Risk of tuberculosis among contacts in a low-incidence setting

[Extract] Contact investigations, which are designed to identify and investigate people who have been exposed to patients with active tuberculosis (TB), are regarded an important component of TB control in low-incidence settings, such as Australia, where the incidence of TB is 6.0 per 100 000 and 88% of all cases of TB occur in people born overseas.

We aimed to estimate the prevalence of active TB at the time of initial screening and the subsequent incidence of TB among contacts of patients with TB living in Sydney, New South Wales (NSW), Australia.

The study population comprised all persons who were screened as contacts of patients with TB between January 2000 and December 2009, at TB clinics within the Sydney West and Sydney South West Area Health Services. Contact screening and management in this jurisdiction is guided by state policy directives. Cases of active TB among the study population were identified by linking a database containing details for all identified contacts and the NSW notifiable diseases database (which includes the TB registry) using a combination of probabilistic and deterministic linkage methods.