Clearing the air

Graphic by Jeremy Gordon.
Graphic by Jeremy Gordon.
A century on from the opening of the Pleasant Valley Sanatorium, some say the threat of Tb still hangs over the country.

A leading researcher believes both the World Health Organisation and the New Zealand Government have got it wrong over the disease, which still kills more than 2 million people each year and has been targeted for elimination by 2050.

Prof Philip Hill believes the WHO's policies are flawed. He also considers New Zealand's policy on testing and treating Tb in immigrants is failing and that policy-makers do not properly understand the biology of Tb. Mark Price reports.

In Otago, you could be forgiven for thinking tuberculosis has been beaten - gone like smallpox.

Just four cases have been confirmed in the past two years and two cases are still awaiting results.

According to the Southern District Health Board, four of the Otago cases involved "overseas residents" and that tallies with a 2003 Ministry of Health statistic that 69% of Tb patients in New Zealand were foreign-born.

Prof Philip Hill, director of the University of Otago's Centre for International Health, has no issue with immigrants, but he does have an issue with the way New Zealand deals with those coming into the country who may be carrying the disease.

He believes policy-makers have got it wrong and a major part of the reason is they simply do not understand the term "biphasic".

In relation to Tb, biphasic means there are two opportunities for someone exposed to Tb to get the disease.

Having been coughed on by someone with Tb, about 5% of people will get the disease in the following year or two.

But another 5% of those coughed on can carry the dormant Tb bacillus for decades before suffering (activating) the symptoms of disease.

Prof Hill says New Zealand's Tb-screening programme for immigrants is not picking up this second group.

"They have an X-ray if they are positive (have been exposed to Tb) and then, if that's clear of disease, they send them into the community in New Zealand."

Eventually, Prof Hill says, a proportion of this group "start coughing up Tb in New Zealand that they got from overseas" - something that could be prevented using medicine at the early stage.

"It's just silly. It's like the biphasic thing is beyond the human ability to policy-make.

"They think of disease: you get exposed, you get disease or not. They don't think of the fact that actually, with Tb it's a biphasic thing, and we need to be thinking about it if we want to control Tb coming into the country.

"We need to be giving prophylactic (preventive) treatment to those who show evidence of infection from when they were overseas."