Tuberculosis in New Zealand: Annual Report 2014

Saturday 21st September 2019


Summary

Tuberculosis disease (TB) is a notifiable condition in New Zealand and the TB notification rate has been stable over the last 7 years. The 2014 TB notification rate was 6.7 per 100,000 population (302 cases). The majority of TB notifications were for new disease, with relapse/reactivation cases contributing sparingly to the notifications. A high proportion of TB cases (87.7%) were laboratory confirmed.

As in previous years, there were demographic differences among new TB case rates. Rates were higher in males than females, especially in the older age groups. The Asian and Middle Eastern/Latin American/African (MELAA) ethnic groups have consistently experienced the highest notification rates, although the absolute number of MELAA cases remains relatively low. As in previous years, higher rates of TB occurred in socioeconomically deprived areas.

Being born outside of New Zealand and current or recent residence with a person born outside New Zealand have consistently been dominant risk factors, whereas exposure in a healthcare setting and current or recent residence in an institution were reported for comparatively few new TB cases.

The pattern of disease detection for new TB cases has been consistent over the past 5 years, with more than two thirds of TB cases diagnosed when they presented with symptoms to a health practitioner. Around 7% of cases were identified through immigrant/refugee screening.

Pulmonary disease was more common among new TB cases born in New Zealand than in cases born overseas. One case of miliary TB in a child aged

Most (92.8%) new TB cases in 2014 were reported to have received treatment. For pulmonary cases where the time between the onset of symptoms and start of treatment could be calculated, 17.1% of cases started treatment within 1 month of the onset of illness and 64.9% started treatment between 1 and 3 months.

Two of the new TB cases notified in 2014 were co-infected with HIV compared with none being co-infected with HIV in 2013.

Two outbreaks of Mycobacterium tuberculosis with 14 associated cases were reported in 2014.

Ministry of Health hospitalisation data showed a decreasing trend in hospital admissions for TB over the last decade. This was true for all age groups analysed.

Three (1.2%) of the 247 culture-positive TB cases reported in 2014 were multidrug-resistant TB (MDR-TB, defined as resistance to at least isoniazid and rifampicin). One of these MDR-TB cases appears to have developed resistance during anti-tuberculous drug treatment in New Zealand. Resistance to all antimicrobials except pyrazinamide was higher among isolates from cases born overseas than among isolates from New Zealand-born cases, although only streptomycin resistance was significantly higher.

Between 2005 and 2014, there has been a significant trend of decreasing pyrazinamide resistance, but no significant changes in resistance to isoniazid, rifampicin, ethambutol or streptomycin. Over the same 10 years, on average, 1.3% of culture-positive TB cases were MDR-TB.

Approximately one third of the M. tuberculosis isolates that underwent molecular typing between 2010 and 2014 had results that matched other typed isolates, that is, were non-unique and could be assigned to a cluster. Most clusters contained fewer than five cases. Five new clusters were identified in 2014 including four clusters with two cases in each and one with three cases.

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Tuberculosis in New Zealand: Annual Report 2014

 

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Tuberculosis in New Zealand: Annual Report 2014

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