which 3% (n1⁄4 28) of cases had HIV/tuberculosis co-infection. There were 20 cases of multidrug-resistant tuberculosis, including one case of extensively drug-resistant tuberculosis. Conclusion: The notification rate of tuberculosis in NSW has remained relatively stable over the past two decades, though small incremental increases since 2003 are evident. Endemic transmission of tuberculosis within subgroups of the NSW population, as well as the ongoing high endemnicity for tuberculosis in neighbouring countries, highlight the importance of tuberculosis control as a continued strategic priority for disease control in NSW. Tuberculosis (TB) remains a disease of global public health significance. The World Health Organization (WHO) estimates that in 2011 there were 8.7 million incident cases of TB and 1.4 million TB-related deaths, as well as an additional 430 000 deaths as a result of TB and human immunodeficiency virus (HIV) co-infection. In Australia the incidence of TB is low: in 2010 it was reported by WHO to be 6.1 cases per 100 000 population. Mortality from TB, excluding HIV-positive cases, was less than one TB-related death per 100 000 population in Australia in 2010. Despite Australia’s low incidence, TB control remains a challenge as the epidemiology of this disease must be considered in a global context given the frequency of international travel and migration from high-incidence countries. The incidence and prevalence of TB in many of Australia’s international neighbours remains high. Twenty-two countries account for 80% of the global burden of TB; nine of these countries are within the South-East Asian and Western Pacific Regions. These two regions also account for approximately 18% of multidrug-resistant TB (MDR-TB) cases. Given the global context of TB epidemiology, elimination of disease within any given country is not considered feasible. The key goals and strategies of the New South Wales (NSW) TB Control Program therefore focus on case finding, early diagnoses and effective treatment in order to minimise and eliminate local transmission. NSW has a strong surveillance system in place, whereby all patients diagnosed with TB are notified to a public health unit or chest clinic in accordance with the NSW Public Health Act 2010. Case details are then entered into a central registry, the Notifiable Conditions Information Management System. The aim of this report is to describe the epidemiology of TB in NSW between 2009 and 2011 by examining the demographic and clinical characteristics, and risk factors for infection, of notified cases. We report on the public health follow-up of cases and the extent of contact tracing activities undertaken by public health and clinical services. We also compare incidence data with data from previous years. Understanding the epidemiology of TB in NSW is critical for informing and evaluating disease control strategies. Methods Data sources TB notification data were extracted from the Notifiable Conditions Information Management System. Data were included in the study when the year of diagnosis was between 2009 and 2011 (inclusive). Population data including NSW mid-year population estimates, estimated populations by country of birth and population estimates by Local Health District (LHD) were obtained from the 10.1071/NB12115 Vol. 24(1) 2013 NSW Public Health Bulletin | 3 EPIREVIEW