Tuberculosis epidemiology in New Zealand: 1995-2004

To describe the epidemiology of tuberculosis (TB) in New Zealand (NZ) for the 10-year period 1995-2004, and to place this in the context of long-term incidence trends.

We calculated TB incidence rates since the early 1920s using published data. A more detailed analysis examined TB notification and laboratory data for the period 1995 to 2004 using population denominator data from the 1996 and 2001 Census. We calculated incidence rates by age, sex, ethnicity, place of residence, country of birth, and deprivation for the two 5-year periods: 1995 to 1999 and 2000 to 2004. We also calculated and compared TB case fatality and mortality rates for those periods. We described outbreaks by using TB outbreak reporting data.

The long-term decline in TB incidence in NZ halted in the mid-1980s, and in the last two decades, annual rates have stabilised at around 10 cases per 100,000. The average rate for 1995-2004 period was 10.3 per 100,000. The TB incidence rate in NZ is higher than that in Australia, USA, and Canada, and slightly lower than that in the UK. Within NZ there are marked ethnic differences in rates, with age-standardised incidence rates 10.5, 22.3, and 36.5 times higher in Maori, Pacific peoples, and people of Other ethnicity respectively than the rate in Europeans. Rates generally increase with age. Approximately two-thirds (64.6%) of people with TB were born overseas. TB case fatality and mortality rates in NZ are declining and are comparable to those in Australia, Canada, USA, and the UK. Twenty-four TB outbreaks, including 221 cases, were reported between mid-1996 and 2004.

TB is not declining in NZ. The burden of disease is very unevenly distributed across the population with marked ethnic inequalities.