The epidemiology of tuberculosis in New South Wales 1975-1995: the effects of immigration in a low prevalence population.

SETTING

New South Wales (NSW) is Australia's most populous state and is home to one third of the country's rapidly growing immigrant population.

OBJECTIVE

To examine the effects of immigration upon the epidemiology of tuberculosis (TB) in a low prevalence population.

DESIGN

A retrospective review of state TB surveillance data in NSW from 1975-1995.

RESULTS

The crude notification rate for all active TB declined from 12.2 per 100000 population in 1975 to 5.2/100000 in 1986, after which the notification rate increased steadily to 7.6/100000 in 1995. Between 1975 and 1995, the proportion of all TB notifications occurring in overseas-born residents increased from 30% (178/601) to 79% (345/435). During this period, the proportion of new extra-pulmonary TB notifications increased from 13% (72/549) to 42% (171/405). Notifications amongst women increased from 31% (188/601) to 47% (218/462) of the total, while the median age at notification fell from 55 to 41 years. The pattern of TB disease has not changed for Australian-born cases, who are mostly elderly men with pulmonary disease. Multidrug-resistant TB remains uncommon (<1%), and co-infection with the human immunodeficiency virus (HIV) and TB has not emerged as a major problem (2% of notifications), but is poorly documented.

CONCLUSION

TB has re-emerged in NSW predominantly because of increased immigration from high prevalence countries. The epidemiology of TB has become dominated by overseas-born notifications, and now younger adults are primarily affected. Enhancing the effectiveness of the TB screening procedures for immigrants is a priority. Information should be provided to all immigrants and to long-term visitors from countries of high TB prevalence regarding TB infection and the TB services available in Australia.